Yet another attempt to fix a 2465B


Grayson Evans
 

I have had a nice 2465B for about 6 years that I bought at Dayton (hamvention). It worked. About a year ago it quit when I turned it on one morning. It has the same symptoms as Dave's in his EEvlog #1203 on youtube. All the front panel LEDs light up but that's it.
Voltages are all in spec except the +5V, it is 4.5V with 400 mVpp ripple. The +15 volt supply also has the same 400 mVpp ripple, but voltage is good.
Whoever had it before me did a very nice recap of the power supply, very nice resoldering work. Looks like a factory job. Replaced the SMDs on the logic board with regular electrolytic.
THe only thing I can figure out is that at least some caps around the +5 and +15 supply need replacing again.
Looks like Tek assumed the power supply would not need servicing. Hard to get in and out and impossible to work on while it's installed. If it breaks, board level replacement. I can't see anyway to troubleshoot the board set.
Has anyone ever hooked up 120V to the boards out of the scope to try to troubleshoot it? Doesn't seem practical or safe.
BTW, I am plowing through the giant eevblog thread, but only up to page 11 (of 68!). Don't know if I can make it.
Thanks,
Grayson

Join TekScopes@groups.io to automatically receive all group messages.