Bump.

Going to put this one out there as a reference and tale of "how to fix".

The Tek PS-5004:

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A '5004 is a very useful gadget to have when you're doing such things as designing or servicing comparator or threshold-detection circuits and must employ a voltage/current source with greater than 1mV/1mA resolution.

They're NOT worth the $200-500+ prices which are being asked, especially for an "as is" unit.

I took a chance on a $99/shipped offering which read "32.740" upon power-up. A normally functioning '5004 should read "0.000". when initialized.

Replacement of all electrolytic capacitors in the -25.5v, 12V, 8V and 5V internal supply circuitry was necessary. Once this was done, the supply was plugged into a TM5006 mainframe using extender cables and powered up. It worked until three transistors in the 12V control supply section decided to go up in smoke.

Replacing them fixed the smoke issue but the display read "32.740" afterwards.

Here's the tricky bit:

The device is set up with a current DAC/current comparator and a voltage DAC/voltage comparator operating in bridged mode, and the supply itself either operates in a constant voltage or constant current manner. If the 8V supply which powers these comparators fails, the output follower device is driven to the supply rail...hence the high voltage reading.

That 8V supply is an MC78L08ACG - TO-39 package. Replacing it with a TO-92 version ( 78L08 ) works just fine.

Moral of the story: If you get one of these units and find the power-up readout doing what I've described, check all supply voltages. Additionally, check the TM9914 GPIB interface IC on the Programmer Board. If it's defective it'll draw the 5V supply low and the front panel will cease to function properly.