hybridfree/eevblog-posts huggingface dataset:
HP5315A Opt002 Question - Page 1
Forum section: electronics / repair

author: jhujara
author_rank: Newbie
timestamp: March 23, 2015, 07:40:47 pm
content: Hello all,Very new to the boards here, but ran across some interesting things in a google search which led me to want to post. I recently acquired an HP 5315A universal counter for a rather fair price of $22.50. Cosmetically it is in great condition, the battery from the opt 002 was removed and I noticed it seems to be slightly off frequency. Well, when I say slightly I mean more like 300 hz @ 10 mhz which is kind of a lot. Anyway, I attempted the internal adjustment from the service manual and the best it can be brought down to is around +292hz before it starts to climb again. Is my crystal old and just simply off? I have put in quote requests for a replacement crystal but I don't feel very confident that they would either have one or be reasonable with the price. Is there something else I can do? Another part that would work sufficiently? A perhaps does someone have a lead on the opt 001 board or what not? The counter is in great shape otherwise and I would hate to part with a good deal over a few hundred hertz. Any help that can be offered will be greatly appreciated. Thanks in advance!And I just wanted to add that all the supply voltages are spot on. Also, for the input offset adjustments, the service manual calls out "A4P1", pins 5 and 6 to put the scope...There is no other reference to a "P1" on board "A4" anywhere, so I am not sure what they are telling me.-John

author: Smith
author_rank: Frequent Contributor
timestamp: March 24, 2015, 06:23:03 pm
content: It looks just like the 5316A I have. Their standard oscilators are not that good. Take a look here: athttps://www.eevblog.com/forum/testgear/hp-5316a-teardown-and-frequency-standard/I used a small pcb with an vctcxo, works like a charm. Unfortionately I cant help you with the option 2.

author: jhujara
author_rank: Newbie
timestamp: March 25, 2015, 02:45:09 am
content: Ah, yes. That is the thread that led me here in the first place. I really liked the idea, but I was a little unsure if I could do the same thing and how much it would cost. I will take another look to see if I can figure out what I would need to do. I have not made a pcb since highschool! hah!
Agilent 53230 Freq Counter Ch1 PCB trace fracture repair - Page 1
Forum section: electronics / repair

author: VK5RC
author_rank: Unknown
timestamp: March 24, 2015, 11:01:08 am
content: HiPosted as a bit of documentation if this fault occurs to another Agilent 53230 frequency Counter owner.Channel 1 was becoming 'intermittent' and the fault seemed to be related to position of the BNC connector/cable, with no force applied no signal was registered, when a little pressure toward the machine was applied to the male BNC, the signal was acquired. Multiple cables would demonstrate exactly the same intermittent fault, and none of these cables would demonstrate this issue with other known good equipment.A look at the PCB (with the case off and from below) did not reveal any visible faults and the signal could not be found beyond the centre connector.Reworking the joint (desoldering and resoldering using lead based solder) only served to stop any signal getting through at all!Tracing the signal in CH2 finds the centre signal goes to an unused (thanks Agilent) resistor PCB pad.A quick bypass from the centre pin to the PCB pad (as show in photo below) has it working again.Hope this is a one-off issue.Ch1 on left side of photo below.

author: HighVoltage
author_rank: Super Contributor
timestamp: March 24, 2015, 11:08:38 am
content: I had exactly the same problem on my Agilent counter.After fixing the loose solder connection, I also noticed that one of the reasons for this problem is the slightly larger hole in the front cover, which allows the BNC post to slightly move around and wiggles. So, before I re-assemble the unit, I used a small piece of thin shrink tubing around the BNC post and then there was no longer a play between the post and the cover and it feels really tight. I think this was an oversight during the design.

author: VK5RC
author_rank: Unknown
timestamp: March 24, 2015, 11:17:54 am
content: Thanks for the suggestion, I will look into how loose the BNC socket is. I must admit I 'cheated' and did the soldering with the board in the chassis.Robert

author: HighVoltage
author_rank: Super Contributor
timestamp: March 24, 2015, 11:26:38 am
content: Under normal circumstances, when you take the BNC connector in the front with tow fingers, you can easily move it up and down and you know right way that this will eventually fail.You have to use a very thin wall shrink tubing. The "normal" shrink tubing I had was too thick and did not fit correctly and I did not want to enlarge the holes.

author: awallin
author_rank: Frequent Contributor
timestamp: March 24, 2015, 01:36:43 pm
content: We've had to repair this on two 53230A's already. Always the left input when viewed from inside the case (like in the pictures)http://www.anderswallin.net/2014/11/53230a-counter-input-channel-fix/Anders

author: nfmax
author_rank: Super Contributor
timestamp: March 24, 2015, 02:08:26 pm
content: QuoteTry (plumbers) PTFE thread tape, wrap as many turns as you need

author: VK5RC
author_rank: Unknown
timestamp: March 24, 2015, 08:03:07 pm
content: I might start using Ch 2 a bit more for single channel activity as it seems more robust.
Looking for replacement Fluke 787 display. - Page 1
Forum section: electronics / repair

author: pallee
author_rank: Contributor
timestamp: March 18, 2015, 03:11:58 pm
content: Hi!I have searched throughout this forum and the entire web for replacement display for a Fluke 787 processmeter to no avail. Can anyone of you help me with a supplier/store/website (that can preferably ship to sweden)? Or is my only hope to scavenge for a donor unit?Cheers,Pallee

author: tautech
author_rank: Super Contributor
timestamp: March 18, 2015, 07:30:31 pm
content: I suggest you put a Wanted add in the Buy/Sell Wanted board.

author: retiredcaps
author_rank: Super Contributor
timestamp: March 18, 2015, 08:04:20 pm
content: You might want to contact this seller and ask if he/she can get one for you.http://shop.flukerepairkit.com/searchquick-submit.sc?keywords=787I have no financial affiliation with this seller and have never done business with him/her so do your own homework. They do say they will ship worldwide.Ebay seller a-fluke might have a 787 lcd, but a-fluke doesn't answer non USA ebay member questions or sell outside USA.

author: pallee
author_rank: Contributor
timestamp: March 22, 2015, 12:07:24 am
content: Thanks for the input!I have been in contact with ebay seller a-fluke and his recommendation was to contact fluke directly. Maybe I will do that, maybe not. Otherwhise I think it is a lost cause since it seems that the 787 isn't that common...Cheers,Pallee

author: retiredcaps
author_rank: Super Contributor
timestamp: March 22, 2015, 04:07:08 am
content: Quote from: pallee on March 22, 2015, 12:07:24 amThe 787 was introduced sometime in 1998 if the copyright date on the calibration manual is any indication. The 787 is still for sale and a current model so it is not discontinued. Thus, Fluke should have parts for it.http://media.fluke.com/documents/787_____cmeng0200.pdfIn that same manual, on page 30 and 31, they have a list of user replaceable parts. The lcd is not part of that list.You may have to call Fluke to get it serviced. If it is too expensive to get repaired, you can try selling yours on ebay for parts. Or send me a PM!
HP 4271B Digital LCR Meter - Page 1
Forum section: electronics / repair

author: George_Race
author_rank: Regular Contributor
timestamp: March 22, 2015, 01:44:06 am
content: I have a great looking HP 4271B LCR Meter that is not functioning properly.Does anyone here have any previous history with the operation and troubleshooting of this particular item?I would sure like to get it going. So far I have cleaned all of the circuit board connectors, adjusted the power supply for proper voltages, and looked at all the boards for anything that may have been fried. So far no luck, and I don't have any of the test fixtures for the unit.I think it should work with some patch cord connections, but can't seem to get any readings that make sense.Some help would be appreciated,George

author: Neganur
author_rank: Unknown
timestamp: March 22, 2015, 03:39:31 am
content: there is a yahoo group that might be able to help you, iirc there was quite a bit of talk regarding that meter in the past.https://groups.yahoo.com/groups/hp_agilent_equipment
Need helb for my BEHA lab bench supply - Page 1
Forum section: electronics / repair

author: KoF
author_rank: Contributor
timestamp: March 21, 2015, 11:55:04 am
content: Hi friends,I've got some problems with on of my pretty old style lab bench supply – the “BEHA NG 309”. I really like these kind of supplies and the are build for a very long time... my NG303 is build in 1978, the NG304 in the mid of 90' and the NG309 is I guess from the 1998.The variable Supply are nearly the same thru several decades (never change a winning team) – I only changed some old rusty and scratchy potentiometer to 10 Turn types and changed dry Caps to new one.But my NG309 has some Problems. It has some fix voltages as you can see on the photo. These voltages are also fold back current protected! But the +15V has an ripple of about 200 til 300 mV also the switch from +15V to +12V (and reverse) is bouncing (the LED is flickering while pressing the switch). The -15V to -12V circuit is working very well and it use the same switch, even its LED isn't flickering. The +12V has an low ripple as the manual (http://www.pewa.de/DATENBLATT/DBL_BEHA_NG309_DATENBLATT_DEUTSCH.PDF) says.If you are interested in these (variable) supplies you can find an old Schematic / Service manual here :http://www.pewa.de/DATENBLATT/DBL_BEHA_NG304_MANUAL_DEUTSCH.PDF(sorry, it is in german language – if you need help, please let me know)But I am searching for one of the fix voltage part. Is anybody familiar with it?I also tried multiple times to make contact with the Company BEHA (today also now as BEHA-Amprobe and part of the Fluke division) but they never answered..PS I'm sorry for my miserable english style

author: SeanB
author_rank: Super Contributor
timestamp: March 21, 2015, 12:28:02 pm
content: Ripple on a rail would imply the main filter capacitor on the rail is nearly failed, so a first thing will be to change the capacitor on the +12/15V rail, and see if that fixes it. As well you could have a dry joint on one of the rectifier diodes, or an open circuit diode. It could also be the switch itself, it is not unheard that one section of a multipole switch goes faulty while the rest still works, especially as it could have been operated a few times at full current. I do not know how this unit does the voltage switching, it could be a physical switch of the outputs of separate regulators, or a simple change of feedback resistor for a single regulator.
LiOn Battery balance board repair 4S5P board - Page 1
Forum section: electronics / repair

author: MondoTV
author_rank: Newbie
timestamp: March 18, 2015, 12:04:41 pm
content: Hi newbie here trying to repair a V lock battery that's out of warranty. It went bad on a recent trip to India so don't know if the supply there caused a problem. I've managed to recharge the batteries themselves as individual packs and it is pretty well balanced and its reading 16.8V unloaded from B+ to B-. Unfortunately the connection from B+ to the positive output terminal (which is also the charge terminal) is broken which means the battery will neither charge or power anything.Anyway by checking a good battery i think I've isolated the problem to the cutoff circuit. I've attached a jpeg of the circuit board and labelled 2 P channel mosfets in a piggyback arrangement which appear to be the source of the problem. I think these are designed as per the attached basic diagram. There designed so that once the circuit reaches a trigger voltage (16.8V) the charge switches to a small holding current. I think..Anyway I'm getting 16.8V on the Supply of the top mosfet but I'm also getting that across the gate. On the working battery there is only a small voltage (mV) across the gate and the supply voltage is across the drain of both mosfets.My question is - is it a straight short between the gate and the supply of the top mosfet or could something else be causing this - possibly the IC which I can't identify but which is probably the protection circuit. As it's all SMT I'd prefer to identify the suspect component before pulling it and replacing it.Link to MOSFET PDFhttp://www.aosmd.com/pdfs/datasheet/AOI403.pdfLink to basic circuit diagram explanationhttp://www.ixys.com/Documents/AppNotes/P-Channel_MOFETs.pdf

author: SparkyBruce
author_rank: Contributor
timestamp: March 18, 2015, 04:29:17 pm
content: Hi,Looking from the picture it looks like the fet's gates are not connected together , but both go to the IC.Bruce

author: MondoTV
author_rank: Newbie
timestamp: March 19, 2015, 12:18:00 am
content: Correct - the drains are connected together - which is why I don't know if that supply voltage I'm seeing on the gate of the top mosfet is a short or whether the IC is feeding it 16.8V. Probably because my electronics knowledge is really only at kit level.. beginner/basic in other words. So that basic circuit diagram is incorrect as it is showing the two supply leads connected together? Not the D leads...oh well it was a guess anyway.Any suggestions?

author: Zucca
author_rank: Unknown
timestamp: March 20, 2015, 08:53:22 am
content: MondoTVthank you for reporting the problem in a proper way.If the mosfet getting warm? Normally a short circuit heat the things up..

author: MondoTV
author_rank: Newbie
timestamp: March 21, 2015, 11:13:13 am
content: No - weirdly I tried bypassing the mosfet by jumping the battery + straight to the drain and the mosfet flipped over. The board is now correctly supplying 16.8V to the outputs and will power up a broadcast camera. I'm yet to drain it and try charging the battery. I'll report back if the batt won't charge.
Service Manual for LeCroy 9310M - Video issue - Page 1
Forum section: electronics / repair

author: lincoln
author_rank: Regular Contributor
timestamp: March 05, 2015, 03:17:07 pm
content: Hello, I'm trying to repair a LeCroy 9310M O scope. The video display has no vertical sweep. On the display driver board I found this carnage:http://imgur.com/a/7tdiR#0I think I have identified all the bad parts but I would still like to see a schematic to try to figure out why they blew up. Dose anyone have a service manual? While it specs are pretty paltry by today's standards I would hate to see it junked.Thanks!

author: tautech
author_rank: Super Contributor
timestamp: March 08, 2015, 05:15:53 am
content: Interesting pics.Hard to say what went pop first, maybe the cap?Check a few around to see how far the have drifted from labeled values.Hope somebody comes up with a manual for you.

author: lincoln
author_rank: Regular Contributor
timestamp: March 12, 2015, 08:45:28 pm
content: Got it fixed:It looks like the cap shorted when it blew and short circuited the other components.The video board was used on several of the 93 series. While I was eventual able to track down a specific manual, all of the 93* show the same video board. The board I have was a newer rev then the service manual show. It could be stuffed to fallow the the older design but the service manuals did show the transistor/trimmer that blew up .

author: AHT52
author_rank: Contributor
timestamp: March 21, 2015, 03:31:26 am
content: Always a good place to look for test equipment manuals is:-http://www.ko4bb.com/manuals/

author: miguelvp
author_rank: Super Contributor
timestamp: March 21, 2015, 08:44:48 am
content: Quote from: AHT52 on March 21, 2015, 03:31:26 amAnother good place to look for links for test equipment manuals is:https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/
Help me identify this transistor - Page 1
Forum section: electronics / repair

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: March 20, 2015, 07:27:37 pm
content: Hello,A transistor started smoking due to a short on a car battery boost device and I would like to know what the specs are and where to buy a replacement from.I've attached a picture of the component and there is sign of physical damage due to overheating.Cheers!

author: Cliff Matthews
author_rank: Unknown
timestamp: March 20, 2015, 07:35:06 pm
content: Just my 2-cents, but with the middle pin cut like that, it was probably a diode... I've got several like that.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: March 20, 2015, 07:37:56 pm
content: Quote from: Cliff Matthews on March 20, 2015, 07:35:06 pmI'm am electronics noob so you might be right. There are three of them soldered next to each other on a plate of copper. Maybe some input protection diodes?It reads T460 on the top and BV0T1A below that but I have no clue what it is and if the other two are defective or not.

author: Andy Watson
author_rank: Super Contributor
timestamp: March 20, 2015, 07:59:23 pm
content: Try Alpha & Omega Semiconductor AOT 460. N-Channel Mosfet.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 20, 2015, 08:36:15 pm
content: Quote from: Andy Watson on March 20, 2015, 07:59:23 pmSeems right, but why would you cut off the drain?Because it is connected to the metal of course...
Peltier Effect Wine Cooler Repair - Page 1
Forum section: electronics / repair

author: notsoseamless
author_rank: Newbie
timestamp: March 13, 2015, 02:00:04 pm
content: Hi, anyone got a circuit diagram for a Peltier effect wine cooler?The PCB has Fosham Hanyi Computer PCB8110FF1 but could not google anything useful.Guess I'll start by replacing all the electrolytic caps but it would be nice to have a schematic of the board.Many thanksJohn

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 13, 2015, 02:28:33 pm
content: Quote from: notsoseamless on March 13, 2015, 02:00:04 pmCheck diodes and switching transistors.

author: peterrash
author_rank: Contributor
timestamp: March 14, 2015, 05:19:21 pm
content: I assume you've checked that the Peltier module itself is good? I had one that got too hot and failed (essentially went open-circuit). You can test that quite easily with a power supply and multimeter.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 14, 2015, 09:28:15 pm
content: Quote from: peterrash on March 14, 2015, 05:19:21 pmGood point, those things get dusty too.

author: notsoseamless
author_rank: Newbie
timestamp: March 20, 2015, 02:28:27 pm
content: Many thanks for the replies.Yes good point and I will check the Peltier out when I open the unit again when the switching transistors and capacitors arrive. Also ordered replacement silent Noctua fans.The cooler has two Peltier devices, one above the other and it was the upper board had failed, possibly due to the failure of the cooling fans. Isolated on the bench one of the 13005 transistors gets very hot. Also two of the electrolytic had rather crispy insulation, though they appear OK with the AVO.Will post when I fix the thing.John
Just dumpster dive NAKAMICHI R1 Receiver - Page 1
Forum section: electronics / repair

author: ilanko
author_rank: Contributor
timestamp: March 19, 2015, 01:04:52 am
content: Hi guys,Just got NAKAMICHI R1 Receiver, power amplifier is silent. Any word of advice or schematic / service manual to give it life back ?Thank you

author: Vgkid
author_rank: Super Contributor
timestamp: March 19, 2015, 05:56:57 am
content: 1st rule check the powersupply.if good, check the output transistors/signalnpath.

author: obiwanjacobi
author_rank: Super Contributor
timestamp: March 19, 2015, 12:02:29 pm
content: Check YouTube, it is loaded with receiver repair videos.Most common:- Power supply (caps)- shorted power Transistors or hi wattage (emittor?) resistor- loose solder connections

author: ilanko
author_rank: Contributor
timestamp: March 19, 2015, 01:45:35 pm
content: Thank you guys,The tenner working fine, I mange to sniff signal from it.The poweramp using Sanyo stk4112 II, how do I get voltage values for it ?Thank you for your help

author: David_AVD
author_rank: Super Contributor
timestamp: March 19, 2015, 08:56:39 pm
content: Barring obvious missing power voltages, cracked joints or physical damage, I'd suspect the STK chip.Trace the audio path to the inputs of the chip (with a CRO for example). If it's there but no output the STK is likely dead.If there is a speaker relay, check to see if it's energised. If not, perhaps one or both outputs on the STK have gone DC.

author: ilanko
author_rank: Contributor
timestamp: March 20, 2015, 02:26:37 am
content: Thank you for the good advice, I just eliminate the relay (there's one), the power supply is fine.Triggering noise (finger tip) to the STK input pin amplified, so I assume issue is on the volume (DiGi 16 level) control build around 4558 Ad JRC.I hope to report some progressThank you

author: David_AVD
author_rank: Super Contributor
timestamp: March 20, 2015, 06:46:47 am
content: Sounds like you're on the way to solving it.

author: jancumps
author_rank: Unknown
timestamp: March 20, 2015, 06:53:33 am
content: Are there preamp out and ampin connections on the backside? Maybe the wire bridges between them are missing.
SOUND TECHNOLOGY:  Need to source a few push button switch plastic caps  - Page 1
Forum section: electronics / repair

author: Rosebud41
author_rank: Newbie
timestamp: March 18, 2015, 02:38:37 am
content: Hello,I have a SOUND TECHNOLOGY ST1710A Professional Distortion Measurement System, which I am trying to refurbish. I need two push button switch caps to finish the external renovation. One is missing and another is chipped.As these rectangular capped switches were common on most of their gear, perhaps someone has a junker unit, they could harvest these caps from....I am willing to pay a fair price for a few of these.Thanks.CJ.

author: rdl
author_rank: Super Contributor
timestamp: March 18, 2015, 03:11:33 am
content: See if you can figure out who made the switches. They may still be in production and the manufacturer may have usable replacement caps available. If you could post a photo it would help.

author: German_EE
author_rank: Super Contributor
timestamp: March 18, 2015, 08:18:10 am
content: I went through a similar search to you about six months ago, in my case it was a set of knobs for a graphic equalizer because some of them had dropped off and become lost. The manufacturer of the unit went bust years ago so there was no chance of getting spares.Try and find your local FabLab or Makerspace then 3D print a new set of knobs. My equalizer now looks like new and your distortion measurement system can look the same.
B+K (Dynascan) Model 430 Signal Meter - Page 1
Forum section: electronics / repair

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 17, 2015, 06:39:40 pm
content: More auction junk, YAY!The old battery pack will still hold some charge, enough for it to work a little while. But the needle won't stop twitching everywhere when you try to tune it, along with static noises coming from the speaker. This happens even connected to the calibration output with a short piece of F connector coaxial. I've tried cleaning some of the controls and tightening the internal F connectors. The attenuator switches might be dirty but they are sealed in a shield box that would horrible to get apart (looks like solder and bent metal tabs). Tried spraying cleaner from the top of the switches with no affect. Anything else that could cause this? I've also noted that it can't be operated while charging because it makes the problem worse and causes buzzing and crackling from the speaker. Is this also a problem or is this normal?As always, any (free) manuals or schematics are appreciated.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 17, 2015, 07:01:41 pm
content: If it is tuned by one of these old-fashioned air variable capacitors it could be that the rotating contact needs a good cleaning:

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 17, 2015, 07:13:15 pm
content: Nope, Just a tiny VR on a big clear knob. Along with another tiny pot on some sort of pull switch labeled "Fine Tuning". It has two exposed circuit boards and four shield cans connected together with coaxial cables on F connectors and some pin header connectors.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 17, 2015, 07:19:26 pm
content: Try to clean the pots.
Having trouble crossing old RCA ic chips in a bk precision 820 capacitance msome - Page 1
Forum section: electronics / repair

author: Napalm2002
author_rank: Regular Contributor
timestamp: March 15, 2015, 03:30:25 pm
content: Hello allI am having a ton of trouble trying to cross reference some RCA ic chips in an bk precision 820 capacitance meter. I assume a few are led drivers but they all have the same or similar numbering that I cannot figure out..google is great but I need an experienced persons help here.The numbers are as follows1.RCA 049307-146 qty of 22.RCA 036307-0613.RCA 118307-0724.RCA 145Ca313de5.RCA 145Cd4011bev6.RCA 049307-1347.RCA 145Ca723e-v8.RCA 145Cd4040bevSome one please helpMike

author: SeanB
author_rank: Super Contributor
timestamp: March 15, 2015, 04:24:08 pm
content: 1,2,3 are all house coded, I do not know offhand unless I dig out the RCA databook I have somewhere and look.4 probably is a CA3130E bimos opamp, in either TO100 or DIL8.5 is a CD4011 CMOS IC, common in a 14 pin DIP.6 is another house coded one.7 is a CA723 voltage regulator, which can be either a 10 lead TO100 or a 14 pin DIP package.8 is a CD4040 ripple counter.

author: Napalm2002
author_rank: Regular Contributor
timestamp: March 15, 2015, 08:27:40 pm
content: Thank you SeanB. If u can sometime can you look in your book bec I need to find replacements and get this thing fixed.ThanksMike

author: tautech
author_rank: Super Contributor
timestamp: March 15, 2015, 08:37:08 pm
content: It also would help if you stated the package of those more obscure IC's.
Data Precison 8200 : need Help for Repair - Page 1
Forum section: electronics / repair

author: kado
author_rank: Regular Contributor
timestamp: February 22, 2015, 07:37:50 pm
content: Hello,is some one familiar with the Repair of a Data Precision 8200 Voltage Standad?My device powers up with all digits on the LED-display showing "0" and no turn onanydecade switch will bring an increment or decrement. (no output any time)But the polarity and the range switch bring some reaction: the relays are clicking and the annunciators will be set correct.Also switching to 1 KV (Module is not installed) bringserrorin the display. The 5 V rail seems to be O.K. on the "mode and polarity select switches" board.Maybe there is a problem with the rotary switches which will fail after long lifetime, but all six switches behavein the same manner: no reaction (cw or ccw) on any digits!I would be very glad to get any advice from the forum members.Thanks for any help,Karsten

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: February 22, 2015, 09:58:03 pm
content: The repair manual is herehttp://www.ko4bb.com/manuals/download.php?file=06_Misc_Test_Equipment/DataPrecision_8200_6.5_Digit_Calibrator_Service_Manual.pdfIf you have a GPIB adapter (and the option), you can try controlling it remotely. It is likely the CPU is at least partially working if the display is showing an error code on the 1kv range and the polarity switch is causing some of the relays to change state.I would look at the components common to the switches like Z1,Z2, or Z5. If you can put a scope on them you should be able to determine which one (if any) is defective.

author: Testtech
author_rank: Regular Contributor
timestamp: March 15, 2015, 04:14:46 pm
content: Greetings!I don't know if you got this fixed or not, but I think you have dirty switches. The rotary switches have grease that hardens and prevents contact. They can be removed from the board, disassembled, the grease removed with alcohol. Burnish the contacts lightly and lubricate with De-Oxit and I think it will work.
ISI Navigator thermal imager help needed. - Page 1
Forum section: electronics / repair

author: medmike
author_rank: Newbie
timestamp: March 25, 2015, 01:55:55 pm
content: Acquired ISI Navigator thermal cam in estate sale. Did tear down and looks like someone had a go at it before. Main power board checks out with all voltage test points, but 7 wire connector (16 total pins, so most are unpopulated) from main board to raytheon imager daughter board has 4 of the wires unconnected. Its 16 pin plug, so impossible to do random guess. Cant find schematics on line and called company with no luck (bought out by Avon group). If anyone has same thermal imager, I'd be willing to compensate for a tear-down with a few quick pics of connector.Mike
GPC-3030 (GWInstek & HopeSun versions)  Schematic - Page 1
Forum section: electronics / repair

author: hector.pascal
author_rank: Contributor
timestamp: March 15, 2015, 02:29:00 pm
content: I have both the GW and Hopesun versions of this commonly cloned 2X30V/3A+5V/3A "Triple Power Supply".Anybody have a schematic for either version, or the same series ones covering different voltages or currents. Even a partial hand drawn circuit would help.I already have the GW Operating Manual for the GPC-M series, which is little help in following the multitude of plug-and-socketed wiring harnesses.RegardsDavid

author: nightmechanic
author_rank: Contributor
timestamp: March 15, 2015, 09:33:01 pm
content: Hi David,I am in the process of repairing a Tektronix PS-280, which, as far as I have learned, is a GPC-3020D,I am attaching a link to the PS-280 service manual (from the wonderful KO4BB manuals repository):http://www.ko4bb.com/manuals/download.php?file=Tektronix/Tektronix_-_PS280_Power_Supply/Tek_PS280-283_Service_Manual_Schematics.pdfI hope it helps!Ran

author: hector.pascal
author_rank: Contributor
timestamp: March 16, 2015, 12:34:44 am
content: Hi Ran,Many, many thanks. I have been looking for something like this for over a year!This Tek Service Manual is for the 30V 2A or 1A versions with digital meters, whereas mine is 3A with analog ones - but it certainly looks good enough to help me find my way around all those confusing wire harnesses.I am greatly indebted to you.Very best wishesDavid
PM3384: need some values - Page 1
Forum section: electronics / repair

author: alesto
author_rank: Newbie
timestamp: March 08, 2015, 02:21:44 pm
content: I've recently aquired one of these babies, and it's got some problems. The horizontal timebase (X-axis) is center-crushed to about one-third of it's normal size including menu text. Vertical Y-axis is OK.My first gut feeling tell's me to look for problems on the Mains/HV board with loads of caps. I suspect a few of them could have lost their initial value over time. Has anyone experienced similar problems?It would be helpfull if somebody with a similar piece of equipment (PM3382/84/92/94) could provide me the measured values on the X-Amplifier endstage, in particular the XCAL signal (/X2501/42) used for feedback to the microprocessor.Thx.

author: KJDS
author_rank: Super Contributor
timestamp: March 08, 2015, 02:51:26 pm
content: the service manual is here, but taking forever to download as my internet is having a bad day, so I've given up waiting.http://www.ko4bb.com/manuals/5.66.236.40/PM3384_service_manual.pdfI've got a feeling that they use an arrangement very similar to this, but rotated 90 degrees.https://www.eevblog.com/forum/repair/help-needed-on-hp-54601a-oscilloscope-display-problem/

author: HighVoltage
author_rank: Super Contributor
timestamp: March 09, 2015, 08:41:28 am
content: I have a 2 channel version (PM3380B) open right now.If you point out to me on the PCB, which values you want, I will measure them for you.

author: oldway
author_rank: Super Contributor
timestamp: March 09, 2015, 03:46:53 pm
content: I have a PM3094. (only analog, four channels, 200Mhz)You should first look if the right and left X plate signals are both wrong, of only one of them. (XOUT0 and XOUT1)What about extended tests ?Some failure message ?

author: alesto
author_rank: Newbie
timestamp: March 14, 2015, 06:20:03 pm
content: Problem solved. A small signaldiode in the -58V supply on the endstage was the cause.Thx none the less.

author: HighVoltage
author_rank: Super Contributor
timestamp: March 14, 2015, 06:56:10 pm
content: Congratulations on the repair
fried laptop motherboard? - Page 1
Forum section: electronics / repair

author: eightofive
author_rank: Newbie
timestamp: March 13, 2015, 03:43:18 am
content: Recenly I've replaced the dc jack and burned traces off my laptop by following the advice I've been given. The link to the thread i made on how to replace the jack is bellow. I tried to power on the laptop after but nothing happened. Could my motherboard be fried now from the burned traces making a short or a dead battery? I've got a multimeter to help diagnose the problem.https://www.eevblog.com/forum/repair/damaged-traces-need-help-re-wiring-new-dc-powerjack/msg626735/#msg626735

author: eightofive
author_rank: Newbie
timestamp: March 13, 2015, 04:44:24 am
content: The dc powerjack pins are bridged with wire to where I sanded on the top of the motherboard and not the bottom of the board if that affects anything.

author: Zucca
author_rank: Unknown
timestamp: March 13, 2015, 08:06:31 am
content: Use your multimeter.What is the DC voltage at the cable plug? Once you are sure the power supply is working we can talk about the rest.Check the resistance between + e - at the DC jack at the Laptop Mainboard. Do you have a short circuit?If everything looks good plug the cable into the Laptop and maybe check if the DC voltage is incoming at the mainboard as expected...
Need front panel for Agilent E3634A power supply - Page 1
Forum section: electronics / repair

author: vinicius.jlantunes
author_rank: Regular Contributor
timestamp: March 12, 2015, 01:26:22 pm
content: Folks,I am looking for a replacement front panel for a nice second hand Agilent E3634A power supply I scored the other day. It's part in attached picture that I'm looking for.It got badly broken during transportation... its plastic is very brittle, I believe this unit was exposed to direct sunlight for its entire life.Would anyone have it by chance, or have any hints where I could find it?I was able to glue the bare minimum together and tape it to the metal chassis so it is usable, but having a replacement would be great. I have contacted Keysight already and am waiting for their response, but they already told me that their repair policy for this equipment is to replace the unit (they don't sell just the part I need) so I guess it will not be economical for me to have them doing it, will probably be more expensive than what I paid for the equipment already.I also had a look at ebay for one of these that was listed as "for parts", but the only one I found is in Malaysia and is too expensive for me.p.s.; I live in Brazil.

author: vinicius.jlantunes
author_rank: Regular Contributor
timestamp: March 12, 2015, 02:38:26 pm
content: All,Nevermind - Keysight replied and they have the part in stock here in Brazil and were OK to just send it to me for a reasonable cost so I replace it myself, no hassle.I am positively surprisedThought that me being just a guy with a second hand equipment needing a single part for repair meant that support would be sub-par and costly, but it was the complete opposite, prompt support and reasonable cost.

author: tautech
author_rank: Super Contributor
timestamp: March 12, 2015, 06:48:11 pm
content: Good result.You might have also tried Sphere, there is a link to them in the first post in the Repair board.
Help with Mosfet - Page 1
Forum section: electronics / repair

author: angelothewolf
author_rank: Contributor
timestamp: March 11, 2015, 02:27:25 pm
content: Hi folks, im trying to repair this PSU and i cant get this part. do you think this mosfet is replaceable???CPH6302http://datasheet.eeworld.com.cn/pdf/SANYO/102163_CPH6302.pdf

author: angelothewolf
author_rank: Contributor
timestamp: March 11, 2015, 05:35:04 pm
content: anybody?

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: March 11, 2015, 09:22:56 pm
content: I assume you tried Digikey, Newark and Mouser with parametric search? Nothing fits?

author: Anks
author_rank: Frequent Contributor
timestamp: March 12, 2015, 02:26:24 am
content: Maybe this is close enoughhttp://uk.mouser.com/ProductDetail/Fairchild-Semiconductor/FDC658AP/?qs=QGk6feVlqMIkh2M6zGj4Vw%3D%3D

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: March 12, 2015, 03:05:50 am
content: This one looks like very good match. What would be important in this case?- Vgs Cutoff voltage/Threshold voltage- Turn On Delay time- Breakdown voltage Gate to Source- Drain current-?

author: Rog520
author_rank: Regular Contributor
timestamp: March 12, 2015, 03:24:32 am
content: Ebay has them. Do a search for CPH6302.
ROTAZ 230VAC 100W two coils inductor motor unknown wiring inside - Page 1
Forum section: electronics / repair

author: eneuro
author_rank: Super Contributor
timestamp: March 11, 2015, 08:43:22 pm
content: Hello,I'd like to reuse this 1 phase ROTAZ 230VAC 100W inductor motor, but have no idea how its two coils (oposite each other with inductor rotor between) are wired inside and what could be external simple circuit to drive this quite nice fanMeasured resistance between all possible two of its four (W)hite, (G)ray, (Black), B(L)ue wires combinations and got something like this marked also on its attached photo:Code:Rwg: 17 RRwb: 34 RRwl: 42 RRgb: 17 RRgl: 59 RRbl: 76 RIf you have some suggestions how to wire this thing to get it working again @ nominal 230VAC please let me know, while those bloody 1 phase AC motors are not I used to drive on daily basis, while prefere nice 3 phase AC motors and wouldn't like to do any teardown of this thing to look how it is wired inside since it's in a very good shape.Note: There were no additional capacitor, just 230VAC mains wires and multipositional switch with b(L)ue wire cracked disconnected...It is from unknown source on local market... no idea if it were other components with this motor.Anclegooglesays nothing about ROTAZ fanThis is not anything similar to this what I've got for $2http://www.tradeindia.com/fp983306/Rotaz-ID-Fans-Cement-Mill-Fans.html

author: tautech
author_rank: Super Contributor
timestamp: March 11, 2015, 09:18:37 pm
content: I'd guess it is a 2 speed unit, the highest resistance being slow speed and the next being high speed.Put a low wattage incandesant bulb in series and experiment.

author: eneuro
author_rank: Super Contributor
timestamp: March 11, 2015, 09:33:50 pm
content: Yep, this multiple position switch probably was to select those different speeds.It looks like that possible internal connection could be like on this schematics, while we get resistance values between each two wires as I've already measured with multimeter:No capacitor needed to help run this motor?I've found quite nice intro topdf: Single phase inductor motorsand those two coils inside this thing in one axis (like on the page 8 schematics image in this pdf) with inductor rotor in the middle-physical construction is like maybe shaded-pole inductor motor -probably I saw those shading coils -need tomorow futher investigate with better light source those two coils inside this thing
HP 5212A vintage counter- repair report - Page 1
Forum section: electronics / repair

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 11, 2015, 07:26:23 pm
content: Hello,Some time ago I scored a nice device on Ebay.Unfortunately the instrument was not working, but the power supplies were OK.There was no direct service manual on the internet but after a while I found out that most important modules are almost identical to HP 5245L. So I had most of the the schematics.After short tracking it was obvious that a lot of germanium transistors used in counting flip-flops were dead.It seems that moisture got inside metal cans.Most of dead transistors were 2N404A.The transistors are available to buy via Ebay but the price is quite high (and I needed over 20pcs of it).I thought about PCBs from very old computers that I was playing with when i was six.They were using early Polish transistors ASY37 (S means switching transistor).I found a seller of ASY37S on local auctions. I bought 40pcs for about 15EUR.Although ASY37S has similar ft (about 10...12MHz), the collector breakdown voltage is in the range of 30V to 50V(typ).So there was a need to select them. I measured HFE of each transistor. I also measured collector current while applying 40V and maintaining Vbe=0V. On the picture You can see that there were a lot of rejected parts (on the right).Two last pictures show final tests after the repair. A modern HP on the top of the old HP illustrates the progress of the technology:). According to the catalogue data, the counter measures up to 300kHz (sorry: kilocycles...), but the test shows proper work up to 600kHz with lower input sensitivity.Edit:the instrument was built in 1963.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 11, 2015, 07:28:22 pm
content: More pictures:

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 11, 2015, 07:29:40 pm
content: final test

author: krivx
author_rank: Frequent Contributor
timestamp: March 11, 2015, 07:41:49 pm
content: Quote from: doktor pyta on March 11, 2015, 07:26:23 pmThese are quite popular parts for certain guitar pedals that use germanium transistors for distortion, it's not surprising that the price has gone up.
Damaged traces need help re wiring new dc powerjack. - Page 1
Forum section: electronics / repair

author: eightofive
author_rank: Newbie
timestamp: March 09, 2015, 02:59:06 am
content: I had trouble de soldering the old dc powerjack and got too impatient and damaged the traces in the process. The other side is undamaged and those three traces are the only problem with this motherboard. I've started sanding the board to expose some copper for the new traces to bridge to the pins on the dc jack. Before I go any further I would like to get more feedback on how to do it correctly. Am I going in the right direction and is this going to create any short? I was also watching this youtube vid as an example. Ill post more pics if needed.http://youtu.be/cTnVg6Pmf-U

author: Tim F
author_rank: Regular Contributor
timestamp: March 09, 2015, 03:22:00 am
content: The technique shown in the video seems like a reasonable solution however you have a few more problems to contend with since it's a multi layer board. You won't be able to easily solder the jack to the traces directly under it since there is no longer plating inside the hole for the solder to wick up from the other side. Ditto with any inner layer connections that go to the jack pins. Pray that there is enough via stitching that it still works being only being soldered to the tracks on one side of the board. Being only soldered to one side of the board will make it significantly mechanically weaker also.Charred PCB material is conductive so that would be the primary concern for a short. Usually you can try scraping any charring on the sufaces and drilling the holes slightly larger to remove the charred PCB material, but you run the risk of hittin the inner copper layers and pinching them together, creating a short. Given that the holes are slots instead of circular, i would just clean them with alcohol, scrape any blackened areas between traces and cross fingers.I would use at least 20Gauge wire.Oh and use slow setting epoxy (the stuff that takes 8hours+ to set) instead of hot melt glue. Glue it only after you have confirmed that the repair works so you have a chance of reworking it.

author: eightofive
author_rank: Newbie
timestamp: March 10, 2015, 11:11:56 pm
content: Would like more feed back before I go any further with this project.
Salvage Helipot and Duodial RB clean/lube? - Page 1
Forum section: electronics / repair

author: Trey
author_rank: Contributor
timestamp: March 04, 2015, 08:24:12 pm
content: I was fortunate (foolish?) enough to buy a sizable lot of salvage Beckman Helipot multi-turn potentiometers (mostly Model A 20K L.25 and Model C 20K L.5) and Duodial RB 14-turn counting dials (from "that" online site). I've desoldered the cut leads from a few and they test out OK on my Fluke, but they are kinda grungy. The dials feel like they could use some lubrication (after a deep cleaning).Any advice on how to proceed and what to do, not do?Many thanks![edit: changed "used" to "salvage"]

author: lowimpedance
author_rank: Super Contributor
timestamp: March 04, 2015, 10:51:48 pm
content: If you have a few of the dials try taking one apart.Since I have quite a few I did just that!. So you will need circlip pliers to remove the first clip, then the dial (knob) will come away from the body. Leave the dial brake clip, should not be required to go that far. Tip ; After taking the clip off make sure the dial is facing up when you remove it so the plastic lever and cog are still on there shafts and you will see how they function !.There's not much to it and you should be able to give it a good clean and light lube before re assembling.Not sure I would be trying to take the pots apart though. Careful clean the outside and perhaps some light lubrication of the shaft bearing to see if that improves.They should move nice and free allowing you to 'feel' the wiper on the WW track.Very nice old pots even if they are huge by modern standards!. I have a box load with dials that I just cant throw away.

author: Trey
author_rank: Contributor
timestamp: March 05, 2015, 08:28:45 pm
content: Thanks. I managed to get the first clip off of one dial with improvised tools (and safety glasses!) and was able to clean more deeply. That, and a bit of light lubrication (I had some RemOil at hand) and it is quite smooth now. As I have 57 more to go, I think I best obtain the proper pliers for the rest.For the pots themselves, I'll stay outside. I read elsewhere about people taking them apart, but that seems a bit chancy. They are nice pots (and manly looking), especially after a cleaning.cheers

author: Trey
author_rank: Contributor
timestamp: March 09, 2015, 03:09:42 pm
content: Here are a couple of photos for anyone interested in what these look like.

author: uoficowboy
author_rank: Regular Contributor
timestamp: March 09, 2015, 03:19:53 pm
content: I have had a lot of success with cleaning old Bourns 10 turn pots. They have a metal clip that comes off and then the back pops off quite easily. I then use a little bit of deoxit and a q-tip to scrub away the nastiness, clean that out with IPA, and then add a bit of deoxit gold to lubricate the contacts. Takes 5 minutes and is very effective.I imagine a similar process would work for your pots if you can figure out how to open them non destructively.
Faulty Fujitsu P50XHA58E 50 inch plasma display - Page 1
Forum section: electronics / repair

author: deephaven
author_rank: Frequent Contributor
timestamp: March 09, 2015, 09:39:28 am
content: My Fujitsu 50 inch plasma has suddenly developed a fault. It was worked flawlessly for several years and has never been moved. It now has a thin vertical line of faulty pixels which is about the centre of the screen horizontally and extends from the top of the picture till about halfway down vertically. The line is picture dependent and is not visible at all on a black scene. Please see attached picture.Is this likely to be the plasma panel itself or a driver? What are the possibilities of repairing this?

author: tom66
author_rank: Super Contributor
timestamp: March 09, 2015, 11:56:47 am
content: Unfortunately looks like a defective PDP to me. You could try reseating the connector for that part of the screen - in itself this might not fix the issue, but if it's a bonding failure when the ribbon meets the panel it might help.

author: deephaven
author_rank: Frequent Contributor
timestamp: March 09, 2015, 07:59:02 pm
content: Quote from: tom66 on March 09, 2015, 11:56:47 amThanks. I'll open it up and see if anything is loose.