Well, I've finally got an opportunity to have a crack at a TV with the TNPA4782.
6 Blink, SOS 6. Expectations are SC board with blown IGBTs everywhere.
At first inspection and I'm rushing , i find a lot of surface corrosion on parts and the SC2 terminal is not healthy or it is a healthy green if it were a plant.
The board has scorch marks from arcing under the connector and with the SC2 lead removed , more tracking and arcing marks.
Cool, I'm thinking clean this up and maybe get lucky - no, still 6 blinks
So go over it more thoroughly and find Q661 shorted C-E, D673,674 shorted. I went with the diodes which are a pain to desolder and was wrong . Ended up being Q661 C-E short.
Q661 RJP6065, I've used a RJP63F3A which is the newer version . replaced Q818 2SK3018, Q702 2PD601 was short, IC773 TC7SH14F was shorted Vcc-gnd(41ohms),
Fired it up, still shuts down 6 blink but nothing blows. panel very briefly energises.
replaced Q701 MMBTA92, Q876 2PD601, IC724,725 78L05
No change, still 6 blink. Tried SC50 bypass, - same
So far voltages are spot on
TPVsus 198.5V
TPVscn -41.1 (- 40V ± 6V)
TPVAD -186.2 (- 185V ± 2V)
TPVe 135.2
There is no Vset cct on this
6 Blink, SOS 6. Expectations are SC board with blown IGBTs everywhere.
At first inspection and I'm rushing , i find a lot of surface corrosion on parts and the SC2 terminal is not healthy or it is a healthy green if it were a plant.
The board has scorch marks from arcing under the connector and with the SC2 lead removed , more tracking and arcing marks.
Cool, I'm thinking clean this up and maybe get lucky - no, still 6 blinks
So go over it more thoroughly and find Q661 shorted C-E, D673,674 shorted. I went with the diodes which are a pain to desolder and was wrong . Ended up being Q661 C-E short.
Q661 RJP6065, I've used a RJP63F3A which is the newer version . replaced Q818 2SK3018, Q702 2PD601 was short, IC773 TC7SH14F was shorted Vcc-gnd(41ohms),
Fired it up, still shuts down 6 blink but nothing blows. panel very briefly energises.
replaced Q701 MMBTA92, Q876 2PD601, IC724,725 78L05
No change, still 6 blink. Tried SC50 bypass, - same
So far voltages are spot on
TPVsus 198.5V
TPVscn -41.1 (- 40V ± 6V)
TPVAD -186.2 (- 185V ± 2V)
TPVe 135.2
There is no Vset cct on this
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