On 7/25/2018 3:09 AM, satbeginner wrote:
Hi Bert & Vincent,
I'll check capacity specs on the FET's as well -although already ordered :-) - but the good news in relation to the secondary power supply:
The scope has been running fine for several hours now on an external 43VDC :-)
I needed it to run, because it turned out there was a problem with CH1 as well. (trace yes, but no signal showing)
I cleaned the switches using IPA, but it looked like it was one of the small trimpots in the attenuator having a dodgy contact.
As soon as I touched that one the signal came back on CH1.
After all repairs are done I will calibrate it.
I updated the album to show the progress.
Thanks for the feedback, un saludo,
Leo
-=-=-=-=-=-=-=-=-=-=-=-
Keep in mind that the upper section has current limiting so it should be able to run, at least for several seconds, with a dead short across the 43VDC secton.
I had a 2213A at one time that was a real dog.
It showed many signs of having been worked on before and not by someone that knew that they were doing.
It ended up as a parts scope because both the voltage multiplier and the upper switching transformer were gone... plus many! other parts.
That was a long time ago but I seem to remember that I was able to check out the IC and gate drive circuit by removing
the fet and adding a small cap between the scource and gate.
-Bert
