KV-27V22 2SC4834 Q601 Q502

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I had one 2sc4834 (q601) pop in this set. I had replaced both (q601 &
q602) and caps c609, c610, c615 about three years ago. From what I read
in this newsgroup, they usually go in pairs along with the 0.1
resistor. Has anybody seen only one of the pair go ? All other
components on the power supply board look good (ESR of electrolytics,
diodes, high freq. caps, resistors). The HOT 2sc4927-01 (q502) also had
a shorted base to emitter. Will a BU508AF work as a replacement for the
HOT ? I resoldered the horz. drive transformer, flyback and replaced
the 0.47uf base drive cap. Is there anything else to do before applying
power ? I guess if the HOT goes again, the flyback could be bad. Any
help would be appreciated.
 
Are you really sure the HOT is shorted B-E?
You might need to consult standard tv troubleshooting repair manuals before
going much further if that is the only failure in the HOT that you think you
are seeing.

David

nospam <nospam@nospam.com> wrote in message
news:f4d00dfd6faf847ab1af54421e8f4635@news.teranews.com...
I had one 2sc4834 (q601) pop in this set. I had replaced both (q601 &
q602) and caps c609, c610, c615 about three years ago. From what I read
in this newsgroup, they usually go in pairs along with the 0.1
resistor. Has anybody seen only one of the pair go ? All other
components on the power supply board look good (ESR of electrolytics,
diodes, high freq. caps, resistors). The HOT 2sc4927-01 (q502) also had
a shorted base to emitter. Will a BU508AF work as a replacement for the
HOT ? I resoldered the horz. drive transformer, flyback and replaced
the 0.47uf base drive cap. Is there anything else to do before applying
power ? I guess if the HOT goes again, the flyback could be bad. Any
help would be appreciated.
Click to expand...
 
nospam:
Do you test the HOT taken out of the circuit??? The base and emitter
terminals on the circuit board will only measure an ohm or two between
them.... and to ground WITHOUT the transistor .... refer to a schematic for
any television that uses a bi-polar transistor as the HOT to see why.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

"nospam" <nospam@nospam.com> wrote in message
news:f4d00dfd6faf847ab1af54421e8f4635@news.teranews.com...
I had one 2sc4834 (q601) pop in this set. I had replaced both (q601 &
q602) and caps c609, c610, c615 about three years ago. From what I read
in this newsgroup, they usually go in pairs along with the 0.1
resistor. Has anybody seen only one of the pair go ? All other
components on the power supply board look good (ESR of electrolytics,
diodes, high freq. caps, resistors). The HOT 2sc4927-01 (q502) also had
a shorted base to emitter. Will a BU508AF work as a replacement for the
HOT ? I resoldered the horz. drive transformer, flyback and replaced
the 0.47uf base drive cap. Is there anything else to do before applying
power ? I guess if the HOT goes again, the flyback could be bad. Any
help would be appreciated.
Click to expand...
 
I have never seen just one of the pair go but I suppose there is a
first time for everything. These Sony sets are so fickle I always
just replace both the transistors, the resistor, the 4 blue caps, the
HOT, the VDR, check for and replace any bad electrolytics and resolder
the board. The comprehensive method never fails. The one time I
didn't use an original HOT it failed again after 2 weeks.
nospam <nospam@nospam.com> wrote in message news:<f4d00dfd6faf847ab1af54421e8f4635@news.teranews.com>...
I had one 2sc4834 (q601) pop in this set. I had replaced both (q601 &
q602) and caps c609, c610, c615 about three years ago. From what I read
in this newsgroup, they usually go in pairs along with the 0.1
resistor. Has anybody seen only one of the pair go ? All other
components on the power supply board look good (ESR of electrolytics,
diodes, high freq. caps, resistors). The HOT 2sc4927-01 (q502) also had
a shorted base to emitter. Will a BU508AF work as a replacement for the
HOT ? I resoldered the horz. drive transformer, flyback and replaced
the 0.47uf base drive cap. Is there anything else to do before applying
power ? I guess if the HOT goes again, the flyback could be bad. Any
help would be appreciated.
Click to expand...
 
Sounds like the HOT is OK and you took a power surge. The only time I see
Q601 shorted and Q602 OK is during lightning season and never when there is
an internal problem in the set beyond the PS pulling too much current. You
need to check ALL of the components in the PS primary carefully, as well as
the standby PS circuits.

Leonard Caillouet

"nospam" <nospam@nospam.com> wrote in message
news:f4d00dfd6faf847ab1af54421e8f4635@news.teranews.com...
I had one 2sc4834 (q601) pop in this set. I had replaced both (q601 &
q602) and caps c609, c610, c615 about three years ago. From what I read
in this newsgroup, they usually go in pairs along with the 0.1
resistor. Has anybody seen only one of the pair go ? All other
components on the power supply board look good (ESR of electrolytics,
diodes, high freq. caps, resistors). The HOT 2sc4927-01 (q502) also had
a shorted base to emitter. Will a BU508AF work as a replacement for the
HOT ? I resoldered the horz. drive transformer, flyback and replaced
the 0.47uf base drive cap. Is there anything else to do before applying
power ? I guess if the HOT goes again, the flyback could be bad. Any
help would be appreciated.
Click to expand...
 
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