Are these things I should consider bad

[old_tv_nut]

Ideally, the B+ has no waveform at all, just a flat line of constant DC voltage. Practically, there will always be a small amount of time variation due to incomplete filtering out of the AC source (unless the device is battery powered). Even if the device is battery powered, there can be small variations due to varying load current drawn by the circuits that use the B+ supply.

[TinCanAlley]

Originally Posted by old_tv_nut

Ideally, the B+ has no waveform at all, just a flat line of constant DC voltage. Practically, there will always be a small amount of time variation due to incomplete filtering out of the AC source (unless the device is battery powered). Even if the device is battery powered, there can be small variations due to varying load current drawn by the circuits that use the B+ supply.

So the flat line I see is correct. About the only thing I can do is move the coupler to GND, move the trace line to the bottom of screen, set the voltage/div, move the coupler to DC and then measure voltage after the trace line moves up. That's okay with me.

If I see ringing on the base of a transistor, do I look at the collector to see if the ringing has been amplified? Also, I seem to recall someone suggesting I ground the base of the ABL transistor to see if the jail bars go away. The voltage on the base is under 1V, so is it okay to ground it? Doing so won't short anything out?

[zeno]

Originally Posted by TinCanAlley

So the flat line I see is correct. About the only thing I can do is move the coupler to GND, move the trace line to the bottom of screen, set the voltage/div, move the coupler to DC and then measure voltage after the trace line moves up. That's okay with me.

If I see ringing on the base of a transistor, do I look at the collector to see if the ringing has been amplified? Also, I seem to recall someone suggesting I ground the base of the ABL transistor to see if the jail bars go away. The voltage on the base is under 1V, so is it okay to ground it? Doing so won't short anything out?

Ringing may or may not be amplified, depends on circuit.
Grounding the ABL base will kill the ABL. If the jailbars are getting
in there they will go away. You may or may not see other changes
without ABL.
B+ lines should be clean, sometimes there is a very small amount
of hash but nothing like 5% or 10% of voltage.
With this problem you have to take things in order.
1) be sure all B+ are clean & correct
2) scope starting with the detected video from IF strip pin 5
3) work your way to the right through video til the
waveform goes "bad" thats where it gets in.

73 Zeno

[TinCanAlley]

Originally Posted by zeno

Ringing may or may not be amplified, depends on circuit.
Grounding the ABL base will kill the ABL. If the jailbars are getting
in there they will go away. You may or may not see other changes
without ABL.
B+ lines should be clean, sometimes there is a very small amount
of hash but nothing like 5% or 10% of voltage.
With this problem you have to take things in order.
1) be sure all B+ are clean & correct
2) scope starting with the detected video from IF strip pin 5
3) work your way to the right through video til the
waveform goes "bad" thats where it gets in.

73 Zeno

When you say the IF strip pin 5, do you mean the one labeled "C1"? I'll post an pic of the waveform I get from the B+. It's unlike any other waveform I get. It is similar to the ringing on the ABL base, but it is a multiple waveform of about 5 or more like you're on acid and tipping. It also expands and contracts from about three to 5 or more. It's only on the B+ that I get more than a single line waveform.

I've traced the B+ to two different sources. One is from a line from the transformer that is amplified by a diode and then is tapped into the canister. From there it goes to the chroma module and makes it way around the boards. The other B+ comes from another line of the transformer and goes though a resistor and then on to the horizontal board where it connects to the pin right next to where the first B+ connects. It's a loop, but why from different lead of the transformer and why is only one end filtered by the caps?

When I get home I'll take a picture of the waveform I mentioned and post it.