hybridfree/eevblog-posts huggingface dataset:
Tektronix A6902A Isolation Amplifier schematics - Page 1
Forum section: electronics / repair

author: xantia_99
author_rank: Contributor
timestamp: June 19, 2015, 12:00:33 pm
content: HiI just got a Tektronix A6902a isolation amplifier and need a service manual to adjust certain things.I already got the A6902B version service manual howewer but that got another PCB and components.I wish to calibrate it. I have done that to 95 %. It works great however the outlevels differ between the channels.Hope anyone could helpBest Regards
Brighten a dull LCD screen? - Page 1
Forum section: electronics / repair

author: nonsuchpro
author_rank: Contributor
timestamp: June 15, 2015, 12:50:00 pm
content: Hi all,I have this 13" el'cheapo LCD TV that is perfect for a project I'm doing. However, the screen is very dull. I'd say say it's putting out 100cd/m2 rather than your standard 250 or so. Of course I messed with all settings. The "brightness" parameter just washes everything out if you set it more than half way.So, anybody know a way to brighten it up a bit? Like give it more juice? I have no problem replacing components.Thanks in advance!Rob

author: amyk
author_rank: Super Contributor
timestamp: June 15, 2015, 01:04:26 pm
content: Make sure to increase contrast if you increase brightness, otherwise the image will become washed out.Change the backlight if you run out of adjustment range.

author: fable
author_rank: Regular Contributor
timestamp: June 15, 2015, 01:07:01 pm
content: You need to see if it has a ccfl or leds for backlight.If there are lamps then they are propably bad and you need to replace them.

author: nonsuchpro
author_rank: Contributor
timestamp: June 15, 2015, 04:32:48 pm
content: Thanks amyk, I did try all settings. This is a much deeper issue.

author: nonsuchpro
author_rank: Contributor
timestamp: June 15, 2015, 04:43:32 pm
content: Quote from: fable on June 15, 2015, 01:07:01 pmIt's a panel, very thin. I've gotten rids of all my CCFL monitors 2 years ago. Here's some pics:
SMPS auto start in half bridge topology - Page 1
Forum section: electronics / repair

author: BennVenn
author_rank: Regular Contributor
timestamp: June 13, 2015, 02:55:02 am
content: I've just scored myself a 12v 60A multi mode lead acid charger with blown BJT's in the power stage. Its of Chinese origin but I'm very happy with the build quality and design. Very neat layout, logical, going to be a pleasure to repair.The power stage is pretty much plain as they come, standard half bridge, BJT drive transformer etc... This got me wondering though, how do these things start themselves up? The switchmode IC (pinout identical to TL494/KA7400 etc) is powered from the high current secondary winding on the transformer. There is an aux winding going to what would be two diodes but they were not fitted.The spec sheet says regulated output from 0-60A output which implies a battery is not required to start the SMPS up.So! with no resonant primary startup circuit, no biasing on the primary BJT's and no way for the TL494 to get a pulse through the drive transformer, how does it start up?Maybe it does require a battery to kick it off?There is no way for current to flow from the battery back past protection diodes.Or is it something about the half bridge topology (voltage divider caps?) that gets an initial pulse through to start the whole lot up?

author: amyk
author_rank: Super Contributor
timestamp: June 13, 2015, 12:32:18 pm
content: If it's anything like a half-bridge ATX PSU you'll find a high-value resistor between the primary DC rail + and one of the transistor bases.

author: wraper
author_rank: Unknown
timestamp: June 13, 2015, 12:48:42 pm
content: Quote from: amyk on June 13, 2015, 12:32:18 pmSure that you won't find anything like that in ATX PSU because they don't need it. They have additional standby PSU.

author: amyk
author_rank: Super Contributor
timestamp: June 13, 2015, 02:11:35 pm
content: Oops. I meant AT, not ATX.

author: BennVenn
author_rank: Regular Contributor
timestamp: June 14, 2015, 12:17:47 am
content: Biasing is the same for both halves of the bridge yet it starts up with no battery attached. Looks like more reading will be required.The secondary side rectifier (one of three) has gone short which explains the destruction in the primary. Dave's trick of a bit of spit on the finger revealed (part number sanded off) a Visahy part rated at 40amps, couldnt get the following two digits. I'll go with 40v? (It is a 6cell Lead acid charger)All the base drive resistors are open but the biasing resistors are fine. Just replaced the resistors and 'borrowed' the BJT's from a smps downlight converter. Powers up fine and I can see the 3 states of the charging circuit switching as it powers a 12v halogen lamp (CC, CV then float)Order placed with RS for the 6 original BJT's + 2 new schottky rectifiers. Cheap fix for a very expensive charger!
STMicroelectronics TDA7372A Replacement - Page 1
Forum section: electronics / repair

author: Kumra
author_rank: Newbie
timestamp: June 11, 2015, 01:38:56 am
content: Hi Everyone,I am trying to repair a Creative Labs Speaker Set as the AMP has failed on the board. I'm trying to find a replacement for it but Digikey say that it is obsolete. Any ideas where I would be able to get an alternative or what I could use instead?Link to existing one:http://www.digikey.co.nz/product-detail/en/TDA7372A/TDA7372A-ND/1665092

author: miguelvp
author_rank: Super Contributor
timestamp: June 11, 2015, 01:51:03 am
content: A bit pricey but found one source via octoparts.comhttp://littlediode.com/product.php?productid=76548No rating at octoparts and never dealt with littlediode.Edit: Or go to ebay and there are some available.http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=TDA7372A&_sop=15

author: Deathwish
author_rank: Unknown
timestamp: June 11, 2015, 02:00:54 am
content: http://www.ebay.co.uk/itm/TDA7372A-Ampli-BF-4x6-5W-CTDA7372-/180982708234?pt=LH_DefaultDomain_71&hash=item2a2368f80ahttp://www.ebay.co.uk/itm/TDA7372A-Original-Pulled-ST-Integrated-Circuit-TDA-7372A-/400667777702?pt=LH_DefaultDomain_0&hash=item5d49a91aa6http://www.ebay.co.uk/itm/TDA7372A-INTEGRATED-CIRCUIT-NOS-New-Old-Stock-1PC-C537CU5F220115-/161569954682?pt=LH_DefaultDomain_186&hash=item259e51db7ahttp://www.ebay.co.uk/itm/integrato-TDA-7372A-TDA7372A-/280940312264?pt=LH_DefaultDomain_101&hash=item416958f6c8http://www.ebay.co.uk/itm/TDA7372A-Integrated-Circuit-I-C-/151140620156?pt=LH_DefaultDomain_3&hash=item2330aed77c

author: Kumra
author_rank: Newbie
timestamp: June 11, 2015, 02:01:34 am
content: Thanks heaps, stupidly didn't even think of ebay!

author: Deathwish
author_rank: Unknown
timestamp: June 11, 2015, 02:05:53 am
content: closer to home ?....http://www.wagneronline.com.au/tda7372a/9/ps/

author: Kumra
author_rank: Newbie
timestamp: June 11, 2015, 02:11:24 am
content: Nice, thanks for the help!
Panasonic PT-AE4000U problem - Page 1
Forum section: electronics / repair

author: Bargainhunter
author_rank: Regular Contributor
timestamp: June 05, 2015, 07:46:07 pm
content: I received a Panasonic Pt-A4000U for repair. The projector is dead. No blown fuse. Visually everything looks okay. I do not have any voltages past the relay which is activated by 15V and the relay switches on the 110V and secondary voltages.It seem the customer had his electrical outlet wired in reverse. Any ideas as to where I should start?Thank you.

author: tautech
author_rank: Super Contributor
timestamp: June 06, 2015, 10:19:26 am
content: http://elektrotanya.com/panasonic_pt-ae4000U-E-EH_sm.pdf/download.html

author: tyguy2
author_rank: Unknown
timestamp: June 10, 2015, 03:49:44 pm
content: You should probably check the usual suspects, Caps (look for bulges or leaks), Power Supply (see if it is outputting voltage to the rest of the device), etc. Look for anything that looks burnt.A few tips and tricks:http://www.doityourself.com/stry/how-to-fix-a-faulty-lcd-projector#b
Hampden engineering H-IEC-B4 PLC trainer. - Page 1
Forum section: electronics / repair

author: electronics-whiz
author_rank: Regular Contributor
timestamp: June 19, 2015, 09:36:14 pm
content: A friend that teaches the electrical apprentice program at the local community college gave me a bunch of these old trainers from like the 80's. They used at one time, then I guess sat in storage for years and they cleaned up during a relocation they decided didn't need them.This unit was made for 208, I removed the old banana input jacks he said it should run fine on 120V. I just put a 3C 120 cord on it and connected it up worked fine. I connected a fairly small blower motor it tripped the breaker/switch on the unit, (motor worked fine) I reset plugged in got small pop from the unit and breaker tripped again. The unit will power up fine, but soon as you turn the speed knob (PWM type drive) it will just trip the built-in breaker.I looked things over I don't see any fuses, obvious blown caps, bad connections, or any holes/burn marks on anything. I see some resistors that when tested are like 1/2 the value it says they should be, but seems could be just because they are connected. I would think if a resistor failed if old carbon comp value would marginally change, or would just go open. Also noticed similar issue in a couple of potentiometers, seems is more issue of being connected though.I noticed the transistors have a bit of a bulge in the top, but I think that is just package design. I see one cap with no vent on top that has a very small raise (hardly detectable) in the top as well as a ring in the center. They are mallory brand which I don't think is one of those junk cap brands.I'll attach pictures I don't know you will spot anything I missed, but possible. If it means removing all the parts with odd values, etc I may just junk it as I have a small Allen Bradley PLC that if I can figure out how to program would do same thing and more in smaller package.
Wiring up a Lumina 7151 & stuck!! - Page 1
Forum section: electronics / repair

author: hyteqsolutions
author_rank: Newbie
timestamp: June 08, 2015, 08:30:21 am
content: Good Evening EEVBlog,Long story:I have a client, my youngest brother, he is mentally ill and cannot deal with change. So while he is at hospital, I have his Lumina oil heater, but I am stuck trying to fix it (the one thing I have never repaired).I have no idea what happened to the wiring, I believe someone at the nursing home attempted a fix and 'it' didn't work, I have rebuilt some items and replaced others (at my own expense). There was some wiring, but it's all broken, snapped or cut (similar to someone doing half a job with a pair of kitchen scissors).I think it's an Aldi's brand and it's back from 2009, same year my little brother was diagnosed, I brought him this little heater and I don't want to put stress on my little brother by buying a new heater, it will 'freak' him out.If anyone has this heater in their house, a photo of the wiring would be amazingly helpful so I can get it working for my little brotherThank you all for your help,- Benjamin

author: Fred27
author_rank: Unknown
timestamp: June 08, 2015, 08:35:26 am
content: It might be worth checking eBay to see if someone's selling the same model. You could either cannibalise it for spares or check how it should be wired. Worst case - he might find it a bit less stressful to have a replacement of the same type.
How to re-attach a lifting pad to PCB? - Page 1
Forum section: electronics / repair

author: krivx
author_rank: Frequent Contributor
timestamp: June 03, 2015, 09:18:00 am
content: I have a PCB where the thermal pad of a DPAK voltage regulator has lifted away, presumably from heat. There is still a trace holding to the board. Can I glue this down and solder a new regulator? I was thinking that CA glue may not work because it will melt during soldering, would a 2 part epoxy with a higher temperature rating work better?

author: krivx
author_rank: Frequent Contributor
timestamp: June 03, 2015, 10:45:27 am
content: This has turned out to be a rush-job, so it ended up as high-temperature epoxy (EpoTek 353nd) under the pad, light clamping force and oven-curing for an hour or two. Fingers crossed.

author: Skimask
author_rank: Super Contributor
timestamp: June 03, 2015, 12:11:19 pm
content: 2 part epoxy is about the only way to go for that sort of repair.Be careful when you go to solder the pad. Even though you used high temp epoxy, the epoxy itself may over-due to the heat and end up a bit crystalized.Used plenty of flux, try not to solder directly on top of the epoxy on the repair, keep the heat down as low as you can while still keeping enough heat to melt the solder quickly enough to 'get it and get out'...etc, etc, etc.

author: krivx
author_rank: Frequent Contributor
timestamp: June 03, 2015, 12:25:25 pm
content: The Epotek was curing in the oven at ~100C for an hour and seemed to work great. I used Kapton as a mask thinking it wouldn't adhere () so I had to scrape away some Kapton where I had squeeze-out but the voltage regulator is providing correct voltage under load now that I have replaced it.I would recommend the epoxy for this kind of work. It should be good for 250C continously and 350C momentarily, so it seems like a good fit for most soldering processes.

author: dacman
author_rank: Frequent Contributor
timestamp: June 07, 2015, 08:06:43 pm
content: If there is nothing on the other side, and the board isn't multilayer, I'd consider installing an eyelet.

author: wagon
author_rank: Frequent Contributor
timestamp: June 07, 2015, 11:43:20 pm
content: I've used a thin piece of copper sheet, cut to size, as a heatsink. Then I glue the copper to the pcb and solder the SMD part to it. Worked well on the couple of boards I fixed. (You'll probably need to extend the two legs a bit, probably won't reach the pads)

author: Deathwish
author_rank: Unknown
timestamp: June 08, 2015, 12:41:34 am
content: http://bee.mif.pg.gda.pl/ciasteczkowypotwor/HP/Publikacje/HP-Bench-Briefs-1982-07-10.pdf

author: wagon
author_rank: Frequent Contributor
timestamp: June 08, 2015, 02:46:40 am
content: Quote from: Deathwish on June 08, 2015, 12:41:34 amThank you! I learned something.
Rohde & Schwarz SMT03 LC display replacement - Page 1
Forum section: electronics / repair

author: davorin
author_rank: Unknown
timestamp: June 04, 2015, 05:45:50 pm
content: Evnin'....Does anyone know what resolution the LC display of the SMT03 and similar models has?Mine has a dark display,,,,and probably the backlight can't be replaced with a newer one...

author: Jwalling
author_rank: Unknown
timestamp: June 05, 2015, 10:28:24 am
content: I don't have the answer to your question, but I've heard that the CMD80 uses the same display.You can get those real cheap - see Ebay item 271755746245 for instance.Also, have a look athttps://groups.yahoo.com/neo/groups/TektronixCMD80/conversations/messages/44

author: davorin
author_rank: Unknown
timestamp: June 05, 2015, 10:36:33 am
content: Thanks for the pointer.....though have to find another one as this one won't ship to Europe...

author: davorin
author_rank: Unknown
timestamp: June 05, 2015, 06:53:02 pm
content: Okay...got something....according to the SMT service manual it says that the SRAM is enough for 4 pages of 640x200....so I assume this is the resolution as well....and is driven by a Seiko Epson SED1351F controller...

author: TiN
author_rank: Super Contributor
timestamp: June 06, 2015, 04:09:55 am
content: I got impression that displays on these not so bright normally, as there is metal glass in front panel to shield EMF.Just like thiseBay auction: #http://www.ebay.com/itm/Rohde-Schwarz-Displayglas-NACHBAU-fur-SMIQ-SMT-SMP-CMD-/351334996484?pt=LH_DefaultDomain_77&hash=item51cd329a04one.Try play with brightness/contrast knobs, if you did not yet.

author: Jwalling
author_rank: Unknown
timestamp: June 06, 2015, 09:26:14 am
content: Quote from: TiN on June 06, 2015, 04:09:55 amAnd a picture is worth a thousand words! (hint hint...)Jay

author: davorin
author_rank: Unknown
timestamp: June 07, 2015, 09:12:48 pm
content: A picture wouldn't help much (o;It's just a matter of aging that those CCFL get darker...and the fact that the EMC filter glass is getting yellow over time...makes the visibility worse....Maybe I'll try to replace EMC glass with a plain one to see the difference....The display is readable when you're looking directly into it (and yes...adjusted contrast/brightness ;o)...but if it's in a shelf where you look at at at a 30 degree angle from below...it is now (o;
Manual for a W & G SPMZ-110 - Page 1
Forum section: electronics / repair

author: johnh
author_rank: Regular Contributor
timestamp: June 06, 2015, 08:45:55 am
content: Does anyone know where you can get a copy the schematics for a W&G SPMZ-110?

author: tautech
author_rank: Super Contributor
timestamp: June 06, 2015, 10:38:16 am
content: These guys have a lot of W&G manuals:http://www.rainer-foertig.de/unterlagen/WG-11_2009.htmMight be worth an email

author: johnh
author_rank: Regular Contributor
timestamp: June 07, 2015, 03:46:09 am
content: I bought the SPMZ 110 because I wanted a cheap 19 rack mount case20 dollars for a manual just to see how it works no thanks.
Marantz 1090 amplifier - Page 1
Forum section: electronics / repair

author: Kenceu
author_rank: Newbie
timestamp: June 04, 2015, 08:31:30 pm
content: Hello everyone!I'm a newbie in electronics and tried my hand at repairing this old amplifier (simple circuity). And noticed that the output stage is beyond saving without spending loads and loads of money.See attached pic below this was after soldering new transistors and biasing the circuit. It blew 3 unrelated resistors.Now the pre amplifier circuit is still in pristine condition and completely in spec. Now I was wondering if it would be possible to separate the pre amplifier from the output stage so that the whole main amplifier part doesn't get any power anymore?I have the schematic if anyone could push me in the right direction or tell me which wires to cut i'll be very grateful!

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 06, 2015, 12:03:16 pm
content: I would simply disconnect the main power from the main amp stage, put bleeder resistors across the main filter capacitors (if there aren't any already) and use the convenient pre-amp out jacks on the rear panel.As an aside - I repair this sort of stuff all the time. My only concern in fixing it would be that this type of output transistor is an obsolete package and it might be necessary to hack in a different physical package. Ugliness potentially ensues.
Trouble identifying a value - Page 1
Forum section: electronics / repair

author: Pscylo
author_rank: Contributor
timestamp: June 05, 2015, 10:46:54 am
content: May have been better of in beginners, but since it's an attempted repair (not critical equipment just to see if I can), I thought I would ask here.The attached is ostensibly a resistor (not seen a green one that I can remember, but still, marked as R "something" on the board). MM shows it as low resistance, but I can't make much sense of the colour bands. The first and last are either white or grey (or one white one grey etc), the middle are red, silver and gold. I can't seem to match this up to the various charts available for resistors (or for axial inductors for that matter). For resistors, I can't position gold and sivler as adjacent bands in those positions and for inductors, five band would indicate military standard and require silver to start which I don't have.Anyway, I'm guessing I'm being dim, so would appreciate some assistance.Thanks.

author: wraper
author_rank: Unknown
timestamp: June 05, 2015, 10:56:42 am
content: 0.91 ohm, 5%. This is 3 band value marking. 4th band is tolerance. 5th band is manufacturer specific, could mean resistor type and some other things.

author: Deathwish
author_rank: Unknown
timestamp: June 05, 2015, 11:09:23 am
content: .92 ohms 5%

author: Andy Watson
author_rank: Super Contributor
timestamp: June 05, 2015, 11:44:58 am
content: If you consider the first band to be grey rather than white you would have 0.82 - which is a preferred value.

author: wraper
author_rank: Unknown
timestamp: June 05, 2015, 12:36:13 pm
content: Quote from: Deathwish on June 05, 2015, 11:09:23 amSuch (standard) value does not exist.Quote from: Andy Watson on June 05, 2015, 11:44:58 amFrom the picture, for me first band looks almost certainly white, second band is obviously brown, not red unless I'm daltonic.

author: mij59
author_rank: Frequent Contributor
timestamp: June 05, 2015, 01:15:47 pm
content: 1.8 Ohms fusible

author: Pscylo
author_rank: Contributor
timestamp: June 05, 2015, 03:15:22 pm
content: From the picture, for me first band looks almost certainly white, second band is obviously brown, not red unless I'm daltonic.Second band could indeed be brown, but the white/grey issue is less clear cut. They certainly appear to be different colours at each end of the component dending on orientation and thickness of paint; if it weren't for that perceived difference and the presence of two bands of a similar coilour I would probably book either one as white individually. Either way I guess I know it's around 0.82 to 0.92 which is precise enough I think. My meter makes it 1.1Ohm though I don't know how accurate the meter is.Thanks all.

author: wraper
author_rank: Unknown
timestamp: June 05, 2015, 04:51:58 pm
content: Quote from: Pscylo on June 05, 2015, 03:15:22 pmGrey bands on resistors are much darker. Not some kind of light grey.
sharp lcd tv 32A33M aquos - Page 1
Forum section: electronics / repair

author: nasali_68
author_rank: Newbie
timestamp: May 24, 2015, 11:28:05 am
content: I have problem with this TV:1-LED power directly getting green after power on2-No picture and no sound3-There is 5V and 3.3V4-There is not 12Vplease can any body help.

author: Hagis2k
author_rank: Regular Contributor
timestamp: June 01, 2015, 05:02:13 pm
content: Well start with taking some photos of the power supply board, and if you have not been working with switch mode power supply smpsbefore be careful if you had it plugged into the net the filter capacitor can be charged with 200-400V so do not touch it oruse a dvm to check and see its discharged.Then trace backwards on the 12V and try to locate the fault, most common fault is bad solder connections and capacitorsBut start with a few good quality photos so all parts and text are easily readable.

author: necroscope
author_rank: Regular Contributor
timestamp: June 02, 2015, 02:57:17 am
content: Service manual available for download herehttp://elektrotanya.com/sharp_lc-32a33m.pdf/download.htmlI would follow the troubleshooting guide in chapter 6....It instructs testing for voltages at different ic locations voltages mentioned are 5v,4v,3.3v and 9v there is no mention of 12v from the quick glance I had, it probably wont tell you how to repair the tv but it should help narrow the problem down.

author: Hagis2k
author_rank: Regular Contributor
timestamp: June 03, 2015, 03:57:47 pm
content: Pin 1-2-3-4 on P2801 shall be 13V so if that is missing then the DC-DC converters will not work either, so start looking in the psu if you can find the fault.
Made a new repair video. 1986 Roland Digital Reverb - Page 1
Forum section: electronics / repair

author: OilsFan
author_rank: Regular Contributor
timestamp: May 31, 2015, 11:52:26 pm
content: I made another repair video. This time it is a Roland DEP-5 Digital Effects Processor circa 1986. Pretty cool first gen multi effects from Roland. Please note that it's pretty long and I am no Dave though I do like to parrot him and DrCassette from Youtube.I'm an entertainment electrician by trade so electronics is not my forte. Just a secondary field I've picked up from servicing gear in the field. Audio geeks might enjoy.https://youtu.be/AIhylmi_YM8

author: Shock
author_rank: Super Contributor
timestamp: June 01, 2015, 04:16:38 am
content: I have some tips...When you clean the pots you can flood it first with a cleaner while you manipulate the pot vigorously, then use air and then contact lubricant. That way the movement of the wiper will clear debris while the fluid will remove it. You can also meter the pot before and during this process and see what progress you made.Adding new solder (flux) can help make those type of joints easier to remove. Break sweat joints if required carefully with a small tool such as a screw driver and look for pin wiggle before removing.When using your desoldering gun gently place it down on the joint to achieve melt, press the button and move the tip for a few seconds in a circular motion to manipulate the lead. Then lift the gun before releasing the button, this will reduce sweat joints and you can do a wiggle test before removing.

author: obiwanjacobi
author_rank: Super Contributor
timestamp: June 02, 2015, 06:00:15 am
content: Haven't seen the video yet, but did subscribe.Do you knowhttp://music-electronics-forum.com? Might be a better audience for music related stuff...

author: obiwanjacobi
author_rank: Super Contributor
timestamp: June 02, 2015, 06:12:55 pm
content: Just watched your video. I had a Roland repair just like that one (GS-6 it was, I think). Had the same symptoms but in my case it was a broken PCB track so the CPU sensing input was floating, causing it the make up all sorts of values. Took me quite a while too before I had that one figured out...

author: OilsFan
author_rank: Regular Contributor
timestamp: June 03, 2015, 07:27:49 am
content: Quote from: obiwanjacobi on June 02, 2015, 06:00:15 amThanks for the tip! Never heard of that one but it looks good!
Marconi 2032 Generator - Page 1
Forum section: electronics / repair

author: EMUD
author_rank: Regular Contributor
timestamp: November 18, 2014, 08:58:14 am
content: Hi,my name is Rudi and I am a hardware developer. Sometimes I try to repair old electronic stuff like this one.One of my problems is that the RTC is not recogniced. I have replaced the PCF8573 clock, but the problemwas not solved.I have scanned the I2C bus data and it seemed that the RTC is ok.In my opinion there is an other problem, wich causes this malfunction. It seemed to me that the display controller(80C31, EPROM, 8K static RAM) could be the problem. The software revision of the unit is 7.0001 , so it would be interestingto have the binaries to check the eprom(s) and the eeprom.Thanks in advanceEMUD

author: EMUD
author_rank: Regular Contributor
timestamp: November 24, 2014, 04:23:37 am
content: Hi,maybe I have solved the problem : The firmware in my 2032 is not ok, the display and the main firmware are from two different revisions. In the service manual it is mentioned, that the display and the main controller have only one set of EPROMs. Has anyone the binaries for me to test ? (Revision 7.00x for the Marconi 2031 or 2032).Many thanks in advanceEMUD

author: Chris Jones
author_rank: Regular Contributor
timestamp: November 28, 2014, 01:47:56 pm
content: Try asking in the Yahoo Groups forum for Marconi Instruments. That is the best source I have found for information about instruments from this manufacturer. Sadly this information seems to be locked away from public searches and archiving as you have to log in to read it afaict.https://groups.yahoo.com/neo/groups/marconi_test_instruments/info

author: EMUD
author_rank: Regular Contributor
timestamp: December 01, 2014, 04:27:34 am
content: Hello Chris,thanks for this information. I have tried to get this firmware at an EBAY seller, but he did not understand (I think there was to little technical knowledge) what I really need.Mailing to Aeroflex, I got no final response if this firmware is on stock (Aeroflex is the service provider for some Marconi and IRF high quality rf - generators). They told me they would not send me the binaries, but they could sell me this EPROM if I have a number. I have sent a number to them ... I think they are looking for it.It seemed that the wrong firmware is the last issue this 2032 has, everything else is working perfekt.EMUD

author: test2
author_rank: Newbie
timestamp: June 02, 2015, 11:47:26 pm
content: Hello Rudi,I have just won a Marconi 2031 & Service manual from eBay and it should arrive within a week.If you still require the eprom binaries let me know and i'll try to help.Tim
If Repairing Meanwell 350W Supplies.......... - Page 1
Forum section: electronics / repair

author: German_EE
author_rank: Super Contributor
timestamp: June 02, 2015, 08:51:15 pm
content: be very careful how you take the PCB out of the case. There are one or two devices at the thin end opposite to the connector assembly and one or two devices bolted to a long side. After removing the screw holding the device(s) to the long side you MUST carefully bend the devices back so that the board can be removed. If you don't bend the devices back and lift the pcb it will crack around the area of the power FETs.The epoxy is now setting around the repaired PCB and once it cures overnight I can attempt to repair the electrical fault

author: tautech
author_rank: Super Contributor
timestamp: June 02, 2015, 08:57:51 pm
content: Good to know, thanks for the "heads up".
philips car radio - Page 1
Forum section: electronics / repair

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 05, 2015, 06:21:14 pm
content: hi dudes! i recently purchased a philips car radio from the late 70s early 80s and it keeps blowing fuses and when i fitted a bigger fuse the light came on but no sound or anything. the model number is unknown but it has the classic twin knob setup and is completley black with no cassette deck. it runs off one ic so i can get the number off that it if it is any help.O0

author: tyguy2
author_rank: Unknown
timestamp: June 08, 2015, 12:02:26 am
content: If you've already placed it in the car, make sure the PCB is not shorting via any metal below it. Otherwise, you might want to provide the forum with a little more information. Good luck!

author: Erik NL
author_rank: Newbie
timestamp: June 08, 2015, 09:49:54 pm
content: I also have a Philips radio that's build in the same period in my old (1972) Trabant. I also happen to live in "Philipsland"See on the back (or side) for the sticker with model info (something like 22rn...)Or google for philips autoradio and find the picture to identify:http://www.radiomuseum.org/images/radio/philips_radios/22rn351_00_901729.jpgParts are getting vintage these days but Philips still can deliver most of themSo, provide the info and maybe I can helpIn the meanwhile solder out the audio amplifier and see if the fuse survives...Once identified, you can request a -free- servicemanual. All manualsare available here but not all of them are digitised yet. Just searc (and request) on:http://freeservicemanuals.info/en/You are lucky to have a Philips because these are well-documented!Have fun!

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 09, 2015, 07:16:19 pm
content: Quote from: Erik NL on June 08, 2015, 09:49:54 pmthey also sound really good

author: tyguy2
author_rank: Unknown
timestamp: June 09, 2015, 08:05:34 pm
content: Have you checked the caps? Make sure they are working.

author: bills
author_rank: Frequent Contributor
timestamp: June 09, 2015, 08:09:12 pm
content: Could it be positive ground ?

author: Erik NL
author_rank: Newbie
timestamp: June 09, 2015, 09:31:54 pm
content: Not likely for a Philips... Blaupunkt had switchable (pos-neg 6/12V) but stopped this in about 1970Also, the negative ground wouldn't matter as long the radio is not built in the car (I understood it is still on the workbench)But, never too old to check it, I guess

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 10, 2015, 03:43:17 pm
content: Quote from: tyguy2 on June 09, 2015, 08:05:34 pmboy, itd do something if the caps were bad but this one isnt doing anything other than glowing

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 10, 2015, 03:44:14 pm
content: Quote from: bills on June 09, 2015, 08:09:12 pmnope, it has a big negative ground symbol on the top

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 10, 2015, 03:45:34 pm
content: Quote from: Erik NL on June 09, 2015, 09:31:54 pmofcourse it is still on the workbench, what dumass works on a car radio...... in the car!
looking for replacement ICR12300 Battery for Livescribe - Page 1
Forum section: electronics / repair

author: Circuitous
author_rank: Unknown
timestamp: May 30, 2015, 12:58:35 am
content: I'm hoping to replace the Li-ion battery in my Livescribe Wifi pen, and I need to find one that will fit and work with the charging/protection circuit.I am not an expert on LI batteries, and I hope someone will recognize this one.Markings: Great Power ICR12300 350 mAh 3.7VDimensions: 11.70mm x 27.6mm (dia x len)It also has long thin solder tabs.I haven't welded tabs onto batteries, and was hoping to just find a direct replacement.In the attached photo you can just see the charging/protection circuit on the end of the battery. This is separate from the battery.Any suggestions for alternative batteries or suppliers would be great!Thank you.

author: Johndi
author_rank: Contributor
timestamp: May 31, 2015, 04:04:49 am
content: Looks like the only thing remotely close is available at aliexpress:http://www.aliexpress.com/store/product/6pcs-lot-ANYSUN-icr12300-3-7V-350mAh-12300-li-ion-rechargeable-battery-cell-for-Livescribe-WiFI/1453301_32313341408.htmlHave you tried contacting the sales department for Great Power? I've found in the past, that sometimes contacting their sales department they will get you in contact with a distributor who is willing to sell one-off.

author: Circuitous
author_rank: Unknown
timestamp: June 01, 2015, 12:55:33 pm
content: I haven't tried contacting Great Power, but I might do that.I did find a new battery on ebay with solder tabs that should arrive in 10 days or so.Thanks for the suggestions. If the eBay one doesn't work out, I'll contact great power.
Lambda LK 342A fm repair - Page 1
Forum section: electronics / repair

author: bobbylin
author_rank: Newbie
timestamp: May 31, 2015, 08:43:20 pm
content: I received this unit. It turns on but the voltage shoots up to 60v and i cannot seem to adjust it. Does anyone have any suggestions on where to start to look for troubleshooting? Would anyone have a schematic or service for this? Googled around a bit and only found people selling the unit or the basic spec sheet. Can anyone shed some light on this for me?Thank you

author: Vgkid
author_rank: Super Contributor
timestamp: May 31, 2015, 09:28:04 pm
content: For a schematic/manual email Lambda. I have, and they are really helpful in that regard. Note you will have to fill out a form before they give it to you, at least I did.
Apple A1097 power supply problem - Page 1
Forum section: electronics / repair

author: Porto
author_rank: Contributor
timestamp: June 12, 2015, 01:21:39 am
content: Here I have a blown Apple Cinema 23" display power supply, the A1097.Some resistors were blown right off the board and now I'm trying to figure out how they were really connected without having the schematics.This example is of a similar board:It concerns of the four '103' resistors in the middle.I already found out (by not fully discinerated PCB traces) that R2 is connected to the diode above it and R1 is going to the drain pin of a STQ1NC45R mosfet. Also, R1 and R2 are serially connected, so are R3 and R4. Here the known connections:I think they are also connected one of the below possibilities, which one would be logical? I don't even know what this circuit is for (feedback? sense? voltage divider?).Also inverted the colors on that specific location. There seem to be more connections visible but I don't just really know for sure.All the possibilities are tested and specifically R1 is getting very hot, around 90 degrees, but the other 3 resistors are maxing out on 40 degrees. Original these are 3/4 Watt smd resistors; I'm testing the circuit with 2W through holes. I know for sure there is a short (to ground) somewhere but that's for later, now I have to know how these 4 resistors interconnect with eachother.My blown board looked like this (already cleaned most of it and remasked it with green PCB paint):All suggestions are welcome!Thanks!
PC UV fluro lights not working. How to test the inverter of CCFL lights - Page 1
Forum section: electronics / repair

author: smudge
author_rank: Newbie
timestamp: May 30, 2015, 10:37:25 am
content: I have 2 CC-FL UV tubes powered by one double output inverter lighting up the insides of my PC. 12v in and x? out. Worked fine until I did an upgrade, they worked for a short time but now nothing. I have power going to the inverter but wish to know the procedure to test out put. knowing this is a high voltage out, is this too tricky for a cheap PC add on and just biff, or is there a quick check to see if its the inverter or tubes?update: believe the output is 680 AC v ± 10%
Help with testing MOSFET - Page 1
Forum section: electronics / repair

author: Bargainhunter
author_rank: Regular Contributor
timestamp: May 27, 2015, 01:12:20 pm
content: Hi,I am troubleshooting a Panasonic PT-AE4000U power supply. I tried testing the MOSFET K3561 with my DMM in diode setting and the mosfet didn't turn on. I order a new 2sk3561 and it would not turn on either. I tried three different DMM's. What is going on? Do my DMM's not have enought voltage to turn on the K3561 or what?I have an old Heathkit IT-121 transistor tester that will test FET semiconductors. Do you think that will test MOSFETs?Any help would be greatly appreciated.

author: Seekonk
author_rank: Super Contributor
timestamp: May 27, 2015, 01:20:57 pm
content: Generally you need over three volts to turn on a FET, some even higher. Your DVM likely can't supply enough voltage. A 9V battery connected to a 250K to 1M pot as a voltage divider would make a useful test device and then use a DVM to measure ohms.

author: w2aew
author_rank: Super Contributor
timestamp: May 27, 2015, 01:39:03 pm
content: You might want to look at my video on this. The first 2.5 minutes describes the DMM method, the second half of the video shows a different method using a few simple components:

author: darkness_electro
author_rank: Contributor
timestamp: May 27, 2015, 03:52:03 pm
content: You could build on a breadbord or something a circuit that supplies 5v on the gate and turns on an LED. Quite simple.
Does some one have CreativeLabs DTT3500 DIGITAL - Page 1
Forum section: electronics / repair

author: kahvikello
author_rank: Newbie
timestamp: May 25, 2015, 07:03:53 am
content: Could someone open and check what ic that is?

author: dom0
author_rank: Super Contributor
timestamp: May 25, 2015, 09:21:00 am
content: There aren't that many car audio amplifiers (the TDA1562 and the TDA8511 run both off 12 V, so assuming the same for the broken one is reasonable, also assuming it's a TDA, too) in Multiwatt-11. Also you can assume it's a mono amplifier (since the TDA1562 probably drives the sub and the 8511 the four satellites only the center is left)- TDA2004/5 (mono bridge)- TDA7396 (mono bridge)- TDA7350 (stereo / mono bridge)- TDA7269/7263 (stereo, actually dual supply, but it could be used as a bridged single supply amp)Most likely candidate is imho the 2004/5.

author: codeboy2k
author_rank: Super Contributor
timestamp: May 25, 2015, 09:28:57 am
content: it's a Creative CT1975-SAMYou can find them on taobao, aliexpress and ebay.It's supposed to be TDA7360 equivalent, according to da' interwebs.

author: dom0
author_rank: Super Contributor
timestamp: May 25, 2015, 09:36:12 am
content: 7350/7360 are nearly identical ; you'd only need to change pins 2 and 4 (see datasheets).

author: kahvikello
author_rank: Newbie
timestamp: May 25, 2015, 09:56:01 am
content: Amazing! thanks!
Help needed to fix Pure Evoke 1 Digital Radio. - Page 1
Forum section: electronics / repair

author: Aksol
author_rank: Newbie
timestamp: May 20, 2015, 10:43:58 am
content: PURE EVOKE 1s DIGITAL RADIO PLUGGED IN AND IS TRYING TO PLAY.THIS WILL PLAY A FEW SECONDS THEN START TO RETUNE, AS PHOTOS SHOW THE DISPLAY GOES FROM THE PURE LOGO TO RETUNING THEN BACK AGAINANY ONE OUT THERE WHO GOT AN IDEA OF WHAT NEEDED TO BE DONE?

author: orbiter
author_rank: Frequent Contributor
timestamp: May 20, 2015, 10:48:32 am
content: Before you pull it to bits check to see if there's a factory reset proceedure for your model... Some of the DABS ive worked on just needed a reset after going into some weird loop.

author: Aksol
author_rank: Newbie
timestamp: May 21, 2015, 07:54:51 am
content: Thanks very much orbiter, I have tried resetting to factory default but the problem persist.

author: Shock
author_rank: Super Contributor
timestamp: May 21, 2015, 01:18:48 pm
content: Is it under warranty? Have you contacted the manufacturer and asked if they know what the problem is and if it needs repair or exchange under warranty?If not, can you tell us your electronics repair experience?What electronics troubleshooting you have done so far (in detail)?What tools do you have to diagnose and repair it?

author: g0uli
author_rank: Newbie
timestamp: May 24, 2015, 10:42:09 pm
content: The interconnect plugs between the various internal modules can develop a bit of surface corrosion. I have had great success just unplugging and plugging everything back in a couple of times to clean up the connectors. Take the opportunity to lightly brush any dirt or dust out of the innards while you are in there too. Some of the devices used are static sensitive, so take the usual precautions to avoid static discharge.
Help needed to repair my Pure Tempus-1 digital radio receiver - Page 1
Forum section: electronics / repair

author: Aksol
author_rank: Newbie
timestamp: May 13, 2015, 10:47:16 am
content: Pure Tempus-1 blue dash board on. There was no display. The radio is not working.Please help

author: g0uli
author_rank: Newbie
timestamp: May 24, 2015, 10:48:30 pm
content: Quite a few of the Pure radios seem to develop high resistance on connectors linking internal circuit boards after a few years. Opening up the radio and unplugging and replugging in all the connectors can very often be successful in restoring the radio to life. There are some static sensitive components on the boards, so take the usual precautions to avoid damaging anything with static discharge. I have had considerable success restoring Pure radios to life with this method.
Keithley 213 quad voltage source nvram - Page 1
Forum section: electronics / repair

author: cncjerry
author_rank: Unknown
timestamp: May 24, 2015, 05:06:50 pm
content: I picked up a keithley 213 quad voltage source out of curiosity. It's capable of pretty accurate voltage sourcing up to +/- 10v and can be used as an 8192 point voltage step generator as well.At power on it indicates a 'ram' failure. It uses a socketed common ram chip with battery backup. It also had a rom for programs. I assume the ram lost battery power. The startup checks the ram, rom, and then the ram checksum. If it lost battery backup, I would assume the last test (checksum) would fail. I don't know how they test the ram. The question is if they can detect the ram has failed other than a checksum, I assume they read a known location for valid data? if that is the case replacing the ram and battery won't do any good, correct?I opened a case on eBay as the seller's picture had only the power light lit indicating a good power on test whereas it fails when I power it on with blinking lights. So I expect to return it unless a new ram (without an image) will fix it.Any experienced 213 users out there?
Pinout EPROM MSM3758 - Page 1
Forum section: electronics / repair

author: olliisit
author_rank: Newbie
timestamp: May 21, 2015, 01:34:25 pm
content: I have an older German made milli ohm gauge.I wanted to save the Firmware of this device , but the EPROM OKI MSM3758AS (M3758AS) is unknown by my programmer.Maybe the EPROM is compatible to standard types - but i could not find a datasheet or Pinout.Could someone help ?

author: amyk
author_rank: Super Contributor
timestamp: May 21, 2015, 02:17:37 pm
content: When was it made? Youi can try looking at these:http://ftp.df.lth.se/pub/bitsavers.org/pdf/oki/_dataBooks/...but at least from the '82 and '86 ones it seems a 37xx is RAM, not ROM.

author: wraper
author_rank: Unknown
timestamp: May 21, 2015, 02:23:25 pm
content: Quote from: amyk on May 21, 2015, 02:17:37 pm

author: wraper
author_rank: Unknown
timestamp: May 21, 2015, 02:31:59 pm
content: Could be compatible (at least for reading) with 2758 eproms.

author: wagon
author_rank: Frequent Contributor
timestamp: May 24, 2015, 11:52:16 am
content: Quote from: amyk on May 21, 2015, 02:17:37 pmWhat a ripper resource. Thank yoU!

author: olliisit
author_rank: Newbie
timestamp: May 24, 2015, 12:57:26 pm
content: Hello all ,Sadly the Problem is not solved.I get my hands on a old Data I/O 288A Programmer which supports 2758 Devices.I used the old programmer with a really old PC with MS-DOS - but i coud not establish communication with the programmer.After all i found the solution about the correct Interface cable pinout.See attachment for a working ! interface cable.The interface cable which was part of the programmer i got was not working (incorrect pinout).But even these old programmer cannot read the MSM3758 EPROM.The ..2758 devices i tried leads to a read error.i tried several other eproms i have - reads all without problems (& file saving). --> programmer is working correct.The gauge i have is working --> Original EPROM is intactMaybe the device have a special Pinout or whatever .So i am still looking for a original MSM3758 datasheet to narrow down my problem

author: amyk
author_rank: Super Contributor
timestamp: May 24, 2015, 01:57:47 pm
content: Try asking Oki, or reverse-engineer how it's connected on the original device. If it's connected to a CPU it should be relatively easy to determine the pinout.
New LCD screen for the Fuji Finepix JZ500 camera! - Page 1
Forum section: electronics / repair

author: simmiv
author_rank: Contributor
timestamp: May 24, 2015, 08:07:31 am
content: I managed to drop my Fuji JZ500 Digital camera some time ago. It kept on working fine, but he LCD screen developed a black spot! I don't use it much as I, like most people use the smartphone camera for most things! However it simply annoyed me that this black spot was there. I managed to get a replacement screen from China for about $14 including shippingIt's dead simple to replace it..Here you can see the black spot!Simply remove the screws from the back side. Three on the bottom as shown here and then two on either side, plus another two one one side under the chrome strip.Then you can simply flip off the back cover and expose the LCD screen within it's holding frame. Here you can see the camera open and the new LCD part.The LCD simply flips out to the right and you pull up a black strip on the connector and remove the cable.Then simply insert the new one, flip the black strip down again and close it all up. For fun I put the broken LCD under the microscope to see the bad pixels.Not much to see, but something must have hit the area and caused the pixels to go to pixel heaven!This is a low cost and easy repair to perform..

author: wraper
author_rank: Unknown
timestamp: May 24, 2015, 08:58:24 am
content: There is round crack in the internal glass layer.