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A word of caution. The U2750 might have been blown in such a way to damage
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circuitry in working plug-in. Personally, I would use this test as a last resort, after verifying other things, like pulling out U1750, sending signal through channel B and checking where does it get lost (or finding out that it was U1750 that was at fault for not releasing commong lines). Regards Miroslav Pokorni ----- Original Message -----
From: "Stan or Patricia Griffiths" <w7ni@...> To: <TekScopes@...> Sent: Tuesday, January 22, 2002 9:58 PM Subject: Re: [TekScopes] Who's up to some remote troubleshooting? Hi Lynn,with IC's in it but here is what I would do, if it were mine, and I had the stuff thatyou have. It sure sounds like U2750 to me . . . and to you too, because you havereplaced it twice with no luck. To be certain it is not U2750, I would like to seethe original U2750 removed from the bad 7A26 installed in the working 7A26, and verifythat it works there. I always worry that something might be blowing every U2750that I plug into the bad 7A26. If that were the case, you could indeed change U2750twice and still not get the 7A26 to work properly . . . and you would have 3 badIC's after that. I would want to see those IC's work in a good 7A26. The next thingI would do is check to make sure the power supplies and grounds are getting to U2750.Could be a bad IC socket. Just a couple of ideas . . .it's not the other scopescope and it's not the 7B53A. Ifand follow it right up to U2750. The input pins to U2750 have the square inputI feed the square wave only into channel A, I can see it on both the thoseand output of U1750.) The DC voltages around U2750 are very close to indicated on the schematic and appear to me to be reasonable. I did |
