Want: NS ADG339C Demux chip for Tektronix TDSxxxD - Page 1
Forum section: electronics / general

author: squadchannel
author_rank: Frequent Contributor
timestamp: May 27, 2025, 12:08:20 pm
content: As the title says, I am looking for Demux chip.I am posting this because it is off the subject of this thread.https://www.eevblog.com/forum/repair/unified-tektool-released-!-(firmware-flash-tools-for-old-tds-series)/msg5927560/#msg5927560Currently the Demux closest to the side connector is damaged. It stopped working a few years ago and was resoldered, but still unusual heat, leading to the conclusion that it was damaged.Nothing had been done to it since then, so I lost the suspicious demux with the last work, the Demux removed. Still, Ch3 (I thought it was Ch4, but it seems not.) tracing is wrong and the self-test gives an error, but it is working fine.I'll try replacing the damaged Demux with the normal Demux next to it to see if it works, just in case something else is wrong with it instead of the Demux.thanks.

author: Tantratron
author_rank: Frequent Contributor
timestamp: May 27, 2025, 12:56:06 pm
content: What method did you use to de-solder safely your ADG339C demux chip ?Do you remove it with its heatsink glued ?I ask because for someone selling this chip to you might need significant time and cost (chipquik) to remove each chip plus shipment to Japan.

author: TERRA Operative
author_rank: Super Contributor
timestamp: May 27, 2025, 01:19:08 pm
content: I only seem to have a scrap C series board with ADG229C chips (These don't have heatsinks), I suppose this chip wouldn't be of much use...

author: squadchannel
author_rank: Frequent Contributor
timestamp: May 27, 2025, 01:28:43 pm
content: The heatsink was removed using the blade of a cutter knife(snap cutter blade?), slipping it into the slight gap between the ceramic package and the heatsink, and applying heat. about 350 degrees.To remove the DEMUX, preheated the board for about 3 mins at about 200 deg C from the backside of the board, then heated the ceramic package at 370 deg C from the surface of the board.when I thought it had warmed up somewhat, I slipped a pick tool(HOZAN P-808) into the gap between the board and the bottom of the package, heated the pins on the four sides, and removed the package while watching it.I didn't use anything special because it's not a BGA. I did everything by intuition, so this may not be very helpful. It is important topreheat the boardbeforehand.

author: Tantratron
author_rank: Frequent Contributor
timestamp: May 27, 2025, 01:50:29 pm
content: Ok I see about the removal task of these specific ADG chips which again I've never done.Since 2019 I've purchased or repaired about twelve TDSxxx/C/D including lately TDS784A (hacked into a TDS784C) and TDS510A (hacked into a TDS540B).I do have left two TDS520D acquisition boards (see attached picture) where long ago I removed one heatsink (heat gun only) to learn what chip model versus C series (ADG299G), it is as you have namely ADG339C. All chips worked but the problem was one hybrid among 4 channels on one board (the one with heatsink removed), the other set of 4 hybrids were used lately to repair and hack TDS784A.Now the problem is Japan far away from France where I live (shipment cost, import...), maybe buying one board so you'd have more parts in case.

author: squadchannel
author_rank: Frequent Contributor
timestamp: May 27, 2025, 02:07:05 pm
content: TERRA Operative, thanks for checking your spare parts.Tantratron, I am grateful. Thank you. Actually, the OP in the original thread also informed me that he has a scrap board and can provide it.However, please take a moment. first, i try to replace it with DEMUX of another channel that is working properly and see if there are any problems.

author: Tantratron
author_rank: Frequent Contributor
timestamp: May 27, 2025, 02:23:25 pm
content: Indeed best to first verify real time this is chip you want to replace because they could be many other reasons explaining your TDS754D partial failure

author: squadchannel
author_rank: Frequent Contributor
timestamp: May 28, 2025, 01:12:21 pm
content: I believe that the suspicion has been cleared to some extent and the suspect has been identified. convinced that DEMUX is the culprit.replaced the first DEMUX from the connector, thought was the suspect, with a good second DEMUX.(Don't worry about heat sinks.)I thought that if the culprit was something other than DEMUX, DEMUX would to overheat as in the original symptom, but it boots normally.only Ch4 is strange. apparently there is no relationship between the DEMUX location and the channel. But I think they are close.looked at the error log,Code:FRI AUG 01 00:53:14 2003 ERROR: diagnostic test failure, digHFStepDiag, ERROR!!digHFStepDiag 200, No step found or <2.5 divs, ERROR!!digHFStepDiag 200, No step found or <2divsFRI AUG 01 00:56:07 2003 ERROR: diagnostic test failure, for DEMUX C, ** exp data= 0x5555 actual= 0xffff for bit # 16 for addr: 0x72c8000, ERROR,regNo: 0x72c8000, *** WAS TESTING DIG C ***ABCD from left to right, it is as expected.

author: Tantratron
author_rank: Frequent Contributor
timestamp: May 28, 2025, 01:29:49 pm
content: Hello, first I admire your skills to desolder and solder such complex pinout chips, I wish to have such mastery.Unless I'm wrong visually, it seems from one picture that you have TDS754D with max 1M option, the 64 SRAMs are not the model found in 2M so each chip lacks 2x2 pins.Would it be possible for you to find say buy a low price broken full TDS500/700D in Japan then you could use it as a donor, it would cheaper than buying DEMUX from overseas ?Now what is still wierd, you have no over-heat now but I might be lost in the sequence of swapping.

author: squadchannel
author_rank: Frequent Contributor
timestamp: October 06, 2025, 05:38:10 pm
content: Well, it took a while. Here are the results.I purchased the Demux chip from@madao. It came from his damaged ACQ board.His desoldering was the best possible result. After I received it, I made a few corrections and was able to install it.I checked each pin, and okay, power on!Huh, still "++FALL Acquisition"Looking at the waveform, it's a straight line all the time. Just a little up and down by about one pixel.Of course, errors occur in the self-test and SPC.It must be my fault, the traces must be broken somewhere. hoping that was it, I desoldered it again.The traces didn't seem broken anywhere.I removed the heat sink before desoldering. The Demux I received from madao had the heat sink attached.Looking closely, it's an ADG339 "D"... wait, not "C". The revision of the part number is also "01", not "00".So there are at least two revisions of the ADG339.Looking at the parts list, it seems there are at least three types on the 754D ACQ board. One is the early QFP version, one is the later BGA version. What about the other one? It makes sense if there are two types of QFP.nah just had different memory capacities.I don't know if this is an issue. But it's highly suspicious.Tomorrow (today), I'll try swapping it with the demux from the working channel.Conclusion. I'm looking for an ADG339 "C".Code:SAT DEC 06 17:16:07 2025 ERROR: diagnostic test failure, in A2D U750 or DmuxC U200, , ERROR ,Breg 2: AData = 0x300, expected Value = 0x7f00, , ERROR ,Breg 4: AData = 0x200, expected Value = 0x7f00, , ERROR ,Breg 6: AData = 0x200, expected Value = 0x7f00, , ERROR ,Breg 0: DData = 0x300, expected Value = 0x7f00, , ERROR ,Breg 2: DData = 0x300, expected Value = 0x7f00, , ERROR ,Breg 4: DData = 0x300, expected Value = 0x7f00, , ERROR ,Breg 2: AData = 0x300, expected Value = 0x8000, , ERROR ,Breg 4: AData = 0x300, expected Value = 0x8000SAT DEC 06 17:18:54 2025 ERROR: diagnostic test failure, digHFStepDiag, ERROR!!digHFStepDiag 200, No step found or <2.5 divs, ERROR!!digHFStepDiag 200, No step found or <2divsSAT DEC 06 17:20:16 2025 ERROR: diagnostic test failure, digHFStepDiag, ERROR!!digHFStepDiag 200, No step found or <2.5 divs, ERROR!!digHFStepDiag 200, No step found or <2divsSAT DEC 06 17:21:29 2025 ERROR: diagnostic test failure, digHFStepDiag, ERROR!!digHFStepDiag 200, No step found or <2.5 divs, ERROR!!digHFStepDiag 200, No step found or <2divsSAT DEC 06 17:25:42 2025 ERROR: Internal adjustment range exceeded, ( 3 @ 7012): 1.4868 => Balance dac #4 (ID #147)SAT DEC 06 17:25:58 2025 ERROR: Insufficient differential response, ( 2 @ 7423): 0.000 divs differentialSAT DEC 06 17:25:58 2025 ERROR: Insufficient differential response, ( 1 @ 7423): -0.001 divs differentialSAT DEC 06 17:26:03 2025 ERROR: Insufficient differential response, ( 0 @ 7443): 0.000 divs differentialSAT DEC 06 17:28:20 2025 ERROR: Characterized values out of bounds, Ch4 trigger gainSAT DEC 06 17:29:25 2025 ERROR: Characterized values out of bounds, Ch4 trigger gainSAT DEC 06 17:29:33 2025 ERROR: 2260 Calibration failed, TriggersPS:I'll enjoy the chocolate with a cup of tea.

author: madao
author_rank: Frequent Contributor
timestamp: October 06, 2025, 09:35:39 pm
content: ouch..kuso.. (japanese "damn" )sometime is suffix meaningless for function (a example, ADG222B (VLSI) is fully interchangeable with ADG222C (NSC), only difference is manufacture)on TDS700D, for software make no difference with difference DMUX-suffix (our board is old style 700D series). Proably make difference pcb layout requiering of specified DMUX. (or mixing of C/D is not possible, or they hasn't surviving desoldering )This DMUX came from mechanical damaged acqusistionboard, which this dmux is working (confirmed).Sorry, i haven't make notice about suffix, because i haven't removing heatsink.can we compare with part number on pcb ? (i can look in about one weeks)gretting from nagoya

author: Tantratron
author_rank: Frequent Contributor
timestamp: October 07, 2025, 05:42:23 am
content: Quote from: Tantratron on May 27, 2025, 01:50:29 pmQuote from: madao on October 06, 2025, 09:35:39 pm@squadchanneland@madaoFollowing my previous post few months ago (see above), here are some closer view pictures of my two TDS520D boards taken from working unit. I keep these as donator, spare parts, mainly recover hybrids, SRAM but anyway, maybe you can check part number, version to analyse or understand if there are real difference for this ADG399x version. Note that one board has 1M installed whereas the other 2M.I'm no expert on soldering or desoldering, will take me years to reach the madao's expertise whom I know from long time except I live in France

author: squadchannel
author_rank: Frequent Contributor
timestamp: October 08, 2025, 05:46:46 pm
content: After my last post, I decided to try getting the ADG339 “D” to working.So, I placed the 339D in ChD and the 339C in ChC.Then, the ChD where I placed the 339D started working.This means the ADG339D I got from madao isn't damaged. Good.This points to the cause being either a problem somewhere in the ChC section of the board or an issue with the ADC.So, I swapped the ADCs between ChC and ChD to see if the problem would switch.It didn't switch. ADC is not damaged.This means the board itself is faulty.To identify the pin assignments for the ADG339, I referenced the 520B CLIP schematic.The memory bus should function even with some pin issues. check if the signals on D1 (main bus) and the ADC bus wit scopes appeared normal.but, its good. The D1 bus received signals similar to other Demuxes.I checked the ADC bus as best I could because I don't have the differential probe. The ADC bus was completely straight. no passive components were inserted in between, I checked it multiple times with a DMM.inductor, MLCC, and resistor are all fine. But it won't work.SHIIIIIIIIIIIITTTTTTT!!!!!!!!!I'm completely confused. I've concluded the board is faulty.One possibility is that the 339C and 339D cannot be mixed and used together.I know that when the ChD Demux is removed, the ChC waveform also becomes abnormal.Also, ChA and ChB are swapped with their actual channels.The board is 679-4165-00, G9D-2412-00.It's also possible the boards are different.Could the 339D be the Demux for 1024k x 8bit (2M opt)? 339C is for 256k x 8bit?If memory upgrades are possible on the D series, this possibility is ruled out.nah, 339D is working. it's not.I've been trying to get it working these past few days. The road ahead looks long. I'm exhausted.if it doesn't work, let's find someone to take it. recapped psu and mainboard, so I think it'll last a long time. I don't think I recapped the CRT.but I'm not giving up yet.

author: Tantratron
author_rank: Frequent Contributor
timestamp: October 09, 2025, 07:04:47 am
content: Quote from: squadchannel on October 08, 2025, 05:46:46 pmYou initially hypothetize 339D only for 2M option and 339C only 1M option. Maybe yes, maybe not because these acquisition board are normally configured by software enable (1M or 2M) and resistor enable (TDS520D or TDS540D or TDS714L or TDS754D or TDS784D).As mentioned before, I happen to have two spare TDS520D boards kept in my lab as spare parts and donors, one is 1M option and other 2M options. For different reasons related to understand why C serie acquisation board were not fully compatible with D serie acquisition board, I did desolder few years ago the heat sink of one U300 to find indeed ADG339C versus ADG229C plus the MCU firmware (U600) to be different. This was done on the 1M option TDS520D board, eventually if it helps you, I could desolder the heatsink of U300 from my 2M board to verify if it is ADG339D or still ADG339C. What is clear from both my posted pictures of each board, these are G9D-2412-00 but this might just describe the PCB traces definition and not necessarily the firmware and chip version.You have validated that@madaochip to work (interchangeable and intermixable), initially you had overheating ADG339C which clearly has an unknown root cause. Now you still have failure so your board seems to suffer of double or triple or cascade failures which might be a time challenge.One easier option would be for you to rather acquire a valid TDS520D board (half populated) then solder missing component coming from your own board. At minimum this would imply to move half of your SRAM, half of your ADG339C, half other chip like U750 and probably half resistor and capacitor network on back side.Just my 2 cents, good luckP.S. One additional question for all members, do you think possible to mix SRAM (1M) with SRAM (2M) on same board

author: squadchannel
author_rank: Frequent Contributor
timestamp: October 09, 2025, 11:01:15 am
content: Woke up this morning, thought about it for a bit, and realized I hadn't checked the attenuator.when I took it out,It's cracked! ceramic on Ch4!I was surprised, but I couldn't help grinning because I knew this was definitely the cause.Come to think of it, when the 754D broke, I bought a TDS7104.7104 also failed, and one issue was that the SPC wasn't passing. at that time, I swapped it with the broken attenuator from the 754D to isolate the problem.eventually, I figured out the attenuator relay was faulty, so I replaced the 7104's attenuator relay and put the 754D's attenuator back in place.That must be when it broke. The ceramic board was slightly misaligned in the aluminum case's groove. It probably cracked when I tightened the screws like that.I have two TDS7104, so I disassembled one and swapped out the attenuator assembly.working! The error log said it was the ADC or Demux, so I kept focusing on that part. I was totally fooled.Both the self-test and SPC is pass. conclusion, the ADG339C and ADG339D are compatible.I was sure replacing the Demux would fix it, so I swapped it out without touching the analog section and assumed no readjustment would be needed.Replacing the attenuator would make repair possible, but since it involves touching the analog section, readjustment would be required. Even now, the trigger level is slightly off.I'm stuck because I don't have the equipment to make adjustments.I'd like to fix it if possible, but I also have a TDS7104. What should I do?Quote from: Tantratron on October 09, 2025, 07:04:47 amMixed use should be possible. but enabling 2M on a channel that only has 1M might be cause errors.Using 1M(no option) on a 2M board should be possible.

author: madao
author_rank: Frequent Contributor
timestamp: October 09, 2025, 11:05:08 am
content: Good to reading, with successful of swapping with ADG399C/D.Sad with ceramic hybride. they is hard getting (otherwise you can catch one with bad relay, you can move relay from mechanical damaged hybride)greetings from tokyoMatt

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 09, 2025, 12:28:35 pm
content: Quote from: squadchannel on October 09, 2025, 11:01:15 amYou should ship it to me in Chiba (Or hand it to me in Otemachi/Akihabara) once I have my DOS PC running again and I'll calibrate it for free.I can do a full performance verification and generate a test report at any time though, so that will tell if there is any further issues or if an adjustment is required.