RCA CTC 177BH2, model 27GT613, excessive width and apparent pincushion problem

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According to the customer this set went dead. I powered it up and it
worked, although I noted a severe tuner shield problem. I repaired the
tuner shield and the picture seems too large. The sound is OK though.
There is also what looks like a slight pincushion problem or a bending
on either side of the picture that looks like a sort of hourglass
effect. I adjusted the vertical and the linearity looks good but the
horizontal width adjustment between 0 and 15 does nothing. Other
adjustments seem to work though. Should I suspect a corrupted eeprom
given the severity of the shield problem, or is it more likely a bad
component is causing adjustment 03 not to work? Thanks, Lenny Stein,
Barlen Electronics.

 

[Rono]

Never adjust EEPROM unless your sure it's not an
electronic problem! There is a large diode with ferrite
beads on it, & a blue capaitor, in the pincushion circuit!
It will "kill" the unit, if you don't fix it! CR 4101, & C 4100,
or something. Not hard to find. Good luck, Rono.

 

[kip]

Change the Blue Box caps first then check the settings in eeprom
chances are they are bagged.
Change the eeprom also but write down the data first.
Thats what I would do.

kip

 

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Thanks guys for the advice. I'm going to dig further into this thing
this weekend. Lenny.

 

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I just thought I would ask. The area of the board under CR4403 and
C4407 had a thick glue on it. Is that supposed to be there or did it
perhaps leak out of the capacitor? I found that CR4403 was indeed
shorted, and the capacitor, C4407 seems to make the ohm meter jump on
high range when going across it but it looks like it could be slightly
bulged. I can not confirm capacitance as I don't have a meter but I
would like to replace it anyway. The diode seems to cross to an NTE 577
and the capacitor looks like a .047 400V NP? Is there anything special
about these two components? Thanks once again in advance. Lenny Stein,
Barlen Electronics.

 

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The NTE cross will not last in that location. Use only the equivalent
RCA part number or exact oem replacement number off the part. I think
the FR### equivalent has also been posted here a long time ago.

The capacitor has failed, very common, causes diode to short.

 

[Bill S.]

I just thought I would ask. The area of the board under CR4403 and
C4407 had a thick glue on it. Is that supposed to be there or did it
perhaps leak out of the capacitor? I found that CR4403 was indeed
shorted, and the capacitor, C4407 seems to make the ohm meter jump on
high range when going across it but it looks like it could be slightly
bulged. I can not confirm capacitance as I don't have a meter but I
would like to replace it anyway. The diode seems to cross to an NTE 577
and the capacitor looks like a .047 400V NP? Is there anything special
about these two components? Thanks once again in advance. Lenny Stein,
Barlen Electronics.

A thing I've seen before in these sets is that there are two capacitors
effectively in series with the diode across one of them, and when the
one capacitor opens up or drops value by an order of magnitude, the
diode gets hit with more voltage than it can handle and breaks down.
I'd be checking capacitor values in the area, or you may be blowing
more diodes.

I've used FR307's with good results.