Hi
I found the next fault. Another shorted Tant cap.
The Wavetek seemingly has hundreds of them (only slight exaggeration). I narrowed down to the main board (there are about 10pcbs)
I used the finger test to conclude that none of the voltage regulators were supplying a dead short.
This left just 5 candidates, one had already failed and been replaced.
After lifting the 3rd cap, I found the faulty one.
All of the failed caps have been on the +18V supply. I have now replaced all of the Tant caps on the +18V DC supply. These were all rated 25V. The new caps are 35V.
The power supply includes a soft start feature. I am going to see if this is working properly. If it is I will look at modifying it to make it a little softer to reduce the surge current seen by the Tant Caps. Surge current is a known killer of Tant caps.
The 2520A has just passed the autocal process. This is a good indicator that the 2520A is functional.
The next steps, in no particular order, are to:
- make a copy of the eproms holding the firmware.
erase and re-burn the eproms
replace the NVRam with a DS1225AD modern version
investigate the soft start, and modify if required
do a full calibration
If there is any interest, I am thinking of doing a video on the repair.
Dazz