hybridfree/eevblog-posts huggingface dataset:
TDS754C Schematic - Page 1
Forum section: electronics / repair

author: jhormilla
author_rank: Contributor
timestamp: April 02, 2023, 05:38:11 am
content: Just purchased a TDS 754C on Ebay, now a TDS 784C and would like to have the schematics for it. I've downloaded all the manuals I can find including the service manual but no schematics in it.Any help would be appreciated.

author: james_s
author_rank: Super Contributor
timestamp: April 02, 2023, 06:45:02 am
content: There are no schematics available for most Tek scopes by that era. The only one I'm aware of is a TDS500 or 600 schematic floating around which is close enough to be useful. I'm not sure what I did with it but hopefully someone else will post a link.

author: jhormilla
author_rank: Contributor
timestamp: April 03, 2023, 01:47:28 am
content: Thank you, that's kind of what I thought.
TDS7854D scope with faint and blurry display - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: September 25, 2020, 06:45:43 pm
content: Dear all,I have bought a TDS784D at Ebay some time ago and had no time to test it.When I finally had time to turn it on, I realized that the display is very faint and the image is out of focus.The intensity adjustment available on the menu is already at 100%.I found a very brief adjustment instruction in the service manual and I fumbled on the pots ( after taking a long time to find them) but they seem to be arranged in a different order than the one described on the manual.There is a list of the appropriate voltages to the display module on the display troubleshooting section and all of them are ok.I found one person on Ebay selling a new display module and he mentions that there is a time consuming adjustment procedure for this module, but I could not find it anywhere.I have uploaded one photo of the menu screen to show how out of focus the display is (the file is TDS784D dim display).My questions are:1 - Where can I find a detailed adjustment procedure for the display module?2 - Is there a way to check if the problem is the CRT being "exausted"?3 - There is a company offering the NewScope-T1 Color LCD replacement Kit as a replacement. is this a good alternate in case I need to replace the CRT?

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 26, 2020, 02:23:02 pm
content: 1- Don't know haven't searched. Hakan has most of the Tek TDS goodies around. (http://www.hakanh.com/dl/)2- If all voltages read as expected and picture is poor chances are the CRT is the cause. Low cathode current is usually a sign of a CRT being at the end.3- Don't know the above mentioned kit but LCD (LED backlight) display would be an excellent replacement AFAIK the video output is standard VGA so if the kit's price is a little steep it leaves some room to go and search for other option far-east.

author: rvalente
author_rank: Frequent Contributor
timestamp: September 26, 2020, 03:16:49 pm
content: Does yours have the rgb conn output in the back? Have you tried to hook up a screen a monitor and check the video?
TDS794D display/VGA output problem - Page 1
Forum section: electronics / repair

author: d0ng3o
author_rank: Newbie
timestamp: April 21, 2023, 01:57:58 pm
content: Hi everyone!I recently got my hands on a TDS794D oscilloscope with a CRT display problem (the VGA output on the back worked at the time). Since I was trying to save some money, I decided not to buy and install the LCD conversion kit, just to refurbish the CRT driver board. While I had to get to the guts of the scope anyway, I decided to swap out the DALLAS SRAM and TIMEKEEPER chips as well. I went for these parts:https://www.ebay.com/itm/302913384290.As I worked my way through the scope, I got to the CRT driver board and noticed no significant failures other than that the CRT anode wire had arced to the enclosure and that the high voltage fuse (2.5A 250V, on the CRT driver board) was blown. No leaky caps, no burned/blown components. I then continued by isolating the anode wire with RTV silicone and added some electrical tape to the enclosue in order to further provide isolation. After replacing the fuse, I assembled the scope and gave it a go - that's where the problems began.At first it seemed to boot up normally but then the scope went into some kind of a rapid boot loop, powering up for a second and then shutting down again. I decided to disconnect the CRT driver board from the main board and then the scope would seemingly boot up normally. But now the VGA output on the back does not work as well. I checked all the voltages detailed in the service manual (https://w140.com/tekwiki/images/3/31/071-0627-02.pdf), they were nominal.Then tried the troubleshooting process described in the manual, but the only thing I got on the on-board led display was a flashing code of ".b", on which I did not find any information.So, have I fried the some components on the main board? Is there any hope to fixing it still? Has anyone else encountered anything similar? What should I do next?Thanks for your time!

author: Tantratron
author_rank: Frequent Contributor
timestamp: April 22, 2023, 06:37:46 am
content: Hello, I've got similar issues while repairing a TDS794D and TDS540C in the past.First the anode arcing failure seems unfortunately more frequent issue, for sure it is explained by this very good YouTuber in this video wether for color CRT or mono CRT.Chances are high your CRT driver is dead which then will trip on and off the main PSU wether your CPU board is OK or not. Disconnecting the J5 connector which derives 24Vdc power bus through the logic board will prove then full boot (no power reset) to work, this happened to me with the TDS540C.So either you repair the CRT electronic board or go with a LCD kit.Now there is another topic regarding the CPU (logic) board which you have replaced the NVRAM's to solve another well know issue (battery life then brick of the logic board). Maybe you did not re-program correctly the DS1486 which could then prevent full boot, you need to provide more information.Anyway there are two topics: CRT failure and logic board boot failure.Albert
TDS8200 Adquisition assembly internal test fail - Page 1
Forum section: electronics / repair

author: Perenken
author_rank: Newbie
timestamp: January 22, 2023, 03:26:52 pm
content: Dear colleagues, good afternoon,I've try to repair a TDS8200 and the main problem after now is that the main adquisition board assembly present some errors when I do the internal test (please see the pictures attached)Could you help me with this issue?Thank you in advance.Kind Regards.Xito.
TDS500 TDS700 serie C and D - SPC with I2C installation - Page 1
Forum section: electronics / repair

author: Tantratron
author_rank: Frequent Contributor
timestamp: January 16, 2021, 09:08:48 am
content: On a general note regarding the outputs of SPC run (in my case TDS540C and TDS784C), the bottom of the screen shows from left to right:• Signal Path• Voltage Ref• Frequency Ref• Pulse Trigger• Comm filtersBoth my Oscope do show on the BANNER the 2C option activated, the 4 first items are all PASS but one thing I do not understand, it was easy to set the 2C option through GPIB but it leaves in my case Comm Filters = NOT PRESENTWhat are the conditions (HW and SW) to have Comm Filter to be seen as PRESENT if required by 2C option ?Thanks, Albert
Tea related equipment repair: Kettle from U S of A.... repairable? - Page 1
Forum section: electronics / repair

author: NivagSwerdna
author_rank: Super Contributor
timestamp: February 27, 2020, 05:30:13 pm
content: OK.. it's not a scope... or signal generator or what-not... but it makes tea (and coffee) so is absolutely crucial to my daily existence...Sometime ago I made a more money than sense purchase and bought this swanky Kitchen Aid 'Artisan' kettle...it'swas rather goodSo today it doesn't heat up anymore so I took it apart and measured the element which comes out at 3M Ohms... I guess I was expecting... 3kW from 240W... i.e. around 20 Ohms...It was a pretty expensive item... are these repairable or is it time for landfill? Greta wouldn't be happy.Anyone with kettle repair experience?PSObviously the leads were disconnected for the measurement only

author: jfiresto
author_rank: Frequent Contributor
timestamp: February 27, 2020, 06:25:39 pm
content: I would be sorely tempted to replace the kettle.I picked up a 40/60/80/100 °CStrix-designedelectronic kettle made for Aldi, that appears to use theU67 control set. The local store had marked them down to 14,99 euros because many of the old flats in this part of the town have trouble supplying 3 kW on a single circuit. I have owned a tolerable few electric kettles, but this one has been easily the best, with only a somewhat awkward and easily removed mesh filter near the spout, to dispute its perfection.Aldi periodically offers electric kettles for sale. You can spot the Strix kettles by the eponymous coaxial power connector at the base.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: February 27, 2020, 06:38:18 pm
content: It looks like the concealed element isn't replaceable in any way.... so looks like I'll have to buy anew... poor planet.

author: LateLesley
author_rank: Frequent Contributor
timestamp: February 27, 2020, 07:22:27 pm
content: I agree with NivagSwerdna, It one of those with a built in element, non replaceable. Maybe when scoping out your new one, you can look for one with a replaceable element.I had a similar problem the other year, got a nice new kettle, and it lasted 8 months, same type of element. I was so annoyed that I had to replace the whole thing.On another note, what I do now is look at the warranty too, many of these that die quick only have a 1 year warranty. So when shopping for a replacement, try and go for one with a 2 or 3 year warranty. There's a better chance of it being built better, of the manufacturer will stand behind their product.
TEAC A-H500 Amp - Hum on Left Channel - Page 1
Forum section: electronics / repair

author: xyberlink
author_rank: Contributor
timestamp: April 18, 2020, 03:46:07 pm
content: Hi,I'm looking at a TEAC A-H500 Amp which is showing hum/buzz on the left channel.Oscilloscope image attached - top (yellow) trace shows left channel, while bottom (pink) trace shows the right channel.It appears to be approx 40mV (peak to peak) at 50Hz, hence assume it's a mains frequency hum, but only on the left channel.I've disconnected the audio cable internally, to prove that it's the amp board itself at fault.I've done a range of comparisons with the right channel, checking various components, including the incoming power feeds which all appear to match up ok (+/- 34.2v). I've also swapped C517 / C519 / C521 / Q517 / Q519 with the right channel - no effect. Also checked the Bias is correct at 11mV both sides.The attached amp circuit is annotated to show some of the test points where I've proven the signal to be good (green dots) and as shown on the oscilloscope image (red dots).Full service manual is available at this link....https://elektrotanya.com/teac_a-h500_sm.pdf/download.htmlAny thoughts / help much appreciated.Thanks.

author: JKKDev
author_rank: Regular Contributor
timestamp: April 20, 2020, 06:14:52 am
content: I assume from what you wrote you checked the Q517 and Q519? Did you try lifting the C521 to see which end of the amp is causing the issue (I would assume it being AC it would pass through a cap)? Did you scope the supply voltages as well as measure them? Maybe there's something there?Just a few questions I thought of. I might be off on this one :p
Teac AG980 tuner amp won't switch on - Page 1
Forum section: electronics / repair

author: sean5302
author_rank: Newbie
timestamp: July 23, 2021, 08:27:58 pm
content: Hi Guys.I have a Teac tuner amp (receiver) that only goes into standby.I checked the power rails and get AC voltages across the board.I do have schematics which I got from here:https://www.manualslib.com/manual/1741324/Teac-Ag-980.html#product-AG-980I see 240V AC on the main feed to the standby transformer and then 30V AC from that into the rest of the board.I'm a Newbie to electronics and expected to see DC voltages across the caps and suchlike. There are a couple of diode bridge rectifiers but I'm only seeing 30V AC on the + and - outputs.There is a large transformer that I haven't been able to test, other than that its resistance shows it be be OK.The front display only lights the standby LED and one for each set of speakers, ie SPKR a/b and SPKR c/d LEDS are lit. Nothing on the main display.I'm puzzled that all of the diodes I've checked show 30V AC on each side of them.What am I missing, please?

author: bob91343
author_rank: Super Contributor
timestamp: July 23, 2021, 08:33:49 pm
content: What do you mean 'on each side of them'? Where are your voltmeter leads connected?

author: m3vuv
author_rank: Super Contributor
timestamp: July 23, 2021, 08:39:34 pm
content: i had the same issue on an old pioneer amp a while ago,it was the tactile on off/standby switch gone bad even tho it felt ok,maybe worth a look.
TEAC remote control RC-1181 no LED switching. - Page 1
Forum section: electronics / repair

author: Dieselman
author_rank: Newbie
timestamp: January 02, 2024, 03:27:54 pm
content: Hi, first post, so Happy New year to you all.I have a non functioning TEAC RC-1181 as a result of no IR-LED function due to the logic chip failing to provide a shunt to Gnd for the LED return.The chip is being supplied with reliable +3v power, Gnd, Pgnd and oscillator inputs. It also appears to register all 30 key inputs, noted by triggering the oscillator when a key is pressed.The LED functions when manually triggered and inverse voltage pulses can be observed on Pgnd, but no shunt to REMout occurs, which leads me to believe the internal gate is functioning, but the output is not connected to Pin 19 of the chip.I can't find any information regarding the remote control itself and the RC-1181, or equivalent are not available.Other remote controls are available, such as the RC-1182, which I also have and is physically identical, but the buttons have different functions.RC-1181 is for the Receiver/Amp and has control for other devices as well, RC-1182 is for the Cd player only.The logic chip is an ADAM22P20SP.I have attached the two datasheets I have found for the ADAM22P20S as one has more detail, but the other more clearly shows the chip pin-outs.My question is really, does the ADAM22P20S(P) need basic programming, which I can't perform, or can I obtain another remote and swap the chip over...if so, I can't see how the remote has different functions for different models of remote.
Teardown, Repair & Analysis of a Keysight 20GHz MXG Analog RF Signal Generator - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: September 04, 2022, 08:58:12 pm
content: Finally the elusive part has arrived!Part 1:https://youtu.be/xN_nj31PdhoPart 2:https://youtu.be/R2zy7dTA2s4
Teardown, Repair & Analysis of a Rohde & Schwarz FSL 9kHz - 6GHz Spectrum Anal - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: July 25, 2021, 06:05:39 pm
content: You can watch the video here: [25 Minutes]youtu.be/60hasxvl5KU* SPOILER *In this episode Shahriar investigates a failed R&S FSL Spectrum Analyzer. The instrument shows an unusual spectrum trace and fails a wide range of self-test functions. The LO Unlock failure is likely the most important item to address which can cause a cascade failure of other functions.The teardown of the instrument shows a single-board RF design. The system architecture is analyzed along with an X-Ray of the main board showing various RF/LO routes and interconnects. The core synthesizer is examined and measured along the signal path to verify the operation of each part. The failure is traced to an open 1-Ohm resistor which feeds the power supply of the divider IC feeding the PFD of the PLL. A ceramic capacitor failure is also observed which may explain the damage to the 1-Ohm resistor. After these components are replaced the instrument passes all self-tests. The functionality of the instrument is verified by measuring tones from 9KHz - 6GHz using a Keysight MXG.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: July 29, 2021, 07:01:56 pm
content: Ugh... Obviously didn't mean Anal...

author: eldden28
author_rank: Newbie
timestamp: August 21, 2024, 06:21:52 pm
content: I have the 18GHz FSL that has recently stopped working right. It passes all self tests but acts like the analog input port is disconnected. The signal amplitude is small for all setting except for the 40db attenuation setting. There are two input ports to the spectrum analyzer board that gets the signal from an RF SPDT relay that seems to switch in and out a 10dB attenuator. I believe the attenuator is functional as it measure 60ohms on the input and 16 ohms on the output when out of circuit. The switch has a DC blocker on the input and it measures 0.47uf from input to output so I believe that is functional. I would appreciate any tips where to look. It seems to be an issue very early in the signal path. I have not verified that the RF relay is functional but in operation I here relays clicking when sweeping through attenuator settings.Thanks,Dennis Eldred
Teardown, Repair & Analysis of an Agilent 83752A 10MHz - 20GHz RF Synthesized - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: July 22, 2022, 07:43:04 pm
content: You can watch the video here:https://youtu.be/IDVm33SvNPQ
Teardown, Repair & Analysis of an Agilent E8267C 20GHz PSG RF Vector Signal Gen. - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: November 29, 2022, 03:34:20 am
content: You can watch the video here: [22 Minutes]youtu.be/IseAQJ9Ew6w

author: magnetchief
author_rank: Contributor
timestamp: November 29, 2022, 03:52:58 pm
content: That was an interesting repair.Thanks for sharing it with us all.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: November 29, 2022, 08:16:47 pm
content: Quote from: magnetchief on November 29, 2022, 03:52:58 pmMy pleasure.
Teardown & Repair of an Agilent E8257D 250kHz - 31.8GHz PSG Analog Signal Gen. - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 29, 2020, 08:15:47 pm
content: In this episode Shahriar repairs an Agilent E8257D PSG Analog Signal Generator generously loaned by AllTest. The instrument does provide an RF output signal. However, there is also a large DC offset voltage present at the output RF port which changes depending the frequency band. The DC voltage is present even when the output RF signal is disabled. Furthermore, the OCXO of the instrument is defective and does not produce a 10MHz output signal.The block diagram of the PSG is examined in details with emphasis on the final attenuator, coupler and doubler RF decks. Interestingly enough the output offset is traced all the way back to the Modulator Filter block. The teardown of the module reveals a series of PIN diode switches and after some investigation the fault is traced to a damaged PIN diode on the sub-3.2GHz path. Since the diode can't be easily replaced, the control voltage to the diode is disabled instead which removed the DC offset problem.The OCXO teardown reveals that during a prior repair, the oscillator module has been damages and torn off the PCB. New pins are added to the oscillator module which returns the crystal back to working condition. The performance of the PSG is verified using a spectrum analyzer and frequency counter.You can watch the video here: [40 Minutes]youtu.be/GaaA46r7DUkwww.TheSignalPath.comwww.YouTube.com/TheSignalPathwww.Patreon.com/TheSignalPath

author: BFX
author_rank: Frequent Contributor
timestamp: March 30, 2020, 05:39:13 pm
content: This is the level of repair knowledge what I'm ready to payNow I'm Patreon and I will increase my donations by level of repairThank you Hugoneus. I wish you even better cooperation with alltest, I think they will catch you soon

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 30, 2020, 06:37:41 pm
content: Quote from: BFX on March 30, 2020, 05:39:13 pmThank you. Much appreciated.

author: vaualbus
author_rank: Frequent Contributor
timestamp: April 03, 2020, 11:29:29 pm
content: Finally I see inside one of this machine! I would really enjoy a teardown of the different boards, but the way this instrument use a lot of the board used in the ESG series of signal generator that you had already repairs in the past (but I think the base model is the Ghz version as the Frac-N, Sampler board are the same) I realize this by comparing the two block diagrams.And of course they had completly different RF section as this instrument can reach up to 67Ghz so amplifier and RF loop is different but I'm pretty sure that the stuff before the YIG is very similar to the base ESG generators.Any way good video as always and I wish you can enjoy the quarantine by making more video!
Teardown & Repair of an Agilent N9020A MXA 20Hz - 26.5GHz Spectrum Analyzer - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 08, 2020, 08:52:09 pm
content: You can watch the video here: [40 Minutes]youtu.be/0a6bpZZS23gMore videos at The Signal Path:www.TheSignalPath.comwww.YouTube.com/TheSignalPathwww.Patreon.com/TheSignalPath

author: bitseeker
author_rank: Super Contributor
timestamp: March 09, 2020, 04:42:23 am
content: That was a fun one. It's a shame that repairing equipment becomes more and more difficult over the years, but it's always a treat learning about how these things work (and I follow along a little better after each video). Thanks, Shahriar!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 09, 2020, 03:26:43 pm
content: Quote from: bitseeker on March 09, 2020, 04:42:23 amThanks. I will keep the module for potentially repairing it in the future.

author: suj
author_rank: Regular Contributor
timestamp: March 10, 2020, 02:27:53 pm
content: I think the unreliable doubler might be type 1GG7-4129. Datasheet available on the Keysight website. As for the amplifier, you missed the symbol on the chip under the microscope. It should also be possible to identify. On ebay I saw sellers of various strange chips. I saw a large selection of Agilent chips, maybe some remains of a fire that affected Keysight's headquarters or another sale. I think in the US it's possible to buy these chips directly from Keysight. If they send you a 110 GHz/256 Gsps oscilloscope to test, I think you should be able to buy these chips (if you can identify it).The question of assembly remains. I have wire bonder and have already made my first attempts but it is not at the level to be sure of the results. Again, the location in the US is helpful here in my opinion. I think a well-equipped laboratory at a technical university should have access to a wedge bonder. The chips are not very high power, so the attachment to the substrate (rather the substrate does not have a window to attach to the metal base) should be possible with a conductive epoxy resin.I keep in mind that I have repaired my E4407B thanks to your tips - the prescaler was damaged. Thank you again.Edit: Amplifier is HMMC-5617/HMMC-5618/1GG6-8002/TC905 type. I was sure that I had seen this chip somewhere before.

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 11, 2020, 04:27:31 pm
content: Quote from: suj on March 10, 2020, 02:27:53 pmThank you. Very useful.

author: vaualbus
author_rank: Frequent Contributor
timestamp: April 03, 2020, 11:25:31 pm
content: Still you haven't expalin how the instrument detect the errors....I would suggest that it look at non fundamental mixer result?Maybe they have a loop co-me out before the filter after the mixer? Or they just digitize the spectrum and look for higher order harmonics?Any way it so interesting looking at this chips, I would like to have photos on what are under the third shield!
Teardown - TWS ear pods - Page 1
Forum section: electronics / repair

author: Tajjbe
author_rank: Newbie
timestamp: September 21, 2021, 12:20:14 pm
content: I bought a very cheap set of wireless earpods from ebay the other day.To my surprise they did not workSo naturally I had to tear them apart to see why they are so cheap and maybe fix the problem.It is only one IC on the pcb which take care of bluetooth, touch-sensor, DAC to speaker and more..I got a clear picture of the IC with numbers and manufacurer I never seen before.Is there any secret way anyone know of to get hold of datasheet for such chips? Or does anyone have any information about this chip?
Technics SL-7 Linear Tracking Turntable Repair - Page 1
Forum section: electronics / repair

author: martinr33
author_rank: Frequent Contributor
timestamp: March 23, 2021, 03:31:28 am
content: Symptom: powers on. Turntable will not rotate. Tomearm will not move. Two short flashes, repeated, from indicator LEDProblem #1: Tone arm slider grease hardened. Cleaned with IPA. Need to manually turn the worm gear to move the carriage, that is slow. Replaced little square belt. Lightly relubed with Super Lube synthetic PTFE grease. Tone arm now works, turntabe spins, but the tracking falls far behind and eventually causes the needle to stick and skip.Problem #2: Had not replaces the hardened grease patch that I cleaned from the inside of lid. This grease has to be replaced, it is there to stop the tone arm leads from causing the tone arm to stall and skip. ***It is not obvious that this grease is missing, other than through the bad behavior of the tone arm***. More Super Lube, in a patch on the underside of the lid and on the cable.Problem #3: many electrolytics leaking with corroded leads. The main smoothing electrolytic (big one) was bad. Most of the rest tested a bit low, but corroded leads are a clear indicator that they needed to be replaced. These caps are not in the signal path. These caps are nearly 40 years old. Strangely, some of the caps had the same value but were from different brands. These caps are all original, I have had this thing since 1983.The deck is now working as it should, with the tone arm following the grooves at a tangent. The mechanism only tracks inwards, so if the disk is pressed off center, the tone arm moves out on its bearing, then the auto track moves it in.The unit is not too bad to work on, if a little clumsy because of the captive wiring on teh PCB.The tracking mech requires removal of about half a dozen screws to get the cover off. Some of these screws have washers, all hardened beyond use.The bottom comes off with four screws in the feet, and then a bunch of screws to get the bottom board out. These screws are all marked.There's a heat sink screwed to the chassis. To get to its screw, you have to reove the back cover ( 2 screws).Many cables have fixed headers, and are not removable unless desoldered. But you can flip the board to work on it attached to the chassis.

author: bob91343
author_rank: Super Contributor
timestamp: March 23, 2021, 03:51:04 am
content: Those units were designed by magicians. They knew where tolerances were important, and they had great support from plastic molding engineers. I recently gave away a Sony unit, very similar. I had repaired it twice but it's too complex so maybe the new owner will figure out what to do. He's not much of a technician so I suspect he will keep it for its nostalgia value.
TECHNICS SU-G95 Integrated Amplifier - Won't Accept Mains Power - Page 1
Forum section: electronics / repair

author: Steve Wayne
author_rank: Contributor
timestamp: January 29, 2025, 06:23:52 pm
content: I’m attempting to diagnose a power issue with a TECHNICS SU-G95 Integrated Amplifier, where the device will not accept mains voltage. When 120V AC is applied, the relay on the main transformer board(REP1741A-P) rapidly cycles closed then open about twice per second, with a quick dim-bulb, weak flash.Assuming a short to ground, I cannot find the causal component.Any advise would be greatly appreciated.

author: mbz
author_rank: Contributor
timestamp: January 29, 2025, 09:10:04 pm
content: The DBT might be "starving" the amp of power, what wattage bulb are you using? As a first step increase wattage to 100W however since bulb is not bright appears it can be dispensed with.

author: Steve Wayne
author_rank: Contributor
timestamp: February 01, 2025, 11:10:55 pm
content: Thanks mbz !!! Yes indeed, the relay circuit does not like the dim bulb tester. Even with a mere 40W bulb. Man, I spent a number of hours looking to track down a short. I've never experienced this trap before. Thanks again.PROBLEM SOLVED
Technics SU-V98 Repair - Page 1
Forum section: electronics / repair

author: SpecialK
author_rank: Regular Contributor
timestamp: October 12, 2020, 01:03:35 am
content: I'm just in the middle of repairing a Technics Su-V98 integrated amp. Low output on the right channel.https://www.manualslib.com/manual/387815/Technics-Su-V98.htmlI've traced the issue to Q202 (see page 9). Removing this TO-92 N-channel Mosfet restores normal operation. I assume that if I had a working remote, then pressing the mute button would cause only the left channel to mute with Q202 missing.Can anyone recommend a substitution for a 2SK301?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 12, 2020, 02:35:51 am
content: for an example if you do a cross check like thishttps://www.digikey.com/catalog/en/partgroup/n-channel-mosfet-metal-oxide/16095youll have some compatible parts, it should be okay to use them as a mute function, you have at least 3 or 4 models in to 92 casingone popular transistors was dtc114theses mosfets tooJ108/ 109/ 110The "RDS" spec would be the first thing to be considered, any low power n chanel mosfet2sk715v or 2sk715u, 2sk223 seems to fit the bill

author: SpecialK
author_rank: Regular Contributor
timestamp: October 12, 2020, 05:06:05 pm
content: Thanks a bunch. I might add something to my next Digikey order. I think it's actually a JFET and not a MOSFET.More perplexing is the remote. The seller sent one, but said it wan't working. Seems to emit IR just fine. It doesn't match the picture in the manual.However, I'm at a loss to see the IR sensor. Do they ever imbed them in the Vacuum Florescent Display?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 13, 2020, 02:37:21 am
content: nope never, its kinda a metallic smal can with 3 legs or somekind of a dark led, they are always on the front panel side, sometimes on the main pcb or its an separated pcb with the metalized can or a infrared diode

author: coromonadalix
author_rank: Super Contributor
timestamp: October 13, 2020, 02:51:11 am
content: Buuuuut i'm not sure if this tuner / amp need to be connected with other sound system componentsYou have some remote plugs on the rear, see page 3 and 4Some of theses systems where not working if they where not complete, tunner, amp, preamp ...

author: SpecialK
author_rank: Regular Contributor
timestamp: October 13, 2020, 02:52:58 am
content: Quote from: coromonadalix on October 13, 2020, 02:37:21 amMy latest theory is that there isn't an IR sensor on the integrated amp. Apparently, the integrated amp was usually (or always?) sold as an ensemble with a tuner tape deck, CD player, and turntable. The tuner clearly has a sensor and then there's a cable between units.The good news, is that I can just leave the FET out as it will never be muted.I see you already posess such knowledge.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 13, 2020, 02:55:40 am
content: Had my fair share or audio video equipment repairs in the past loll but im getting old loll
Technogym Run Race D140 - Page 1
Forum section: electronics / repair

author: jpalmeida
author_rank: Newbie
timestamp: November 18, 2019, 12:38:03 pm
content: Hi all!I am reparing a Threadmill Technogym Run Race D140, It doesn't turns on.It only sends a beep and slygtly ilumintes the digits at the controll board, only for quite half a second, than remains off.I saw here some reference to a similar problem posted by member senso from portugal.Senso, if you reach this post, can you please help?Best regards.Joao Almeida
Technomate TM-TWIN-OE burned IC SD4841P 67k65yw3j0fz , equivalent IC required - Page 1
Forum section: electronics / repair

author: lineofstars
author_rank: Newbie
timestamp: January 20, 2020, 06:56:41 pm
content: Hi everyone.Few weeks ago I had a power cut in the building and after that my satellite receiver got broken. The device display does not work, but the HDD it can be heard that it is spinning.The image on TV got the boot image frozen.I opened the lid and I found the burned IC: SD4841P 67k65yw3j0fz which is visible burned.I would like to know what equivalent can be installed since the SD4841P is a bit difficult to find it to local IC store vendors or it takes 2-3 weeks to get it from abroad.For example if can be TOP221-227 , TNY264/266-268, TNY274-280P/G and if yes, from the given range which exactly and why.Also what can be done to avoid to happen such circumstances.Thanks in advance

author: lineofstars
author_rank: Newbie
timestamp: March 10, 2020, 09:38:01 pm
content: Hi guys.Good news, the IC SD4841P was replaced on the mother power supply board.Bad news, when I unscrewed the power supply board, I saw other burned area, as you can see in the pic I send in this email.The worse scenario, I have searched in Google “B TSFM 10100 10C” and …nothing comparing with the other burned IC SD4841P that I have found suppliers on Ebay. So I do not know what component to search.That area it belongs to the D3 , on the component is wrote: B TSFM 10100 10C as you can see in the pic attached.Diagnosis: I have picture on the TV, the “OPENPLI”, but in the receiver, the display does not work, the remote control does not work, the buttons in the front panel does not work.I have to power off from the back side of the device( the I/0 button).I can hear the Hard Disk Drive(HDD) spinning , and also the fan.So basically I do not know the component type to search it , I do not know the manufacturer, the "B" letter printed on the component is not helping a lot in this situation....So I hope with all my heart someone knows.Waiting your reply, anything could be helpful.Thanks in advance.

author: SpecialK
author_rank: Regular Contributor
timestamp: March 12, 2020, 02:35:58 am
content: mbrf10100ct perhaps?
Techtronix 5110 - Page 1
Forum section: electronics / repair

author: TerryCtjc
author_rank: Newbie
timestamp: May 17, 2020, 03:28:32 pm
content: I have a Techtronix Oscilloscope Model 5110 The display is restricted to the top right hand quarter of the screen and cannot be moved by the position controls to any other area of screen. When try to move display to bottom of screen trace stays at center and magnitude of waveform decreases. Any help or advice as where to look for problem would be most helpful.Modify message

author: perdrix
author_rank: Frequent Contributor
timestamp: May 17, 2020, 03:42:44 pm
content: Don't post the same question on more than one forum.

author: TerryCtjc
author_rank: Newbie
timestamp: May 17, 2020, 04:39:15 pm
content: OK new this but will learn quickly.
Teco inverter 7300CV - Page 1
Forum section: electronics / repair

author: keland_uk
author_rank: Contributor
timestamp: June 22, 2023, 08:02:43 pm
content: Teco inverter 7300CV. I have been asked to look at one of these where I think a Power thermistor on the i/p has burnt out. Photo 1. It looks like 1 20SP UEI thermistor, but Ohmage has been destroyed. Anyone any ideas how to identify blown device, assuming it is a thermistor in the 1st place. I can't find any circuit diagrams for this inverter anywhere.Any help appreciated.Best RegardsChris

author: fzabkar
author_rank: Super Contributor
timestamp: June 23, 2023, 02:26:37 am
content: It's definitely an NTC inrush current limiter.https://m.media-amazon.com/images/I/818qjMHQldL._AC_UF894,1000_QL80_.jpghttps://images.tokopedia.net/img/cache/500-square/product-1/2020/9/29/7285560/7285560_3f61c650-2d7c-4aa9-91ba-ecb3cfcfb695_1449_1449.jpghttps://ae01.alicdn.com/kf/HTB1kRLtKbSYBuNjSspiq6xNzpXai/New-and-original-MF72-5D20-NTC-20SP005-20SP-thermistor.jpgIs the device bypassed by a relay after the power rail has come up to spec? If so, check that the corresponding area is working properly, otherwise the burnt NTC may just be a symptom of the real problem.

author: keland_uk
author_rank: Contributor
timestamp: June 23, 2023, 08:58:53 am
content: Thank you. any Idea on value tho. those you showed seem to be 2.5/20 and 5 ohm respectively.I found a picture of a different board by Teco, also marked as TH201, NTC marked 20SP 012 but the schematic the guy had done seemed to have a 15 Ohm NTC. Of course different cct
Tectronix 2213a no trace - Page 1
Forum section: electronics / repair

author: Simon101179
author_rank: Newbie
timestamp: November 27, 2021, 07:22:02 pm
content: Hi I have a tectronix 2213a which released the magic smoke some years ago I tried fixing it but gave up and shelved it.I've recently started on it again, so it would switch on with I wide dot on the crt with no horizontal sweep and no vertical gain. I've recently found a 4.7 ohms resister open circuit in the power distribution setup and also had a 1ohm resistance to ground which I traced back to a shorted cap so I replaced both of them but now it's worse. Any ideas greatly welcome.

author: bob91343
author_rank: Super Contributor
timestamp: November 28, 2021, 06:00:08 am
content: I think many scopes of that ilk run on 43 Volts from a switching power supply. If yours does, did you measure it?The power supplies are a common place for failures.
Teensy 4.1 Ethernet problem - Page 1
Forum section: electronics / repair

author: Serhii
author_rank: Newbie
timestamp: April 04, 2023, 12:23:51 pm
content: Hi everyone!My Teensy 4.1 is connected to a pcb that has ethernet port. But I can't get connection. It looks that Teensy works fine through a serial port(USB) but when I trying to connect with an ethernet cable noother devices can see the board(tried with a bunch of computers and router). I blame myself that I fried something while soldering.Can anyone give me a hint how to check ethernet on Teensy? I have DMM and an oscyloscope. Any information is highly valuable! Thank you for your time!

author: ZigmundRat
author_rank: Regular Contributor
timestamp: April 04, 2023, 03:01:27 pm
content: You have to include the Ethernet support in your project of course. This varies by the environment used (PlatformIO,CircuitPython,etc). But until you do this you won’t have a MAC address, much less an IP address. What have you done to enable Ethernet on the software side?
Tefal GV7781 repair - Page 1
Forum section: electronics / repair

author: duzycinek
author_rank: Contributor
timestamp: July 17, 2023, 06:00:06 pm
content: Hello, I am looking for flash file for Tefal steam station. MCU is damaged sadly. Is there any chance that someone has flash file for PIC16F1933? I found flash file for same station with other MCU which is PIC16LF1903. Are they compatible? Will flash work on PIC16F1933? Looking forward to hearing from you!
TEGAM AVM-2000 100nV - 1000V Null Detector / Nanovoltmeter Repair & Teardown - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 08, 2025, 09:25:43 pm
content: You can watch the video here: [35 Minutes]youtu.be/BaVrLsYVGOIIn this episode Shahriar takes a look at a faulty PPM (TEGAM) Null Detector. With its massive dynamic range (10 orders of magnitude!) this instrument is capable of nano-Volt range measurements. Unfortunately the unit is faulty and does not display or measure anything at the input.The unit requires a battery for operation (6V Lead-Acid) which can be bypassed by using a 7.4V LiPo battery. The unit powers on and the power supply section is fully functional. Detailed block diagrams and schematic analysis of the unit is discussed during the video.The analog front-end is also verified to be functional through internal measurements and although there is digital communication between the various internal modules, the ADC only transmits a fixed (faulty) data sequence to the front-panel. The fault is traced to be a corrupted firmware which the manufacture does not agree to share.Thanks to a helpful internet friend, firmware from a working unit is extracted and compared with the faulty instrument. It becomes clear that the corrupted FLASH memory is responsible. After transferring the calibration coefficients to the modified new firmware the unit comes back to life! Several measurements showcase the units capabilities and functionality.

author: branadic
author_rank: Super Contributor
timestamp: March 09, 2025, 04:39:10 pm
content: Shahriar, are you eager to share the hex-file for the unit?-branadic-

author: Hugoneus
author_rank: Frequent Contributor
timestamp: March 09, 2025, 04:42:17 pm
content: Quote from: branadic on March 09, 2025, 04:39:10 pmOf course - anyone who needs it can reach out and I'll email it to them. This HEX file really has no other uses except for this instrument.
TEK 11801A - possible bad ext trigger input - how to test? - Page 1
Forum section: electronics / repair

author: CDN_Torsten
author_rank: Regular Contributor
timestamp: January 03, 2022, 04:37:10 pm
content: My TEK 11801A for the most part appears to be working correctly. I can view the calibrator output and the TDR pulse form the SD-24 module all using the internal triggering.When I attempt to view external signals which require an external trigger input, I am unable to get the scope to trigger. I am starting to suspect the previous owner damaged the external trigger input circuitry.There is also a chance the I am not doing this correctly...Can anyone suggest a simple setup which I could use to verify that the external trigger input is (or is not) working??(Available modules: SD-24, SD-26, SD-14)Thanks!Torsten
Tek 120-0879 or 120-0823 transformer - Page 1
Forum section: electronics / repair

author: harrison@cs.unc.edu
author_rank: Contributor
timestamp: October 06, 2022, 07:42:59 pm
content: Hello everyone, I have a dead HV supply for my 7603. There is arcing in the windings of the step up transformer. If anyone has one to sell or trade, I am willing!!I can trade a 7603 CRT, some 7000 series modules, or even some pcb's from a 7603.Send direct mail please. harrison@cs.unc.edu
Tek 1741 removing faceplate / replacing the scale illumination light. - Page 1
Forum section: electronics / repair

author: gorplop
author_rank: Newbie
timestamp: January 01, 2020, 04:04:25 pm
content: Hello,I've recently picked up a tek 1741 PAL Waveform monitor/vectoroscope combo in a rather sorry condition (very dirty, came with a half of the rack enclosure because some muppet cut the rack with an angle grinder).I'm unable to find the service manual for the vectorscope sadly.I've adjusted the focus and trace rot on the CRT (the pots on the CRT board are labeled), so signal wise it displays sensible data.However, It still has three issues..- First, the scale illum knob doesn't do anything, the scale is not illuminated at all. I can see the illumination bulbs (?) PCB on the left hand side of the CRT (see photo).- Second, theres some dirt between the CRT protector pane and the graticule.- Third, the UN CAL led is ON all the time, do I need to run some calibration software (if there's any)?How do I take off the front panel in a safe way so that I can test/replace the bulb board and clean the graticule?Thanks
Tek 2215 Preregulator MOSFET ID - Page 1
Forum section: electronics / repair

author: melling
author_rank: Newbie
timestamp: May 26, 2022, 08:23:21 am
content: Hi all,I pulled this cooked MOSFET out of a Tek 2215 preregulator board, but I can't find anything about it. I have the Service Manual, but it does not list a reference to the component (this is on board A18, SM only has detailed BOM for A19 which A18 replaced). Component designation is Q933, which is found on the schematic attached. I've included the waveforms from the test points.It doesn't help that Motorola have another product called 8226, as well as it being used for that ubiquitous Espressif board!Another post suggested that this is an IRF820 so I have some ordered, and I believe that it will work, but of course now I am second guessing myself on whether this will be a suitable replacement part.Any suggestions?Thanks!

author: Per Hansson
author_rank: Unknown
timestamp: May 26, 2022, 11:10:55 am
content: It is a Motorola part with date code 1982week26."1152" is a Tektronix part number, the full number is: 151-1152-00This thread and the following pages has allot of detail on this part:https://www.eevblog.com/forum/repair/tektronix-2215-scope-repair/msg1824401/#msg1824401If you can't find it in your service manual you are using the wrong one, the 2215 was first done without the preregulator board A18.Starting with serial number B022000 it was added, so there exists older service manuals without that board...

author: seronday
author_rank: Regular Contributor
timestamp: May 26, 2022, 11:37:00 am
content: Q933 on the preregulator board is Tek PN. 151-1152-00.The TEK part number cross reference document lists this as an IRF820.http://www.ko4bb.com/getsimple/index.php?id=download&file=Tektronix/Tektronix_Miscelaneous/Tektronix_Xref_sm.pdf

author: melling
author_rank: Newbie
timestamp: May 26, 2022, 12:40:42 pm
content: Thank you both! Silly of me to mix up the date code with the part numberQuote from: Per Hansson on May 26, 2022, 11:10:55 amYup, that was the source of some head scratching until I woke up an realized the assembly number on the board was A18 not A19. Confused the hell out of me because Q933 on the A19 schematic is a BJT, and on the board A18 board 2 of the pins are marked G and S.Quote from: seronday on May 26, 2022, 11:37:00 amThanks seronday for the link, I can see that coming in handy. Glad I got a confirmation of a suitable replacement part before blowing something up.

author: t1d
author_rank: Super Contributor
timestamp: May 28, 2022, 08:00:43 am
content: I did a lot of research for documents for my 2215. I put them on Dropbox, to share. Here is the link:https://www.dropbox.com/s/s72iu3thvknaolb/Tektronix%202215%20Oscilloscope.zip?dl=0