Repairing Tektronix DM501 and How to Clean a Board

[David Hess]

I finally got around to have a look at my instrument and it turns out to be a DM502.  Sorry for the confusion.

I have two DM502s and about 4 years ago replaced the aluminum electrolytic capacitors which were worn out and bridge rectifiers because one of them failed.  I also added TSV diodes to the supply rails to try and prevent damaging anything if the regulators failed, and replaced some Texas Instruments edge wipe sockets with collet sockets, and replaced some solid tantalum capacitors.

My DM502s only require calibration, which I have done, but the trimmer resistors need to be replaced.

At one point I had plans to modify one of my DM502s to extend its AC low frequency response down to 2 Hz for audio work, however that proved not to be necessary.