hybridfree/eevblog-posts huggingface dataset:
yihua 852d+ pot value? - Page 1
Forum section: electronics / repair

author: ironman187
author_rank: Newbie
timestamp: June 26, 2018, 11:08:32 pm
content: Hey all, I have a yihua 852d+with a bad air pump control pot. I tried replacing it with another 500ohm pot, it works, but it smokes, and gets hot. Obviously it's not rated for the amperage the fan control is pushing. Unfortunately I misplaced the original pot, but it didn't have a part number on it anyway, so it wasn't useful. Does anybody know what the direct replacement is? Better yet, has anybody replaced it with one that has a switch?
WaveTek function generator - unexpected amplitude in MHz range - Page 1
Forum section: electronics / repair

author: beowulfenator
author_rank: Contributor
timestamp: June 16, 2018, 03:07:44 pm
content: Hi!I got my hands on an oldWaveTek model 20 2MHz function generator. The schematics are available:http://bama.edebris.com/manuals/wavetek/20/My unit works, but at higher frequencies there is some attenuation for all three waveforms (sin, triangle, and square). At 200 KHz and below the amplitude is the same, but as the frequency increases, the amplitude goes down. At 2MHz the amplitude is about half of what I have at 200 KHz. This attenuation happens at all amplitude settings, so 20V p-p goes down to 10V p-p and 4V p-p goes down to 2V p-p.I'm using a 10MHz scope with a 10MOhm/40pF input. The manual suggests to terminate the cable with a 600 Ohm resistor, and I'm not doing that (can't do that easily, the scope uses an unusual connector and its pins are not exposed).Is this the expected behavior of this generator?

author: David Hess
author_rank: Super Contributor
timestamp: June 16, 2018, 09:12:11 pm
content: That much amplitude variation is consistent with the specifications so I suspect it is working fine. Unlike most function generators, it has a 600 ohm output impedance intended specifically for audio applications instead of 50 ohms for general purpose use.You can still use it in 50 ohm applications but the output amplitude will be reduced to 1/13th or by 22.3dB. There is nothing wrong with using it without any termination for a higher output voltage.

author: beowulfenator
author_rank: Contributor
timestamp: June 26, 2018, 06:10:21 am
content: Thanks! Now all I need to do is to modify it to accept a modern battery type!
LeCroy 9354AM broken knob repair - Page 1
Forum section: electronics / repair

author: exit_failure
author_rank: Regular Contributor
timestamp: June 25, 2018, 08:36:10 pm
content: A couple of days ago, I bought a LeCroy 9354AM in good working condition. The only things that was wrong with it, were some broken off knobs, including volts/div and time/div:Dave Jones' has a video about how to disassemble the larger parts of a 9384C. It's exactly the same for a 9354AM except that mine doesn't have a floppy drive but a built in printer with a much shorter cable under the top cover.After undoing two screws at both sides of the case, continue by unplugging the two ribbon cables connecting the CRT driver with the main processor board. Now you can pull the whole front panel including the CRT away from the main chassis (see Dave's video.)Undo the four screws securing the control panel to the front cover.Lift the keypad out of the font panel and guide the ribbon cable gently though its cut out. (Here, the replacement knobs are already in place since I forgot to take pictures of those steps before the repair.)Pull the key pad's flat flex connector out of its socket.Undo the screw holding the front cover and the PCB together.One of the broken knobs. My first plan was to buy replacement part and just solder them in. The parts I would have needed were three Bourns ECW1D-Y32-BC0024 and one Bourns ECW0D-Y32-BC0024. These exact parts weren't really available in Germany but I found compatible ones with different axes on Mouser and Digikey. German electronics shops didn't have them unfortunately. The 20€ for the parts would have been ok but the 20€ postage pushed it over the limit on what I wanted to spend on the repair and since the rotary encoders that were already in the scope still worked, I looked for another solution:I searched a couple of local euro-shops and found these 7mm knitting needles and some epoxy totalling 4€Since 7mm where too thick (doh!) I had to sand them down a millimetreI cut them to size and used my dremel to cut a tongue on one end and the respective groove into the axes of the encoders.I glued the knitting needle pieces in place with the epoxy, let it set and cut them to length using a little circular saw blade for my dremel.Reattaching the front coverI had some knobs that fit quite well lying around from another project.Works like a treat.The only thing left to do is replace the incredibly loud fan in the back of the 'scope. I already ordered a replacement fan and will put it in next weekend./editspelling

author: precaud
author_rank: Frequent Contributor
timestamp: June 26, 2018, 01:23:52 am
content: Nice work! I look forward to hearing about the replacement fan's noise compared to the original. I have a 9430 that I'd like to quiet down a little in that department...
Power Switch (table saw) with one way turning screws? (how to open) - Page 1
Forum section: electronics / repair

author: onesixright
author_rank: Frequent Contributor
timestamp: June 24, 2018, 02:51:44 pm
content: Hi All,I need to replace the power cable of this switch. Its from a table saw, but as you can see on the picture the screws turn only one way (I think)I can order a complete new unit (E 80), but only the cable is broken (E 6)Anybody a clever idea how to deal with this ? And I don't mean cutting the cable :-) and put a new connector on it..I would like to replace the whole cable from the socket into the box.Thanks!

author: Monkeh
author_rank: Super Contributor
timestamp: June 24, 2018, 03:01:25 pm
content: Usually you just press harder to stop the screwdriver sliding off...Alternatively, just cut a slot in them.

author: cheeseit
author_rank: Regular Contributor
timestamp: June 24, 2018, 03:24:34 pm
content: Or use locking pliers/vise-grip to remove them, then throw them away and replace with something sane.

author: BradC
author_rank: Super Contributor
timestamp: June 24, 2018, 03:59:42 pm
content: If the other good and easier suggestions fail, I'd drill a hole in each and use a left hand extractor (like an ez-out). Failing that, a left hand drill bit. If that fails and it's not surrounded by plastic then I'd TIG a bolt to the head of each screw and back it out with a socket. The heat of the TIG loosens it up nicely.

author: alpher
author_rank: Frequent Contributor
timestamp: June 24, 2018, 04:05:28 pm
content: https://www.mcmaster.com/#one-way-screw-remover-screwdriver-bits/=1dfb9l1

author: james_s
author_rank: Super Contributor
timestamp: June 24, 2018, 04:05:56 pm
content: If the heads protrude above the surface you can file a slot in them to use a standard screwdriver.

author: Monkeh
author_rank: Super Contributor
timestamp: June 24, 2018, 04:06:21 pm
content: Quote from: alpher on June 24, 2018, 04:05:28 pmTrust McMaster to have a $20 solution to a $0 problem!

author: james_s
author_rank: Super Contributor
timestamp: June 24, 2018, 04:22:57 pm
content: If you're paying an employee to do work that requires occasional removal of such screws, $20 for a tool that makes it easier is a bargain. Sure for someone who only needs to do it once there are other ways but if I regularly encountered 1-way screws I'd buy a set of those tools.

author: nanofrog
author_rank: Super Contributor
timestamp: June 24, 2018, 04:26:13 pm
content: Quote from: Monkeh on June 24, 2018, 04:06:21 pmThey'd be useful in paid jobs. Removing bathroom partitions in public restrooms for example (remodel).Edit:james_sbeat me to it.

author: onesixright
author_rank: Frequent Contributor
timestamp: June 24, 2018, 08:27:13 pm
content: Thanks all!Sent from my iPhone using Tapatalk

author: ignator
author_rank: Regular Contributor
timestamp: June 25, 2018, 02:09:32 am
content: I would use a Dremel tool with a cutoff blade, and grind a standard screwdriver slot. I didn't see that suggestion.
Fluke 725 repair  - Page 1
Forum section: electronics / repair

author: Pumbaadk
author_rank: Newbie
timestamp: June 19, 2018, 07:15:28 am
content: Hii Just got a Fluke 725 it in good physical condition, but unable to soures mA, in the display it just says OL, and nothing comes out of the terminals. I have check the fuses and all are okay, And nothing looks burned inside, I notes that there are some relays and the connected runs to the mA terminals and have not checked them, don´t if it could be them ?Does any of you have a schematic,or know what to look for ?

author: Squarewave
author_rank: Frequent Contributor
timestamp: June 24, 2018, 09:29:25 am
content: I'd be surprised if a 725 could be easily repaired given all the miniaturisation inside one, but someone may be able to.What are you trying to drive in mA source? I'm assuming you know that what you're driving is working ok?

author: PTR_1275
author_rank: Frequent Contributor
timestamp: June 24, 2018, 10:28:49 am
content: Is the Ol flashing?Which fuses did you check? That sounds familiar to one of the issues I had with a 725 and it ended up being a blown fuse. One of the odd looking 2 pin push in fuses
Calculator Texas Inst. TI-30 (old model) some keys not responding? - Page 1
Forum section: electronics / repair

author: Peter63
author_rank: Contributor
timestamp: June 17, 2018, 10:15:24 am
content: HelloMy old Texas Instrument TI-30 calculator, not working. Some keys not responding? Any tips for cleaning or ....Peter

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 19, 2018, 08:55:23 am
content: I do not know the model well enough to advise on the keyboard, if they are soft rubber contact keys usually a little abrasion on a cotton textile is enough, you need to get any "shine" off the rubber, make them look even and dull.Keyboards with metal domes are more annoying, you'll usually have a brown/black layer of oxidation where the dome circumference rests on the PCB, that needs cleaning off.The most delicate still are keyboards with conductive deposit on mylar, they also suffer from brown oxidation.Avoid solvents/contact cleaners on any keyboard that uses silver or carbon deposits on plastic.Usually IPA is ok for carbon deposits on a PCB.In any case start by looking for a cut track due to battery corrosion.My tool of choice for cleaning contacts (Notice I have no tool of choice for cleaning my workbench...):

author: Peter63
author_rank: Contributor
timestamp: June 21, 2018, 04:37:47 pm
content: Yeeehaa!!After some cleaning tips from shakalnokturn, my Texas Instrument TI-30 from 1979 is now up and running

author: drussell
author_rank: Super Contributor
timestamp: June 22, 2018, 03:11:20 pm
content: Hmm... I have one of those red-bubble-display TI-30s somewhere. It was my firstREALcalculator. I wonder where it is, as I don't recall seeing it for many years, though it is probably around here someplace.I love how the digits kind of "roll up" on themselves when it calculates something, then you see it shift the answer back in. A really nifty unit and a true classic.I should see if I can figure out where I've stashed it.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 22, 2018, 03:37:13 pm
content: One additional tip: if the operations on the calculator seem erratic, change (or charge) the battery - the calculator gets to a brownout state and can't properly discriminate between a single or multiple button presses, or sometimes it gets confused by which key was actually pressed.Brownout circuity was not yet invented at that time...

author: Peter63
author_rank: Contributor
timestamp: June 23, 2018, 03:05:37 am
content: After 30 sec the calculator scrolls a decimal point on the screen (power saving mode). I recall that sometimes in the 80' when i used thiscalculator most, it was irritating short power saving time (still it is). I measure some current consumtion used my power supply:Power supply setting 7V, 0.100A ( calculator 9V battery normally )Current Display status0.006 Power saving mode (scrolled dots)0.009 1 char0.014 2 char0.017 3 char0.020 4 char0.025 5 char0.028 6 char0.036 7 char0.041 8 charused 0.041 if display is filled with character 8, need to by some 9v battery
Sourcing parts for 3478A? - Page 1
Forum section: electronics / repair

author: TERRA Operative
author_rank: Super Contributor
timestamp: June 18, 2018, 04:19:22 pm
content: I managed to pick up an old HP 3478A in Akihabara for 3250yen today (around $35), a price I couldn't pass up working or not..I got it home and it turn out that it actually powers up and self tests ok, the voltage readout matches my other meters too!Not bad for $35!Funniest part of it all is that I just ordered a 34461A yesterday... Murphy strikes again....Now, I want to fix it up for the bench, and apart from the usual battery and capacitor replacement, there are a few bits I need that I am having trouble finding.I need the current input jack/fuse holder, and also the two little push button caps for the power switch and the front/rear jack selection switch, also case feet too, but I could just 3D print them.Does anyone know where I can find these parts, or even maybe happen to have an old machine they are willing to sell me some parts from?

author: ddcc
author_rank: Regular Contributor
timestamp: June 19, 2018, 12:33:56 am
content: The fuse holder looks fairly similar to the one used on the 34401A. If it's the same, you can get the parts through Keysight:https://www.keysight.com/main/editorial.jspx?ckey=365873&id=365873&nid=-11143.0.00&lc=eng&cc=INor Schurter:https://www.eevblog.com/forum/testgear/rear-fuse-cover-for-agilent-34401a/.

author: TERRA Operative
author_rank: Super Contributor
timestamp: June 19, 2018, 01:42:03 am
content: Nah, the rear fuse cover is ok, I need the front panel one that has the current measurement jack integrated into it. It seems these are somewhat harder to get.

author: ddcc
author_rank: Regular Contributor
timestamp: June 19, 2018, 02:56:17 am
content: Oops, missed that. Looks like you want part numbers 5061-1163, 4135-0415, 4135-0416, and 5040-7201, respectively. The first and last seem to have shown up on eBay in the past, but there's nothing there now. An older thread (https://www.eevblog.com/forum/testgear/hpagilent-snap-in-cabinet-feet-all-the-same/) suggests that you can substitute 5041-8801 for the latter, which are available on e.g. eBay.

author: TERRA Operative
author_rank: Super Contributor
timestamp: June 19, 2018, 03:12:11 am
content: Oh nice, there's one thing struck off the list.Thanks!

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: June 22, 2018, 07:23:06 pm
content: Found two fronts

author: TERRA Operative
author_rank: Super Contributor
timestamp: June 23, 2018, 02:35:25 am
content: PM Sent!
Need dimensions of Hakko (& other brands?) soldering tips - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: June 28, 2018, 04:40:14 pm
content: Hi all-I can't find replacement tips for my aging but good OK Industries pencil. I'm wondering if any other brands of tips would fit.I've attached a photo showing the dimensions of the OK tip. Would you be so kind as to measure your Hakko / other tips to see if I can find one that would fit? Thanks so much....

author: stj
author_rank: Super Contributor
timestamp: June 28, 2018, 05:28:10 pm
content: your handwriting is crap - consider joining the medical profession!what's the inside diameter?

author: cvanc
author_rank: Frequent Contributor
timestamp: June 28, 2018, 06:47:03 pm
content: Quote from: stj on June 28, 2018, 05:28:10 pmLOL I wish this was the first time I've heard that!The I.D. is about 5.1mm. Thanks.

author: helius
author_rank: Super Contributor
timestamp: June 28, 2018, 06:48:31 pm
content: The SAI-640 uses the same tips as the Hakko 900M-T series. Also second-sourced by Vanier, Plato, etc.
Onkyo A-9355 DC Offset measurement  - Page 1
Forum section: electronics / repair

author: stojke
author_rank: Regular Contributor
timestamp: June 18, 2018, 12:31:14 pm
content: Hello, I´m having a hard time trying to figure out how to measure DC Offset on an Linear Class D amplifier. Usually it is indicated to measure on certain test points between two transistors on class A/B and it is usually in 10~25mV range.From this device Service Manual I understood the following:Disconnect speakers, Volume to minimum, no input, Disable Speaker terminal B and enable terminal A, measure at terminal A RED (+) and BLACK (-) and adjust using R5022 and R5021 untill it is either 0V or in tolerance of +/-10mV.What i get as reading is 220mV for LEFT and ~170mV for RIGHT (Where right starts at 0 and climbs up on its own).When trimming i get no difference in values, not down nor up, even when i close or open the trimmers all the way.(EDIT - Measures the same with Speakers connected)Can anybody guess what the problem might be, could it be bad trimmers?

author: stojke
author_rank: Regular Contributor
timestamp: June 19, 2018, 10:24:59 am
content: Bad pots. Managed to get it , measured, down to 0.5mV after an 1h of playback.

author: cvanc
author_rank: Frequent Contributor
timestamp: June 19, 2018, 02:14:54 pm
content: Interesting, did you have to replace the pots or did you just 'exercise' them to clean up the behavior?

author: stojke
author_rank: Regular Contributor
timestamp: June 22, 2018, 07:10:43 am
content: I had to replace them as they were faulty. They increased and decreased the value on their own. On closer look they look melted, like if they were getting hot for some reason, one is also a bit busted.It is probably the one who repaired before me that damaged them because all the transformer wires were either scratched or cut. The person who worked on it also completely cut the CPU/Relay power cable.

author: drussell
author_rank: Super Contributor
timestamp: June 22, 2018, 03:03:30 pm
content: I'm glad you managed to get it working after someone else's butchery...
Protek 9205 Function Generator - Page 1
Forum section: electronics / repair

author: Lee Leduc
author_rank: Regular Contributor
timestamp: June 22, 2018, 12:55:14 pm
content: I have an old non-working Protek 9205 Function Generator. Looks like one of the current sources is not working. I'm looking for a service manual or schematic so I can get it working.I plan to donate it to the local High School electronics club or better yet, use it to show the kids how to troubleshoot and repair it. I emailed the manufacturer but got no reply. I can find the user manual online but no service manual or schematic.Any one know where i can find a service manual or schematic?Thanks.
Replacement fuse for EEVBlog BM235 DMM - Page 1
Forum section: electronics / repair

author: OutbackBob
author_rank: Contributor
timestamp: August 05, 2017, 05:08:30 am
content: Hi Guys,I've blown the fuse on the millamp range of my BM235 metre and can't seem to find a replacement.The milliamp jack on the meter reads "MAX 600ms HBC fused", however the fuse is a "SIBA FF 400ma DMI 1000V 70 172 40".Jaycar have a 500ma, will that be okay (https://www.jaycar.com.au/fuse-for-cat-iv-dmm-1kv-500ma/p/SF2278)?Element14/digikey also only seem to have 500ma fuses.Thanks.

author: Muttley Snickers
author_rank: Unknown
timestamp: August 05, 2017, 05:56:11 am
content: I don't have any spares in that size either so I'm probably due to order some as well, $25 including postage for these is a pretty good deal, anyway I will be sure to leave a review for the fuses on his ebay page just like the other person has done, I found it hilarious.

author: OutbackBob
author_rank: Contributor
timestamp: August 05, 2017, 02:03:12 pm
content: Awesome, thanks for the heads up! Will order now... rather give my money to Dave than anyone else!Thanks Dave!

author: Russ
author_rank: Regular Contributor
timestamp: December 02, 2017, 05:53:22 am
content: I ordered a pack of spare fuses from Dave a couple days ago. What is the normal delivery time to the United States?ThanksRuss

author: AlanS
author_rank: Unknown
timestamp: May 31, 2018, 12:33:10 am
content: I found these:https://www.ebay.com/itm/SIBA-70-172-40-FF400mA-Fuse-Ultra-Rapid-FF-400mA-1000V-DMM-DMI-Fuse-JPSF083-/272037418391?var=570850656334and thesehttps://www.ebay.com/itm/SIBA-50-199-06-10-x-38-mm-DMI-Fuse-Pick-Your-Rating-type-gR-1000V-5019906/272213230269?hash=item3f612c42bd:m:mtYRA2b2s-BQ8l4GCpMf9ww

author: iainwhite
author_rank: Unknown
timestamp: June 01, 2018, 01:26:16 pm
content: Quote from: AlanS on May 31, 2018, 12:33:10 amI bought from this seller (before Dave started carrying the fuses) and can confirm they are correct (i.e. match the installed SIBA fuse).

author: Russ
author_rank: Regular Contributor
timestamp: June 01, 2018, 03:09:26 pm
content: Thanks.

author: AlanS
author_rank: Unknown
timestamp: June 22, 2018, 02:17:44 am
content: These arrived within a week of order. Good service.
Ctek MXS 5.0 Resister R26 burnt out - what it the resister value - Page 1
Forum section: electronics / repair

author: basilcedric
author_rank: Newbie
timestamp: November 26, 2017, 11:56:35 am
content: HI, My Ctek MXS 5.0 has died. It was purchased in Aug 2011 so is out of warranty. A quick inspection shows that R26 is burnt out. It is blackened so much that I can not read the color code to determine what value resistance to replace it with. You can see from the photo that the first ring is brown so I know the first digit is 1 but that's it. Has anyone got a MXS 5.0 apart (or kind enough open it - assuming warranty has expired) that can tell what value to use or post a photo of R26. I have looked at the tear down featured in another article on this site and the photos unfortunately do not show R26. Has anyone else had this problem and repaired it?R26 =?? ohms?

author: Vetor
author_rank: Newbie
timestamp: May 17, 2018, 10:37:50 pm
content: I also have a MXS 5.0 that sttoped working. My model is a 220V but the differences in the circuit board suggest that mine has a newer layout.I found this topic because my also broken but has not such resistor. At least I can compare the circuit and tell you what's the value of the one that seemed be replaced by a SMD. Can you tell me between it's connected to?

author: Brettv
author_rank: Contributor
timestamp: May 21, 2018, 02:11:06 am
content: old post... same model, but different revision.In case it helps, pic attached.

author: Shonky
author_rank: Frequent Contributor
timestamp: June 17, 2018, 11:09:00 pm
content: Mine just died recently. I got around to pulling it apart. My R26 is damaged but not as bad as yours and measures open circuitColours appear to be orange, orange, black, silver, gold which I now put at 3R3 (330 x 0.01 5%). Does that seem right? I originally read it as 33R (ignoring the 4th band). Looks to be about 2W?

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 21, 2018, 04:20:52 pm
content: The one shown with orange, orange, and black, silver and gold appears to be 3.3 ohms 5%
1979 Atari Asteroids with no video other than a dot in the middle of the screen - Page 1
Forum section: electronics / repair

author: Vohlf
author_rank: Newbie
timestamp: June 21, 2018, 03:16:22 am
content: Hello all,I am not an electronics guy but was wanting to see if I could repair the issue I have with some help. I have a 1979 Atari Asteroids arcade machine that has no video other than a dot in the middle of the screen after adjusting a pot on the circuit board connected to the monitor. The board hooked up to the monitor shows a red light when the game is on. There appears to be some type of power supply as well on the other side, it is a silver box and hums pretty loud. Game play works and so does the sound. I appreciate any help provided, I would really like to keep my original monitorThanks!

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 21, 2018, 03:30:58 am
content: A dot in the middle of the screen suggests the deflection coils aren't operating, which could be any number of issues, from power to an input signal problem to the display. The chances are the whole system will need checking over, and probably a lot of capacitors replaced, and with the high voltages involved, I wouldn't recommend you attempt this with little experience. I'd look for someone local who is competent with electronics to go through it, and bring it back to life. I say this, as there's some pretty high voltages (1,000s) kicking about some of those circuits, and it's far from an ideal first project if you are unfamiliar with electronics and safe ways of working with high voltages.Get someone with experience to help you. In Person.

author: floobydust
author_rank: Super Contributor
timestamp: June 21, 2018, 03:48:41 am
content: Wait - this is a vector display, so no signal to the monitor just gives a dot in the center of the screen.Don't leave it like this long, it can burn the phosphor.The main board might be dead, so no signal being made to the screen.More info and manuals:https://www.arcade-museum.com/game_detail.php?game_id=6939

author: Cyberdragon
author_rank: Super Contributor
timestamp: June 21, 2018, 04:27:29 am
content: The schematic scans on that site are terrible. Total garbled mess of chopped up bits. I have yet to find the flyback driver, that'll tell you what voltages are good.

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 21, 2018, 02:16:27 pm
content: Quote from: floobydust on June 21, 2018, 03:48:41 amI'd never come across a vector display before. I thought it was just like an ordinary CRT. Thanks for the lesson.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 21, 2018, 02:23:30 pm
content: Quote from: Vohlf on June 21, 2018, 03:16:22 amLooks like you need to become one!Have you seen this...http://arcarc.xmission.com/Tech/Asteroid%20Tech/asteroidsrepair.htmland an old thread...https://www.eevblog.com/forum/repair/asteroids-arcade-game-vector-issues/and... youtube videos....
TEK2213a Service Manual - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: June 15, 2018, 07:27:45 pm
content: Can someone point me to a SERVICE Manual for Tektronix 2213A? It has to be the A version.I found an user's manual but not the service manual. Thank you.

author: cheeseit
author_rank: Regular Contributor
timestamp: June 15, 2018, 10:01:59 pm
content: I searched the usual places and googled a bit as I'm sure you have too but no dice.ArtekManualshas it.Edit: I meant searched for one that was free to no avail, then checked Artek

author: David Hess
author_rank: Super Contributor
timestamp: June 16, 2018, 10:44:26 am
content: Except for the dual delayed sweep, the 2215A is the same oscilloscope so the 2215A service manual can be used.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: June 16, 2018, 10:54:33 am
content: You have to sign up but is free.http://ebaman.com/files>electronics>scope>tektronix>2xxx second page at the top

author: tkamiya
author_rank: Super Contributor
timestamp: June 16, 2018, 09:32:34 pm
content: Thanks.Yes, I found one at ArtekManuals but I was looking for a free one. Maybe I shouldn't be so cheap.With information that 2215A is essentially the same, I found the portion I was looking for.Thank you very very much.My scope collection is multiplying!

author: Chris56000
author_rank: Frequent Contributor
timestamp: June 20, 2018, 06:20:06 pm
content: Hi!https://www.dropbox.com/s/3w6jp7qd75v5u2g/Tek%2B2213A%2BOscilloscope%2Bebaman.pdf?dl=0I found I had no problems reading any of it!Chris Williams
Siemens Thyristor SPNO 3RF23101AA02 shorted - Page 1
Forum section: electronics / repair

author: applecruncher1
author_rank: Newbie
timestamp: June 20, 2018, 09:02:48 am
content: Hi,We have a jacketed tank with a heating element (220 VAC, 650W) that is connected to a Siemens Thyristor SPNO 3RF23101AA02 as shown in the picture below. Our tank has a "Day", "Night", and "Off" options that can be controlled with a SP3T switch that determines whether to heat the tank to 45C, 31C, or no heating at all respectively. My problem is that the leads (1 and 2) of the Siemens Thryistor are normally closed even when its switch supply (A1 and A2) is not energized. Because of this, even when the SP3T is set to "Off" option, the heater is turned on.This is how it looks like with the front cover removed:Removing the pcb, I think underneath is some sort of a circuit inside a silicon gel. I tested the leads 1 and 2 and they are shorted. Sorry I do not know what I'm seeing below as I have a limited knowledge in electronics. Is this supposed to happen? The Siemens Thyristor is an NO contactor so there should no connection from Lead 1 to Lead 2 in the first place. What could be the cause of this?Thanks,
Topward 6303D - 25V max - Page 1
Forum section: electronics / repair

author: Mr_Chupon
author_rank: Newbie
timestamp: June 07, 2018, 04:21:38 pm
content: Hello,I'm trying to debug a broken Topward 6303D. The maximum voltage that I can reach on one of the channel is about 25V at which point the power supply start draining 0.09A.On the other channel, the relay clicks at about 25V and then I can reach 30V no problem.This is only my first steps in debugging a power supply and my first intuition would be to simply change the relays since it doesn't seems to change state.Could you guys give me a couple pointer that I could check to debug why the power supply cannot reach 30V?Thank you

author: Mr_Chupon
author_rank: Newbie
timestamp: June 13, 2018, 06:54:48 pm
content: Hello,I've been trying to find the problem of this and I think I found the relay that doesn't click it's L6.On the channel that works I can hear 3 clicks. One at about 7.5V, one at 16V and one at 24.5V. On the channel that doesn't work, I only hear one click at 7.5V which I guess is L7.I was wondering how to make sure this is the problem. I was thinking of desoldering L6 and manually switch between 18V and 32.5V.Could someone suggest me a way to debug this problem?Thank you*** Made a little mistake here it's not L6 but L2.

author: Mr_Chupon
author_rank: Newbie
timestamp: June 15, 2018, 07:14:12 pm
content: Little update:I don't think it's the relay the problem anymore. I got the old oscilloscope out and started probing around. It seems that Q3 is not responding like the transistor on the working channel. I get only 20V max on the base of Q3. On the other channel it goes beyond that. So my guess is that Q2 doesn't turn on so the relay is never switched.So I guess the problem lies in the rest of the circuit. Unfortunately it's a little more involved than I would of liked.So the next part is to reverse engineer all the 741 functions and check the regulator 78L12.Help would be appreciated if you guys ever saw similar circuits or part of it. For examples the potentiometer VR1, VR2.

author: Shock
author_rank: Super Contributor
timestamp: June 20, 2018, 07:17:53 am
content: Can you post the full schematic or all the full pages you have?After the channel switches the transformer taps at the relays it goes to the rectifier circuit and the filtering cap (i.e. C22), you want to monitor voltage there for a start to see if you are getting a comparable voltage level between channels.The idea would be to see what minimal voltage can supply current (without issue) on the defective channel to narrow it down.As for comparing the transistors, measure each collector/base/emitter voltage (channels set the same) and if unsure show where and what you are measuring then include it on an edited schematic in a post here.If you suspect a specific transistor due to the voltages seen, test it in circuit then pull it out and test out of circuit.
Leader 3216 AM/FM Signal Generator_AM/FM no output signal  - Page 1
Forum section: electronics / repair

author: anupong1983
author_rank: Contributor
timestamp: June 22, 2018, 06:11:08 pm
content: Hello All,I'm hoping someone out there can give me a bit of insight into this.I tried to repair RF board of Leader 3216. the 3216 no AM/FM output signal (RF level is fine) measured by measuring receiver.I don't know which parts are AM/FM block on RF board because I don't have circuit diagram.kindly advise if you know which parts are AM/FM block and also advise which component is defective.Hope anyone can help to find out this case, I will so appreciate.Thank you so much.Anupong
8W LED Bulb - From 220VAC to 120VAC - Page 1
Forum section: electronics / repair

author: lynspyre
author_rank: Newbie
timestamp: June 16, 2018, 07:28:16 pm
content: Hello everybody,A friend brought me from Spain (220VAC) a LED Bulb (8W / ~40mA). As an electronics enthusiast, I decided to give it a try and see how it was powered on and if I could make it work on 120VAC.Here are some pictures of it and the schematic I drawed.Thanks in advance.,

author: Seekonk
author_rank: Super Contributor
timestamp: June 17, 2018, 01:45:26 am
content: Seems to have a lot of resistance for 8W. Does it currently work at all at 120V? If it does, you could just lower the resistance. Measuring the voltage on the LED will help determine what it needs if it does illuminate somewhat. Might be just easier to jumper the resistor and run a capacitive to vottage doubler in the base of the lamp it is used in.

author: lynspyre
author_rank: Newbie
timestamp: June 17, 2018, 02:44:20 am
content: It runs at 220VAC, as stated in the package. It also says it's dimmable, I haven't tried to run it at 120VAC yet, i'm looking for an isolating transformer. I openned because some LED bulbs come with transformer baser circuit and if I run it at 120VAC I would have toasted it.I measured the LEDs, as the have partial "wire" outside the silicone protection, I managed to power each one with the DMM diode mode, but got no reading on voltage drop. Don't know why, DMM is good, i've recently repaired an 3D Printer SMPS with it, and readed voltage drops of its diodes.

author: SeanB
author_rank: Super Contributor
timestamp: June 17, 2018, 04:22:27 am
content: You would not get a forward voltage drop on the LED itself because the forward voltage drop is around 3V, and your meter likely only shows up to 1.999V in diode test, though it might put out up to 4V open circuit in that mode. However those LED strings have a typical forward voltage drop of around 100V, if they are all LED's in series, or a forward voltage of 3V if they are all in parallel. You can just plug it straight into 120V and see if it lights, and if so just use it that way, otherwise you will have to fit into the inner space a voltage doubler to run it off 120VAC.As you already have one capacitor and a bridge rectifier all you need is another 15uF 400V capacitor, and unsolder the negative lead of the existing capacitor, add the new one positive to it, connect the new one negative to the hole you unsoldered from, and then remove the power lead not soldered to the resistor, and solder it to the junction of the 2 capacitors, and you have the voltage doubler that will light it on 120VAC.

author: lynspyre
author_rank: Newbie
timestamp: June 17, 2018, 04:54:34 am
content: It should be something like this, right?

author: SeanB
author_rank: Super Contributor
timestamp: June 17, 2018, 10:50:54 am
content: Pretty much right.
Casio FX-602P - Page 1
Forum section: electronics / repair

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 15, 2018, 08:41:57 am
content: I know this is a long shot but here goes.My beloved Casio FX-602P that has been with me since my college days has finally errored after more than 35 years.The display, even with new batteries, shows garbled characters and is frozen. It had been left with discharged batteries for a long while.Any quick and dirty possibilities to try would be gratefully received before I admit to the inevitable.Thanks.
CMU200 serial number - Page 1
Forum section: electronics / repair

author: RF_fanatic
author_rank: Regular Contributor
timestamp: May 18, 2017, 06:54:18 pm
content: Does anyone know where the serial number is defined?I have one with serial number 000000 so obviously it losts it's orginal serial number, it happend after an unsuccesfull firmware update board change.I checked the swop and identity file but no clue at this moment.Anyone help would be appreciated

author: Nusa
author_rank: Super Contributor
timestamp: May 19, 2017, 08:03:49 pm
content: See if you can spot any resistor clusters that differ in values between two mainboards. That could be a serial number. Much harder to spot than jumper pads. I remember Dave found some option pins done that way on a Keysight scope teardown a couple months back.

author: Bicurico
author_rank: Super Contributor
timestamp: May 19, 2017, 08:10:38 pm
content: I m on my phone so here is a short quick reply.Try booting into the service menu and run the maintenance.Regards,Vitor

author: RF_fanatic
author_rank: Regular Contributor
timestamp: August 12, 2017, 09:07:33 pm
content: Gentle BUMPStil got serial 000000Doe anyone know how to change it back into the original number?

author: Qw3rtzuiop
author_rank: Frequent Contributor
timestamp: June 29, 2018, 09:13:40 pm
content: @RF_fanaticAny success? I suspect that the serial number is stored on the FMR somewhere. Its not stored on the HDD.
DMM can't detect voltage range above 6V! - Page 1
Forum section: electronics / repair

author: M.David
author_rank: Newbie
timestamp: June 14, 2018, 12:49:00 am
content: Hello,I have a cheap DDM called RICHMETERS RM102 (here's a similar DMM reviewed on the EEVblog: youtu.be/xdGQEVdxmQQ ).When I try to measure any voltage above 6V it can't detect the range and it will try to find it but it can't.Here's a video for the problem:https://imgur.com/a/FSjZ7Gf

author: mikerj
author_rank: Super Contributor
timestamp: June 14, 2018, 08:23:38 am
content: Open it up and take a close look at the PCB for damaged or badly soldered components, or evidence of components that have fallen off the board.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: June 14, 2018, 10:41:46 pm
content: See if it works if you turn off AutoRanging. If so, it may be a software issue.Hope this helps...
HP 4262A, anyone? - Page 1
Forum section: electronics / repair

author: Mrt12
author_rank: Regular Contributor
timestamp: June 14, 2018, 06:15:56 am
content: Hi,I got an offer for a HP4262A. The device looks very nice and powers on, but fails self test. I wonder whether there are any experiences with those?The unit would cost me $100, am I am wondering whether it is worth it concerning that it needs repair. Is it repairable? any experiences here?

author: lowimpedance
author_rank: Super Contributor
timestamp: June 14, 2018, 10:23:13 am
content: See the mini teardown thread of the HP 4274a on here , has quite a bit of info that might help with the decision.One error that you get is simply related to not connecting the input terminals correctly.So maybe nothing wrong with the unit.https://www.eevblog.com/forum/testgear/hp-4274a-lcr-meter-mini-teardown/edit : added link to thread.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: June 14, 2018, 09:05:09 pm
content: Can you find those codes in the manuals?https://www.keysight.com/en/pd-4262A%3Aepsg%3Apro-pn-4262A/digital-lcr-meter?pm=PL&nid=-536900197.536897553&cc=US&lc=eng
Breaking and now trying to fix a sad Tektronix 2245 Oscilloscope - Page 1
Forum section: electronics / repair

author: Ferrix97
author_rank: Contributor
timestamp: June 10, 2018, 05:23:49 pm
content: Hi!I recently paid another visit to the same recycling center where I scored the Keithley 2000. This time I found a Tek 2245 scope in a very sad shape: both front and back plastic covers have cracks in them, the metal chassis is all dented and to top it off one of the knobs (holdoff) is missing. It was also covered with a fine white powder.When I got home I plugged it in and it started working: all four traces and readouts were present on the screen. I din't try feeding a signal into it.Seeing it working I decided to take it apart to better remove all that white powder off of it. Upon opening it, the chassis snagged on Q702 heatsink's and partially pulled out one of it's legs... Doh!At first I didn't notice the damage, but when I turned the scope back on, the display was "shifted" up: the readouts on the bottom were in the middle of the display.Reading online this seems to be quite a common issue:https://bradthx.blogspot.com/2014/01/how-i-accidentally-destroyed-my.htmlUpon desoldering and measuring it out of circuit, it became clear that one of the legs wasn't making contact with the silicon die inside, so having nothing to loose, I carefully cut it open and noticed that one of the bond wires was disconnected. I fixed that and soldered the can back on.Soldered back the transistor to the board and turned it on: it worked again! I then reinstalled the heatsinks and powered it up again. This time around the screen was shifted again, but the other way around! now the trace would sit in the middle with the position set to the top.Measuring the transistor again results in a collector-emitter short...Does anybody happen to have a spare transistor lying around? In the meantime I'll get a 2N3866 to see how it behaves. The main difference between the two is that the base is tied to the case on the original 151-0846-00 part, while on the 2N3866 the case should be tied to the emitter. The pinout between the two is also different (it should be "flipped").To alleviate that I was thinking about covering the case in thin kapton and then soldering a wire from the base to the heatsink. Is that a good idea?Thanks!

author: Ferrix97
author_rank: Contributor
timestamp: June 14, 2018, 07:51:59 am
content: Fixed!The 2N3866 works perfectly as a 151-0846-00 replacement. They just have a different pinout (https://groups.io/g/TekScopes/topic/7658065?p=,,,20,0,0,0::,,,0,0,0,7658065)Quote

author: Terry01
author_rank: Frequent Contributor
timestamp: June 14, 2018, 08:03:03 am
content: Nice fix! I hope it lasts and that you get the rest of it fixed up ok. Pretty cool!
Lecroy 7200 repair - help sought - Page 1
Forum section: electronics / repair

author: pushpin
author_rank: Newbie
timestamp: March 20, 2018, 01:53:16 pm
content: Hi folksI have an old 7200 that I am restoring. But to get this beast up and running I need a rotary switch for the Timebase Control.As with many of these machines, this one has decided to give up the ghost.It is marked on the circuit as RSW 1 and it belongs to a 7242 plugin.Or maybe a Lecroy lover can identify it enough for me to find a replacement.BestAlan

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 21, 2018, 08:06:09 pm
content: Hello,I do not know if you can still find these parts new anywhere.I'll check my stash as I do have some 7200 bits around. (Well I for sure have a 7242B with one good channel, not sure if it should be parted out yet or sold as-is.)Try the LeCroy yahoo group there maybe people there who know better for parts sources.

author: pushpin
author_rank: Newbie
timestamp: March 21, 2018, 08:10:31 pm
content: HiI've tried as many sources as I can. Lecroy themselves are looking for a match but I doubt if they will have one in stock, but they may be able to point me in the direction of the manufacturer of the 12 pos switch.Tried the yahoo group but no joy as of yet.If you find any bits that you think might help just let me know. I'd be grateful.

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 22, 2018, 06:26:15 pm
content: I had a few rotary switches removed from a front panel but they are all in poor condition, good enough to read "AB elektronik" from the rim though.The closest match is the AB elektronik / TT electronics / AVX Type 419 series if those can still be bought anywhere. The shaft will probably need shortening to fit the 7200.If that option fails let me know I'll part my 7242B out....

author: shakalnokturn
author_rank: Super Contributor
timestamp: March 22, 2018, 08:08:08 pm
content: http://www.abelektronik.com/fileadmin/images/Produkte_und_Datenblaetter/Datenblaetter/Bauelemente/E_419.pdfhttp://www.ttelectronics.com/themes/ttelectronics/datasheets/transport/components/419.pdfhttps://produktinfo.conrad.com/datenblaetter/700000-724999/705713-da-01-ml-Miniatur_Drehschalter417_1x12_de_en.pdf

author: pushpin
author_rank: Newbie
timestamp: March 22, 2018, 09:05:54 pm
content: It's very kind of you to find this information.I've ordered one of these switches from Conrad Electronics. My only concern is that the original has small round pins and this switch seems to have normal size connectors - still pins but they seem slightly larger, and the solder pads on the board are very small.When I receive it I'll let you know how I get on. I wouldn't want you to part-out the plug-in as it might be useful to you in the future but if you ever want to sell it just let me know.Al

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 12, 2018, 10:38:43 pm
content: Did this turn out as a repaired plugin?
Scam warning(?) - TVRepairKits.com (service manuals) - Page 1
Forum section: electronics / repair

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: June 14, 2018, 01:19:32 am
content: Following some helpful advice here about repair my CRT TV, I decided to track down a copy of the service manual. I found fragments here and there but I wanted to whole document. I was willing to pay a few dollars.I ended up athttp://www.tvrepairkits.comand duly paid $9.95. After taking my money, they sent me a download link that gives a 404 page not found error.I've contacted them multiple times in multiple ways and have not heard anything from them.Maybe there's a legitimate reason but I decided to flag this here.

author: amyk
author_rank: Super Contributor
timestamp: June 14, 2018, 02:05:22 am
content: Post the model and maybe we'll find it for free

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: June 14, 2018, 02:12:18 am
content: Thank you.Sony Trinitron KV27S22 (1997 vintage CRT).I found a few pages about the service menu settings. I had a lot of fun fiddling around with them

author: Nusa
author_rank: Super Contributor
timestamp: June 14, 2018, 02:20:49 am
content: Hopefully you were smart enough to pay by a method that allows you to file a dispute. e.g. Credit card or Paypal

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: June 14, 2018, 02:26:36 am
content: Of course

author: tsman
author_rank: Frequent Contributor
timestamp: June 14, 2018, 02:29:20 am
content: Removed direct link. Get the Mk1 magnifying eyeballs out for this though as the diagrams are tiny! It isn't too bad if you zoom in 300% though.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: June 14, 2018, 02:45:58 am
content: Wonderful - thank you very much.I've downloaded it and, yes, it's quite fine print in places but readable.Thanks again.
Basic Transistor Replacement - Page 1
Forum section: electronics / repair

author: Bigkim
author_rank: Contributor
timestamp: June 12, 2018, 08:30:28 pm
content: I have 3 transistors that need replacementAre my replacements correct?:1- 2sa945 replaces with 2n22222- 2sd467 replaces with?3- 2sb561 replaces with 2n3904Thanks in advace....

author: MadTux
author_rank: Frequent Contributor
timestamp: June 12, 2018, 08:56:58 pm
content: You can't tell that easy. Look at the schematic, on what the transistor is supposed to do and decide then.Sometimes you can replace exotic transistors with simple ones, if they don't do exotic stuff (low noise, fast, high current....)Sometimes you can't, if the designer used that transistor for a reason.2SD467 for example has lower voltage, but higher current rating than 2N3906.2SD467 IS NPN, 2N3906=PNP, big NONOPinout also doesn't match, either. But that can be fixed with a bit of fiddling ;-)

author: Bigkim
author_rank: Contributor
timestamp: June 12, 2018, 09:13:23 pm
content: Thanks for that npn/pnp heads up, that was a transcription error.All these are used in a rc controller for the 3vdc motor