Re: 7904 - Very Dim Trace

Brian Bloom

From what I've been reading (books and forums), it doesn't have to be just the resistance that changes, does it? Or will that change first and indicate a change in other characteristics?

What I'm getting at, is from what I gather so far, a carbon comp resistor can act totally different when it's loaded and under high stress yet still measure relatively close to it's nominal value. Much in the same way that a transistor can check out fine from a dmm or even simple tester, but when hooked up to a curve tracer it will become apparent that the device has failed.

I could have misinterpreted what I've read so far, and I welcome corrections to my understanding & interpretation of info.

---In TekScopes@..., <jimmcintyre22@...> wrote :

No joy. The Service Manual Parts List calls out a 10 ohm series resistor in the heater, and that's what's in there. It measures 9.8 ohms. Re-checked deflection. Both X and Y are within 2%.

I'm still not convinced the 14kV is the only problem. This scope is new to me, and it could well have been 'mal-adjusted' to make up for the low PDA voltage. Still noodling on this. Continued comments welcomed...

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