Electronics > Repair

Need help repairing a Keithley 2182

(1/2) > >>

droffsite:
I recently acquired an inoperative 2182 nanovoltmeter for the princely sum of nothing, hoping to get it back in shape. This will be my first time working on something this complex (previously fixed a PB-503 for grins).

On power up, all display segments light up nicely, then it shows REV:A06 A02. That's it for the good.

It then goes to OVR.FLW V with a rapidly flickering period off to the far right.

I opened it up and took a look: everything looks good (all the caps look brand new with no apparent leakage).

I've gone through the repair manual trouble shooting steps (page 4-11 in the service manual).

StepItem/componentRequired conditionRemarksResult%4U304, pin 2+5V ±5%+5VD, referenced to TP3015.0120.20%5U305, pin 2+37V ±5%+37V, referenced to TP30136.35-1.80%6CR313 anode-6V ±20%-6VD, referenced to TP301-7.5926.50%7Q304, pin 2-5V, ±5%-5VD, referenced to TP301-7.6452.80%8U302, pin 3+15V ±5%+15V, referenced to TP30315.151.00%9U303, pin 3-15V ±5%-15V, referenced to TP303-15.775.10%10U301, pin 3+5V ±5%+5V, referenced to TP3034.99-0.20%11CR305 cathode+29V ±20%+29V, referenced to TP30331.498.60%12CR309 anode-29V ±20%-29V, referenced to TP303-8.88-69.40%13CR310 V+, pin 1+18V ±20%+18V, referenced to TP30321.1717.60%14CR310 V-, pin 2-18V ±20%-18V, referenced to TP303-20.7515.30%15CR306 anode-7V ±20%-7V, reference to TP303-9.5736.70%16CR308 cathode+7V ±5%+7V, referenced to TP3037.8712.40%
So clearly something's off, particularly on the negative side. I replaced Q304 (ordered several of each of the out-of-spec parts) to no avail, then thought I might be getting ahead of myself.

I'd like to validate that the transformer is good, but I can't find any specs on what the secondaries should be.

Any inputs, guidance, donations, well-wishes... whatever would be more than welcome.

chekhov:
Check out K2000/K2010 repair threads, transformer is the same at least.

Sorry, transformer is different for analog section, it seems I fooled myself long time ago, only now realized it's the same for K2000/K2010, but K2182/K2182A has indeed different one.
* Service manual for K2182 says it's TR-299B, but teardown pictures clearly say TR-372.

Kleinstein:
I would not expect the transformer to be faulty. They are relatively robust and often postive and negative voltages are driven from the same winding.
It looks like the regulator for the -5 V is somewhat broken.

The -29 V look like there is something really pulling it down, a open diode (rare) or maybe a bad / not connected capacitor.

droffsite:
Thanks for the reply!


--- Quote from: chekhov on March 07, 2021, 08:59:30 pm ---Service manual for K2182 says it's TR-299B, but teardown pictures clearly say TR-372.

--- End quote ---

Interesting. Mine has a TR-299B. I meant to post the voltages first time.

4 pin connector:
Brown: 97 V
Brown: 92 V
Yellow: 83 V
Yellow: 64 V

5 pin connector:
Green: 1.5 V
Green: 3.0 V
Orange: 3.4 V
Orange: 5.9 V
Purple with red stripe: 1.7 V

droffsite:

--- Quote from: Kleinstein on March 07, 2021, 10:17:54 pm ---It looks like the regulator for the -5 V is somewhat broken.

--- End quote ---

I ordered several new voltage regulators; I'll see about putting one of those in.


--- Quote from: Kleinstein on March 07, 2021, 10:17:54 pm ---The -29 V look like there is something really pulling it down, a open diode (rare) or maybe a bad / not connected capacitor.

--- End quote ---

Another good thing to check.

Thanks!

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version