Re: 556

bill koski

First the Repair, Rebuild or Restore issue. While it is very nice cosmetically with just a little road rash from 50+ years of use, it's going to continue to be used and not sent to a museum. And it is currently working well so that puts it pretty much in the rebuild category. The question is how much to touch. The, "If it ain't broke" has its strong points. But there's the counter argument, "You can pay me now or you can pay me later!"
So I'm looking at do what's necessary but do no harm.
Old lytics can fail at any time. Depending on where it can take a transformer winding or maybe a hard to find regulator transistor with it.
So I'm inclined to consider replacing all the electrolytics which in itself I'm sure is no small undertaking. At the absolute very least I should at least get a look at the bottom of all the can caps and look for any bulging or leakage. And check any of the dropping resistors in the supply for correct value and signs of heat fatigue and replace and upgrade wattage if necessary. My thinking is that I at least want the power supply section solid and reliable as failures there can cause chain reactions that could doom the unit.

Then I would like to go through and at least check all the carbon comp resistors I can for proper value. I know especially higher values in HV situations are are most prone to drifting.
So these are the things I'm considering and my mindset is, "Do what seems necessary but do no harm."

As far as tubes go, I checked one at a time and returned each to its original spot. I only replaced a couple that had really low emissions and I had to replace one vertical output 8608 tubes because the trace was jumping around and I could see arcing in the tube.
I checked one at a time and returned each to its original spot too.
And yes that's a rare one I should get a spare or 2 of that one! Thanks!

Now as far as trouble spots. The unit triggers fine on anything I've thrown at it so I assume that I have no tunnel diode problems at the moment. I also assume that I don't have HV problems as I have bright sharp traces. I'm not familiar with the HV transformer rot problem. Is there any preventative measures for working ones? I assume there is a thread or 3 somewhere here dealing with this problem?

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