RCA CTC187 - U4101 runs hot

[Big Mike]

I am working on a CTC187 chassis. The usual Cr4106 & U4101 were the
problem. I have been out of the repair business for a few months because of
health issues that require surgery and recoop time. I am now getting back
into service repair. The problem is the set is running just fine, but the
heatsink on U4101 is getting very warm to hot. All voltages seem to be fine,
and I just flat out can't remember if these do normally run at a pretty high
temp or not. Is this normal? Or should I be on the lookout for a bad part
somewhere? Thank you.

 

[Ol' Duffer]

I am working on a CTC187 chassis. The usual Cr4106 & U4101 were the
problem. I have been out of the repair business for a few months because of
health issues that require surgery and recoop time. I am now getting back
into service repair. The problem is the set is running just fine, but the
heatsink on U4101 is getting very warm to hot. All voltages seem to be fine,
and I just flat out can't remember if these do normally run at a pretty high
temp or not. Is this normal? Or should I be on the lookout for a bad part
somewhere? Thank you.

RCA had a rash of problems with contaminated solder joints
on a small choke in the base drive circuit. Poor contact
resulted in weak drive which left the transistor in linear
conduction longer than normal, therefore excess heat.

If the set has this little choke, try cleaning and
re-soldering the leads.