hybridfree/eevblog-posts huggingface dataset:
Data I/O Unisite PSU Issue (It don't work) - Page 1
Forum section: electronics / repair

author: martinator
author_rank: Contributor
timestamp: May 17, 2017, 07:10:47 pm
content: Hi,I've got a Data I/O Unisite that has a power supply problem.It will try to kick out some voltage for about 2 seconds and will then shut down.The initial power-on whine sounds normal like it's trying to get going (no screeching or anything before it shuts down)There's no visible damage or strange smells.There's no discernible shorts between the supply outputs and the circuit boards in the Unisite itself don't seem to have any shorts or visible damage.I'm slowly trying to isolate parts in the supply from each other so I can test them. I haven't yet found any dead shorts with the transistors/diodes.My guess is shorted transformer windings or maybe a hybrid board problem but maybe someone else knows more or maybe even has a schematic or knows what I should check first?Could the MOV's cause a problem without exploding like they usually do when bad?I had planned on replacing the electrolytic capacitors and the metallised paper caps as they crack with age anyway but I found no faulty ones amongst the old.There's more photos herehttp://s1200.photobucket.com/user/apprenticemart2/library/Unisite

author: helius
author_rank: Super Contributor
timestamp: May 17, 2017, 07:13:13 pm
content: Is CR20 supposed to be missing?

author: martinator
author_rank: Contributor
timestamp: May 17, 2017, 07:43:57 pm
content: Yes. I've started to remove/lift one end of some parts so I can measure things/test them.The 2 and 3 legged devices on the periphery areCR17 - PHS2402CR20 - MBB2045CTCR21, CR22 - BYW29CR36 - MCB69-3Q11 -IRF533CR24, CR25 - BYV73Q1 - BUP22CQ2 - TIP50

author: helius
author_rank: Super Contributor
timestamp: May 17, 2017, 07:58:37 pm
content: There's a Data I/O yahoo (ugh) group:https://beta.groups.yahoo.com/neo/groups/Data_IO_EPROM/You might be able to search for PSU issues there. I think the Unisite shares its design with the 2900/3900/3980, so it may have the same PSU.

author: martinator
author_rank: Contributor
timestamp: May 17, 2017, 08:04:19 pm
content: Yep, already joined the group and asked there.I will check the documentation for the 2900/3900/3980.Thanks.
Opinion on LCD TV Panel damage - Page 1
Forum section: electronics / repair

author: Jfcarrer
author_rank: Newbie
timestamp: May 17, 2017, 01:08:39 am
content: Today i noticed that my parent's tv has this "stain" on the screen. It wasn't there yesterday and both denied having hit the screen with something.Is this really impact damage or is there another possible cause?The tv is an old 2007 Samsung 46'' IPS LCD.

author: mzacharias
author_rank: Frequent Contributor
timestamp: May 17, 2017, 01:24:41 am
content: Certainly looks unusual for impact damage but can't rule it out. In any case the set is toast. Time for a new one. Samsung is still good.

author: james_s
author_rank: Super Contributor
timestamp: May 17, 2017, 05:21:07 am
content: Looks to me like moisture damage or the panel is delaminating, likely due to a manufacturing defect. I agree that replacement is probably the only option.

author: BMack
author_rank: Regular Contributor
timestamp: May 17, 2017, 02:47:14 pm
content: That's not an impact, that is either pressure or moisture. Panel replacement is only option, not worth it even if the part is available. Buy a non-working set of the same model and product code and use the parts in this set to fix it or buy a new TV and chuck this one.
Kentucky fried my laptop's charger circuit - Page 1
Forum section: electronics / repair

author: CrashBandigood
author_rank: Newbie
timestamp: May 17, 2017, 02:56:03 am
content: hey EEVBlog,so last year I got myslf a nice acer laptop for like 300 bucks which has served me well. however, eventually the charger cable became dodgy and I had to fix the connector myself (especially because the model wasnt sold anymore) this work fine for like a month or 2 but I had to resolder the connector every 2 weeks or so so I got myself the amazing chinees all in one laptop charger solution. which also worked, however, it had multiple voltage settings which was controlled by a pretty crappy switch and one day I noticed that I accidentally left it on 24V instead of 19, i hastily switched it back to 19, forgetting that the laptop was still plugged in.the magic smoke escaped from the whole charger circuit which renders that whole area useless. the charge port is basically a dead short now, but the laptop functioned exactly as before, it only was unable to charge. my idea to get the thing to work was to try and more or less trick the computer into thinking that the battery is full and would then actually just cut the +- of the battery connector and connect it voltage source that should provide the 11.5V as the battery indicates. one question is, will this fry this laptop even more? still a first years electrical engineering student and I almost should kinda work but I still have doubt. do you guys have any idea on how to get it to work.In short, I cant charge the battery over the conventional connector, do you guys maybe know of some alternative way to still get it to work.

author: Monkeh
author_rank: Super Contributor
timestamp: May 17, 2017, 02:59:27 am
content: It's dead, Jim. Either repair the charging circuit (good luck!), or replace the laptop.

author: james_s
author_rank: Super Contributor
timestamp: May 17, 2017, 03:11:32 am
content: You might get lucky and be able to replace a diode or converter IC and fix it, but it may not be trivial to identify the bad part(s). You might also find a spare motherboard or an identical laptop with a broken screen or other fault on ebay. You'll have to decide whether the laptop is worth investing the time, effort and money into.
Repair of Tenma 72-3060 Oscilloscope - Page 1
Forum section: electronics / repair

author: Jubullu
author_rank: Newbie
timestamp: May 16, 2017, 07:20:06 pm
content: I recently bought this scope for $15 to tinker with trying to fix it as a first attempt at electronics repair. I was able to find a service manual for it here:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Goldstar/OS-9020P.pdfunder an LG rebadge.The scope powers on and the CRT display lights up and the horizontal control seems to work fine as the x direction moves as it should and the t/div knob slows down the trace just fine but the vertical control seems to do nothing at all and no signal shows up when I introduce a signal. So this is where I started. The scope has a channel one output on the rear so I connected the calibration signal of my working scope to the Channel 1 input and connected the output to the Channel 1 input of my working scope and the signal came through fine, if slightly out of calibration. Also when changing the V/div on the problem scope the signal responded accordingly on the working scope. So I am assuming that the signal is getting lost somewhere between the input, which seems to be working fine for now, and the CRT display.So my question is where the most likely fault would be and what I should be looking at first. Would this likely be in the CRT control or in the vertical mainamp or some other part of the circuit that I'm not aware of? Unfortunately, I just don't know enough about how CRT scopes work to know what would cause the signal to not make it to the CRT. My gut says it's probably the vertical mainamp but I wanted to appeal to someone with more experience in CRT scoopes.Thanks for the help.

author: P90
author_rank: Frequent Contributor
timestamp: May 16, 2017, 07:35:17 pm
content: is the input coupling switch selection set to ground?

author: Jubullu
author_rank: Newbie
timestamp: May 16, 2017, 07:46:16 pm
content: Yes changing from AC to DC to Ground had no effect

author: oldway
author_rank: Super Contributor
timestamp: May 16, 2017, 08:05:06 pm
content: Wellcome on the forum.Security advise :the CRT of an analog oscilloscope works with high voltages , this can be lethal, you try to repair it at your own risk.If you are aware that you have not enough knowledge and experience for working with high voltage, ask for help to somebody who knows.The first thing to do is always a visual inspection: look for burned or broken components, bad solders, bulged or with leakage capacitors, loose connectors or wires, cracked boards,After this, check all the power supplies .
Philips CDI 450 repair - Page 1
Forum section: electronics / repair

author: Anks
author_rank: Frequent Contributor
timestamp: April 12, 2017, 11:11:36 am
content: Hi I'm trying to repair my old CDI450 that was showing a black screen on the TV.I got the service manual and followed the tests for checking clocks and such and everything is correct and present. At this point I made a null modem cable to preform the LLT(low level tests) but had a really hard time trying to get into the console by pressing space.The console was outputting "syser" that i assume means system error. I was using termite and found that if i continuously press enter and space while turning the CDI I could get to the LLT. At this point all test pass fine apart from number 4 the DRAM test. this would get stuck testing DRAM0.At this point I pulled the two dram chips off and soldered one back on its opposite footprint. Now the CDI would still not boot but on the console in termite I could see a message "unable to assign name table" then "system reset".Now I retried the LLT and the DRAM0 was passing the test but of course DRAM1 was showing data lines that had issues (The LLT is actually very good).So just to rule out any other issues I placed the other ram in the other ram position to check that I was on the right track and not just fixed a few cold solder joints. Sure enough the chip now at DRAM1 was showing the issues it did in the DRAM0 position.Now I'm pretty confident that the drivers on the chip controlling the dram are Ok and replacing the ram would be a worth while thing to do. So now onto the next issue.The chip used for the memory is a HM541270ATT-8 in a 44pin tsopII package I believe. This is the the package that s only 40 pins broke out with a gap in the middle. The TMS45165DGE is the equivalent part but both these as far as my google powers go are unobtainable.There are some very close chips with 262,144 word x 16bit drams out there but these do not use the LWE (lower write enable) UWE. Instead the seem to use the more common LCAS(strobe) HCAS and hence had slightly different pin out.I can find HM541270 on ebay in a 40pin SOJ package but obviously this wont fit on the board and I'm tempted to try and bodge one and hope for the best but wanted to know if anyone had a better idea before I go down this route.If anyone come across this post in future and would like and help with this system just send me a PM and ill try my best to help.Thanks KrisI tried to attach the service manual but its too big I will try and split it into two parts or something if anyone is interested.

author: Anks
author_rank: Frequent Contributor
timestamp: May 16, 2017, 05:40:40 pm
content: Just to let anyone that maybe interested I managed to dead bug the soj40 part onto the pads of the tsopII pads and after clearing 1 short between data lines 14 and 15 the I found via the LLT terminal all is working correctly.It looks a bit "how you doing" but its all very solid and was the best I could do with no magnification and what was lying around the lab.And here it is working
Fluke 8200a repair help / schematic need - Page 1
Forum section: electronics / repair

author: lamygalle
author_rank: Newbie
timestamp: March 13, 2016, 08:14:51 pm
content: Hello,I've just bought a 8200a multimeter, this multimeter has nixies !!!But, if you read successfully the title of this topic, it's not functionning, no light nothing coming from the tubes nor the display...So here is the question : is there someone here that has this multimeter ?Second question for the same price (extra bonus): do you have any schematic of this element (I've searched on the net and not found the desired document) ?Thanks a lot !!!

author: Paul Moir
author_rank: Frequent Contributor
timestamp: March 14, 2016, 02:21:47 am
content: In the mean time, perhaps you could post a picture or two of the circuit board? If the 8200A is like the 81xx we can start running through the power supply, which is likely at fault if the 8200 is anything like the 81xx.

author: lamygalle
author_rank: Newbie
timestamp: March 14, 2016, 07:52:43 am
content: Good idea !I've searched and looked in other Fluke manuals without finding anything that's looks like the 8200a...Here are the pictures :I've only placed the supply board picture (lets check it first)

author: Paul Moir
author_rank: Frequent Contributor
timestamp: March 15, 2016, 07:31:59 am
content: Oh, that is completely unlike the 81xx ones. I'm afraid I won't be much help.

author: lamygalle
author_rank: Newbie
timestamp: March 20, 2016, 10:57:27 pm
content: I've got a +15V test point in the supply board that provides only +1.7V.So the problem may come from the +15V supply (at least) on closer to the main and the transformer.Let's dig deeper (in a new episode)....

author: Rafael
author_rank: Regular Contributor
timestamp: May 15, 2017, 10:52:02 pm
content: Hello, did you get any scheme?I have the same equipment, but it does not make any measurement, it does not come out of the zeros...
Interstate High Voltage Log-lin Sweep Generator - F47. Schematics needed. - Page 1
Forum section: electronics / repair

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: May 18, 2017, 07:04:17 am
content: Dear All,I just got a Interstate High Voltage Log-lin Sweep Generator - F47, which may be know also from Racal-Dana.It is not in working condition,so before starting to search for the fault, I would be very grateful if someone has a schematics or service manual of this device or anything close.I have searched on the web with no success.ThanksJacquesPS: the photo is an illustration, and not a picture of my unit.
Cleaning up after bad tantalum - Page 1
Forum section: electronics / repair

author: Gip-Gip
author_rank: Contributor
timestamp: May 14, 2017, 03:36:05 pm
content: A tantalum went bad in a HV supply and seems to have left some corrosion. Would anyone know what that could be?I've tested everything else and it all seems good

author: David Hess
author_rank: Super Contributor
timestamp: May 14, 2017, 09:12:06 pm
content: What kind of tantalum? We tantalums use sulfuric acid which is an obvious problem that needs to be neutralized. Solid tantalums just leave a dry inert residue which can be cleaned with anything which will remove it.
SOAR 3430 + MONACOR DMT-6500 - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: April 17, 2017, 09:53:08 am
content: Hello everyone! I am looking for the documentation and diagrams of the multimeters SOAR 3430 and MONACOR DMT-6500 (see photos). Can anyone help me? Thank you very much

author: lionelkjh
author_rank: Frequent Contributor
timestamp: April 17, 2017, 09:54:22 am
content: the following....

author: retiredcaps
author_rank: Super Contributor
timestamp: April 17, 2017, 05:48:00 pm
content: Since you posted this in the repair section, what is wrong with the two meters? Maybe we can make suggestions even without schematics and/or documentation?

author: lionelkjh
author_rank: Frequent Contributor
timestamp: April 18, 2017, 03:03:01 pm
content: Hello; What I'm looking for is the diagrams of the 2 multimeters, because some components are erased and burned, so iliisible ..... Only the shema can help me .....

author: retiredcaps
author_rank: Super Contributor
timestamp: April 18, 2017, 08:09:01 pm
content: I know it is a long shot, but post clear focused pictures of the pcb (both sides)? Some of Soar's multimeters were made by Yokogawa. If we can see the insides, maybe we can see if there is a picture of a Yokogawa meter that might help identify the components?

author: lionelkjh
author_rank: Frequent Contributor
timestamp: May 14, 2017, 08:42:12 am
content: Hello; Can not help me ??

author: retiredcaps
author_rank: Super Contributor
timestamp: May 14, 2017, 04:49:34 pm
content: Pictures of the insides as requested?
Dirty dial switches on a Metra Blansko L110 decade box - Page 1
Forum section: electronics / repair

author: onesixright
author_rank: Frequent Contributor
timestamp: May 13, 2017, 05:51:44 pm
content: Hey Guys,I got a old L110 decade resistor box (Czech made, Metra Blansko). I looks good, but unfortunately the rotary dials are, i think, pretty dirty. I opened the box, but each decade is soldered against the other. Anyone has a amazing trick how to clean the each switch (easily)?daqqdid a peak inside the box,https://www.eevblog.com/forum/metrology/metra-blansko-resistance-decade-peek-inside-)/I measured the output (4 wire), its often wrong. If you just wiggle the dial a bit it gets better, but great its not.I could only think of desoldering each decade (and hope I can access the switch), it seems just one solder joint. But im not sure if its wise to do.See the pictures, Thanks!

author: SeanB
author_rank: Super Contributor
timestamp: May 14, 2017, 12:50:08 pm
content: how about some contact cleaner down the front opening where the thumbwheels is, on the side where the board is, followed by a shot in the rear side with the front down, and then run each switch a few times through a few revolutions while wet. That should clean them up a lot and get better contact repeatability.

author: onesixright
author_rank: Frequent Contributor
timestamp: May 14, 2017, 12:56:51 pm
content: Thanks!Well my problem with that approach was, shouldn't you dry/clean the contact fluid? Or can you just let it vaporise?If the latter its worth a try...

author: SeanB
author_rank: Super Contributor
timestamp: May 14, 2017, 01:12:26 pm
content: It will evaporate off naturally, no need to dry it, just use enough so the dirt is washed out of the contact area.

author: Smith
author_rank: Frequent Contributor
timestamp: May 14, 2017, 04:09:53 pm
content: Normally I would use IPA. But because of the printed dials I would be careful with IPA because it can harm the paint on the dials. IF you can disassemble the encoders (some can easily be disassembled, some do not.) you could just clean the contacts with some simple erasers.If you are using a strong contact cleaner it might be a good idea to wash it off with some distilled water and let it dry thoroughly. Contact cleaner can really hurt contacts in the long run.
DANA 5100 Digital Multimeter - Page 1
Forum section: electronics / repair

author: danadak
author_rank: Super Contributor
timestamp: May 13, 2017, 12:27:04 pm
content: Looking for a pdf of the manual, schematics, etc..They are available for sale, just trying to avoid the cost.Regards, Dana.

author: danadak
author_rank: Super Contributor
timestamp: May 14, 2017, 08:22:03 am
content: Finally found it.Case closed.Regards, Dana.
Trimmer Pot Autopsy and Repair - Page 1
Forum section: electronics / repair

author: Cyberdragon
author_rank: Super Contributor
timestamp: May 18, 2017, 10:22:30 pm
content: I found out why these upright trimmers fail. It appears to be that the plastic knob is rubbing off some sort of conductive coating causing a high resistance or break where the knob touches the track. (shown by the two light colored bands on the track). You can repair them by applying a very thin solder bridge across the break, as long as it doesn't get in the way of the knob.
SOLVED: Keithely 225 Manual missing page 13 and 14. - Page 1
Forum section: electronics / repair

author: halexa
author_rank: Regular Contributor
timestamp: May 12, 2017, 05:35:47 pm
content: Hi,My keithely 225 broke on me it always goes to constant voltage mode. I start looking in the scanned manual that is on the internet and notice that pages 13 and 14 is missing from the scans. Does any one have a manual with these pages. These pages describes the test point location and trouble shooting information.Thx.

author: halexa
author_rank: Regular Contributor
timestamp: May 12, 2017, 07:50:21 pm
content: I'm blind....The two pages I was looking for was in the end of the document.
Replacement display for Tektronix PSU PWS2326 - can you help? - Page 1
Forum section: electronics / repair

author: Mrnt
author_rank: Contributor
timestamp: May 12, 2017, 05:38:27 am
content: I obtained a PWS2326 which unfortunately has a broken VFD and as far as I can tell from Google (and after contacting Tek) replacement VFD's are not available. I have a spare front panel for a Tektronix 4000 series PSU and although the pinout for the connector between the front panel and the main board seems to be the same as the 2326 it does not display anything when plugged into the PWS2326.The front panel contains a processor which interfaces the keypad and VFD to the main board via 4 logic signals, but when I probed them I couldn't make much sense of how the front panel and main board are communicating. In the event that a replacement VFD is not available I was thinking of removing the VFD and replacing it perhaps with an OLED driven by a microcontroller which passively observes the interaction between the existing processor and main board, displaying whatever is appropriate on the new display.So two questions:1) does anyone know of a source for VFD's for this unit - the original appears to be made by BOE model VFD30-1202?2) has anyone reverse engineering the communication between the front panel and the main board or could give me some pointers as to where to start?
Mettler Toledo Safeline MD old industrial metal detector - JED firmware dump  - Page 1
Forum section: electronics / repair

author: florin1up
author_rank: Newbie
timestamp: May 11, 2017, 10:26:31 pm
content: Hello everyone. I have a big problem with an old Safeline Mettler Toledo Metal detector model MD assembled by sassib Packaging Italy. (picture)The fault is on the CPU board (see picture). I know that because I had 2 units: one good and one faulty. I swiched the boards between them and after I saw that the CPU board is faulty, I switched the CPUs between the boards (HD63b09). That looks like was a really bad ideea because now, both cpu boards have the same problem - no text on lcd, no detection, nothing but some leds on).Looks like, somehow the programmable logic array (U9 = PALCE16v8h - with the white label "DEC 3" ) has been corrupted. I came to this conclusion after I bought and tested all the IC's from that board. The eeprom is ok (I have read it before switching the procesors). Maybe with some luck someone have a good or faulty board? or I need the JED or BIN dump file from the U9 chip.I am in trouble because the working PCB died in my hands. This board has more than 20 years old and I guess when I heated up the pins (max 200 degrees C) in order to change the CPU, the heat "helped" the PAL logic array to "forgot" his program (in datasheet, the Pattern Data Retention Time is @10 years).I made the schematic and the chip enable pin of the RAM and EEPROM are connected to this logic array.Other info:- I programmed the PALCE chip with some random data and sometimes the watch dog led blinks.- I have many years of experience in soldering and good tools, so the circuits have not been damaged (also I tested 98% of circuits)- I have the option to unlock the security bit of PALCE16v8 chip, I attached the dump file(changed to .txt) Unfortunately I read the chip after problem occured.- The PALCE from the other board, after I unlocked it, gives me a different code at every reading so I guess this is faulty too.Any sugestions?Thank you !
Improving the probes on my little Extech meter - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: May 10, 2017, 06:29:58 pm
content: Hi all-I have one of these little Extech DM110 metershttp://www.extech.com/display/?id=14419...It seems like a decent example of the type (tiny and convenient but nothing special) with one exception: the plating on the probe tips makes getting a good connection very hard. This problem makes the meter nearly unusable.I'd love to replace the probes with something better but it will have to fit into the zipper pouch the meter is stored in. That means the probes can't be any longer than about 4.5 inches (11.5cm) from the metal tip to the back of the strain relief. I'm not having much luck finding specs for 'overall probe length' on Probemaster, etc.Open to suggestions here; got any thoughts? Thanks.

author: DimitriP
author_rank: Super Contributor
timestamp: May 10, 2017, 06:54:53 pm
content: I'd probably first file/grind/polish the existing probe tips.If there is no improvement, get the probemaster probes and a bigger pouch

author: BMack
author_rank: Regular Contributor
timestamp: May 11, 2017, 04:23:58 am
content: I'd try filing the coating off, I don't see why you'd want to throw money at that DMM. It's a less than $30 DMM, why would you want to buy decent leads that are $20+ for it? Just my opinion.

author: Shock
author_rank: Super Contributor
timestamp: May 11, 2017, 07:03:59 am
content: Don't grind or file, first just buff surface of the probes tips on a clean cloth rag. Grab tips between tightly the cloth your thumb and forefinger and draw it out many times over and over and rotate between drags. It's like a very fine abrasive polish if you do it correctly.

author: daybyter
author_rank: Frequent Contributor
timestamp: May 11, 2017, 09:16:17 am
content: I use a 1000 or 1500 sanding paper and then clean with alcohol. Worked on my cheaper tips, like the 830 dmm ones.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: May 11, 2017, 06:38:47 pm
content: Slip on some of the Fluke fine point adapters, you can always take them off and they are pretty good with piercing and providing contact to the board.
Fluke I2000 FLEX part lists or schematic ? - Page 1
Forum section: electronics / repair

author: Falkra
author_rank: Regular Contributor
timestamp: April 29, 2017, 01:54:47 pm
content: Hello,I am trying to fix a non-working Flue i2000 Flex.The power led blinks and never stays on and it doesn't read anything.I opened it and checked battery leads everything is ok.I am suspecting three tiny capacitors, but they are surface mounted and I don't know what should be the correct readings.Has anybody got a schematic or part list ?I am suspecting C6, C16 and C7.

author: Falkra
author_rank: Regular Contributor
timestamp: May 10, 2017, 10:31:25 am
content: Anyone ?

author: ace1903
author_rank: Regular Contributor
timestamp: May 10, 2017, 01:10:38 pm
content: Nice design, not very complicated. What are the ICs on the board?It should be possible to find the defect using only info from datasheets.While waiting for schematic or service manual you can share info about ICs and get feedback from the readers here.
Danica TPS20 - Page 1
Forum section: electronics / repair

author: Heiko1052
author_rank: Newbie
timestamp: May 09, 2017, 02:57:22 pm
content: Hello, on my Danica TPS20 (with analog Voltage/Amp display) the 5 Volt dc is working ok. The adjustable 0-10 Voltage and 0-30 Voltage both gives an pernament output of - 0,53 volts. Does someone has any idee what this could be. I don't have an maintenance cirquit drawing). The transformer (ac) power is ok. Thanks, regards, Henk
Wavetek 159 Function generator - Page 1
Forum section: electronics / repair

author: Pentagonyst
author_rank: Newbie
timestamp: May 09, 2017, 01:37:32 pm
content: Helo everybody!I recently bought a Wavetek 159 with some problems. I'm new to TTL so I want to ask for some help.My problem, is that the instrument not responding for the keyboard properly. Firstly I thought maybe there is a dirt problem, or a problem with the keyboard multiplexer. What is happening when I press something, is that a nother function is responding, like somebody changed the keys. (They're in place, of course). For example when I press amplitude, the offset can be changed. Sometimes 1 turns on 6 turns off the display. There is not even a button for it. And what is the most interesting for me, is that for every even number 8 shows up, and for every odd number 9 shows up on the display. Only the minus sgn works properly.
Simple PCB lifted pad question - Page 1
Forum section: electronics / repair

author: haku
author_rank: Newbie
timestamp: May 09, 2017, 12:24:28 am
content: Hi everyoneVery new to all this and not so electronic savvy so please forgive if this is a silly/obvious question.Was trying to replace a relay and some caps without proper desoldering tools (very silly) and managed to lift off some pads. The PCB came out of a mini fridge that I was wanting to repair (the starter relay and compressor are okay). I ended up buying a proper desoldering gun and got everything apart without more damage.Anyway,There are 2 PCBs stacked on top of each other, held together by soldered legs/pins, circled in red here:The pad that lifted was one of the set of legs/pins, as pictured here:My question is, was the lifted pad attached to anything pertinent? From my inexperienced eyes, I don't see it being connected to anything obvious? unless the dark green areas mean something...-if it was connected to something pertinent, how should I proceed in fixing the pad?

author: ataradov
author_rank: Super Contributor
timestamp: May 09, 2017, 12:39:02 am
content: Dark green areas are actual conductors. It is not a lifted pad, it is a part of the track ripped off. Easy fix - just scrape a bit of solder mask and solder the pin to the open area.

author: james_s
author_rank: Super Contributor
timestamp: May 09, 2017, 12:42:00 am
content: You don't even need to scrape off the mask, there are already some exposed areas there, as well as a nearby pad on the same trace.

author: haku
author_rank: Newbie
timestamp: May 09, 2017, 12:48:08 am
content: Quote from: ataradov on May 09, 2017, 12:39:02 amHelloDo you mean just solder the 2 pins/legs where the ripped off track here to any of the existing pads where the dark green areas are? Such as the lines in purple that I drew or where the hole where the "R9" is?

author: ataradov
author_rank: Super Contributor
timestamp: May 09, 2017, 01:21:33 am
content: Yes, use those openings in the solder mask as contact points.
Faulty HP E3631A - Page 1
Forum section: electronics / repair

author: z01z
author_rank: Regular Contributor
timestamp: April 03, 2017, 08:26:14 am
content: Hello everyone, thank you for taking interest in this issue.This is an older E3631A, from '96 with 1.5 firmware version.After power on the fan tuns on, there is a beep and the VFD lights up then it goes blank. When pressing the recall button, the unreg indicator is shown.All voltages on the power rails appear good.From the discussion in various topics on this forum, it appears that this indicates that the communication between the different CPUs doesn't work properly. So the signals from the main CPU was checked. On J4 to the front panel the supply voltages are present but all the signal lines are static. On J3 to the bottom panel some pulses can be seen from the IO CPU (which is passed on from the ASIC to the main CPU) but there is not response to that from the main CPU.The oscillator of the main CPU is running, there's activity on the address/data lines.On the reset pin (from the 5V regulator to the main CPU and the ASIC) however, there is periodic reset signal after ~200us. The reset pin of the regulator was lifted and it is stable, so the reset signal must come from the CPU or the ASIC.It looks like something very basic is wrong here, that prevents the main CPU from properly starting.Did anyone see this kind of failure? Any tip is welcome on what to check, how to proceed.The contents of the EPROM was read, it looks valid but I cannot be sure that it is not corrupt. If someone had this firmware and could post it, it would be highly appreciated.Thanks!

author: vtp
author_rank: Regular Contributor
timestamp: April 03, 2017, 10:24:10 am
content: Quote from: z01z on April 03, 2017, 08:26:14 amYes, exactly like that. Change the SRAM.

author: Samogon
author_rank: Frequent Contributor
timestamp: April 04, 2017, 05:51:38 am
content: Quote from: vtp on April 03, 2017, 10:24:10 amYeah same with me. U15 was dead.

author: z01z
author_rank: Regular Contributor
timestamp: April 04, 2017, 05:58:19 am
content: I'll get a replacement and report back.Thanks!

author: z01z
author_rank: Regular Contributor
timestamp: April 04, 2017, 06:46:58 pm
content: It was the RAM indeed. Now the diag test is passed without an error.The +6V output doesn't work properly though, it is stuck at -0.29V and 33mA in CC mode. Back to making measurements...@vtpFunnily I've just found your topic about the 1.6 fw, in which you described the faulty RAM symptom.Drop me a PM with your email address, if you need the 1.5 fw.

author: z01z
author_rank: Regular Contributor
timestamp: May 08, 2017, 05:22:14 pm
content: For the record, the 6V channel malfunction was caused by a faulty HCNR200 optocoupler, the LED measured 90 Ohms.
Denon AVR-1912 Firmware Update failure   NO OSD !!! - Page 1
Forum section: electronics / repair

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 01, 2017, 04:25:30 am
content: The 1912 model was getting a firmware update via the network... something happened it failed. update failure 56.According to Denon just hold the power button 5 seconds and it will resume the update. It did not. I reset the MPU several times to no avail. Left connected to the net, it never auto updated, or restarted. No OSD now, or just a blue graphics screen no text at all. I tried updating firmware using the web app, but there is no firmware update feature on it, unlike the AVR-3312 which has that FW update feature on the web app.So no way to get it updated. No OSD, No web app feature... what to do.I thought on this for a day or so. Then, it suddenly occurred to me I could control 2 AVR1912s with one remote. So I watched the second 1912 menu OSD while I used the remote for both AVRs, with the failed unit connected to the net.Voila!!! was able to successfully update it. All is well, once again!

author: sokoloff
author_rank: Super Contributor
timestamp: May 01, 2017, 11:47:41 am
content: Nice!

author: mzacharias
author_rank: Frequent Contributor
timestamp: May 01, 2017, 11:49:51 am
content: If possible, in the future download the update to a USB stick and use that. Updating via the internet can be risky, as you found out.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 02, 2017, 07:06:35 pm
content: Not quite...While there are a few models that have downloadable files, there is no downloadable file version of firmware available for this AVR-1912 that I am aware of.Live Internet connect through LAN port only.Unless you have some secret link Denon is not divulging...

author: mzacharias
author_rank: Frequent Contributor
timestamp: May 03, 2017, 12:26:15 am
content: Quote from: SoundTech-LG on May 02, 2017, 07:06:35 pmI was not aware of this with the Denon "12" series , but I have personally been told this by Pioneer and Yamaha service reps and I regard it as fairly standard, common sense advice.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 03, 2017, 07:47:57 pm
content: Yes, shame on them. Shame too that they provide the FW upgrade ability on higher priced models such as the AVR-3312 in the Web App, but not on the 1912 for some reason. Can't be that difficult to include on the app. Another sell feature for higher priced models I presume...

author: SL4P
author_rank: Super Contributor
timestamp: May 04, 2017, 12:48:32 am
content: Are you holding for 5 secsafterpower has been on, or holding downwhilewhen you apply power - if it makes any difference.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: May 08, 2017, 02:19:52 pm
content: No difference. Tried both... no go. Tried a few other things too. The dual unit, guided tour to the "firmware update" screen/button, seems to be the quick, cheatin' n' easy, way to gitter' done!
Identifying 24 Way PCB Header on Repair - Page 1
Forum section: electronics / repair

author: bookaboo
author_rank: Frequent Contributor
timestamp: May 05, 2017, 10:05:30 am
content: Hi,I have a PCB with a damaged connector identical to the one in the photos attached.Does anyone have any ideas as to the manufacturer or product range I should be searching for? It's from an old 1990s era Houchin generator.

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: May 05, 2017, 03:01:05 pm
content: Can't really tell the spacing from the picture, but i suggest you measure the exact pin distance and gauge with a caliper.If it's a clean millimeter value, instead of 2/10 inch, then you can at least rule out US/UK manufacturers and narrow your search on european brands.

author: Monkeh
author_rank: Super Contributor
timestamp: May 05, 2017, 04:20:28 pm
content: https://www.digikey.com/product-detail/en/itt-cannon-llc/TST24RB01T/1003-2492-ND/2643056

author: bookaboo
author_rank: Frequent Contributor
timestamp: May 05, 2017, 05:45:30 pm
content: Thanks, that's saved me hours probably!!!

author: Monkeh
author_rank: Super Contributor
timestamp: May 05, 2017, 05:52:55 pm
content: It took about 2 minutes to find
HP6236B Triple Output Power Supply Current Gauge not working - Page 1
Forum section: electronics / repair

author: parasabuy22
author_rank: Newbie
timestamp: March 30, 2017, 03:07:49 am
content: Hi folks... I have an HP 6236B Triple Output Power Supply. The volt meter seems to be working fine, but the current meter is not responding to any input. The meter looks like it took a hit during shipment and broke. I'm open to replacing the Ammeter but I can't seem to find one anywhere for a reasonable price.Any suggestions? I would appreciate leads to suppliers or advice on how to go about faxing this ammeter.Thank you.Paras.

author: JXL
author_rank: Regular Contributor
timestamp: March 30, 2017, 04:58:06 am
content: Search youtube for "HP6237B Meter Replacement". The HP6237B is almost the same as your HP6236B.

author: parasabuy22
author_rank: Newbie
timestamp: May 06, 2017, 08:03:11 pm
content: OK, thanks... saw the video. Are there any others that are similar? It seems the gauges are supposed to be the same across many models but with the faceplates changed. I also don't seem to find much on eBay, so perhaps I'm not searching with the right terms? Or if there is someplace else I should search that you know, I would appreciate the direction. Thanks a lot. Paras.
Repairing a DP823: Broken LCD - Page 1
Forum section: electronics / repair

author: Zazzmatazz
author_rank: Newbie
timestamp: May 09, 2017, 04:54:56 am
content: Good morning, gents!My little hellion of a nephew (with love, I assure you) decided that my DP823 would be a great thing to pull to the ground. Lo and behold, broken LCD. I tested most of the other functions through the programming interface, and all else seems normal.I managed to disassemble the supply and remove the broken LCD, which appears to be a TM035KDH03 QVGA display. Before I order one to replace, is there anything particular about the display that I should know about? Alternately, are there any equivalent displays that would work?Thanks!Side note: If anyone has one of these displays sitting around, I'd be happy to work out a deal for it
Anritsu MS710a  23 GHz Spectrum Analyzer I/P  repair query - Page 1
Forum section: electronics / repair

author: rickells
author_rank: Regular Contributor
timestamp: May 04, 2017, 07:56:35 pm
content: hi,Recently acquired Anritsu MS710a powers on fine, but no legitimate I/P signal is displayed.All other functions appear to work, including the internal calibrator signal when tested with a friends SA; including test RF signals(on friends unit).Wondering if the I/P diodes or amp has been blown ?Any hints about possible repairs, & schematics ?thank you
DSE Q1760 Power Supply - Page 1
Forum section: electronics / repair

author: garymck
author_rank: Contributor
timestamp: May 03, 2017, 10:30:05 pm
content: Hi,I have an old DSE Q1760 power supply. 0-30 volt, 5 amp, analogue meters, current limiting.A bit of research indicates that these apparently give a pretty massive power spike at first turn on (can't verify as I don't have a DSO yet, but do see a significan flick on the meters).This may be problematic if I ever have something hooked up when I switch on. I have seen that a lot of cheap power supplies have the same issue, and have seen videos of people doing simple mods to remedy this. However, probably due to age, I've not seen any info on how to cure this supply.Can anyone assist with info about fixing this? I'm a complete beginner in electronics, so sorry if this is a pretty basic question.cheersGary

author: garymck
author_rank: Contributor
timestamp: May 04, 2017, 12:25:03 am
content: Thanks Wilfred,I was unable to access the circuit - as you indicated there seems to be a forum issue. I would really appreciate a copy of the circuit if you could supply it.cheersGary

author: wilfred
author_rank: Super Contributor
timestamp: May 04, 2017, 04:36:14 am
content: OK. Here it is.

author: garymck
author_rank: Contributor
timestamp: May 04, 2017, 05:02:32 am
content: Hi Wilfred,thanks so much,cheersGary
Car Radio Repair - Page 1
Forum section: electronics / repair

author: IanBerry
author_rank: Contributor
timestamp: May 02, 2017, 05:28:38 pm
content: My car radio has been pretty much broken for awhile now, it never plays sound except occasionally when I hit a bump. Figuring it was a loose connection I took it apart and noticed the antenna plug was loose, so I cut it and soldered it directly onto the board. That helped a little bit but it still cut out very frequently. I took it apart again and found that if I pressed down on a specific part of the circuit board, flexing it a little bit, the radio would play sound. It would continue to play sound without fail while I was pressing on it. What the heck is going on? Is it a broken trace? Can I repair that?

author: dicky96
author_rank: Regular Contributor
timestamp: May 02, 2017, 05:46:41 pm
content: Some pics would be goodWhere are you pressing on the board?Is this just a radio or does it play CDs or USB or whatever?If so do you only have the fault on radio or on other sources as well?Rich

author: Armadillo
author_rank: Super Contributor
timestamp: May 02, 2017, 06:42:53 pm
content: Dried out solder joints probably. Just look at every and each of the solder joints for dullness and gaps/cracks on the solder joints.

author: mikerj
author_rank: Super Contributor
timestamp: May 03, 2017, 09:12:48 am
content: Check the solder connections of any power devices that are bolted/clamped to the chassis of the radio (typicaly one or more power amplifier ICs) and also the main ISO connector solder joints. These joints tend to be put under much more stress than others and are quite prone to cracking with age.

author: sokoloff
author_rank: Super Contributor
timestamp: May 03, 2017, 11:56:15 am
content: As two prior posters indicate, I'd start by resoldering the connections in the area of the board you flex (you can probably just remelt, but if it looks polluted, you can pull off the old solder and apply new with fresh flux)Though you haven't asked, do not do that with power applied to the radio. (It will be tempting to do so, so you can "quick check" the results. Don't. There's too much risk of creating a short circuit with the iron or with a solder bridge.)
hp Agilent 54502A  - Page 1
Forum section: electronics / repair

author: Dtec
author_rank: Contributor
timestamp: April 30, 2017, 12:44:58 am
content: Nv ran shows good but channel 2 is failed in all calibrations a/d fails d/a fails and analog trigger has a 1991 nv ram so I'm going to try since I have machined sockets and 1230y -100 has a1230y-120 so it should work any ideas I do nv ram test and it comes out goodSent from my iPhone using Tapatalk

author: xrunner
author_rank: Super Contributor
timestamp: April 30, 2017, 01:02:45 am
content: Quote from: Dtec on April 30, 2017, 12:44:58 amYou mean the scope already has sockets or you have machined sockets you want to install?I restored an HP 54501 (I have a thread on it in the forumHP 54501) and put in a socket for the NVram. It was a bugger getting the soldered-in chip out.

author: Bushougoma
author_rank: Regular Contributor
timestamp: May 01, 2017, 09:19:18 am
content: I wouldn't use machine pin sockets for NVSRAMs the pins are very thin and prone to bending as it is. The lower insertion force of dual wipes is safer for the pins.

author: Smith
author_rank: Frequent Contributor
timestamp: May 03, 2017, 07:52:35 am
content: The NVRAMS work perfectly in sockets, just be carefull.What exactly does the scope do? Is channel 2 working at all? If not, try swapping the input attenuators, or reseating/cleaning the A/D hybrids.
Relay part substitute  - Page 1
Forum section: electronics / repair

author: cryptlabs
author_rank: Contributor
timestamp: May 02, 2017, 10:35:42 pm
content: Hello,I'm trying to fix a radio hf transceiver. The part which i need to replace is obsolete and not available anymore.Fujitsu FBR321D012 Relay.What can i get to replace this relay.RegardsSent from my SM-N915F using Tapatalk

author: gadget73
author_rank: Regular Contributor
timestamp: May 03, 2017, 03:22:47 am
content: Do you have a datasheet or any spec info on this? That would help a huge amount.Also knowing if there are any particulars that are a limiting factor would be good. Can the replacement be physically bigger, or does it need to plug into a socket that you can't rewire, anything along those lines.