hybridfree/eevblog-posts huggingface dataset:
Adventures in HP 70000 series repair. - Page 1
Forum section: electronics / repair

author: Raindog
author_rank: Contributor
timestamp: May 20, 2020, 08:04:45 am
content: Thought I might share this with the group. I recently took possession of a nice HP 70000 series spectrum analyzer, upon receipt I noticed it had a few issues but was still functional. Starting from knowing little to nothing of this series I downloaded all the manuals I needed. Since I was going to add more modules my first challenge was to figure out how to set the module dip switches for the appropriate "rows" and "columns" and WHY the were set the way they were. Next was to acquire spare SMB jumper cables and any necessary semi-rigid hard line interconnects. Next was to purchase two replacement RAM back-up batteries for the HP70206A Graphics display and the HP 70900A local oscillator. Next was to figure out why the I/O check lights were always illuminated on the HP 70001A and the HP 70206A. After much experimenting the issue wound up being that one of the cables I received with the unit wasn't a real HP-MSIB cable, just a standard 37 pin DSUB cable. I wound up DYI'ing my own cable with the assistance of this sitehttps://www.rbarrios.com/projects/HP-MSIB/now I'm up and running! No more I/O issues!I didn't take any images of my repair process because it was mostly dead RAM back up batteries and a bad MSIB cable. Battery replacement on the 70206A is nothing more than removing the battery compartment door and replacing it. The 70900A replacement was done by removing the unit, removing the 8 cover screws, then position the unit so the front of the oscillator is on your left. Remove 3 retaining screws and spacers, remove the small ribbon cable on the top left, then carefully remove the board, the battery is on the left side. The batteries replaced were a Tadiran TL-5104/S for the 70206A and a Tadiran TL5104/P for the 70900A. Hope someone here finds this helpful.This unit is certainly a major upgrade for me from the HP 853A / 8557A you see next to it, lastly will be a tracking generator to test filters and antennas without the need to use my HP 8644A. Now I need a Bourbon on the rocks. Cheers!

author: eb4eqa
author_rank: Regular Contributor
timestamp: May 21, 2020, 10:22:29 pm
content: Glad to have helped!That weights a ton but it is a fine instrument.Regards,Roberto EB4EQAWww.rbarrios.com

author: genesilvernail
author_rank: Contributor
timestamp: November 09, 2021, 12:17:00 am
content: Great thanks for your post on battery locations. I just acquired a 70k system and know very little but am learning. Before pulling the 70900a board i did a pretty thorough hunt for the Easter egg, peeking ans snooping finding nothing. So ith your input a openned it up and still no battery....what the @@!$$. Looking closer I finally ound where the battery...was. Someone removed it and it never got replaced... on order will do.The thing that puzzles me the 70k came from a gv-surplus auction, not a private party and my thinking remains why was it removed. Why the 70900A scrutiny? it doesn't show up on the address screen while the balance of modules do.Again thanksK7QHO/Gene
Advice needed ,ccfl board,external or placed inside my scope? - Page 1
Forum section: electronics / repair

author: nic77
author_rank: Contributor
timestamp: January 26, 2022, 01:27:26 pm
content: Hi to all ,as my scope's ccfl lamp ,transformer is not working anymore i ordered a small single lamp board ,all i need now is some advice ,should i place the new board inside the scope or place it in a sealed box outside the scope ,greetings to all to all ,nic.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 26, 2022, 01:28:43 pm
content: ccfl wiring emits a lot of noise, so should be kept as short as possible, i.e.inside

author: nic77
author_rank: Contributor
timestamp: January 26, 2022, 07:29:59 pm
content: Thanks Mike ,i have ordered a led strip as well to see which is the best option just going to have to experiment , on the left side of the scope where the monitor is there is nothing,only the power supply board ,and the main acquisition board is totaly to the left ,thanks and the best greetings .
Advice needed - DSLogic Core non responsive - Page 1
Forum section: electronics / repair

author: bsccara
author_rank: Contributor
timestamp: April 09, 2024, 02:21:09 pm
content: My DSLogic Core logic analyzer seems to have blown a gasket; it enumerates with VID, PID and serial number identifiers set to zero. I've already dessoldered the USB ESD protection diodes (seems to be a PRTR5V0U4D-Q part) but the device still enumerates as zeros.The USB interface is handled by a Cypress CY7C68013A-56PVXC, which may have been blown.Has anyone ever had one of these Cypress parts fail and enumerate as zeros ?
Advice needed for DIY spot welding of 18650 cells - Page 1
Forum section: electronics / repair

author: emece67
author_rank: Frequent Contributor
timestamp: January 20, 2022, 11:49:37 pm
content: .

author: abdulbadii
author_rank: Frequent Contributor
timestamp: January 21, 2022, 12:17:11 am
content: Have a work inspecting, reviewing the pack situation is worth itmeant if there's possibility an extra space in all dimensionwe'd try transform it to 'normal way' ie. replace them with the bumped (+) pole ones, give them the on-market-available houses and charging them with their special quality chargerby this all drawbacks of resistance-welded pack get avoided, mainly dissimilarity temperature surrounding batteriesthe ones in the inner position always get hotter hence degraded more quickly .temperatures above 60°C gives Li-ion battery loses capacity linearly, in turn its performanceit's must be within 10°C to +55°C.temperature range, but when charging take place must be ~ +5° - +41°C.preventing from going down to nominal V is not hard to do manually as the using tool performance should be a telltalewhenever it shows noticeable down performance quickly pull out and put into charger one by one,could google better than me ones:https://charger.nitecore.com/product/ums4IMHO this'd give the Li-ion battery far longer lifetime as they get rolled over position and evened in high temp. impactmight benefit readhttps://www.plarad.de/fileadmin/downloads/FAQ_related%20to%20lithium%20ion%20rechargeable%20battery%20care_DA1_en_0216.pdf

author: emece67
author_rank: Frequent Contributor
timestamp: January 21, 2022, 11:15:44 pm
content: .
Advice needed - Identify a diode - Page 1
Forum section: electronics / repair

author: Caribo
author_rank: Newbie
timestamp: April 10, 2024, 06:56:42 pm
content: Hello everyone,I need your enlightened help to identify a diode to replace.Here's the context:I have a monitoring active speaker, model PM5 from brand E-MU, which suddenly failed on me. I opened it up to see if I could find any clues to the malfunction, and came across components that seemed burnt. I cleaned up as best as I could. The capacitors are easily identifiable for replacement, but I have absolutely no idea how to find the reference of the diode to change, D105. This one is probably the same as D106. The regulator behind it is an LM337SP.As I'm writing this message, I thought I'd take a look at the LM337SP datasheet, to see if there were any examples of setups involving diodes. There's one with 1N4002 and 1N4148. Given the package, I don't think it's a 1N4002.Could it be a 1N4148? If someone could enlighten me, I would be greatly appreciative!Thanks in advance!

author: fzabkar
author_rank: Super Contributor
timestamp: April 10, 2024, 08:07:04 pm
content: It would help to know where the diode connects. Is one end grounded? Does it connect to any of the regulator's pins?

author: isometrik
author_rank: Regular Contributor
timestamp: April 10, 2024, 08:21:11 pm
content: Based on the symmetry of the components in that area of the PCB, I suspect D105 is identical to D106, as you suggested in your initial post.I suggest you desolder D106 to read its part number.

author: Haenk
author_rank: Super Contributor
timestamp: April 11, 2024, 06:52:11 am
content: The package and size would match a 1N4148.It is certainly not a 1N400x - these are all plastic packages.Unfortunately, this only helps to rule out things, but is no confirmation. In my opinion, a 1N4148 will do.

author: Caribo
author_rank: Newbie
timestamp: April 11, 2024, 01:14:34 pm
content: A big thank you for your initial responses.I found a way to read what's written on the package: 1N4 and below it, a 5.Could this help someone?Thank you

author: fzabkar
author_rank: Super Contributor
timestamp: April 11, 2024, 05:21:32 pm
content: 1N45 is a germanium diode, which is a relic from the past. It would help if you identified the connection points. Does it connect between Vin and Vout, or between Adj and Vout, or between Adj and Ground?A germanium diode would make some sense if it were connected between Vout and ground, reverse biased.From National Semiconductor's handbook:Quote
advice needed on a wavetek si4015 smps - Page 1
Forum section: electronics / repair

author: ME
author_rank: Frequent Contributor
timestamp: July 23, 2025, 03:18:17 pm
content: My 4015 is away being repaired , This is the email i got , Any ideas what would cause the noisey psu ?.:Your 4015 is giving me a headache!Was working fine last night, this morning it was failing self-tests, unplugged the duplex option and all was good without it when I emailed you. Then it started failing synth, RF unit and computer tests.Had a few other things to sort, so left it running. Came back to it about mid-day and all's fine again, so I'm thinking a temperature related fault. Tried freezer spray on all the un-shielded boards - no difference. Put each of the RF units in turn in the freezer for half an hour - still fine. Put the whole 4015 in a fridge at 1 degree C for a couple of hours - still fine. Left it switched off for the last 4 hours and still OK.Whilst it's good that its working, I don't like faults that just disappear. Unfortunately, it seems to be a bit of a thing with Schlumberger. 4015's do it, 4031's, 4032's and 4040's. I've had them do this before and put them on soak test for about a month on and off before I dare sell them, but they never go wrong again. The annoying thing is that it seems to work fine even when the self-test fails.Your demod board seems to be Ok. It makes no difference whether I fit your board or mine, when its working, both work and when its not, neither work.It certainly seems happier on the replacement PSU. I think the one previously fitted is probably a cheap Mean-Well or similar, I haven't extracted it from the housing to investigate, but if I set the 4015 to generate a blank carrier, there's about 500Hz of spikey noise on it, similarly, if I feed a blank carrier into the 4015 and look at the demod scope, the same noise is there, whereas, with the Schlumberger PSU, the noise is only about 30Hz.I'll see what its doing tomorrow and take it from there. Ideally, I'd like to find the cause of it misbehaving for my own peace of mind.Best Regards,Peter Arscott
Advice on cleaning rotary encoders and potentiometers on a scope - Page 1
Forum section: electronics / repair

author: killingtime
author_rank: Regular Contributor
timestamp: April 21, 2022, 07:04:06 pm
content: Hello,Anyone on here have experience cleaning up switch contacts and potentiometers?I have an old Hameg 204 CRT scope. It works - sort of - if you tap and wiggle the rotary controls. It's 80's vintage and the rotary encoders exhibit intermittent contact. Some of the pot controls need a wiggle before the wave form settles down.There are many threads on this, on many boards, but my questions are specific to this scope:1. How do you get the contact cleaner into the pots - they're metal and sealed?2. How do you get the contact cleaner into the rotary encoders - there' s no access to contacts?Here's a picture showing the encoders and pots.There's a wealth of info around this on audio forums. Some suggest drilling a hole in the pot (upwards, so any metal chips fall down away from the pot) and squirt cleaner in. I can't take the pot apart as it's riveted together and made of metal. I suppose I could just replace them with an equivalent.Then there's the rotary encoders. Timebase pictured, they're a work of mechanical art, and the contacts are flanked by plastic. I read somewhere you're not supposed to get contact cleaner on plastic parts - which rules out drilling a hole and squirting cleaner in..Depends on the cleaner I suppose.The original plan was to drill some holes and hose everything down in contact cleaner, but after a bit of research this seems to be a bad idea. Some switch cleaners attack plastic. I've read many times on audio boards that a targeted approach is the way to go. Use 'switch contact cleaner' on the actual metal contacts only, and potentiometer cleaner on the pot tracks. A common mistake is to use too much cleaner which then also removes grease in other areas.I really don't want to desolder the rotary encoders. That's a car crash waiting to happen. Broken / lifted PCB tracks etc.I was going to use 'Servisol Super 10' on the mechanical switches and ' Kontakt PR Potentiometer Cleaning Spray' on the pots. Other posts suggest using a liberal amount of IPA although but you'd have to remove the switch/pot from the PCB for this to work.Any ideas?Thanks.

author: bob91343
author_rank: Super Contributor
timestamp: April 21, 2022, 08:00:11 pm
content: I wouldn't mess with it. The cause of the wonkiness is probably lack of use. Exercise the pots and switches and they are likely to fix themselves.
Metcal MX500P Soldering Station? - Page 1
Forum section: electronics / repair

author: stbaratheon
author_rank: Newbie
timestamp: August 08, 2019, 08:58:20 pm
content: Hello everyone,This is my first post here, so sorry if this is the wrong forum for this.I am trying to fix aMetcal MX500Psoldering station power supply. I have 3 old broken power supplies to choose from, each with their own issues, and can only choose one. They are as follows:1) Doesn't turn on, even with adequate connector.2) Turns on, but doesn't recognize when a working wand is connected.3) Turns on, recognizes the wand but green light flickers and tip doesn't heat up.I've just started my journey into fixing electronics and would love to resurrect this treasure. I've read the previous related forums and understand that there are various errors that can the cause the issues listed above.So from your experience, which Metcal supply would you advise I start with (eg. blown fuse or transistor)?I would appreciate any feedback, even if it about a similar piece.Thank you,Danny

author: MosherIV
author_rank: Super Contributor
timestamp: August 09, 2019, 10:20:01 pm
content: Try searching youtube for metcal repair.There is a video with the same symptoms as 3.Guy did not find actual source of the problem, just unkown dry joint some where.Ps. Welcome to the forum.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: August 11, 2019, 10:13:27 am
content: Hi there. These units are very complicated for a first attempt at a repair. Having said that the schematic is available online and there is info on EEVblog on various faults and repairs. The main starting point is to identify a working RM3E wand with a working tip so that the MX500P can be tested. The wands are not impossible to repair and/or fault find, and if faulty will likely have break(s) in the coax inner near the handle. The only external indication that the unit is working is when the top switch is switched and a good wand gives a green LED or bad gives orange (from memory.) Post any progress or questions.Regards, BT

author: benj38
author_rank: Frequent Contributor
timestamp: August 12, 2019, 01:11:32 pm
content: If it were me I would go with option #2 without hesitation.This would be either some bad connection to or in the wand, or some fault in the wand detection circuit. Both should not be hard to fix. In particular, the wand contains no electronic components, and the detection circuit is a simple DC circuit with the main players being two transistors (2N3904, 2N3906) and a comparator (LM393).The other two faults may involve the RF circuit and/or the buck converter circuit, both of which can be easy or very hard to fix, depending on how (un)lucky you are.That said, if you have very little experience in electronics repair, even option #2 may not be a walk in the park.
AEG washmachine AC motor controller - Page 1
Forum section: electronics / repair

author: RetiredElectronicus
author_rank: Newbie
timestamp: January 07, 2024, 05:27:16 pm
content: Hello,Recently the ball bearings of our washmachine AEG 74650 drum are broken and to repair this, it is too expensive for this old machine.By dismanteling the machine, I found a nice AC motor with tacho and frequency controller that I like to use as a stand alone speed control unit..It looks that the speed control of the motor driver is controlled by a serial link but I miss the information of the serial data protocol and also the hardware configuration of the serial link.The motor controller label is "ELUX ASSEMBLY CODE 132527705/SUPPLIER NAME POWER-ONE/ SUPPLIER TYPE 4334991L" (Made in China).The main control board is "Electrolux 132541724" or pcb "EWM2500".I found some general info on service manuals of the washmachine but no electronic diagrams or info about serial communication between the boards.If by chance somebody could share this info, I would be happy.I found a electronic diagram of a previous control board but unfortunately this board had not the serial link yet for an AC motor controller. (The former machines had a DC motor controlled by a triac assembled on the main board).Thanks in advance for any help.
Aermec MODUCONTROL power issue - Page 1
Forum section: electronics / repair

author: kosmonooit
author_rank: Contributor
timestamp: August 14, 2025, 06:21:25 am
content: Greetings all,I am trying to sort out a Aermec MODUCONTROL power issue for someone . This is a controller for an industrial heat pump, costs a fortune to replace. The problem is a simple power issue: 13V AC not getting to the remote key pad. Otherwise the controller seems to work, its turning on the heat pump.I have dug deep in the Interwebs cannot find any circuit diagrams for this board.There is a conventional linear power supply with two secondary windings, one goes to a 7805 regulator for controller Vcc supply the other out to a connector for auxilaries. Those are okay. That is the largish black transformer in the middle to the one side.But the 13V AC supply is the problem a mystery. I can trace the tracks to the coil device (transformer?) on the side, brown windings, adjacent to the black transformer, Above that is the 230V AC supply from the mains filtering section along the top. There is a 8 pin DIP IC just above the small transformer, I cannot read the IC number at the moment. Might be some sort of chopper / regulator? Other than that there are a few caps and a sizeable resistor. I don't think this is switch type PSU arrangement, I don't see optoisolators.When i got the board. the blue cap adjacent to the small transformer and large black transformer had a lead loose which I re-soldered. This might that have caused something else to go.I don't have a ton of experience with analog repair. more a digital / sw guy but giving this a crack, it seems such a simple thing to resolve. I understand switching PSU theory but not much experience with fixing.Thanks in advance for any insight or suggestions.

author: kosmonooit
author_rank: Contributor
timestamp: August 14, 2025, 06:52:38 am
content: Update: I desoldered the cap that had one leg flapping in the breeze to test it with my EEVBlog BM235 and its looks like it open circuit but not too sure of its value, 25pF?BM235 MM reads 0.01nF just with the leads. Then .06 nF on the cap. I do not have an LCR meter.Crappy pic attached.Go / No Go?
Aeroflex 3283 Spectrum Analyzer (Serie 3280) - Page 1
Forum section: electronics / repair

author: kaureto
author_rank: Newbie
timestamp: September 06, 2022, 05:56:23 pm
content: HiI have a defective Aeroflex 3283 Spectrum Analyzer. the signal analyzer software cannot be started. the error appears in the picture. I suspect that the software cannot communicate with the DIP and RCON cards because the firmware on the cards has been lost. I found a tool on the hard drive that can be used to load the firmware onto the cards. unfortunately I'm missing the HEX files.(pioneer.hex, main.hex, adc.mcs)Can someone help me with this problem ?
Aeroflex RDL NTS-1000C Noise Analyzer - Page 1
Forum section: electronics / repair

author: mjames
author_rank: Newbie
timestamp: March 21, 2023, 11:37:30 pm
content: Hi. I recently bought one of these units and was wondering if anyone has any manuals on it? I see the models on eBay are A and B versions and never found anything on a C. I would be happy with any version of the manual.Thanks in advance.
Affordable plated through hole repair-Anything available? - Page 1
Forum section: electronics / repair

author: djsb
author_rank: Super Contributor
timestamp: October 26, 2021, 03:05:58 am
content: Are there any affordable alternatives to the CIF rivets and the CircuitMedic/Intertronic repair kits I've seen online? The CIF rivets themselves are OK (how many sizes are available?) but a bit expensive. The Chinese tubular rivets don't look like very good quality and arent in the size I need (1.6 mm outside diameter and around 1 mm (or slightly larger) diameter). Is there anything out there for a reasonable price and quality? Thanks.

author: sean0118
author_rank: Frequent Contributor
timestamp: October 26, 2021, 04:00:37 am
content: I couldn't find any that were high quality and cheap. I bought these awhile back, only used it a few times but seems to work okay, but it's annoying they don't come with an anvil to put under the PCB:"PCB Rivet / Eyelet Punch Tools for Rivets / Eyelets A, B, C, D, E and F"https://www.ebay.com.au/itm/273601184461
AFG3000 repair - Page 1
Forum section: electronics / repair

author: lern01
author_rank: Regular Contributor
timestamp: December 03, 2023, 03:17:48 am
content: I am repairing an AFG3101, and it has diagnostic and self-calibration error codes: 2303 and 1103. When referring to the maintenance manual, I suspect that one of the prompts in the maintenance tree is wrong, and I am asking for your help. Thank you all!As shown in the red box below
Again questions on TL866ii Plus ! - Page 1
Forum section: electronics / repair

author: Wawavoun
author_rank: Regular Contributor
timestamp: December 28, 2020, 10:09:49 am
content: Hello there,I'm trying to do a cool little trick to program the 2716s with the TL866II Plus.First point with an eprom directly in the device everything is fine:1) reading ok, pin detect ok etc ...2) writing ok by applying an external 25 V on pin 21 (pin out of the support of course), the pin detect and verification must be deactivated but after returning to 1) reading is perfectBend pin 21 : it's ok once, it's ok twice ... but quickly it breaks ... hence the assembly, see pictures.It's not complicated. We shift everything directly to a zif next to it except pin 21 which goes through a jumper that we can put in read (connected to the programmer) or write (connected to VPP). The 0V and VPP pins are used to connect the external 25V. No need to bend the leg anymore ...Well simpler there is not ... but it does not work !!! Already pin detect not ok and fanciful eprom reading if ignored ...I had already tried with a more complicated assembly (see herehttps://www.dr-bosch.com/volker/umbau/index.html) and which did not work either ... Well I said to myself there are diodes, not exactly the same references, ditto for the transistors etc... in short I did not insist ...But there ... I tell myself that I understood nothing...Of course everythins has been check, continuity and zif ok and no short !If you have any ideas i'm listening.RegardsPhilippe

author: Wawavoun
author_rank: Regular Contributor
timestamp: December 28, 2020, 07:16:47 pm
content: Well it's always the most unlikely thing that we do not test that is at the origin of the problem !!I first tried inserting a support (double lyres) between the assembly and the TL866 history to have more flexible pins ... Same problem!But I observed that the faulty pins at the "pin detect" were different each time I mount - unmount the assembly from the programmer ...Obvious sign of false contacts ...So I sent contact deoxidizer in the zif of TL866 ... and everything works!Also the more complicated system with diode and transitors works !!!Here it is ... conclusion the metal of the contacts of the TL866ii Plus zif oxidizes quite easily!Good evening everyone.Philippe
Agilen 8563EC  - Page 1
Forum section: electronics / repair

author: tchiwam
author_rank: Regular Contributor
timestamp: June 13, 2023, 04:53:20 pm
content: C716 tantalum shortNow only having a straight line above the scale across the range...I 'm suspecting the U909 MC33284D to have disliked a negative input while the -15VDC was near 0V shorted by the C716...IF on A3 is complaining too... so I guess that it might not behave until the GAIN is about right.All input and outputs are near the same potential, it looks like it got hot too...Anyway... ordered the part, let's hope

author: tchiwam
author_rank: Regular Contributor
timestamp: June 13, 2023, 05:08:14 pm
content: The suspect U909 that go hot ...Both rails are good measured on the side of the caps and the IC pins

author: tchiwam
author_rank: Regular Contributor
timestamp: June 13, 2023, 05:29:15 pm
content: If I keep the span around 1MHz and add a signal I can see something ...Well once I get the part... if it works or not... I'll let you know. And I hope this thread will be useful to someone someday.
Agilent E3632 - Page 1
Forum section: electronics / repair

author: Igorela
author_rank: Newbie
timestamp: March 14, 2024, 02:47:08 pm
content: Good time of day.Please tell me, I am currently repairing the agent E3632, there are doubts about the operability of the U7 chip on the front panel. The device turns on and emits two beeps, the display does not light up. I want to replace it with atmel, but I can't find the firmware. I found a file from KO4BB similar to 3646, but I can't download the file, writes that it was not found. Maybe someone has a firmware with N80C51BH 34401-88804 or something similar for testing. I used a translator, please do not scold for mistakes.

author: Igorela
author_rank: Newbie
timestamp: March 20, 2024, 07:38:56 pm
content: Thanks to all the many who responded. I found the necessary file and started the device.

author: alm
author_rank: Super Contributor
timestamp: March 20, 2024, 07:43:30 pm
content: Can you post where you found the files to help the next person who has this problem?

author: Igorela
author_rank: Newbie
timestamp: March 21, 2024, 08:09:47 pm
content: The file was found on the websitehttp://www.ko4bb.comThere was a problem with the download, perhaps the site was not working correctly. I am attaching it to the file, it is suitable for E3632. At startup, the power supply emitted two beeps and the display did not start.
Agilent 16702B problem  - Page 1
Forum section: electronics / repair

author: geshka
author_rank: Regular Contributor
timestamp: June 17, 2020, 05:35:20 pm
content: Hello gang.Looking for help with Agilent 16702B logic analyzer - it stopped running. When I turning it on green light next to the on/off switch is continuously flashing, all buttons on the panel are lit. Screen hasn't had any picture. is that a power supply? short somewhere? Any ideas what to look at would be greatly appreciated.
Agilent 1NB7-8477 RF Transistor Amplifier Replacment - Page 1
Forum section: electronics / repair

author: bostonman
author_rank: Super Contributor
timestamp: May 17, 2021, 02:58:14 am
content: I'm uncertain whether to ask this question here or in the Manufacturing & Assembly area.Maybe some of my posts regarding repairing an Agilent scope have been read already, however, I've come to the end of the road troubleshooting this and believe the hybrid is the culprit.I've search and the only place I can find these hybrids is through Ebay (see link below) - buying these is a big gamble. My questions: does anyone know whether these are counterfeit? The main question is replacement and whether anyone knows a procedure for replacing these type chips?My understanding is a ground pad exists underneath making this more challenging. I have a hot air pencil, however, I don't have much experience with replacing these type chips (i.e. how much heat to apply, head shape to use, etc..). Not that discoloring it is a big deal, but it's obvious a safe way exists to replace them that doesn't involve enough heat to show burn marks.Just for reference, the hot air pencil I have is: 852D+https://www.ebay.com/itm/323642939494?hash=item4b5a9f5866:g:swsAAOSwv~lavdgE

author: bostonman
author_rank: Super Contributor
timestamp: May 24, 2021, 11:49:54 pm
content: Should I remove this post and move it into manufacturing instead?I wasn't sure which place to post it.
AGILENT 33220A - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: December 10, 2020, 03:53:09 pm
content: Good evening everyone! I am looking for the diagrams of the AGILENT 33220A generator to repair mine broken down. Can someone help me ?? Thanks in advance

author: Andy Watson
author_rank: Super Contributor
timestamp: December 10, 2020, 04:13:40 pm
content: http://literature.cdn.keysight.com/litweb/pdf/33220-90012.pdf

author: HighVoltage
author_rank: Super Contributor
timestamp: December 10, 2020, 04:15:36 pm
content: Quote from: lionelkjh on December 10, 2020, 03:53:09 pmWhat is wrong with your generator?

author: lionelkjh
author_rank: Frequent Contributor
timestamp: December 12, 2020, 10:30:11 am
content: Hello; the failure is complicated: on ignition it gives me an error code 606 (no communication with the main circuit); If someone has an idea....

author: YetAnotherTechie
author_rank: Regular Contributor
timestamp: December 12, 2020, 12:05:27 pm
content: the optocouplers?

author: lionelkjh
author_rank: Frequent Contributor
timestamp: December 12, 2020, 01:10:26 pm
content: no, I do not believe that the failure is at the level of the optocouplers, but an error in the various dialogues of the integrated circuits processor / microprocessor ....
Agilent 33220A display problem - Page 1
Forum section: electronics / repair

author: chilternview
author_rank: Frequent Contributor
timestamp: September 09, 2024, 12:17:28 pm
content: I have an Agilent 33220A 20MHz function generator which has a display problem - basically it looks like the display backlight has gone. It's just about possible to read a little on the left of the display, but not enough to read it. Factory reset does not help.Anyone managed to fix one of these before? I've not opened it up yet to find out if the display has to be replaced as a unit or whether there is a LED tucked away that can be replaced.Edit: I read the service manual, seems like the LCD display uses a CCFL backlight. I'm guessing that's gone; apart from that the 33220A seems to be working correctly. I wonder if the backlight can be replaced with a 12v LED strip?

author: coromonadalix
author_rank: Super Contributor
timestamp: September 09, 2024, 02:52:05 pm
content: in some cases you can convert some ccfl to led ... it depends on how it is made, or some lcd could substitute your's if its really a dead ccfl supply ....but you have to check all the supply lines, there was known cases of leaked caps in theses

author: chilternview
author_rank: Frequent Contributor
timestamp: September 09, 2024, 03:04:00 pm
content: Yes, checked supplies and they are ok (and the unit passes self-test).The LCD display is a module on its own with a +12V supply and an inverter driving the CCFL. The CCFL is a plain straight tube about 3 inches long integrated into the display. I guess it may be possible to remove it and replace it although everything in that module is tightly packed.

author: chilternview
author_rank: Frequent Contributor
timestamp: September 09, 2024, 03:49:04 pm
content: Keysight quoted me £104 for a new 33220A display module which is less than I thought it would be.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 09, 2024, 04:19:40 pm
content: could be a very standard one, see in the service manual the specsbut you could try with a small led flashlight to the lcd side if it is really working, and the ccfl just died, some ccfl lamp can be found ...

author: gamerpaddy
author_rank: Regular Contributor
timestamp: September 10, 2024, 02:23:53 am
content: check the smd foil capacitorsseehttps://www.peel.dk/Repair/index.html

author: chilternview
author_rank: Frequent Contributor
timestamp: September 17, 2024, 12:53:57 pm
content: Well a new display module came in the post today from Keysight. It appears to have a LED backlight unlike the CCFL original. Fitted quite quickly and all works OK now.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: September 18, 2024, 09:21:32 pm
content: I wonder if somebody out there knows how to enable the arbitrary waveforms in those generators. Mine came without this option.Also, take the picture when it's put together. Wanted to see how this new screen actually looks installed.

author: chilternview
author_rank: Frequent Contributor
timestamp: September 19, 2024, 04:51:11 pm
content: Sure, here's couple of images. Can't compare with 'before' as that was just blank.
Agilent 33220A phase noise - Page 1
Forum section: electronics / repair

author: d-el
author_rank: Regular Contributor
timestamp: September 03, 2025, 05:18:27 pm
content: I noticed that one of my arbitration generators #1 started making noise in phase. This manifested itself as unstable frequency readings on the frequency meter.Photo of phase noise and STD DEV frequency measurement:Photo of time base generator:Noise on supply voltages is normal. Control signal VCO U602A is normal.Any ideas?Photo of phase noise and STD DEV frequency measurement of the working arbitration generator #2:

author: d-el
author_rank: Regular Contributor
timestamp: September 03, 2025, 10:52:34 pm
content: I swapped VCXO U602:After swap and frequency calibration the phase noise at 10 Hz offset decreased to -80 dBc, the standard deviation of frequency measurement decreased to 0.073 Hz:I wonder if the stock VCXO was bad from the factory or failed during use?

author: inse
author_rank: Super Contributor
timestamp: September 04, 2025, 06:39:38 am
content: Interesting failure
Agilent 33250A function gen output amp replacement - Page 1
Forum section: electronics / repair

author: feedback.loop
author_rank: Frequent Contributor
timestamp: February 13, 2023, 01:04:06 am
content: This is an attempt to come up with a replacement for Agilent hybrid output amplifier in 33250A function generator. The prototype almost works, but shows some sort of instability at the very limit at 80MHz and 10Vpp output.

author: w1k
author_rank: Newbie
timestamp: February 13, 2023, 09:11:48 am
content: Maybe the adjustment can help? It requires additionall power meter and 20db att.

author: HighVoltage
author_rank: Super Contributor
timestamp: February 13, 2023, 10:58:07 am
content: Very nice repair!At these frequencies the perf board might have a big influence and it will look much different, when you design your new PCB.Looking forward to your next step.

author: anotherlin
author_rank: Frequent Contributor
timestamp: February 13, 2023, 06:18:15 pm
content: Very nice repair video.As a follow on project, it would be great to make it an open-source standalone module, that can be build by anyone in need of a 80MHz (maybe make it up to 100MHz since the IC looks like capable of more) signal output driver.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: April 18, 2023, 07:04:27 pm
content: Part 2. A board was designed, and the new version of the amp was tested. After some tweaks it seems to work.

author: HighVoltage
author_rank: Super Contributor
timestamp: April 18, 2023, 09:43:53 pm
content: Very nice work you did here with the replacement !
Agilent 33250A Hangs up on Self-Test - Page 1
Forum section: electronics / repair

author: vinovino
author_rank: Contributor
timestamp: November 27, 2024, 03:12:47 am
content: I have an Agilent 33250A that hangs up on Self-test even after a couple of minutes.I can hear the relays switching inside while performing the self-test.Can, anyone of you know how to resolve this kind of problem?Thanks!!!

author: vinovino
author_rank: Contributor
timestamp: November 27, 2024, 05:13:12 am
content: After around 3 hours of self-test. It passed.Then when i perform again the self-test, it passed at around 30 seconds multiple times.But when I power off the unit and turned it on again. It hangs again at self-test.I suspect that it will take around 3 or 4 hours again to gain results.

author: Paceguy
author_rank: Regular Contributor
timestamp: November 27, 2024, 12:21:46 pm
content: I would start by checking the power supply voltage rails and then the caps.
Agilent 33250A Waveform Discontinuity - Page 1
Forum section: electronics / repair

author: dfox416
author_rank: Contributor
timestamp: December 03, 2019, 05:12:03 am
content: I recently acquired an Agilent 33250A function generator for free, since it has an issue. There is a strange jump in the waveform, like the bottom peak is chopped off and shifted upwards (shown in the attached images). The voltage at which this discontinuity occurs scales with the amplitude of the waveform (-250mV for a 1Vpp wave, -500mV for a 2Vpp wave) and the magnitude of the voltage jump at the discontinuity also scales with the waveform amplitude (60mV for a 1Vpp wave, 120mV for a 2Vpp wave). I can see this issue clearly for the sine, ramp, and arb waveforms, and assume that it is also occurring on the square/pulse but can't be seen because of how fast the edges are. Does anyone have an idea of what could cause this, or where would be a good place to start looking for a cause? I appreciate your help.

author: Renate
author_rank: Super Contributor
timestamp: December 03, 2019, 08:29:46 pm
content: It looks like your DAC is screwed.In olden times the MSBs on some DACs would have trims.But this ain't that.If it were there would be 3 breaks at 1/4, 1/2, 3/4.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 04, 2019, 10:02:37 am
content: First, check all power rails to be sure they are OK.But I agree, this is most likely a DAC issue.

author: Renate
author_rank: Super Contributor
timestamp: December 04, 2019, 09:48:41 pm
content: Yeah, I thought about the negative rail.But the signal is not crunched or non-linear and more telling, the entrance and the exit of the offset is identical on the sine.Well, if thus does arbitrary, you've got overlap.You can design a custom sine that has that jump inside it so that the output is clean.
Agilent 34401A K101 Relay Replacement - Page 1
Forum section: electronics / repair

author: rubidium
author_rank: Regular Contributor
timestamp: May 01, 2020, 09:27:00 pm
content: This topic has been reviewed here a lot before, so I won't go into all of the detail. In summary, it has to do with drift in the 2W resistance measurement attributed to a failing K101 relay. The original part is essentially unobtanium by an individual from Keysight even if one is willing to pay their insane price, but in this post:https://www.eevblog.com/forum/repair/agilent-34401a-2w-drift-and-high-readings-when-power-up/msg1346379/#msg1346379it was suggested to use the COTO 3540-05-911. I made such a swap about a year ago with a 34401A and the repair was quite successful, but now I own another unit that is displaying the same problem. The issue is that even the 3540-05-911 isn't to be found anywhere, as it's essentially obsolete. However, Newark has the COTO 3501-05-511 for only $15 !!The differences among all of these appears to be as follows: The OEM part had a contact rating of 1000V, and the COTO 3540-05-911 has contacts rated at 500V. The 3501-05-511 has contacts rated at 200V. However, the latter also has a factor of 10 lower thermal EMF rating (<0.5uV, which should make it better), as well as a factor of 5 greater life expectancy (5E8 cycles). All of these have the same form factor and pin arrangement, so they will all be a simple drop in replacements. Should I be concerned with the lower contact voltage ratings? I don't see how anywhere near these voltages enter the 2W resistance measurement. But, of course, I may be missing something.Thanks,Jim
Agilent 34405A VFD - Page 1
Forum section: electronics / repair

author: EddyInChicago
author_rank: Contributor
timestamp: June 29, 2021, 12:26:18 am
content: Hi All,I have a bad VFD on my Agilent 34405A. Can anyone point me to where I can purchase a VFD for my DMM?All help is appreciated.Thanks,Ed

author: coromonadalix
author_rank: Super Contributor
timestamp: June 29, 2021, 10:10:18 am
content: You have to ask at Keysight first, i don't think this vfd was ever clonedBe prepared to spend a good price

author: HighVoltage
author_rank: Super Contributor
timestamp: June 29, 2021, 10:15:56 am
content: I don't think the VFD was ever available from Keysight for the 34405A. Many years ago I had a bad 34405A and could not find the VFD. Luckily I was able to repair it.

author: voltsandjolts
author_rank: Unknown
timestamp: June 29, 2021, 10:31:15 am
content: ...and so begins the graphic LCD replacement for 34405A project

author: HighVoltage
author_rank: Super Contributor
timestamp: June 29, 2021, 10:53:59 am
content: This first question is: What is wrong with your VFD?Pictures?
Agilent 34410A parts identification - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: December 08, 2021, 02:24:47 am
content: Can anyone identify U800 that is located right behind red shroud of input terminals? It is a 6 terminal device and mine becomes awfully hot. (too hot to touch)Someone posted a nice photo of it here on another thread, so I'm going to repost it. I hope he/she doesn't mind.... only marking I could read is "8K72".Unlike it's cousins, service manual does not have any parts identification section or a circuit diagram.Help!

author: floobydust
author_rank: Super Contributor
timestamp: December 08, 2021, 03:31:22 am
content: 34410a schematicshttps://doc.xdevs.com/doc/HP_Agilent_Keysight/34410A/34410-66521_schematics.pdfPage 2 of 14 shows U800 as a buck-converter generating 3.3V_FPGA and 3.3V_A. Agilent 1827-0634.SMD marking 8K72 led me to a few Torex Semi parts like XC9258 but not a match. This is as far I can help.

author: fzabkar
author_rank: Super Contributor
timestamp: December 08, 2021, 04:00:29 am
content: The feedback voltage is 1.25V.LM2736 looks suitable (wrong marking):https://win.adrirobot.it/datasheet/integrati/pdf/LM2736Y.pdfI would check whether the output is being overloaded.More candidates (wrong marking):https://www.micros.com.pl/mediaserver/info-st1933ltes6.pdf(LT1933)http://www.farnell.com/datasheets/85166.pdf(LT1934)

author: tkamiya
author_rank: Super Contributor
timestamp: December 08, 2021, 04:06:02 am
content: Thanks both! Greatly appreciated!
Agilent 34410A U1001 flash dump  - Page 1
Forum section: electronics / repair

author: kevinwolfsky
author_rank: Newbie
timestamp: November 02, 2021, 04:53:13 am
content: This is my 34410A flash dump,dumped from chip U1001 use RT809h programmer, hope I can help someonehttps://mega.nz/file/aGYk2JKS#JC0poBAYbqirRZDuLFD_f2KfhoBipDT4VguNgliIAw0
Agilent 34411A repair "FPGA COMMS FAIL" - Page 1
Forum section: electronics / repair

author: Fabi1
author_rank: Newbie
timestamp: March 28, 2020, 04:11:21 pm
content: Hi all !I succeed to repair an Agilent 34411A DMM, I share the solution if someone get the same problemThere was an "FPGA COMS FAIL" error display on power up, it comes from 3,3V power supply, provided by U800.The problem disappear when I put my finger on U800, I add tin-lead solder on each SOT23-6 pin of U800, then it works fine !see attached files, 34410A schematics (almost same as 34411A ?), and pictures to localize U800Fabi1.Agilent_34410A_schematics.pdf(848.8 kB - downloaded 1286 times.)
Agilent 34461A Error Codes - Page 1
Forum section: electronics / repair

author: Metex
author_rank: Newbie
timestamp: January 02, 2025, 03:13:02 pm
content: Welcome!First of all, I wish everyone a happy new year!I want to ask for help.I have an Agilent 34461A with the error codes shown in the picture.I updated to version 3.03.Sanos, that didn't fix the error.If anyone could help me with this, I would greatly appreciate it.Welcome! Csaba

author: coromonadalix
author_rank: Super Contributor
timestamp: January 02, 2025, 05:36:32 pm
content: retry the self test with shorted inputs ... seem you have some offset, but did the meter received some voltages / over currents or else before trying any fw updates ?history ?

author: Metex
author_rank: Newbie
timestamp: January 02, 2025, 05:54:50 pm
content: I tried but same error.As far as I know, he didn't get anything.When the 1.09 update was on it, these errors were not present, only the AC offset error, which was corrected with the new update. Maybe I made the mistake of accidentally starting a calibration with open inputs? I read that maybe the zero points are gone?
Agilent 34461A NAND Dump (Firmware) - Page 1
Forum section: electronics / repair

author: RichTamim
author_rank: Newbie
timestamp: July 22, 2025, 03:18:43 pm
content: I’m looking for a full NAND flash dump for the Agilent 34461A digital multimeter. The original dump from my unit seems to be corrupted (firmware update always fails, device falls back into demo mode).If anyone has a working unit and can share the dump (preferably with spare/OOB), it would be extremely helpful. I have an RT809H and can flash the chip properly.

author: voltsandjolts
author_rank: Unknown
timestamp: July 22, 2025, 03:30:15 pm
content: https://www.eevblog.com/forum/repair/agilent-34461a-corrupted-flash/msg5879394/#msg5879394The post after that one has an explanation of memory layout, beware of the ecc in the spare bytes of nand.The firmware version may also matter, to match up with the firmware on your mainboard. Someone else may have more info on that.

author: RichTamim
author_rank: Newbie
timestamp: July 22, 2025, 03:39:02 pm
content: Hi @voltsandjolts,Thanks a lot for the reply and the pointer!I’ve checked that message - it’s really helpful to understand the memory layout and ECC structure.Right now my multimeter shows firmware version A.03.04 in demo mode.So ideally I’m looking for a full dump (with spare/OOB) from a working 34461A with the same version - just to avoid any mismatch between the front panel and mainboard firmware.

author: voltsandjolts
author_rank: Unknown
timestamp: July 22, 2025, 05:44:38 pm
content: The v3.03 at my link above is very likely close enough to your v3.04.

author: RichTamim
author_rank: Newbie
timestamp: July 22, 2025, 10:47:29 pm
content: Thanks voltsandjolts for the detailed explanation and the memory layout - really appreciate it.I’ll flash this 3.03 dump to the NAND and let you know what happens.

author: voltsandjolts
author_rank: Unknown
timestamp: July 23, 2025, 09:40:27 am
content: I would recommend using a new nand, since you are going to this effort anyways.

author: RichTamim
author_rank: Newbie
timestamp: July 25, 2025, 05:14:49 am
content: Sorry voltsandjolts, unfortunately, the MEGA link to the 3.03 NAND dump shared by testpoint1 seems to be dead - the file has been removed. Do you happen to have a local copy of that dump or could you possibly reach out to testpoint1?I’d really appreciate any help - trying to move forward with the repair.