Teardown : Keithley 2510 TEC SMU repair and calibration [complete]

[TiN]

Here Keithley gear goes again. I probably already won title of Keithley hoarder multiple times. 
This time it's about TEC-oriented SMU. For those who don't know - TEC is a semiconductor module working based on Peltier principle,
which is basically describing forces heat transfer effects by using electrical P-N junctions from cold side to hot side.
This SMU capable of directly controlling 10V@5A TEC element, to a specific temperature setpoint.

Model 2510 is pretty expensive and rather specialized device to be in most of lab. But if unit is broken with diagnosis "Does not power on",
then it's tempting to get one and try to fix. I was thinking to build small temperature chamber for testing voltage references and
measuring tempco of resistors, and small PCBA's, so if I can manage to fix this TEC SMU - it will make controlling temperature for such a project an easier job.

Let's see how this evolve. I expect to receive it somewhen next week.

If anyone have experience with KI 2510, or have any internal photos - those are very much welcome!

So far I only have this photo 



Service manual
User manual

For calibration of Keithley 2510 we will need next standards:

Resistors
1?, ±0.1%, 100W
100?, ±1%
1k?, ±1%
10k?, ±1%
100k?, ±1%

For measurement they recommend using Keithley 2002 (which I luckily have, along with calibrated this year Model 2001).
2002's spec:
DC Voltage  +20V: ±6.8ppm
Resistance
20?: ±23ppm
200?: ±19ppm
2k?: ±7.4ppm
20k? ±7.4ppm
200k?: ±29.8ppm

Project tracker

[Vgkid]

I liik forward to the repair.

[ManateeMafia]

TiN,

PM sent. It was 15 minutes to get inside. Much easier than the 2001.

[ManateeMafia]

I uploaded my pics to your ftp server.  I need better lighting but I can take more tomorrow. Let me know if you need anything else and I can get them for you. Unfortunately, I don't have an adapter(yet) for my programmer or I would make a backup of the firmware. I will look into this as well for my GQ-4X.

Good luck.

[TiN]

Very nice, thanks a lot. You don't mind if I post them here as well?
Is it possible to get a closeup around U125,U172? These are Voltage references according to service manual.

U125 have just LT005 marking if I see it correctly. I wonder what that is.
U172 is near output connector and three-legged metal can current source (LM334)

Based on photos it's easy to spot Digital and ADC section borrowed from Keithely 2000

Wonder if there could be way to hack current/voltage limits. Also autotuning function from 2510-AT model

I also have Model 2000, would be fun to see what are differences on schematics level between two.

So far my plan :

* Get a unit, check for any physical damages. Check VFD.
* Check any leaking caps, burnt/missing components, relays.
* Power unit on, check voltages, +10.4V, +4V, +6.3V, -12.5V, +12.5V, 0V, 0.5V, 5V
* Check front panel (I am 99% sure front panel from 2001 will just work fine )
* Debug issues as they come...

[ManateeMafia]

I uploaded two more pics. You can share them here if you like. I did not see any unpopulated pads, I am willing to bet the AT is all in FW, maybe it can be unlocked. I did see the jumper on the board but it did not look like it was documented.

It definitely has LT005 on both references.

[TiN]

Alright, I got my 2510 today.

* Get a unit, check for any physical damages. Check VFD.

Done..
No visual damage anywhere. Dirty outside, but everything nice inside. Front display board seem to be replaced, as datecodes on it are 2007, but mainboard is dated 1999.

Back of it:



Same board with onboard HV voltage boost is used in Keithley 2002 and 2400. 2001,7001 have HV voltage boost for VFD on their boards, not front panel board.

Face:



Display board and VFD are fine and working (supplied +5.000VDC from KI2400, VFD draws 0.45ish Amps, and showing "No Comm Link" which is what MCU on display board outputs if no serial link data received.



* Check any leaking caps, burnt/missing components, relays.

Done, everything seems fine visually. Relay coil is fine.

* Power unit on, check voltages, +10.4V, +4V, +6.3V, -12.5V, +12.5V, 0V, 0.5V, 5V

Power on - nothing is happening. No any segments lit on front panel, no reaction on output button toggle, no buzz or fuzz.
Checking test points using my KI2001 as per service manual:

J1033 front panel +5V: 4.715 VDC (below -5% specified in manual, but I think it's OK, just voltage for front panel)
J1003 p3 : 14.985 VDC (OK)
TP102 : 4.980 VDC (OK)
TP112 : 5.010 VDC (OK)
TP101 : 14.958 VDC (OK)
TP105 : -15.162 VDC (OK)
TP106 : 5.020 VDC (OK)
TP107 : 4.974 VDC (OK)

* Debug issues as they come...

Popped firmware PLCC32 into MiniPro to read it (ATMEL AT49F040 chip), as it have sticker 2510-800-A11, and
tada...



It's blank (all bytes 0xFF)..



I flashed it with C32 firmware from Keithley 2400, now it shows No Comms Link...
So it's a "progress", meaning it might be just borked firmware...

And I need our fellow community help, a firmware dump of AT49F040 PLCC32 ROM to be exact, as mine seems to be blank (all bytes are 0xFF).
All voltages seem to be just fine (did not check ripple/noise, just measure with K2001).

Keithley website, nor their forum does not have 2510 firmware available for download

As a appetizer for a thread, some hi-res photos (clickable).

Overview on mainboard:



GPIB and firmware flash chip (ATMEL AT49F040).



Isolation and digital I/O



Output connector and circuitry around it. According to service manual, U172 is voltage reference. Anyone knows what that part is?



Multislope custom ADC chip leveraged from Keithley 2000.



CPU and SRAM



Infamous TF-245 resistor network, same as Keithley 2000. Some analog stuff around..



Voltage regulator circuits and front panel connector.



Voltage regs switcher



LDO's for +15. -15 and 5V.



Another switcher.



Amp controller



Voltage reference (U125), some PTF56 resistors and analog circuits.



More output circuitry..



DC-DC taking +15V from mains AC/DC and downconverting into +5V



That's it for today, hope it's just missing firmware...

[TiN]

Posted a request on Keithley forums

[ManateeMafia]

I see you have version A11. I hope you can get an update as mine is apparently A03. I will verify it when I get home. Maybe mine was updated after is what manufactured.

[TiN]

Well, I have none, as firmware chip is blank
So I need anything to get it flashed and try if unit works.

[krivx]

How could the chip be erased? Failed upgrade? AFAIK any ageing or failure of the part would cause minor corruption.

[ManateeMafia]

My 2510 is reporting version A03. I am looking for an adapter for my programmer. Hopefully I can get one on order for tomorrow. I will need to backup my 2001's too.

[TiN]

Help is appreciated!
Also for 2001 I have dumps from my units available in repository here, as well as calibration EEPROMs.

A08 (regarding 2001) is the one you want, as it have fixed some TRMS operation issues, without which Tek service was unable to calibrate my 2001.

[Vgkid]

What is the voltage reference chip?  I'm bad at figuring them out without a more useful part number.

[TiN]

As Linear Top markings document shows, 0425 code corresponds to LT1004CS8-2.5 20ppm/°C voltage reference zener.



So that mystery did not hold for very long

[Vgkid]

Thanks for that. I was wondering why ltc100 was not turning anything useful up. I thought that  the bottom number was a date code.

[TiN]

Folks from Keithley forums shared firmware for 2510, so as expected, flashed it to ROM, everything booted up fine.



Boot message



Calibration dates



I think calibration might be corrupted, as serial number is lost?





Hooked it up with my 2002, output seems off too much



I think it's time to find good resistors and calibrate this thing

[ManateeMafia]

I just noticed someone posted the fw to the Keithley forum. Good job!

[TiN]

Let's calibrate it...



Resistors:



1 Ohm : Vishay VPR5 1R0000 0.1% 5W 10ppm/K
100 Ohm : VPG VHP202Z 120R00 0.05% 0.2ppm/K
1 KOhm : VPG VHP202Z 1K0000 0.01% 0.2ppm/K
10 KOhm : VPG VHP202Z 10K000 0.01% 0.2ppm/K
100 kOhm : Fluke wirewound 142349 100K 0.1% 5ppm/K

[TiN]

Resistors characterization, +26 room temp, 10 NPLC, 8.5 digit Model 2002.







Various calibration steps, entering measured resistance values into K2510











Finish, enter new dates...





Checking now output voltage with calibrated (in Feb 2014) Keithley 2001.
REL to null output offset (2510 output ON, Set voltage 0.00000 VDC)











Checking current output source:





Repair and calibration is complete, easy score here....
Now need to build little thermally insulated chamber with TEC element and RTD (I have few Honeywell HEL-705's) and ready to measure
tempco of resistors and devices for my KX project!
In worst case Model 2510 can be used as 10V 5A four-quadrant power supply

[TiN]

Video of stepping from 0V to +10V and to -10V

[TiN]

ManateeMafia, is your 2510 have fan running when power on?
I suspect fan on mine is broken, as it does not operate.
But not sure if it supposed to be working all the time (like on all of my 2001's, 2002) or just turn on after reaching certain loading/temperature.

[TiN]

Noone really probably care, but I was using 2510 last few days for some testing and gotcha few scope screenshots of
voltage and current behaviour on turn on/turn off source

It's pretty slow during ramps, doing it in funky steps, but when it get's there, it's pretty damn accurate





Ramp to 2.0000 Amps into 1.7 ohm resistor



Turn off



Step measurements..

[ManateeMafia]

TiN,

I checked my 2510 and the fan does not seem to come on by default. Hopefully that is a good sign. Great work on the cal and graphs.

[TiN]

Just for completeness, combined all data into article, including enabling to 2510-AT