AOIP PJ6301 schematic - Page 1
Forum section: electronics / testgear

author: masterx81
author_rank: Frequent Contributor
timestamp: February 09, 2022, 10:52:10 pm
content: Hi!I have bought at a cheap price this nice piece of test equipment. The input section works perfectly, and agree with great accuracy with my 34401a. The output section have seen better days. Traces burnt, an some components replaced.Would be easier repair it with some schematics, or at least, know the value of the original components used (and replaced).I not see any custom component, so the repair seem quite possible. I've already sent a mail to AOIP without any answer.Thanks!

author: 2N3055
author_rank: Super Contributor
timestamp: February 09, 2022, 11:11:12 pm
content: There is no schematic in public that I know of. AOIP won't give it to you, probably.It's a shame it is output because output is quite more complicated.Take detailed photos of boards and post them here. We'll give it a try.As you said, apart from special A/D module for the meter (that works well for you), most of the components are off the shelf, at least active part. There are quite a lot egzotic resistors and relays though..

author: masterx81
author_rank: Frequent Contributor
timestamp: February 10, 2022, 12:08:49 am
content: Here some pictures.In the next days i'll do some reverse engineering of the traces, as usual with missing schematics. The board seem a 4 layer, but the internal layers not seem used a lot for routing, mostly used for power supply/ground plane.I see replaced diodes and seem also the capacitor. I suspect that also the TO220 was replaced (now an irf9610). I not know what is the purpose of the diode placed across the capacitor under the board. Another strange thing is a single component replaced with 2 in what seem anti-series connection. They are marked CM 3AGUB (can't find anything about them, i can't neither recognize the logo of the maker).I hate when i find boards with a repair attempt, i never know if the component replaced are compatible with the original parts.Thanks for the help!

author: masterx81
author_rank: Frequent Contributor
timestamp: February 20, 2022, 07:02:32 pm
content: So, anyone have a photo of this device, please?I've started removing the relays for made easier the repair. I've noticed 2 relays, one 5v and the other 6v (connected to the same uln driver ic), i suspect that one of them was replaced with wrong voltage rating.

author: masterx81
author_rank: Frequent Contributor
timestamp: January 21, 2024, 10:06:46 pm
content: Hi!Today i've put my hands for the second time on this device...I'm fixing some burnt traces, but i'm sure that some components were replaced by someone before me, and i not know what there was before...In the meantime, maybe someone have worked on this nice thing, and have some photos of the pcb?Thanks!

author: masterx81
author_rank: Frequent Contributor
timestamp: February 04, 2024, 08:48:21 pm
content: I've found an uln driver (used for driving the relays) shorted on one channel.But now i'm trying to understand what components have replaced who have tried to repair it before me.He had replaced an Sma component with 2 of this things in series:I can't find what component is, and i not know neither the manifacteur. Seem a CM 3AGUB.I'tried to identify it, without success. When low current (2ma)/"high" voltage is applied, it stops at around 38v.Seem to not have polarity, i think that is a mov...Someone know exactly what component can be? Thanks!

author: masterx81
author_rank: Frequent Contributor
timestamp: February 13, 2024, 09:38:47 pm
content: And, it's working! The damaged uln was making a mess.The backlight seem a bit low, and there is a 0.19mv offset to deal with, but seem ok.

author: masterx81
author_rank: Frequent Contributor
timestamp: February 14, 2024, 07:30:38 am
content: I have one last thing to fix, the binding posts of the device are in really bad shape and needs to be replaced, but i can't find anything that can be adapted[ Specified attachment is not available ]The back thread is 4mm, quite long, and they allow a wire to be clipped. Thay allow to use safety plugs.Anyone have seen something similar?Thanks!

author: masterx81
author_rank: Frequent Contributor
timestamp: March 07, 2024, 09:18:06 pm
content: Little update. I was not able to source similar binding posts, or with the safety shroudings, or the screw type, but nothing with both the features. So, i've used cyanacrilate and sodium bicarbonate to rebuild them, and the result is quite good.The only problem is that after the repair the device is a bit off calibration (most of it on the current output mode, almost 2ma, as a fixed offset on all the scale).Someone know how to calibrate it? On the output section it has 3 multiturn pots, but i've a bit of fear touching them.... and i hope/think that the calibration is stored on the nvram....

author: 2N3055
author_rank: Super Contributor
timestamp: March 07, 2024, 09:35:47 pm
content: Quote from: masterx81 on March 07, 2024, 09:18:06 pmDON'T you touch a thing!!Calibration is fully in software. CFG->ADJ menu (9456)Get docs here.. I will remove it in few days..https://drive.google.com/drive/folders/1KSJduUsf-sB5nqVKtSFHcdqdH_yZwq2j?usp=sharing

author: masterx81
author_rank: Frequent Contributor
timestamp: March 08, 2024, 12:37:36 am
content: I've seen that menu before, but i not knew the password, thanks!With the adj menu i've managed to match the voltage with my 34401 on both 60mv and 0.6v range, but on 60v range it goes very well up to 56v, when i try to go above that voltage seem that something is clipping it.In current output, i can't made adjustments as seem that the error is too much, and give me an error. An output of 0ma give -2.5ma, and 50ma give 47.5ma. An offset of -2.5ma. So i think that i need to understand why the current output is so much out of specs.. The repair job isn't ended 😅Really thanks!!

author: 2N3055
author_rank: Super Contributor
timestamp: March 08, 2024, 06:26:04 am
content: Quote from: masterx81 on March 08, 2024, 12:37:36 amNo problem.On mine display was really bad and I managed to find a replacement that was not backlit. It is old bitmap display not easy to find. I had to reverse engineer the protocol before I figured out which one...But on mine analog worked fine.It is really useful instrument.I hope you manage to fix it.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 08, 2024, 06:41:39 am
content: Whoa! That's an insane time consuming job reverse engineering the protocol to replace the display!For that occasion, i've managed to find an AOIP SA 32 broken on ebay, that shares the same frontend, so thag i have some spare parts...I think that the first thing that i need to check is the psu rail voltage used to generate the current and voltage. Maybe is a bit too low and clip the voltage output, and moved a bit low the 0 point of the current output.Maybe are the multiturn pots? Need to check better the circuit, but i can't exclude that someone before me have moved the pots....

author: 2N3055
author_rank: Super Contributor
timestamp: March 08, 2024, 07:12:12 am
content: Quote from: masterx81 on March 08, 2024, 06:41:39 amNot so much. When I say people MSO scopes are very useful, they don't listen. It was enough to see what kind of traffic goes over the bus to realize it was bitmap, and then a little research on old displays came up with possible candidates. Bit more verifying and that was it. It was standard display at the time, but fell out of fashion, I guess.Yes, verify power buses. Multiturn pots are not going to move 10%. Something is wrong.Or someone before you was in and they screwed up by tampering with pots.Verify semiconductors in output stage... you know, the usual...LT precision opamps used inside are sensitive. One slip of meter probe, you touch something wrong and pufff.. If someone was in there before, check them.As long as ADC module and reference is good and stable, all other parts are repairable.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 05:00:07 pm
content: You still have to know how decode the various formats, so you have found a compatible display with the same protocol?In any case i've measured the voltages, and there are 66v, seem to me a bit low. The output range is -10 to +60, but i get only 56v, and i not think that is a coincidence..First i try to remove the mov that had been replaced by who have tried to repair it before me, then i've seen a strange diode across the supply line, i think a zener, soldered on the bottom layer. If without this i still get low voltage, i'll start the search...--- Edit ---Without mov and diode i still get 66v on the main line, and i can confim that i can output from to -10v to +56v...

author: 2N3055
author_rank: Super Contributor
timestamp: March 09, 2024, 05:34:05 pm
content: Quote from: masterx81 on March 09, 2024, 05:00:07 pmDisplay protocols are connected with display chips and are quite standard. It was older "dumb" bitmap protocol. I do have " a bit of experience", that is true..Trace a schematic a bit, before just soldering in and out components.Voltage reference uses PWM to create 0-Max voltage signal.It is always the same -1V to +10V on my other calibrator from AOIP.There is attenuation and amplification in output.Try to isolate part that creates variable reference input to power amp.Measure voltage there. Than you know how much is amplification in 60V range.Try to trace part of circuit that switches amplification. If you find one of trimmers is in that circuit, than it might be that it needs to be adjusted.But my experience is that with these calibrators, these parts of circuit are using fixed parts (for stability) and with such tolerances so it is sufficiently close to be pulled in perfect cal just by software.Make good hires photos, so you can make notes on them. That way you can also post them here so we can maybe be able to discuss it better.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 06:03:50 pm
content: The real problem is that i not know how the output voltage is generated, and i'm having difficulties finding also how the 66v voltage is generated. Near the transformers i have only 63v, 50v and 25v capacitors, but near the output section i have this 66v line (with 100v cap), and i not see buck transformers around. I think that they use a center tap. As is a 4 layer pcb, it's quite difficult to trace the inner lines. Can be seen a little with a strong light and watching "through".First of all i'm trying to understand what is the purpouse of the 3 multiturn trimmers, and trying to understand how the voltage goes from the isolation transforers to the 100v capacitor... I think that the capacitor was replaced by who have made the first repair attempt, as it's different from the others. Also the replaced mov were in parallel to this capacitor, so the damage was for sure here (and the uln that i've replaced was in the same zone).Here an high res photo...On the top leftnsection there is the input signal conditioning, bottom left the the voltage input of the board, with isolation transformers, top right there is the output section, there were a lot of burnt traces, i've replaced the uln (tssop 18 package near the heat sink), and a relay (who have made the repair before have used a compatible but a wrong voltage relay), who have tryied to repair before me seem that have replaced the fet attached to the heat sink, some diodes around it, the blue electrolytic, the mov (that now are 2 mov in series) and the relay.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 06:18:50 pm
content: And this is a thermal view. The hottest components are some 78l05 and 78l15, nothing strange

author: 2N3055
author_rank: Super Contributor
timestamp: March 09, 2024, 06:25:22 pm
content: From memory my board is slightly different.Two trimmers in up right are part of PWM DAC I think .

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 06:47:25 pm
content: Quite strange, the voltage output from the transformer seem to decrease over time. The 66v is generated by 2 secondaries in series. One at 31v and the other at 36v, and both decrease.There is one transformer for acquisition and one for output, there are 2 smps driven by two si9112dy, input voltage steady at 20vdc. Quite strange, i not see a voltage feedback section. Need to trace a bit.On the output sections goes a +5, a +/- 15, and this 2 31/35v generated by the smps.Quite cool, communication between digital board and analog board seem to be via optical coupling.EditActually the voltage decrease, then is pumped up, and so on, so there must be a sort of feedback

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 07:32:23 pm
content: I still think that the problem is on the voltage supply section. I think the the ouput voltage of the 2 windings must be 35v and 35, but one of them is only at 31v. I'm tempted to interrupt the line to the circuits and see if without load the voltage is the same. And... i can't really tell how the si94112 chip get a feedback, as there isn't anything that can send back.I have fear that the problem is the transformer itself, that output a lower voltage. That would be a great problem, as it's a custom made....

author: 2N3055
author_rank: Super Contributor
timestamp: March 09, 2024, 08:15:46 pm
content: Quote from: masterx81 on March 09, 2024, 07:32:23 pmAll is possible.With power off, can you measure secondary coils resistance?And try to wiggle transformer a bit while measuring voltage when it is on.You might have a problem with winding end not connecting pin (not soldered or broken) correctly.I had that exact problem with one of the windings on my calibrator (other one).I had to perform delicate surgery in epoxy around terminal to get to wire and connect it.Worked well.It is perfect now.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 09:18:53 pm
content: I've made some measurements and discovered some interesting things. I think that the smps controller work only with the feedback of the primary current.Once rectified both secondaries of the transformer go directly to a relay, that choose the range. When set in 60v output it select the 35+35v output, else it choose only the first "tap" at 35v. When in 60v range i measure around 35 volt on the first tap and around 31v on the second tap (the 66 volts of the prvious tests).When in 6v range i get aroud 33v on the first tap, and aroud 36v on the second tap (70v total)Measuring the ac voltage with the 34401, directly at the output of the transformer (before rectifier diode), i get in 60v range 22.7vac on the first tap and 21.8vac on the second tap, while in 6v range 22.3vac on first tap and 22vac on second tap. I know that is an high frequency signal, but can be quite indicative.After the relay, there are 2 current limiting resistors in series (total 13.6ohm) that allow me to measure the voltage drop, and i get 90.7mv on both ranges (6.6ma) at 0v output and 113.3mv at 50v output (8.3ma).6/8ma can be too much current without load? This thing in output current mode must source at least 60ma....I've checked diodes, capacitors and inductances after the widing, and all is good.In current mode it choose the first tap with aroud 33.9v with 0ma output. With the output at 60ma it go at 32v.The voltages in current output mode are quite good, so i can't explain the 2.3ma offset.The dc voltages of the +/- 15 and 5v windings are similar to the voltages of the other transformer (+/-18.9vdc vs +/-18.4, 7.4vdc identical).Measuring the voltage drop across the current sensing resistors on the primary side, i get (on 2x 1r resistors in parallel) 256mvac with 60ma output current set, and 179mvac with output set at 60v...The current on the primary side not seem too bad in 50v dc output vs 60ma current output, the ac voltages out of the transformer seem quite good, it's the dc voltage of the second tap that seem to drop too much. The diode measured with the tester seem good.I think that the current offset and the clipping of the output voltage are 2 different unrelated problems.But by now i'm more confused than before doing all the tests...I'm starting to think that the problem it's really the transformer, at best it output 70vdc, that not leave any room on a -10+60v output. I think that the correct rectified voltage must be something something around 80vdc.

author: 2N3055
author_rank: Super Contributor
timestamp: March 09, 2024, 09:35:32 pm
content: The switcher that feeds output stage is basically tracking pre regulators for output stages.That keeps dropout on output transistors getting too high and keeps dispation low.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 10:04:41 pm
content: I've removed the transformer, and the feedback is given by a second primary, it's a type of feedback that i not see very often, most of the times i see a feedback from the secondary via an optocoupler.According to the de5000, the resistance/inductance of those 2 windings are :From gnd to first tap: 285mohm / 154uHFrom first tap to last tap: 265mohm/ 142,5uHFrom gnd to last tap: 0.536mohm/ 588uHWhy both windings in series have an inductance that ins't the sum of both single inductances?In general, not seem too badI've also found that the 2 6.8ohm resistors in series are out of spec, both at 7.4ohm. Not change much, this are here only to allow a soft discharge of the capacitor after them.

author: tatel
author_rank: Frequent Contributor
timestamp: March 09, 2024, 10:38:02 pm
content: Quote from: masterx81 on February 14, 2024, 07:30:38 amI have... but it comes on an AOIP resistor decade box. Identical.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 10:43:15 pm
content: I have too an aiop resistor box, but i use itI've rebuilt them using cyanacrilate and sodium bicarbonate. For a 60v device i think that i not have insulation problems.The result is not perfect, but good enough.

author: tatel
author_rank: Frequent Contributor
timestamp: March 09, 2024, 10:50:33 pm
content: Here it is... I'm going to machine the new parts from teflon

author: tatel
author_rank: Frequent Contributor
timestamp: March 09, 2024, 10:56:26 pm
content: Yours look much more modern than mine. Plastic isolation looks quite a lot thinner. It surprised me you was able to get the cap out. Where they already broken? Not going to touch caps on mine, just replace the isolation.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 09, 2024, 11:02:24 pm
content: I'm looking at my decade box, and not have the safety shroudings like the meter. You can replace them easily. The threads are m4, cam be found also qute cheap on aliexpress, or quality one form hirshmann or staubli

author: masterx81
author_rank: Frequent Contributor
timestamp: March 10, 2024, 12:18:36 pm
content: Quote from: masterx81 on March 09, 2024, 10:04:41 pmI think that the power section is good...I've found a -15v voltage source on the board (i've still not found what generate it, i not see inductances), that is used to generate the -10v output, so the 66v are enough the 60v positive part output.I think that is better, as the other components can be replaced.I'm unsure about few components that were replaced by who have tried to repair it before me.One is the mosfet, then the 2 diodes in photo:I not know if were replaced with equivalent components.I not know the mosfet what is used for, but i suspect for generating the output voltage (but if is generated with pwm, i would suspect that there is the need at least of a filter capacitor after the fet, but i not find any).Now, i think that is time to use the scope for the next part of the fault finding....EditWhops, the other secondaries that generate +15,-15 and +5 have gnd in common with the 35+35 taps, so the -15 is the same used for the opamps.

author: masterx81
author_rank: Frequent Contributor
timestamp: March 26, 2024, 09:41:12 pm
content: After have replaced the two 6.8ohm resistors, the 6v and 60v ranges works very well. Allowed me to do the calibration, and are really accurate from -1/-10v to +6/+60v.Now remain the problem on the 0.6v range, at 0v output i get near 0.820mv, and at 500mv i get 500.814mv, but during the calibration it give an out of range adjustment error.And on the current output i still have an unwanted -2.368ma offset, that can't be adjusted...Let's find the next problem....

author: masterx81
author_rank: Frequent Contributor
timestamp: April 05, 2024, 08:13:26 am
content: I've still not had time to check for other problems but, just for curiosity, normally, how is generated a constant current? Only to be able to identify the sections involved.Thanks!

author: electrolux
author_rank: Regular Contributor
timestamp: April 11, 2024, 09:35:18 pm
content: Came across this thread when googling the model number. Thought I would post some PCB pics incase anyone finds them useful as there is very little info on this thing.This particular unit is dead as it wa plugged into 230V while switched to 115V. Dont have the time to tinker with it unfortunately.Also, first forum post in 6 years. bye bye for now.

author: masterx81
author_rank: Frequent Contributor
timestamp: April 19, 2024, 03:08:06 pm
content: Quote from: electrolux on April 11, 2024, 09:35:18 pmWow, really clean and nice unit.Seem aged better than mine.Hope that have fried only few things after the transformer, from the photos not seem that much have smoked.Comparing the output of this device with a 34401A, seem that it's pretty accurate (at least 4 digits), it's a nice unit, and i think that can be a nice addition to a workbenchLet me know if there is something that i can help you for fix it, in my unit that section is good, and i can take measurements/photos..Maybe, it's possible to have the p/n of the FET, and maybe a photo of the diedes in front of him? I think that who have tried to repair mine before me, have replaced it, and i not know if he used a compatible part.Really thanks!!

author: Joseph_S
author_rank: Newbie
timestamp: May 15, 2024, 09:05:55 pm
content: QuoteWhat is the FET you're interested in?I may post a high definition picture of the surround area in the analog board.

author: masterx81
author_rank: Frequent Contributor
timestamp: May 28, 2024, 07:20:35 am
content: Quote from: masterx81 on March 10, 2024, 12:18:36 pmI'm interested in the fet in this photo, and the 2 components under it...As i have this small (but uncorrectable with calibration) offset first of all i need to know if the parts where replaced with compatible ones, then i'll try to search for faulty or out of spec components....Thanks!

author: masterx81
author_rank: Frequent Contributor
timestamp: November 10, 2024, 07:51:52 pm
content: Hi! In this days i have some spare time and i want to try to fix the unit. As now the only remaining problem is the little offset on the current output mode (that can't be fixed with the calibration), i want to focus on how this thing generate currents, so that i can check on that circuit section.Anyone have an idea on how this device generate the current?Maybe now all the components are ok, and for example the only remaining problem is a trimmer moved by someone else, or a component replaced with something different... i not know 🤷‍♂️In any case by now the fet is an irf9610...Thanks!

author: masterx81
author_rank: Frequent Contributor
timestamp: November 14, 2024, 09:48:34 pm
content: Little update. I've replaced any semiconductor of the output section (were all low cost components, so i've ordered them all), and after a warmup, now i'm able to do a full calibration of any range without problems 👍While in doubt i've also measured every resistor.So, by now seem fine

author: masterx81
author_rank: Frequent Contributor
timestamp: November 16, 2024, 07:25:28 pm
content: This thing is driving me crazy..Now, both current and all voltage ranges are fine (i see a little "shaking" of the low values, bit as seem that the output is generated via pwm, i think that can be normal).But if i go on the ohm output mode, at 0 ohm output i get 70ohm, while at 600ohm it's pretty accurate (603ohm).How is "emulated" ohm output on this type of devices?Thanks!

author: masterx81
author_rank: Frequent Contributor
timestamp: November 16, 2024, 08:50:57 pm
content: Nevermind, found another damaged resistor, and now the resistace range works. Just for info, the section that do the resistance is around P3. The burnt resistor was the 39ohm one near it.There is a residual problem. Despite been accurate from 0 to the upper range (0.6v, 6v and 6v) when i try to output negative voltages, i get good values down to -60mv at 0.6v range, at -0.7v i get -0.691, and at -100mv i get -94.356mv...On 6v range i get pretty good values down to -0.4v, then at -0.5v i get -0.492v, at -0.6v i get 0.578 and at -1 i get -0.922v.On 60v range, it's worse. At -5v i get -4.48v and at -10v i get -5.6v.Seem that lower is the voltage, and worst are the results. I susptect still something still damaged near the output... i've replaced almost all... remain few sot32 devices and few diodes...

author: 2N3055
author_rank: Super Contributor
timestamp: November 16, 2024, 09:31:18 pm
content: Resistance is emulated standard way like on active loads, by making current proportional to applied voltage.Make note that circuit is not unconditionally stable, so it can oscillate with some instruments..

author: masterx81
author_rank: Frequent Contributor
timestamp: November 17, 2024, 04:14:26 pm
content: Trying to find what's wrong on the negative voltages, i'm understanding a bit more on how this thing works.There are 4 pwm signals (generated by 68hc68w1 ic's), that are converted to analog with a opamp and some capacitors. The hardest thing to understand is how this 4 signals are combined to generate the + and - output voltages. Using the system ground as reference (halfway referrend to the -15v and +15v used for almost all the ic's), both 2 output signals vary (there isn't a situation where one of them is stable). Seem that the four signals are then combined in 2 different signals (both processed in different ways).Now i'm trying to do some statistics on how the voltage varies at the various sections of the circuit based on how is set the output voltage, for understand where it stop to be linear and "clip" the negative voltage. So loooong job

author: masterx81
author_rank: Frequent Contributor
timestamp: November 17, 2024, 06:17:59 pm
content: Damn... measuread almost anything. Replaced almost any semiconductor. The semiconductors that i've not replaced, were moved aroud, swapped with same in other position. No change.Remain only one thing... the multiturn pots. But i'm pretty sure that aren't they the problem. I'll take a good measure before moving anything, and i'll try to meve them. I think that p2 and p4 are the interested ones (as p3, as previously discovered, seem related to the resistance output.

author: masterx81
author_rank: Frequent Contributor
timestamp: November 17, 2024, 08:10:19 pm
content: The multipot actually adjust a bit, but not an error so big.Strange thing: sometimes it clip at little less than 6v, sometimes (especially after powering on) at little more than 7v (with 10v set in software).I've tried heating the board wiled powered on with the hot gun, and nothing. Maybe it's time to check all the capacitors....

author: masterx81
author_rank: Frequent Contributor
timestamp: November 18, 2024, 08:29:37 pm
content: Someone have idea of what is this thing? It's a precision resistor, but i can't find specifications. From side to side 1-3 is 3.786k, 1-2 626ohm, 2-3 3.160kValues are quite precise, so i think that is ok, bit as i can't check...

author: masterx81
author_rank: Frequent Contributor
timestamp: December 08, 2024, 01:26:12 pm
content: Still fighting with it on spare time...Would be nice to have, when function set on output 60v, the individual voltages of both output terminals referred to system ground, with the output configured via software to 0v.I'm trying to understand what is the correct procedure for calibrate the trimmers... seem that one of them (P2) move the voltages referred to ground.Would be great also have the individual output voltages at other voltages (for example 0v, -1v, -2v, -5v, -10v and +1v, +2v, +5v and +10v)By now i've checked or replaced almost every single component. Remains two variables:- someone before me touched the calibration trimmers- some components were replaced with something not adeguate (i suspect the to220 mosfet, and the 2 diodes on the drain).As the problem seem only with negative voltages, i suspect more the second one, but i can't know for sure until someone not tell me what are the correct components 😥Thanks...

author: masterx81
author_rank: Frequent Contributor
timestamp: December 15, 2024, 03:30:27 pm
content: Still searching the damn problem.I've excluded the diodes on the drain of the irf9610, as one of them is in reverse polarity while generating negative voltages, and the other seem not matter the type (seem an 1n4007, replaced it with a shottky and nothing changed, and to me can't be a zener - but i can't be sure on what there was originally).Maybe remain the uncertainty of the irf9610.One thing that i've noticed testing the ad588 voltage reference, is that on the -5 -10v configuration suggested on the pdf, i get only -9.972v on the unbuffered output, while by pdf on -10v configuration i need to get +/- 3mv error, after the buffer i get -9.962v... the -5v unbuffered is at -4.996v (also out of tollerance).While generating positive voltages is pretty spot on.All measured with a 34401a.I think that have drifted a bit...

author: masterx81
author_rank: Frequent Contributor
timestamp: December 24, 2024, 01:33:09 pm
content: Received the new AD588... On -5v i get -4.9981 unbuffered/-5.020 buffered and on -10v i get -9.977 unbuffered/-9.978 buffered . A little bit better but not the accuracy specified on the pdfAll with 34401a set on 10gohm input.I've also checked my 34401 against a known ad584 reference and is spot on.I know that a voltage reference is more important to be stable than accurate, but seem strange that is so out.In any case, the drift wasn't the cause of the error on the negative voltages... sooo keep searching

author: masterx81
author_rank: Frequent Contributor
timestamp: December 30, 2024, 10:41:24 pm
content: Seem that i've fixed it.Every component was tested or replaced, and still had the problem. I've tried anything...So, as i wasn't able to find anything bad, i've restarted from the beginning. I've started checking the traces from the back terminals, writing down the schematic. Not an easy task as it's a 4 layer board...While checking, i've discovered an interrupted trace in an inner layer. That have fixed the output problems.Now i leave it powered on for 24h with the 34401a, and tomorrow i'll calibrate it.Thanks to all!

author: masterx81
author_rank: Frequent Contributor
timestamp: December 31, 2024, 02:04:09 pm
content: Aaand, after the calibration:Range 600mv-100mv=-99.9979mv0mv=0.0001mv100mv=99.9972mv200mv=199.996mv300mv=299.997mv400mv=399.997mv500mv=500.000mv600mv=600.002mvRange 6v-1=-0.999983v0=0.0020mv1=0.999982v2=1.99997v3=2.99997v4=3.99997v5=5.00000v6=6.00003vRange 60v-10=-9.99969v0=0.0158mv+10=9.99970v+20=19.9996v+30=29.9997v+40=39.9997v+50=50.0000v+60=60.0005vRange ma0ma=0.00014ma10ma=10.00005ma20ma=19.9997ma30ma=29.9998ma40ma=39.9998ma50ma=50.0003ma60ma=60.0008maRange 600ohm0ohm=0ohm100ohm=99.9991ohm200ohm=199.9999ohm300ohm=299.9999ohm400ohm=399.9999ohm500ohm=499.9999ohm600ohm=599.9998ohmRange 6kohm0ohm=0ohm1kohm=1.00001kohm2kohm=2.00009kohm3kohm=3.00007kohm4kohm=4.00005kohm5kohm=5.00002kohm6kohm=6.00000kohmI think that is good enough