hybridfree/eevblog-posts huggingface dataset:
anicent tube Oscilloscope Repair - Page 1
Forum section: electronics / repair

author: Supercharged
author_rank: Regular Contributor
timestamp: March 12, 2017, 08:39:36 pm
content: A while ago i bought a Siemens "Oscillar". It worked fine for some time but one time when i turned it on the magic smoke escaped. This wasn't ordinary magic smoke however. It literally smelled like sh*t.So since it wouldn't do anything i suspected a Power supply fault, and sure enough i measured a dead short across one Cap, which took out a Selenium rectifier (see picture 1). It didn't have any blow marks on it, but my knowledge on chemistry was enough to know, that selenium is able to stink horrifically. So i replaced The cap (with 2 caps in series, with balancing resistors) and all of the rectifiers, since i didn't want the horrible smell again if another one failed. Doing this however is easier said than done, since one can't just mount different components on a PCB, just because there isn't a single PCB in there. So i glued the rectifiers to the case, where the old ones were. The caps i culdn't just glue in place, so i 3D printed a hold down plate and secured it with a zip tie (Picture 2 and 3). And voila it works again.I just posted this here, because I thought some people might find this interesting.

author: MickM
author_rank: Regular Contributor
timestamp: March 13, 2017, 10:30:47 pm
content: Hi;watch out - your HV is now much higher.Normally a dropping resistor is added in series to bring it back down.If you don't have schematics look at the electrolytics connected to the diode for working voltage, then subtract a third.Mick M.edit:Also when that was sold the line voltage from the wall was probably 105-110 VACI just measured mine at 123 VAC.Seleniums drop about a volt per fin, silicon 0.7v.Try 100 Ohms at 5W.The electrolytics should also be changed, along with any wax/paper caps.

author: james_s
author_rank: Super Contributor
timestamp: March 14, 2017, 02:13:44 am
content: The worst smell I've ever smelled in my life was from a selenium rectifier burning up. Blech!

author: Supercharged
author_rank: Regular Contributor
timestamp: March 14, 2017, 07:19:46 pm
content: Quote from: MickM on March 13, 2017, 10:30:47 pmI do have the scematics (atached), i actually aded a 100 Ohm Resistor, problem was i thought a quarter watt would do the trick and yes i was wrong, so i took them off. For now it seams fine but i might put some higher wattage resistors back on if i can be bothered. and don't worry about potential damage to caps they are all rated way above even maximum Voltage.PS I'm from swizerland so our Grid runs at 230V and this scope is switched to that.
Schematic Harrison Model 865C Power Supply - Page 1
Forum section: electronics / repair

author: blackdog
author_rank: Frequent Contributor
timestamp: March 12, 2017, 07:23:56 pm
content: Hi,I bought at a flea market power supply, a Harrison type"Model 865C"To do a good checkup i need a schematic and i cant find oneDoes anyone has this schematic for me, I can only find companies that sell a schematic well above the price I paid for this power supply.This is a picture op the power supply.Kind regarts,Blackdog

author: blackdog
author_rank: Frequent Contributor
timestamp: March 14, 2017, 11:37:00 am
content: Hi,Really, more than 50 times is this topic been viewed and no one can help me with a schematic?That makes this old dog sad...Kind regarts,Blackdog

author: RayRay
author_rank: Frequent Contributor
timestamp: March 14, 2017, 12:17:04 pm
content: Well, to be fair, some of the views could be search bots, and not everyone who reads a topic knows how to provide assistance.Now, as for the subject at hand, I was unable to find a (free) schematic/service manual. However, it's often possible to repair things without one.So if you'll specify what the exact issue is (and maybe provide some pics of the internals) I'm sure someone would be able to help you out.

author: blackdog
author_rank: Frequent Contributor
timestamp: March 14, 2017, 01:00:58 pm
content: Hi RayRay,Thanks for your remarks :-)I Know its a old power supply, about 53 years...And the age of course is the reason i can't find a schematic, and its a little obscure unit.Harrison is the brand that designed the schematic that almost all brand use if they design a good benchtop power supply.I payd 15$ for this power supply and a manual with the shipping cost is between 30 and 50$ to send it to the Netherlands, no way that i pay this amound of money, i'am old but not stupid.The power supply is now in working condition afther a good cleanup and on a Dutch Forum i wanted to explane the schematic of this unit, just fore fun.Kind regarts,Bram

author: JoeO
author_rank: Frequent Contributor
timestamp: March 14, 2017, 01:30:11 pm
content: Look here. There is a picture of 90% of the supply.http://www.ebay.com/itm/142214753142

author: blackdog
author_rank: Frequent Contributor
timestamp: March 14, 2017, 02:18:17 pm
content: Hi JoeO,Nice find!Thanks!Bram
Repair Acer AL2223W Monitor - Comes on for a Second then Screen Goes Black - Page 1
Forum section: electronics / repair

author: tpowell1830
author_rank: Frequent Contributor
timestamp: March 13, 2017, 06:57:58 am
content: I have 2 Acer AL2223W Monitors and one of them has stopped working. When the computer boots up I get an Acer logo screen and then the monitor shortly goes black. Also, if I unplug the VGA cable and plug back in, the screen shows my desktop for a second and then goes black. I haven't opened the back yet to see what I can see.I was hoping to get some feedback if anyone has ever seen this before. I just want to get an idea where to start looking.Any ideas are welcome.

author: Cupcakus
author_rank: Contributor
timestamp: March 13, 2017, 07:31:55 am
content: Check the electrolytic caps, that is almost always the culprit. If they are bulging, they're easy to spot. Just replace them all.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: March 14, 2017, 01:52:55 am
content: Shine a torch really close to the screen. Do you see the image ?

author: james_s
author_rank: Super Contributor
timestamp: March 14, 2017, 02:12:02 am
content: Is this LED or CCFL backlit? I've seen the same problem with a TV I fixed that had a bad LED in one of four series strings in the backlight. I've seen it happen with a CCFL that had a bad tube.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: March 14, 2017, 05:08:02 am
content: Thanks to all replies. I did the deed and opened the back and found a bunch of bulging caps on the power supply. I am in the process of replacing them now.I will update when I get them in and tested.

author: james_s
author_rank: Super Contributor
timestamp: March 14, 2017, 06:39:52 am
content: Sounds like you're on the right track, I bet it will work fine once you replace those.I remember when LCDs first came out everyone was moaning that they'd be impossible to repair. Surprise surprise, turns out they have one of the same problems that CRTs had. I've fixed dozens of them by replacing capacitors.

author: Kim_555
author_rank: Contributor
timestamp: March 14, 2017, 07:03:43 am
content: After the power supply is malfunctioning, the processor may be damaged. Perhaps replacing capacitors to nothing lead. Since the condenser when dry - loses its parameters, and the voltage that it must filter - comes to monitor circuit.Regards.

author: james_s
author_rank: Super Contributor
timestamp: March 14, 2017, 03:51:48 pm
content: I've repaired dozens of LCD monitors and TVs by replacing capacitors. Usually when I get them they won't turn on at all though. Only a small number of them were not resolved when the capacitors were replaced.
Hameg HM203-6 Scope -  capacitor identification - Page 1
Forum section: electronics / repair

author: Dave_h
author_rank: Newbie
timestamp: March 09, 2017, 12:29:46 pm
content: Hi guys,Newbie but getting oldie here, hoping you might be able to help.I've been interested in electronics in a small way for just about ever and have enjoyed repairing simple obvious faults but always feared getting down to the real component level understanding and those more invisible faults. Well the time has come to change all that. I'm learning lots about the fundamentals and how this stuff all works now, thanks to this blog and some experimenting, and I decided to buy an old scope to help with that - Hameg HM203-6 (listed as not working) and here is my first problem...The problem with the scope is that there is no trace in the X direction, Y appears to be fine and all controls apart from X-related work ok. I believe I've found the fault down to a shorted capacitor in the X Final Amplifier which has blown a nearby resistor.I now have two issues.1. The values of the blown resistor (R799) and ceramic(?)capacitor(C724) according to the schematic are both different from those fitted to the board - Should I replace like for like and ignore the values on the schematic?2. The markings on the cap suggest it's a 0.1uf (?) but I'm not sure of the exact type or voltage. It's on a -12v line so guessing nothing too special voltage-wise, but the blue colour and shape are like nothing I can find online.I'd really appreciate any help or advice with this so I can get down to some real learning.Some pics of the area/schematic for reference attached.Thanks for reading,Dave

author: EPTech
author_rank: Regular Contributor
timestamp: March 09, 2017, 04:14:37 pm
content: Hi there,Looks like the capacitor has shorted out and fused the resistor. It is a leaded MLCC (Multi Layer Ceramic Capacitor) of 100nF and judging from the size, no more than 100V, 50V is pretty standard and more than enough for your application.I would replace the resistor with the same value as the schematic, looks alright to me. And it looks that the other rail +12, I guess has the same value, better to keep that balanced. So 6R8 sounds right.For good measures I would also check the transistor. If you are not familiar with measuring a transistor, there are plenty of threads explaining that.Happy repairing.

author: Dave_h
author_rank: Newbie
timestamp: March 09, 2017, 04:45:37 pm
content: Thanks for the confirmation Pascal!Yes I'll replace the transistor too while I've got it stripped down.Will let you know if I succeed!Dave

author: Dave_h
author_rank: Newbie
timestamp: March 10, 2017, 11:56:09 pm
content: I now have a working scope! I'm sooooo happy!!Tomorrow I shall be mostly poking around in amplifiers and seeing what really goes on
Agilent 34401A repair "1SK6-0001" - Page 1
Forum section: electronics / repair

author: v1t0r
author_rank: Contributor
timestamp: March 09, 2017, 06:50:04 pm
content: Yesterday I received a 34401a which was listed for parts and repair, quickly opened the meter and to my surprise I noticed that 1SK6-0001 Was missing.So my question is any of these good?The price is reasonable?https://pt.aliexpress.com/item/1SK6-0001/32787378610.html?spm=2114.02010208.3.1.CscL1l&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10068_433_10136_10137_10138_10060_10062_10056_10055_10054_302_10059_10099_10103_10102_10096_10052_10053_10050_10107_10051_10106_10084_10083_10080_10082_10081_10110_10111_10112_10113_10114_10078_10079_10073_10070_10122_10123_10126_10124,searchweb201603_9,afswitch_1,ppcSwitch_4,single_sort_0_default&btsid=7255eb16-fc17-4c49-9fcd-2f9e7c9478e2&algo_expid=fcf2328e-739e-4f10-a361-623386669831-0&algo_pvid=fcf2328e-739e-4f10-a361-623386669831https://pt.aliexpress.com/item/1SK6-0001-PLCC44/32787386021.html?spm=2114.02010208.3.9.CscL1l&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10068_433_10136_10137_10138_10060_10062_10056_10055_10054_302_10059_10099_10103_10102_10096_10052_10053_10050_10107_10051_10106_10084_10083_10080_10082_10081_10110_10111_10112_10113_10114_10078_10079_10073_10070_10122_10123_10126_10124,searchweb201603_9,afswitch_1,ppcSwitch_4,single_sort_0_default&btsid=7255eb16-fc17-4c49-9fcd-2f9e7c9478e2&algo_expid=fcf2328e-739e-4f10-a361-623386669831-1&algo_pvid=fcf2328e-739e-4f10-a361-623386669831

author: HighVoltage
author_rank: Super Contributor
timestamp: March 09, 2017, 08:07:59 pm
content: I have no experience with the parts out of your aliexpress linkBut, I have bought one of these at UT-Source before and was very happy with it and it fixed my Agilent meterhttps://www.utsource.net/ic-datasheet/1SK6_0001-9914.html

author: v1t0r
author_rank: Contributor
timestamp: March 09, 2017, 08:42:07 pm
content: Thanks!How much did you pay?
How it know? Again - Page 1
Forum section: electronics / repair

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: March 09, 2017, 08:08:39 pm
content: I just bought a new multimeter (DT -somthing), just the cheapest. Anyway, I was trying to test the buzzer by injecting some voltage into it and I blew out the LM358 soc dual op amp. I removed it and powered up the meter, and guess what, it seems to work with the chip off the circuit board.Why is this so?

author: Refrigerator
author_rank: Super Contributor
timestamp: March 09, 2017, 08:12:12 pm
content: 5$ says the amp range won't work.
SMD code / part identification - Page 1
Forum section: electronics / repair

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: March 06, 2017, 06:36:03 am
content: Hi, I accidentally shorted an output to a small computer fan and I think Q12 is a goner.Three pin package Q12 reads "UDSW3" with small possibility it reads "UD5W3".I think it maybe aBCR151, but power rating seems kinda low. Anyone have a guess?Thanksedit BCR151 pnp device, layout is npn

author: Tsvetkov
author_rank: Newbie
timestamp: March 07, 2017, 07:19:46 pm
content: Please, look here -http://chip.tomsk.ru/chip/ChipDoc.nsf/vc1!readform&view=smd&cat=U&start=1001&count=500

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: March 07, 2017, 07:42:04 pm
content: Thanks Tsvetkov, I will bookmark site. However device seems not to be listed. I've gone thru several code books now and can't identify. I will use a generic guess part.

author: senso
author_rank: Frequent Contributor
timestamp: March 09, 2017, 01:46:27 am
content: Try to guess any jelly bean N chan mosfet.

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: March 09, 2017, 08:54:41 am
content: Quote from: senso on March 09, 2017, 01:46:27 amThanks for confirmation, already have component and is a mosfet
Wavetek 148A --component ID needed (with photo) - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: March 08, 2017, 08:27:31 pm
content: Dear all,I was browsing a local junk store and I could not resist the temptation to preserve it.The general appearance was very good so I bought it reaaaaaly cheap.First attempt to power on was unsuccessful.Found a copy of the manual for the 148 online and downloaded it.After opening the case, the first culprit was evident -- A blown component, probably a Tantalum capacitor (see picture).Unfortunately the 148A has a different circuit from the 148 and I need to find this part id.Can anyone help me on this issue.Thanks

author: RayRay
author_rank: Frequent Contributor
timestamp: March 08, 2017, 08:28:32 pm
content: Where's the picture?

author: jericho.ar
author_rank: Newbie
timestamp: March 09, 2017, 06:31:02 am
content: Maybe this might lead you in the right direction on some part info since it is hard to see the pic, at least on my iPad mini. It has some details at the end.http://exodus.poly.edu/~kurt/manuals/manuals/Other/WAV%20148A%20Instruction.pdf
Advice - Repair a Z-Wave Controller LCD Display - Page 1
Forum section: electronics / repair

author: xrunner
author_rank: Super Contributor
timestamp: March 08, 2017, 02:20:51 pm
content: Can this LCD be fixed? I believe the cable is not making contact properly. I am not familiar with the way this flex cable is attached. I know about zebra strips but this seems to be glued on - I don't know. Any possibility of fixing it?Thanks.

author: bktemp
author_rank: Super Contributor
timestamp: March 08, 2017, 04:03:04 pm
content: This failure mode is quite common for this type of connection: When moisture gets in, the glue fails.Repairing is possible, but if it is not done correctly, it will not last long:You need to heat up the connection while applying pressure to the connection and let it cool down while holding the pressure.It can be done using a soldering iron set to a low temperature. It is not the correct way, but often works.

author: xrunner
author_rank: Super Contributor
timestamp: March 08, 2017, 04:35:49 pm
content: Quote from: bktemp on March 08, 2017, 04:03:04 pmInteresting. OK, do you happen to know what temp to use? My Hakko can go down to 200 C.

author: Rasz
author_rank: Super Contributor
timestamp: March 09, 2017, 04:14:37 am
content: similar maybe
Rotel RT850L Tuner - Page 1
Forum section: electronics / repair

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: March 05, 2017, 04:27:02 pm
content: I have had this tuner for some time having picked it up for next to nothing with a known problem. The original problem was a rumbling noise that appeared some time after the turner was turned on and got gradually worse until sound disappeared altogether. The rumble was traced to a couple of trimmer capacitors which were removed, cleaned and retuned to the PCB. This cured the rumble, but the tuner would still suddenly stop working - no audio, no signal on the meter. A tap in the vicinity of the antenna tuner seemed to restore the signal. I re-flowed a number of joints in the vicinity and this seemed to cure the problem. However, it was while working on this that the third problem came up.The problem I have now is that the frequency is no longer shown on the digital display. I can change between AM and FM and the radio still tunes, I can receive stations and the tuning band is shown, but I have no idea which frequency I am tuned into.I have established that I have both an FM and AM frequency signal going to the TC9175AP PLL/control chip. The AM frequency signal goes directly from the LA1245 AM receiver chip to pin 39 of the TC9175AP. The FM frequency signal goes first to an FM pre-scaler (TD6104P) and the output of that goes to pin 38 of the TC9175AP. The correct voltage is present on pin 28 of the display driver.Voltages around the TC9175AP seem to be as per circuit diagram but I am uncertain as to how to check that data is being sent from pin 24/25/26/27 to the display driver. I couldn't find a datasheet for the TC9175AP (if anyone has one a copy would be appreciated) but according to the datasheet for the TC6301AP display driver chip, data transfer is accomplished using a serial system via 3 wires - DATA, CK1 and CK2 (and I would imagine a GND). Assuming that it is being sent, is it possible to read this data with anything?

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: March 08, 2017, 08:12:59 pm
content: Finally got around to probing the serial data line between the two ICs with a logic analyzer and got absolutely nothing on it. Changed tuning frequencies, bands etc and still no change, just a flat line. On the oscilloscope I am seeing a steady 40mV sine wave signal at approximately 45-70MHz with some 120mV peaks at around 25kHz. What I am not seeing is any square data signal.I have measured the frequency signal between the IC and the AM section and it is consistent with the tuned frequency plus a 450kHz IF. The tuner is tuned to 106.5FM and I was picking up a frequency signal of 106.3xx at the pre-scaler which became 49.995 after the pre-scaler.I guess that the TC9157A IC has failed in some way and is not outputting data to the driver anymore. Strange that the PLL part is still working as the tuner still receives OK.
LCD Backlight Inverter Board - Inline capacitors? - Page 1
Forum section: electronics / repair

author: bookaboo
author_rank: Frequent Contributor
timestamp: March 08, 2017, 09:44:12 am
content: I've been asked to repair a backlight inverter from an old Sharp LQ104V1LG81 LCD monitor. The units not worth much time but I figured it would be worth a shot replacing the blown cap. Unfortunatley the remaining "good" one is also blown open circuit so I cant get the value for this.I'm no expert on backlight inverters and a general schematic search doesn't show anything for typical values. I've made a crude sketch of the blown part of the circuit. Anyone got any ideas what values I could try?

author: bktemp
author_rank: Super Contributor
timestamp: March 08, 2017, 10:21:08 am
content: Typical values are in 2 digit pF range. 15-50pF. 22pF and 33pF working voltage 2-3kV seems to be most common, but their value depends und CCFL tube voltage, current and actual inverter design.
Guess the part game - SOT23-5? with 81M2M marking - Page 1
Forum section: electronics / repair

author: rx8pilot
author_rank: Super Contributor
timestamp: March 21, 2017, 01:01:38 am
content: In a repair effort I have ID'd every part on the PCB except this one. Pin 4 is connected to a battery fed voltage bus between 10-18v and I am guessing it is a linear regulator with a 5v out. Pin 2 appears to be GND, Pin 3 is N/C, Pin 1 goes to a section of the circuit that I have not yet figured out. Pin 5 appears to feed a 3v3 LDO input.Take a guess.....

author: amyk
author_rank: Super Contributor
timestamp: March 21, 2017, 02:40:54 am
content: MCP1804T-5002I/OTSee attached image if you want more evidence...

author: rx8pilot
author_rank: Super Contributor
timestamp: March 21, 2017, 02:44:04 am
content: Amazing! Thank you - curious how you figured it out. I tried the usual search options but never found it.

author: amyk
author_rank: Super Contributor
timestamp: March 21, 2017, 10:34:52 am
content: Here:http://chip.tomsk.ru/chip/chipdoc.nsf/vc1!readform&view=smd&cat=8&start=501&count=500Look for "81Mxx"
Could someone please help me Identify this part? - Page 1
Forum section: electronics / repair

author: Housedad
author_rank: Frequent Contributor
timestamp: March 07, 2017, 01:22:45 am
content: I have a Acer Laptop that fell off a chair with the power cord plugged in and it messed up the jack. However, I'm at a conundrum as to what part this is. I have spent the last couple of days looking through the net, but to no avail. To be honest, I don't really know where the best places are to look, so it has been a rather ad-hoc search.The laptop is an Acer R5-571T-59DCThe Jack has what looks likepossiblyone SMT leg, and the others go through the board. Thank you. (click for a larger image),,

author: amitchell
author_rank: Regular Contributor
timestamp: March 07, 2017, 01:34:24 am
content: It looks like a mid-mount Barrel jack.https://www.google.ca/search?q=3.5mm+barrel+jack+through+hole&espv=2&biw=1366&bih=750&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjDzcfsn8PSAhVN1GMKHeKXBaAQ_AUIBigB#tbm=isch&q=mid+mount+barrel+jack+&*What is the OD and ID?Can you power and charge via the USB-C port? Does it implement USB-C Power Delivery?

author: Housedad
author_rank: Frequent Contributor
timestamp: March 07, 2017, 02:10:38 am
content: As far as size, the only thing I know is that the plug is 3mm x 1.1 (micro pin) and that it is mid mount.It cannot charge through the usb. The USB 3.0 on it will provide charge and power to devices.

author: amitchell
author_rank: Regular Contributor
timestamp: March 07, 2017, 03:09:22 am
content: You could add shielded to your search term.Likely a custom low profile part though.

author: Housedad
author_rank: Frequent Contributor
timestamp: March 07, 2017, 03:32:57 am
content: Quote from: amitchell on March 07, 2017, 03:09:22 amI hate proprietary stuff. Will keep looking.

author: Housedad
author_rank: Frequent Contributor
timestamp: March 07, 2017, 04:25:33 am
content: Well, I figured out the logo. Singatron. On top of that, I found out that the numbers on the top are YYMMDD. date.

author: Housedad
author_rank: Frequent Contributor
timestamp: March 07, 2017, 05:35:32 am
content: ok, i found something. It looks like the jack for the Acer CHROMEBOOK 11 CB3-111 is very similar. Except for the plastic color, they are identical. It takes the same charging jack as the Acer I have. They aren't cheap at 16 bucks apiece, but I think I'm gonna try it out anyway.http://www.ebay.com/itm/DC-Power-Jack-Socket-Charging-For-Acer-Chromebook-11-CB3-111-C670-CB3-111-C4HT-/282227364139?hash=item41b60fd12b:g:TL0AAOSwHsRYCXPe

author: amyk
author_rank: Super Contributor
timestamp: March 07, 2017, 11:50:01 am
content: Quote from: Housedad on March 07, 2017, 04:25:33 amIt's worth asking them, but from theircatalogit looks like a2DC3079. Maybe you could try asking for a sample...
Dead PROOPS MULTITESTER Model TS-55A - Page 1
Forum section: electronics / repair

author: NottheDan
author_rank: Frequent Contributor
timestamp: March 05, 2017, 01:30:39 pm
content: The movement still works and I guess the problem lies in the bolded part in the schematic, which I'm not quite sure what it actually is.A selenium bridge rectifier?If it is that, can I actually straight replace it with one made from diodes? Or does it need more?

author: SeanB
author_rank: Super Contributor
timestamp: March 05, 2017, 02:33:22 pm
content: It is a few diodes in series. There to provide meter protection from 2 diodes in reverse parallel across the movement, and as well contains another diode to allow use on AC voltage. The 2 diodes in reverse parallel can be 1N4007 diodes, there to protect the 500R meter movement (meter plus trim resistor) from minor overloads, and then a 1N4007 for the AC rectifier.If you are willing to lose the AC voltage ranges just connect the 2 reverse parallel diodes across the meter movement terminals, and then connect the plus of the meter movement to the pot terminal that used to connect to the diode block, and leave the other 2 wires not connected. That will at least allow you to see if there is drift in the voltage divider resistors, and if the resistance range still works somewhat.

author: NottheDan
author_rank: Frequent Contributor
timestamp: March 06, 2017, 07:59:16 pm
content: I assumed selenium rectifier because I've never seen diodes in this form factor or any similar one while it has at least a passing resemblance to the other one.
Agilent 34970A Error Code 740 - Secure State - Page 1
Forum section: electronics / repair

author: BH
author_rank: Contributor
timestamp: March 11, 2017, 06:25:31 pm
content: Hello all,BACKGROUND:Recently I acquired a faulty 34970A from Ebay. The symptom was "Dead unit". Sure enough, I tried to power it on and it was totally dead.After some investigation I found that the internal backup battery was totally flat, and that this was upsetting the supervisor IC inside the unit. I replaced the battery and all good; unit powers on fine.However...At power on, the unit was beeping and recording an error. The error code was 740, which I looked up in the manual and found that it relates to the cal data. The entry in the manual is:740 - Cal data lost: secure stateI started to worry that this would mean a 24C02 replacement and a re-cal of the instrument: more than I bargained for! But I started to wonder what "secure state" actually means and I decided to check the Cal Secure settings on the instrument. The instrument was un-secured, so I secured it with all zeroes for the pass code. After this, no more errors on power up!I put the unit back to the unsecure state but still there are no longer any errors on power up.MY QUESTION:Does anyone know what the "Cal data lost: secure state" error actually means?

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: March 12, 2017, 02:37:39 am
content: I believe it is similar to the 3458A when it loses its NVRAM cal constants. The 3458A will display an error "Secure Required".Basically, you save a new security passcode and the message is gone. It is probably there to warn the user that the calibration lockout no longer exists and someone may be able to tamper with the cal.No worries once a new code is set.

author: HighVoltage
author_rank: Super Contributor
timestamp: March 12, 2017, 01:22:25 pm
content: If the error is gone and stays away, you are good.If the error comes back you need to replace the 24C02 FRAM because it might be corrupted.Also, you should check the calibration of your unit. I had one with a flat battery and it had lost some calibration data.

author: BH
author_rank: Contributor
timestamp: March 12, 2017, 06:48:12 pm
content: Thanks for the replies both.Fortunately, in my case, the error messages have stayed away. But it's a stroke of luck that I went down the path of trying out the security code because I was actually gearing up for an FRAM change; even ordered in replacement ICs.I checked all the measurement options and they seem pretty accurate when compared with my other Test Equipment, so it seems like I have been pretty lucky here!Many thanks.
Replacement Micro SD Memory Card Socket from raspberry - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: March 06, 2017, 02:54:03 pm
content: Hello,Does anyone know the part number of the Micro SD Memory Card Socket Slot for the raspberry or where can I buy the same socket so to replace it? Thanks in advance.

author: Rasz
author_rank: Super Contributor
timestamp: March 06, 2017, 06:16:58 pm
content: why not press it and solder back ?

author: 2X
author_rank: Frequent Contributor
timestamp: March 06, 2017, 07:43:23 pm
content: Because the problem is that on pin is broken internal of the socket.
Elna Lotus (vintage) sewing machine manual - Page 1
Forum section: electronics / repair

author: Shock
author_rank: Super Contributor
timestamp: March 06, 2017, 12:39:08 am
content: https://www.scribd.com/doc/3714035/Elna-Lotus-Instruction-Booklet#Anyone got access to download this manual? Please add it as an attachment or provide an alternative link.

author: amyk
author_rank: Super Contributor
timestamp: March 06, 2017, 12:52:03 am
content: How abouthttps://www.manualslib.com/manual/799196/Elna-Lotus.html

author: Shock
author_rank: Super Contributor
timestamp: March 06, 2017, 01:45:14 am
content: Wrong manual, the one I need is in the link I posted.

author: amyk
author_rank: Super Contributor
timestamp: March 06, 2017, 04:03:58 am
content: http://d1.scribdassets.com/ScribdViewer.swf?document_id=3714035&access_key=key-jpqj2p6p9yqogup6pmcYou can click "Print" and then use your system PDF driver to output a file. It is 14MB, which I cannot attach because it is too big, but you should be able to do the same.
Why buy D2PAK form factor chips? - Page 1
Forum section: electronics / repair

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: March 04, 2017, 08:39:14 pm
content: Can't TO-220 be milled down on the tab to be used instead? The priced differences between the 2 forms can be significant.

author: Monkeh
author_rank: Super Contributor
timestamp: March 04, 2017, 08:43:13 pm
content: ... Because milling and lead-forming a part is substantially more expensive and risks leaving you with damaged parts?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 04, 2017, 09:13:28 pm
content: And it may not be solderable anyway. I once SMT'd an ST part, which I think was nickel plated. Very difficult to tin.Tim

author: Monkeh
author_rank: Super Contributor
timestamp: March 04, 2017, 09:14:23 pm
content: Quote from: T3sl4co1l on March 04, 2017, 09:13:28 pmWeeeelll, if you're milling it you can just assault it with some sandpaper while you're at it!

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: March 04, 2017, 09:33:59 pm
content: It does seem that the manufactures of basic TO22O parts just use a different drain pad size and cut the metal center pin off and call it a D2PAK.

author: David Hess
author_rank: Super Contributor
timestamp: March 05, 2017, 07:16:53 am
content: Quote from: blueskull on March 04, 2017, 09:23:46 pmI have run across the exact same problem that T3sl4co1l describes with some new TO-220 parts although I do not remember if they were from ST; they were a major manufacturer though. The tab looked nickel plated and was very shiny but also practically impossible to solder; I ended up using sandpaper to remove the finish.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 05, 2017, 01:26:42 pm
content: Hmm, could be. Seems thin, yet pretty hard. Could be consistent with a high-P electroless deposit?Could definitely be oxidized too.Bad pic:You can't really tell the color because of the lighting, but in the area where I've scratched through, it looks coppery, and with not much scratching necessary. It did take some pressure to scratch through, otherwise the scraper just skated right across.Exact part,http://www.st.com/content/ccc/resource/technical/document/datasheet/07/2c/12/ed/d3/c2/42/99/CD00218149.pdf/files/CD00218149.pdf/jcr:content/translations/en.CD00218149.pdfbut they don't specify plating (at all, it would seem). A quick search doesn't suggest anyone is doing bare nickel (I saw one hit for IR's packaging: lead-free tin plate, nickel underplate).Rather a lack of information...Suffice it to say: it's up to you. If you have the parts, and they solder well -- or not -- that's that. Don't expect to be able to look it up in the datasheet, before ordering parts, or without looking at the parts in hand.Tim
Inverter stick welder  - Page 1
Forum section: electronics / repair

author: leftek
author_rank: Regular Contributor
timestamp: March 04, 2017, 06:25:05 pm
content: Hello, i have an damage inverter welding machine and would like a opinion for repair it.The machine have normal output voltage when it is in idle status without load.When i connect the outputs (+/-) via a small cable, spark it a little and just cut down the output to 0V and i think that the problem is on IGBT's K30H603 or on driving circuit of them.But the spark is stronger when i adjust the potentiometer.The question is : may the problem is to driving circuit of IGBT's while the potentiometer affect on the spark?

author: strawberry
author_rank: Super Contributor
timestamp: March 04, 2017, 07:10:22 pm
content: What device model, pictures, schematics, topology? Does it have Lift start? Then it is not starting main power.Propably current feedback is not working and main power is cut off by short circuit protection.

author: Armadillo
author_rank: Super Contributor
timestamp: March 04, 2017, 07:43:23 pm
content: Sounds like the potentiometer is the problem, loose or dirty contacts. Maybe you should use a contact cleaner like Deoxit to clean the potentiometer first.

author: leftek
author_rank: Regular Contributor
timestamp: March 05, 2017, 12:32:14 pm
content: Thank you for your reply "strawberry" and "Armadillo". Finally the only problem was the welding cables and torch and its ok now.The mention for "Lift start" from "strawberry" had help me.To help anybody in the future : "It's correct the response of machine to cut down the output voltage when bridge the outputs."This operation avoid the stick to adhere.
Dyna Quik 650 - Tube Tester [SOLVED] - Page 1
Forum section: electronics / repair

author: StEeLz
author_rank: Newbie
timestamp: March 04, 2017, 05:25:32 am
content: Hi EEV Community!I recently acquired a couple of tube testers including this B&K Dyna-Quik 650 but I can't get it to work. I narrowed down the problem to the Full-Wave rectifier tube area.Looking at the following schematic :http://bee.mif.pg.gda.pl/ciasteczkowypotwor/B&K/BK650%20Cal.pdfI do NOT have 205VDC on Pin 10.However, this dotted lineis giving me trouble. What is it? What does it mean???I thought this was a regular link and connected this (no trace of this connection before) and suddenly, I have a voltage on the Pin10, but 450VDC, way too much.Oscilloscope shows barelly 3VAC whithout connection, and a large sine with DC offset when connected.What did I miss?Any suggestion or help would be very welcomedCheers!B.

author: singapol
author_rank: Frequent Contributor
timestamp: March 05, 2017, 02:24:01 am
content: Please note that stated voltages are measured open with switch at position 1 or unless stated otherwise.As for 205 Vdc it's measured at position 2.Are you reading from built-in analog meter or using digital multimeter? Do also note that rectifier diode 83 (gas type) is getting rarer by the day as hifi enthusiasts are also looking for them.You may need to modify to another type of diode (non gas dual diode) if you want to carry on using this BK650.If you trace from pin 10 it goes to center tap of heater of 83? Another place to look is the meter circuit.Do also note position 4/5 are connected to cathode of 83. About connecting links..leave them open for time being as it is used for testing grid/heater shorts? Please see service manual as to what changes are done on your 650 based on serial number.

author: StEeLz
author_rank: Newbie
timestamp: March 05, 2017, 05:37:30 am
content: singapol, Thanks for the smart analysis!Pin #10 does indeed center taps with the 83 bulb.As for the reading, I used variety of devices, but oscilloscope seems to be the most useful for this case.Interesting fact : When I am connecting the link or grounding that 83 tube pin #3, even with a 10MOhm, voltage instantly jumps!Any explanation why the Schematics shows a smaller plate for Pin2 than Pin3 as it seems both sides are identical too (Full wave rectifier diode)?Let me look at the revs as you suggested and I'll post if any interesting!

author: StEeLz
author_rank: Newbie
timestamp: March 05, 2017, 06:32:18 am
content: singapol : You are right, my SN included that 10MOhm resistor as per the note in the repair manual. I do have exactly 205VDC now!Thanks a lot for your help!

author: singapol
author_rank: Frequent Contributor
timestamp: March 05, 2017, 06:55:25 am
content: Great that means the 83 rectifier is working and putting out the high voltage correctly.Also there should be a faint purple glow of 83 tube because of the gas.Normally pin2 which is the plate or anode is drawn shorter than pin 3 cathode.Rectifier output is taken from cathode or pin3.
TTL future life after shock - Page 1
Forum section: electronics / repair

author: Radarmus
author_rank: Newbie
timestamp: March 04, 2017, 11:39:13 pm
content: Hi I have been missing around with a Deckel FP3a CNC there was dead in the controller.We found some TTL there was physical open and when bringing the power supply to life on at testbench the problem was +5 volt was too high. After repaire of that board It seems to do something with the relay (CPU was running) but other board was also bad. A 74xx was exploded and who knows what number it had? The Ram was cracked open in the house, that could be replaced. We was taken the Eprom out for reading and the first show FD FD FD, The other was FF FF FF. We looked at the microscope and could see wire fused under the window. :-(. Now we gave up. But now i'm thinking if the eprom survive, how would the future be for a shocked TTL family, will they die for a while og be ok?

author: singapol
author_rank: Frequent Contributor
timestamp: March 05, 2017, 02:35:21 am
content: I'm sorry to say...might as well sell for parts as this machine is not highly favoured by machinists.See here:http://www.practicalmachinist.com/vb/deckel-maho-aciera-abene-mills/get-deckel-fp3a-out-my-shop-247674/I don't think it's worth your time even to modfify it using modern cnc controls.Best to invest in a proper cnc.
Scientific Atlanta  Reverse Injection Filter (65/88 MHz split) - Page 1
Forum section: electronics / repair

author: IconicPCB
author_rank: Super Contributor
timestamp: March 02, 2017, 10:00:09 pm
content: I am looking for assitance with locating a Scientific Atlanta reverse injection filter model number 548531.Scientific Atlanta are no more, they have been acquired by Cisco.Cisco can supply the filter but only if I am happy to purchase 100 pieces as a special production run.This is ofcourse a bit difficult to swallow.The filter is used to inject signaling tones in the reverse direction ( towards mast head). May be someone knows of an MATV /CATV company whihc might still have some old stocks or may be a circuit diagram and or bill of material so that I may be able to build a filter.The filter consists of a ( i suspect ) power passing stage a reverse injection coupler and a may be diplexer /low p[ass/high pass filter.

author: IconicPCB
author_rank: Super Contributor
timestamp: March 05, 2017, 02:06:57 am
content: Any takers?
Integrated circuit equivalents... - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: March 04, 2017, 04:50:34 pm
content: Good evening everyone! Can you tell me whether the following integrated circuits are compatible and equivalent? : NJM062 (SMD) / TL062 (SMD); NJU4051 (SMD) / CD4051 (SMD); NJU4066 (SMD) / CD4066 (SMD); NJU4053 (SMD) / CD4053 (SMD). Are NJU integrated circuits Japanese made ?? Thank you for your lights

author: grumpydoc
author_rank: Super Contributor
timestamp: March 04, 2017, 05:10:06 pm
content: Quote from: lionelkjh on March 04, 2017, 04:50:34 pmGoogle is your friend, data sheets for all of the ICs you mention are easy to find.However I would assume that they are equivalent.New Japan Radio sounds as though it should be a Japanese company but I have no idea where they make their ICsQuoteDid you mean knowledge or insight here? (lumière in French in the sense of knowledge or understanding?).

author: singapol
author_rank: Frequent Contributor
timestamp: March 04, 2017, 05:24:37 pm
content: Yes they are equivalents but do check the chip package size/dimensions even if they are smd eg. SO,soic orother package size by comparing their respective datasheets.yes the company is japanese...NJR aka New Japan Radio corparation.http://www.njr.com/

author: lionelkjh
author_rank: Frequent Contributor
timestamp: March 04, 2017, 05:51:15 pm
content: OK; Thanks (I am french and use google translation to speak in english in this forum, nothing is perfect!). I have, however, a doubt as to the correspondence between the NJM062 and the TL062; I looked at the datasheet, and the internal mounting of the integrated circuit is totally different, although the pinout is the same. What do you think??

author: wraper
author_rank: Unknown
timestamp: March 04, 2017, 05:57:54 pm
content: Quote from: lionelkjh on March 04, 2017, 05:51:15 pmSimplified circuits in the datasheets of NJM062 and TL062 by ST are the same, did not check others.
Schema Interpretation - Page 1
Forum section: electronics / repair

author: @rt
author_rank: Super Contributor
timestamp: March 04, 2017, 09:48:35 am
content: Hi GuysOne of these chip ceramics is reading 43k across it (in circuit, while the other two read 33M across them.Unfortunately the capacitance measurement function on my meter appears to be broken.The shorter measuring ceramic is in the path of blue in an RGB video path, and blue is actually the problem.Everything in the video has a blue tint, so it appears to be the culprit.For C250_1, C250_3 & C250_5... what is 0.22 a measurement of?Cheers

author: Armadillo
author_rank: Super Contributor
timestamp: March 04, 2017, 10:28:09 am
content: In uF.it should be 220 nF or 0.22 uF. Datasheet shows 470nF can be used or 0.47uF, same.

author: @rt
author_rank: Super Contributor
timestamp: March 04, 2017, 10:31:08 am
content: Thanks, I did find the data sheet example for the ST video DAC,but three randoms took care of the problem (randoms as in I don’t know their value, but they are the same as each other).Who would have thought... a chip ceramic failed close to DC short without physical damage...One fixed $500AU vintage full motion video module for the Commodore Amiga CD32

author: Kleinstein
author_rank: Super Contributor
timestamp: March 04, 2017, 11:26:46 am
content: MLCC failure mode with a dead short is not that unusual.

author: @rt
author_rank: Super Contributor
timestamp: March 04, 2017, 01:18:05 pm
content: Well not quite short, just a lot more than the others.Measuring resistance across it while still on the board also includes any path through the PCB from each side of the capacitor, so 43k is really a minimum.But I take it short enough to be useless for coupling the video.I have given one of these away with the same problem. Sent it to Sweden and everything, and am pretty sure now it’s one of the same caps.

author: SeanB
author_rank: Super Contributor
timestamp: March 04, 2017, 02:36:42 pm
content: When you took them off measure again, the resistance should be up into the megohm region again, showing you the fault is a crack that has been contaminated with adsorbed moisture. Common on ceramic caps, and more common is the crack is enough that it falls into 2 or more pieces on removal. Most likely cause is an auto placer that applied a little too much force to the cap in gripping it, or pushed it down too far on the board.

author: @rt
author_rank: Super Contributor
timestamp: March 04, 2017, 03:26:35 pm
content: All three I removed were in one piece and still looked ok removed.... and I do have the suspect one separated from the other two.Still have them, but too late (early morn) here to look again tonight
UNI-T UT61E dial selector contacts - Page 1
Forum section: electronics / repair

author: andrezibaia
author_rank: Newbie
timestamp: March 03, 2017, 03:53:37 pm
content: Hello all,I have been reading your forum for quite a lot of time now, but I have just registered, because I made a stupi mistake: trying to install an LED backlight in my UNI-T UT61E, I have managed to break one of those tiny copper switch contacts that fit on the selector dial.Since then, of course my DMM has gone berserkDoes anyone know where I can find (or how to make) one of those things?Thanks!André

author: ZomBiE80
author_rank: Contributor
timestamp: March 03, 2017, 04:10:30 pm
content: Why not try to make one from an old tin cover from scrap electronics? I made one for my old Fluke 12B

author: andrezibaia
author_rank: Newbie
timestamp: March 03, 2017, 11:42:23 pm
content: That's actually a pretty good idea!Thanks, ZomBiE80!I will try to find some and test my skills with an x-acto knife and a drill. Will post my results later.Thanks again!André

author: Rasz
author_rank: Super Contributor
timestamp: March 04, 2017, 12:46:13 am
content: those cheap throwaway $2 multimeters have same wiper inside from what I remember when restoring my 70A

author: Fisher77
author_rank: Regular Contributor
timestamp: March 04, 2017, 04:13:56 am
content: Quote from: Rasz on March 04, 2017, 12:46:13 amI have one of those cheap meters torn apart in front of me. If you can give me the demensions of the contact, I will measure one in this meter and tell you if it is the same size.
Tektronix 2230 5. minuts after start screen not show "menu - Page 1
Forum section: electronics / repair

author: petr-p10
author_rank: Newbie
timestamp: March 07, 2017, 07:32:59 am
content: Hello,i'm from Czech Republic. My Tektronix 2230 had problem, 5. minuts after start, my screen not show "menu" and digital information. Work only analog. Thanks for replies.

author: cnqhdszq
author_rank: Regular Contributor
timestamp: March 07, 2017, 11:07:06 am
content: Why don't you take a photo when the scope error happened ?

author: petr-p10
author_rank: Newbie
timestamp: March 07, 2017, 11:19:52 am
content: Osciloskop spojena s generátorem, a asi po páté minut? se zastaví na zobrazení digitálních dat a menu. N?kdy to padá po displeji. Když p?ístroj vypnout a znovu zapnout Potom se již zobrazí na displeji B?hem skok?, ale digitální data.

author: petr-p10
author_rank: Newbie
timestamp: March 07, 2017, 11:30:39 am
content: Oscilloscope connected to the generator, and after about the fifth minute stops to display digital data and menu. Sometimes it falls across the display. When you turn the unit off and on again Then, the display During jumps, but the digital data no longer appears.