It turns out that lack of -15V and yet some other problems are all caused by interconnect cables not seating properly / totally
After I got my bearings straight on the power supply regulator board and the lack of -15V. the problem was traced to one of the interconnect cables. While flipping the scope over and upside down the thing suddenly came to life. I buttoned up and it was dead again.
I started plugging and unplugging cables and finally found the culprit. At that point I should have continued "exercising" the rest of the interconnects ( There are a lot !!) . Anyway with -15V reliably in hand, i I started checking my "collection" of plug-ins and stumbled on the fact that the right most time base would not trigger in internal mode from either the left or right vertical plug-ins, but triggered just fine with a external trigger source. Discovered that i could get the internal trigger to work by pressing on the interconnect board behind the push button switches, confusingly the right most time base was affected by a cable on the far left hand side of the board !
The MORAL to the story:? got an old 7904 that is acting flaky open it up and exercise the *ALL* the interconnect cables . This scope is over 35 years old and hadn't been used in almost 10 years... You get the idea. Note the connectors did not appear to be unseated nor were they corroded that I could see they just want to be "exercised I guess. I can hardly wait when in another 10 years some of those transistors that are plugged an and not soldered start to go intermittent.
Dave
ARTEKMANUALS
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Dave Manuals@... www.ArtekManuals.com ( )
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