A few words on HP part numbers... Firstly, HP used their own part numbers for generic parts and often had manufacturers mark them with the HP number. Generic part numbers consist of two groups of four digits. The first four digits tell you what type of part it is. For example with part 1854-1028, the 1854 tells you it is a silicon NPN transistor, and the 1028 tells you it's a 2N3904. Many HP service manuals up to the 1980s contain replaceable parts lists that actually cross reference HP numbers to the manufacturer's original designation, so if you have a part with one of these HP numbers on, but don't have the service manual, it can be helpful to search through other HP service manuals for instruments likely to contain the same part. Other parts, like the PAL in this video, have 10 digit numbers. These are parts specific to one instrument or a few instruments. They can be used for individual parts or for sub-assemblies. The format of the number is abcde-nnnnn. 'abcde' is the model number of the instrument, with a leading zero for four digit model numbers. If the first digit of the second group began with a 6, this generally meant it was a complete board as I recall. There used to be a program where defective boards replaced in field service were sent back to the factory for repair. These came back with the second digit of the second group replaced by a 9. The PAL in question here was used originally in the 4263 LCR meter. I hope somebody finds this info useful. Apologies if I made any errors -- it's a long time since I was a field service engineer.

Thanks for the memories. I was the HP product manager on the 4263A, 4338A and 4339A. Fun stuff working with my Japanese colleagues.

@TERRAOperativeOriginal

2 ай бұрын

You wouldn't happen to have access to the Adjustment Programs for any of these instruments by chance?

@alanfryer5670

2 ай бұрын

@@TERRAOperativeOriginal Sorry no. I've been out of loop for 25 years.

No doubt you know the “word” ADC but I’m not sure whether you know the word failure. Just wanna express my appreciation for the superb videos you make. Thank you big time.

I have a 4338A on my workbench for repair.........very happy to see Shahriar working on the 4338B and providing info on the AK9201A ADC. Gives me a great place to start.

The PALCE 16V8 family does indeed allow for outputs to be registered. However, it does not have "internal-only" registers, e.g. you cannot have hidden state in the chip. It has only one type of macro cell. If you want a flipflop which acts as an input to another logic cell, you can use internal routing of a !Q output to the neighboring cell, but at the same time, the non-inverted Q output of the flipflop is available on a pin. So it is quite possible to reverse engineer those, even if this is mask-programmed (and another commenter stated that it might not be). 16 inputs, 8 outputs, slowest speed grade. Probably not even all inputs used. That's a truth table that can be (reverse) engineered by hand. Contact me if you want to discuss options on doing that.

Apparently those PAL device can be read in some way or form, as LSC suggest in their PAL to GAL datasheet "A GAL device may also be programmed from a master PAL device by reading the pattern of the master PAL into the programmer memory" I could imagine, that the EE memory on the PAL is just corrupted due to aging (it has a nominal data retention of 10/20 year depending on temperature). So it could be as easy as reading the "good" PAL into a programmer and re-writing the "dead" PAL. PS: The datasheet actually mentions something about a security bit so it may be a bit more tricky. But reverse engineering the truth table of that pal should make a fun video ;-)

For a minute there it was fun to see a few basic components in a breadboard like us regular mortals. Then all goes back to normal as he plugs it in to a thirty thousand dollar 'scope. Sigh. :-)

@kirkpennock2997

6 жыл бұрын

I was doing the "I am not worthy worship at that point and laughing.

@dtiydr

6 жыл бұрын

That scope looked to had a screen bigger then the computer screen I´m watching this at..

@ToltecMerc

6 жыл бұрын

30K was my guess as well.

@guyfamily5323

5 жыл бұрын

Don't worry. You can archive the same result hooking the wires up to a 15$ USB logic analyser from PRC. And the signals on screen would be also in color

@leozendo3500

5 жыл бұрын

You can probably game on that scope.

I am in love with the MSO58.

Thank you for sharing your knowledge! (And thanks Patrons for supporting him

Thanks for all the work that went into this one. Very interesting.

Thanks again Shahriar! So exciting when you post a vid!

I hope you find the part you need. Thanks for helping me understand some very advanced topics for this hobbiest. Makes the patreon very worth while.

Beautiful explanation!

Another great video! Thank you for sharing your time and wisdom

Great repair. Well diagnosed!

greatness

Enjoyed this one!

Great video!

It seems like the world's top engineers are gathering up in this comment section. This is probably the highest quality advanced EE video channel on youtube.

Useful video

Another great video, I just love your lab. Seems like there is nothing you cannot repair.

Great video Shahriar :-) The ferrites on the coax cables you are talking about at 3:05 are not for getting rid of any transients. They are acting as a common mode chokes to reduce common mode signals that could enter front end amplifier and affect its operation.

Nice video. The 16V8 is a relatively simple device, most likely used as an address decoder to generate the ADC hold signal. Connect up the LA and characterize its behavior.

Hi again Shahriar! Others suggested doing PAL device reverse engineering. I think that would make a great educational video. Consider for example using a cheap modern FPGA like Spartan from Xilinx to generate all combinations of the input signals to PAL device and record the responses on its outputs. These results could be stored for example in FPGA RAM. Of course some voltage level shifting would be required to interface FPGA with PAL. Having both FPGA and PAL present in the same system would allow you to compare and show in action basic blocks in both PAL (macrocell, AND array, EE configuration memory) and FPGA (CLB, RAMs, PLLs, CMBs, fast carry chain, switch boxes, I/Os). You don't have to go into too much of the details there and it would allow someone watching to get general idea about the difference between PALs and FPGAs. You could also throw in an overview of CPLDs capabilities, which are somewhere midway between PALs and FPGAs. Next thing to do would be to use captured truth table of PAL device to show boolean equation simplification aka circuit minimization in real example. For example using either straight math approach or Karnaugh map method. These days most of boolean equation simplification is done under the bonnet by synthesis tools and people struggle to understand how all of this works. The result of that simplification then could be implemented with one of the languages commonly used to program PALs (PALASM, CUPL or ABEL). Or alternatively you could use Verilog or VHDL. The point is to show how to perform simplification manually rather that letting the tool do it for you. At the end you could program the resulting fuse map into new PAL device, put it in the system with FPGA to scan it and prove that your PAL device responses are the same as the reverse engineered ones. And of course as a side effect you would have a system to clone PAL device to fix your 4338A ;-) All, What do you think about the idea described above?

Hey Shahriar, thanks for sharing. As always, great video. Regarding the probe lead, the Keysight Impedance Measurement Handbook has few good illustrations for different terminal configurations. As far as I remember, these series (including capacitance meter, milliohmmeter and LCR meter from the same era) work with customized four-terminal pair configuration. As you noticed the test fixtures cost a fortune. I hope you will decide to build a DIY one so that we can follow along :)

I am thankful I don't operate in a world where uOhms makes a difference. mOhms are enough of a struggle. Nice video as usual!

It looks like if one really wanted to it would be feasible to probe all in inputs and reverse engineer a logic table. The datasheet shows 1 clock input plus 8 data inputs. It would be interesting to see exactly what is failing on the chip. If it was a single line problem, maybe even try a decap and see if it is a broken bonding wire that could be replaced.

A Stradivarius will sound crap in my hands! but in hands of a skilled musician...:-) Well done and thanks for another superb class!

Great! This time was not a single cable failure...

Good video like always, but reading that keysight had annuced new high end scopes to reach 110Ghz at 256GS/s I guess we are wating for a keysight tour like you do for lecroy a while back :) Anyways keep with dows videos

Hello - I enjoy your teardown and repair videos so much I have rationed them out so as to get one a week or so. It's going to be a bummer when I get all caught up. Now I make a request for a repair video that will be beneath your contempt. I am a happy electronics tinkerer on a tiny fixed income, and cannot afford good test equipment (in fact it would be wasted on me anyway), but I have been fighting using handheld chinese VOM's for years. After having to take apart the vom and replace a fuse because 200 mA smoked it, for the 20th time, I decided a try and find a decent benchtop vom. The two things my chinese handheld has going for it are autoranging, and I don't have to change lead input positions to measure volts, ohms and milliamps. That is convenient. But if I inadvertently let it see, even very briefly, over 200mA, it is dis-assemble the case time again. The only benchtop VOM that I could find that was in my price range was a used Keithly 179A. It doesn't autorange, but it will handle considerably more current than 200mA. There are many available on eBay, and I bought one that purports to work, but no gaurantee. And there were maybe a half dozen that need repair. It seems to me that if you bought one or two of these, and went thru your analysis and repair process, you would be helping a number of poor people like me who would buy these broken (but very inexpensive meters) if we had some sense of what to expect. So that is my suggestion to you.

Another great video by Sharir. Only he would imagine to remove a component and test it in isolation - while mere mortals would just hunt for a replacement ;) In fact, I would have replaced that ADC 2 or 3 times (by removing it from old busted music gear I have or get on eBay) before realizing that it wasn't the problem. By the way - an 8-channel analog scope is simply a wet dream for most of us. But as I look at the tests performed - it was indeed possible to make the same determination with a 4-channel scope (or even a 2 channel scope) accessible by the common man. You just wouldn't get it all in one screen shot sequence. I also wonder what PAL programmer you would use to read those HP PALs? I have lots of HP gear I try to repair and those SMD PALs are everywhere. And while I don't have one of those microohm meters (or its cousins) I'd bet there was some reuse in ADC control circuitry across various models of gear - and I'll see if I don't have a board somewhere with one on it I can remove and send to you. Thanks again for the video (behind which it's obvious there's a ton of work).

Fantastic videos as always, I have a couple of ideas for future videos, one would need to drop the frequency down a few pegs into the audio realm and do a teardown and repair of a HP 8903A audio analyser (as an example) the other idea is something a little different and demonstrate what is involved in replacing dead CRTs in older equipment (non VGA type) with LCDs? I think the later would be extremely interesting to the masses as repalcement CRTs are difficult to source and a viable replacement would bring new life into older but still useful equipment that many have on the shelf? Cheers H

What kind of clamp are you using to connect to the IC at 25:37?

The 4339B has a range up to 16 petaohms! I didn't think that was even possible

@benbaselet2026

6 жыл бұрын

It seems the people who designed HP devices shared my working philosophy. "Miracles we do every day, it's the impossible stuff that takes a bit of time and effort to complete." :)

Thank you for your great training videos, I learned already a lot from your Signal Path videos. One comment I have, when you de-solder components why not do include a short version of the mechanical chip swap in your videos, I would be also of interest to see how you manage this. Regards from Germany, Helmut. PS: I am looking for a EIP/Phase Matrix 598A counter service manual, if somebody can help I would appreciate this.

Should have used a hot air tool removing those chips. Or just a regular heat gun with a nozzle made out of aluminum foil. I've tried the latter - works like a charm.

@frac

6 жыл бұрын

Yeah! You tell him! It's clear from all of his fantastic videos that he has no idea what he's doing.

👍👍

Nice video ! could you show how you did try to copy the content of the chip at 26:18?

Did you ever find a replacement PAL device to get your LCR meter back up and running?

If you have some time to spare, and cannt find the replacement part for this PAL, you can try reverse engineering it. If you are lucky it is just combinatorial logic, and should be easy to figure it out, build truth tables and reprogram blank device to do the same. If there are sometiming or flipflops it might be a bit more tricky, but not super tricky, because this device has only small amount of inputs anyway.

The PALs are field programmable and erasable. I looked at the datasheet and it doesn't mention anything about a security bit.

Hi shahriar would you ever consider maby doing some videos on audio synthesizers? maby a repair, i think it would be cool subject. Im interested what others think? just an idea

He got lucky that the PAL device from the LCR meter was the same (or similar enough) that it worked in the milliohmmeter. If you monitored the inputs and outputs of the PAL during operation you would have a chance of reverse engineering the logic in it. It would allow you to program a new part.

Could that PAL device be reverse engineered by analyzing input and output signals and building logic table from that? Sometimes programming can be quite simple just to make layout simpler, and to deal with timing issues that multiple logic ICs could cause. I hate it when mask rom device or custom chip is cause of issue, it may doom whole equipment unrepairable if no donor unit is available. I had problem with one scope where front panel was not working correctly and all symptoms pointed to broken subprocessor with mask rom but luckily it was caused by just broken logic gate in communication bus.

@s3sebastian

6 жыл бұрын

I also thought about that while watching it. If it's clear from the board which pin on the PAL is an input and which is an output it should be possible as long as it's really just using the combination of logic gates. This part also seems to contain flip flops as well though, so the output can also be dependent on a state and not only on the inputs, which makes things more complicated.

@DIYTAO

6 жыл бұрын

I love these repair videos... That programmable logic chip is definitely not mask-programmed device. Palce is an EE-prom series made by Lattice Semiconductor. It does have security bit so it's highly likely it's not fully readable. For reverse engineering. I think it should be quite possible since it only has 8 registers. Could be tricky, but with right tools.. Edit: But it would be nice if companies could release the data files themselves, that would make testing and rerpairs a lot easier. Datasheet for 16V8 can be found at www.latticesemi.com/en/Support/MatureAndDiscontinuedDevices/PALPALCE

@DextersTechLab

6 жыл бұрын

i have done this in the past on simpler pal and gal devices but in the case of the 16v8 there are internal registers, which greatly complicates matters. I'd hook up a LA to the working unit though and just see how complex the logic is, it could be they are not using all the features and the truth table isn't that bad.

@movax20h

6 жыл бұрын

Yeah, internal registers, shift registers and flip flops complicates reverse engineering, but it is still possible, especially if we monitor device dynamically in a working unit, and know what happens to inputs and outputs, we can figure out if there are clock lines, latches, and with some progmable bit analyzer and generator reproduce these signals and reconstruct what they are doing. Or read the ROM for the main CPU and disassemble the code to find out what is going on. It should be even possible to debug and monitor the this main CPU fully in real time with modern tools.

I have an older RLCG meter made by Tesla. It's a BM 595. Do you have any tips on how to find documentation or schematics? Would love to get it back into working order...

@jenda386

6 жыл бұрын

How about this one: elektrotanya.com/tesla_bm595.rar/download.html ? It's in Czech, but it might be a good start.

@warrenmasters3036

6 жыл бұрын

I hadnt found that one thank you. but i really need a service manual/schematics. it has a problem with the power rails somewhenre. I just need a way to figure out where the problem is. I'm no where near as talented as Shahriar.

@jenda386

6 жыл бұрын

I did look for a service manual also, but could not find anything else. Sorry.

@warrenmasters3036

6 жыл бұрын

jan386 No need to appologize. I really appreciate the effort you gave a complete stranger. Thank you very much for what you found, it's more than I had before...

Aw man, a broken pla :( that sucks, especially as there's not a snowball's chance in hell that HP would release that...

But if that logic device is a pal it should have only combinatorial log in x, why not find the input of the chip and apply all possible combinations and look at the outputs? Than you could generate the logic function that drive the output and make another pal. There is some security mechanism that I'm anaware?

@pa4tim

6 жыл бұрын

I have now a similar problem with a dead clpd in a Fluke DTX1800. I used JTAG to find the problem pin and I also had a working unit to swap them (the slave unit is 99% the same) .I am making a video about that repair. It would be nice if someone could make a video about reverse engineering and testing pal/gal/cpld etc because they seem to fail a lot (relative) and there is not much info about it. In a SA I once could hard-wire it but most times it is game-over. And that is a pity because these are often rather time-consuming repairs. I did not find a way to read the cpld guts. I controls the power supplies. (it is a VQ44 package, not easy to put on a breadboard) I use the breadboard test also, nice to see I'm not the only one who does this. I knew I'm not mad :-) to make it faster I made a tester for IC's based on the tubetester setup. A ZIF socket and 16 12-position switches, 32 leds, neg/0/pos supply, some bnc's, some potentiometers, headers for bridging or inserting series or parallel components etc. Very handy. (I use it in some videos on my channel (look for pa4tim)

@vaualbus

6 жыл бұрын

pa4tim note that cpld and pal are way different. Pal contains only combinatorial logic, a programmable plane of nand and a fixed plane of nor gate, cpld contains more complex block like muxes LUT and flip flops so is can be not only combinatorial logic in there.

@pa4tim

6 жыл бұрын

Thanks, I already was afraid of that. Hard to find good info about testing the hardware part. Most info is about programming. But besides that, I like videos about serious reverse engineering/trouble shooting. Signalpath is one of the few that goes deep (that is, if he finds a serious dead instrument that needs more as a new fuse, some caps or a loose connector :-) he has more luck with that as me). That is why I make repair videos, I hope someone can learn a bit from the techniques I use. 95% of the repairs I do are without schematics on measurement and calibration gear that is no longer supported by their dealer or the manufacturer, so I often have to be creative and do a lot component testing

If that thing is only combinatorial logic, then it should be possible to “read it out” by just trying all the combinations, essentially treating it as a ROM? (In fact, the difference to a ROM would only be how much gates are necessary to implement the logic.) This is feasible if that thing has at most, say, around 30 or so inputs, which seems to be the case. Of course, if it’s actually sequential logic, then enumerating all possible internal states becomes infeasible pretty much immediately.

@enojelly9452

6 жыл бұрын

Ah, never mind. Only after writing my comments I of course realize that plenty of people have suggested the same already.

Great video, as always. I have a general question, regarding your repair philosophy... It came to mind, because this is a 1997 unit... Do you replace all the electrolytic caps in these units? For the effort that it takes to open up these high end devices, I would think that re-capping would be standard procedure...

How would someone without an 8 channel logic analyzer with the ability to see all of the lines at once be able to perform a similar test?

PALCE IC has AMD Logo. Maybe, datasheet for this IC will be helpful? www.dataman.com/media/datasheet/AMD/PALCE16V8.pdf Looks like this PLD have a Security Bit feature.

I'm not sure if I like or hate the fact that you just jumped to the more complex problem and did not even measure voltages, clocks or test those relays first :) (at least not on the video anyways).

@ulbed

6 жыл бұрын

He topped the bill when he showed us his scope. 8 voltage measurements at once. So you should be more than satisfied.

Hi Dr. Shahriar Thank you so much for your videos, I learn a lot form you and the great information you introduce . I am not sure if i am able to help you with this repair or not but i own a SmartPro 5000 programmer which from the device support list it can read and program this chip . if you would like to send this chip over so i can try to read it i can help you with that , Here is a link for the programmer i have so you can check it out www.zlg.com/tools/tools/product/id/118.html . Thank you again for the great information you present and your teaching.

As soon as Shahriar mentioned the acronym PAL, my skin began to crawl. They are such an unreliable piece of junk

AUDIO TOO LOW, SUCKS!!! SPEAK UP

Old overpriced electronics as usual.

Xdevs seems to have a full set of manuals (including service manual) for this device, just an fyi. Just not much in terms of schematics.