Sony SCC-F84A-A

S

Stan

Guest
Hi Group, Can someone help please...? I'm working on a Sony Trinitron
#32TS36, SCC-F84A-A, Owner said won't power up, so after intial
testing & probing I found a couple of shorted components, Q601 & 2,
R607, Q591HOT, changed those,& resoldered t501 & 2, and yep you
guessed it, they got fried again. so I changed them again and, now I'm
using my head, I applied 30-40v Ac, and I used a probe to monitor the
wave form on the emitter of q601 & the collector of 602, I'm expecting
to see a clean sign wave, with some clipping action, but Nooooooooo, I
got a distorted wave. I checked all the diodes and caps in that
section all check out fine. any suggestions on this matter will be
taken seriously, and you will be rewarded with my sincere gratitude,
Thanks in advance, Stan.
 
First off, the SMPS will be essentially a square wave when it is regulating.
The SMPS will regulate at around 40VAC. Do this with the HOT removed from
the set and a 60 watt light bulb in place of the flyback and HOT on the main
b+.

Second, shorted CRT guns and failing flybacks ar pretty common in certain
32" Sony sets from that era, double check those. If the HOT is shorting, it
will always take out the SMPS.

Third, the VDR's, capacitors, and other SMPS parts are all common failure
items. There is no way to check the VDR's except to replace them, unless
you have the correct current limited sweeping power supply with curve tracer
display and the spec's for the VDR's as well.

David

Stan <stan1k1@yahoo.com> wrote in message
news:ae1d175c.0311291512.6b0caf5b@posting.google.com...
Hi Group, Can someone help please...? I'm working on a Sony Trinitron
#32TS36, SCC-F84A-A, Owner said won't power up, so after intial
testing & probing I found a couple of shorted components, Q601 & 2,
R607, Q591HOT, changed those,& resoldered t501 & 2, and yep you
guessed it, they got fried again. so I changed them again and, now I'm
using my head, I applied 30-40v Ac, and I used a probe to monitor the
wave form on the emitter of q601 & the collector of 602, I'm expecting
to see a clean sign wave, with some clipping action, but Nooooooooo, I
got a distorted wave. I checked all the diodes and caps in that
section all check out fine. any suggestions on this matter will be
taken seriously, and you will be rewarded with my sincere gratitude,
Thanks in advance, Stan.
Click to expand...
 
OK...with the HOT removed I placed a 60w bulb in the main b+, and it
lit up dim..and I recheck the HOT and it was shorted, from base to
emitter, .024...but q601 & 2, are ok....I guess the dim bulb telled me
that the short isn't there...?

"David" <dkuhajda@locl.net.spam> wrote in message news:<3fc961c5@news.greennet.net>...
First off, the SMPS will be essentially a square wave when it is regulating.
The SMPS will regulate at around 40VAC. Do this with the HOT removed from
the set and a 60 watt light bulb in place of the flyback and HOT on the main
b+.

Second, shorted CRT guns and failing flybacks ar pretty common in certain
32" Sony sets from that era, double check those. If the HOT is shorting, it
will always take out the SMPS.

Third, the VDR's, capacitors, and other SMPS parts are all common failure
items. There is no way to check the VDR's except to replace them, unless
you have the correct current limited sweeping power supply with curve tracer
display and the spec's for the VDR's as well.

David

Stan <stan1k1@yahoo.com> wrote in message
news:ae1d175c.0311291512.6b0caf5b@posting.google.com...
Hi Group, Can someone help please...? I'm working on a Sony Trinitron
#32TS36, SCC-F84A-A, Owner said won't power up, so after intial
testing & probing I found a couple of shorted components, Q601 & 2,
R607, Q591HOT, changed those,& resoldered t501 & 2, and yep you
guessed it, they got fried again. so I changed them again and, now I'm
using my head, I applied 30-40v Ac, and I used a probe to monitor the
wave form on the emitter of q601 & the collector of 602, I'm expecting
to see a clean sign wave, with some clipping action, but Nooooooooo, I
got a distorted wave. I checked all the diodes and caps in that
section all check out fine. any suggestions on this matter will be
taken seriously, and you will be rewarded with my sincere gratitude,
Thanks in advance, Stan.
Click to expand...
 
The HOT is only shorted if it reads a short between the C-E. HOT
transistors almost all have an internal resistor of around 40 ohm between
the B-E and will read some really low voltage drop on the diode check of a
digital meter. FYI digital meters on diode/transistor check are reading you
the forward bias voltage drop if it reads a diode or resistance.

If the 60 watt light bulb is on the smps main output b+ to the flyback and
you have the smps on a variac at around 40vac, you should be able to verify
proper regulation and operation. Do not forget to put the tv set on an
isolation transformer before connecting the scope to the primary side of
that smps, your ground probe location is also going to be critical as Sony
uses a voltage doubler before the SMPS.

David

Stan <stan1k1@yahoo.com> wrote in message
news:ae1d175c.0311301433.7c5632b0@posting.google.com...
OK...with the HOT removed I placed a 60w bulb in the main b+, and it
lit up dim..and I recheck the HOT and it was shorted, from base to
emitter, .024...but q601 & 2, are ok....I guess the dim bulb telled me
that the short isn't there...?

"David" <dkuhajda@locl.net.spam> wrote in message
news:<3fc961c5@news.greennet.net>...
First off, the SMPS will be essentially a square wave when it is
regulating.
The SMPS will regulate at around 40VAC. Do this with the HOT removed
from
the set and a 60 watt light bulb in place of the flyback and HOT on the
main
b+.

Second, shorted CRT guns and failing flybacks ar pretty common in
certain
32" Sony sets from that era, double check those. If the HOT is
shorting, it
will always take out the SMPS.

Third, the VDR's, capacitors, and other SMPS parts are all common
failure
items. There is no way to check the VDR's except to replace them,
unless
you have the correct current limited sweeping power supply with curve
tracer
display and the spec's for the VDR's as well.

David

Stan <stan1k1@yahoo.com> wrote in message
news:ae1d175c.0311291512.6b0caf5b@posting.google.com...
Hi Group, Can someone help please...? I'm working on a Sony Trinitron
#32TS36, SCC-F84A-A, Owner said won't power up, so after intial
testing & probing I found a couple of shorted components, Q601 & 2,
R607, Q591HOT, changed those,& resoldered t501 & 2, and yep you
guessed it, they got fried again. so I changed them again and, now I'm
using my head, I applied 30-40v Ac, and I used a probe to monitor the
wave form on the emitter of q601 & the collector of 602, I'm expecting
to see a clean sign wave, with some clipping action, but Nooooooooo, I
got a distorted wave. I checked all the diodes and caps in that
section all check out fine. any suggestions on this matter will be
taken seriously, and you will be rewarded with my sincere gratitude,
Thanks in advance, Stan.
Click to expand...
 
Hi David, Thanks for your expertise, I changed all the critical
components, q601&2, VDR601, .1 Ohm fuse resistor, and the HOT,
resoldered t502. working fine, Thanks again.

"David" <dkuhajda@locl.net.spam> wrote in message news:<3fcada0f@news.greennet.net>...
The HOT is only shorted if it reads a short between the C-E. HOT
transistors almost all have an internal resistor of around 40 ohm between
the B-E and will read some really low voltage drop on the diode check of a
digital meter. FYI digital meters on diode/transistor check are reading you
the forward bias voltage drop if it reads a diode or resistance.

If the 60 watt light bulb is on the smps main output b+ to the flyback and
you have the smps on a variac at around 40vac, you should be able to verify
proper regulation and operation. Do not forget to put the tv set on an
isolation transformer before connecting the scope to the primary side of
that smps, your ground probe location is also going to be critical as Sony
uses a voltage doubler before the SMPS.

David

Stan <stan1k1@yahoo.com> wrote in message
news:ae1d175c.0311301433.7c5632b0@posting.google.com...
OK...with the HOT removed I placed a 60w bulb in the main b+, and it
lit up dim..and I recheck the HOT and it was shorted, from base to
emitter, .024...but q601 & 2, are ok....I guess the dim bulb telled me
that the short isn't there...?

"David" <dkuhajda@locl.net.spam> wrote in message
news:<3fc961c5@news.greennet.net>...
First off, the SMPS will be essentially a square wave when it is
regulating.
The SMPS will regulate at around 40VAC. Do this with the HOT removed
from
the set and a 60 watt light bulb in place of the flyback and HOT on the
main
b+.

Second, shorted CRT guns and failing flybacks ar pretty common in
certain
32" Sony sets from that era, double check those. If the HOT is
shorting, it
will always take out the SMPS.

Third, the VDR's, capacitors, and other SMPS parts are all common
failure
items. There is no way to check the VDR's except to replace them,
unless
you have the correct current limited sweeping power supply with curve
tracer
display and the spec's for the VDR's as well.

David

Stan <stan1k1@yahoo.com> wrote in message
news:ae1d175c.0311291512.6b0caf5b@posting.google.com...
Hi Group, Can someone help please...? I'm working on a Sony Trinitron
#32TS36, SCC-F84A-A, Owner said won't power up, so after intial
testing & probing I found a couple of shorted components, Q601 & 2,
R607, Q591HOT, changed those,& resoldered t501 & 2, and yep you
guessed it, they got fried again. so I changed them again and, now I'm
using my head, I applied 30-40v Ac, and I used a probe to monitor the
wave form on the emitter of q601 & the collector of 602, I'm expecting
to see a clean sign wave, with some clipping action, but Nooooooooo, I
got a distorted wave. I checked all the diodes and caps in that
section all check out fine. any suggestions on this matter will be
taken seriously, and you will be rewarded with my sincere gratitude,
Thanks in advance, Stan.
Click to expand...
 
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