[TinCanAlley]

Originally Posted by zeno

Tough question 50-50 ?.
Anyhows the 121-831 was used for years, even in 9-160 sets IIRC.
Newest # is 921-500 IIRC. The ECG sub works fine, cant speak
for others. If you are real lucky the cause of the jail bars
caused it & you kill 2 birds.........
After replacing since you prob dont have a variac you should use
a "rubber fuse" to protect it. You have many of them, a 75W
lamp. Remove the wire from pin 4 of the FBT. Hang in the lamp in
one end to pin 4 & the other end to the wire. If it lights dim
& you get a small dim pix things are OK for now. If it glows
bright you have problems.........
If things look good reattatch the wire, turn set on a few seconds
then off & fell the HOT. It should be cool. keep doing it extending the
on time say 5sec, 10sec, 20sec, 1mn 5mn etc. The HOT will
get warm but not hot. You may also want to put an ampmeter
in place of the lamp, should be abt .5 amps tops.
When changing clean & replace the compound with the white,
pink or blue stuff. Inspect the mica. Check R353 & C264 at HDT.

73 Zeno

I ordered two NTE238s today. They should be here on Monday. I've also got a new damper diode for the HOT, a new LV transistor and all the resistors that go around those components. I will do the diode, test the voltage regulator and then put in one HOT as a sacrifice. If it goes, I've got a few other things to check and one more HOT to test again. I'm hoping that one will be enough and leave me with a spare.

C264 was replaced during the recap, but I didn't change the resistor. I'll put it on my list for inspection/testing.

Is the HOT supposed to have a mica? This one didn't. It was just sitting on a bed of thermal compound. Even the legs had the stuff on them. A real mess.

I'm tired of being on the floor most of the time, so I'm going to pull the chassis for testing/replacement.