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| HP 33120A waveform is distorted. Video inside. What is going on? |
| << < (7/9) > >> |
| nctnico:
Which points did you check in the output amplifier? It can be anywhere in the driver stage as well. Maybe simply replace all transistor as free_electron suggested in his post 10 years ago. |
| strawberry:
CDIL makes TO-18 TO-39 |
| fran:
I get back to the notes I took tomorrow night - but the basic premise was that up to the entry to the amp inputs, the signals are clean. After that the distortion is there. I'll go looking at what each of the transistors are and see what is available, but I also note that even though free-electron replaced all of them, the DC offset still wasn't working at his last post. Thanks for the direction and suggestions. |
| free_electron:
--- Quote from: fran on August 07, 2022, 03:53:56 pm ---Even though I pulled them and they showed "ok" in a tester? Although I don't have the metal can transistors, I'm sure I'd have something I can substitute in to test at least.... I'll have a go and report back. --- End quote --- You need to run them on a curve tracer. They degrade. It's not just work/no work. Just replace oll of them. they work hard in that design. if you have the version 1.0 of this design : i have the schematics and actual part lists. It is not available as PDF. There are many differences between the "pdf" schematic and the older generation. |
| fran:
Ugh - although there are only a handful of transistors involved, there are a few out of stock even if I was to do 2 or 3 separate orders. So I will try to source them but only as I'm ordering other stuff over time. The parts shortages are quite the pain.... I think it's time for a new generator. |
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