E
Emanuele Girlando
Guest
Ahhhh! Help!
Got a philips 2b TV set (actually a Pioneer sv-2103).
Arrived with shorted HOT and a couple of (safe) resistors burned out.
Replaced all of them and turned on the set through a "bulb limiter".
SMPS seems working: 140V, +20 and-20 and +13V lines were all low
(because of the bulb) but present and reasonable. Scoping primary and
secondary sides of the SMPS gave me signals in good shape....
But: no HT, no standby 5V. Signals in horizontal path were ugly.
Replaced the LOPT. Now I have good shaped signals in the horizontal
path, good signal @ HOT's collector, some HT, some filament current,
some standby 5V.
So I decided to go without series bulb. ... opss! Something is now
tripping down the SMPS after few milliseconds.
To better trace the problem I connected a bulb in place of the HOT:
140V in perfect as they are +20 and -20 and 13V ... confirming the
SMPS is properly working. Turning the 140V trimmer effectively
regulates B+ as expected, letting me argue that the SMPS' regulator is
also working properly .
Suspecting something in the HOT circuit I replaced the two (damper?)
diodes, the resonating cap, checked resistors .... without any
result.
Turning back to the series bulb arrangement, the circuit doesn't trip
working as described before... but with further testing I noted that
sometime the signal @ the HOT's collector is somehow irregular.
Sometime it shows a third irregular swing in the middle of the main
two.. -> checked EAST-WEST correction circuitry... it seems ok.....
Ahhhh! HELP!!
..
Got a philips 2b TV set (actually a Pioneer sv-2103).
Arrived with shorted HOT and a couple of (safe) resistors burned out.
Replaced all of them and turned on the set through a "bulb limiter".
SMPS seems working: 140V, +20 and-20 and +13V lines were all low
(because of the bulb) but present and reasonable. Scoping primary and
secondary sides of the SMPS gave me signals in good shape....
But: no HT, no standby 5V. Signals in horizontal path were ugly.
Replaced the LOPT. Now I have good shaped signals in the horizontal
path, good signal @ HOT's collector, some HT, some filament current,
some standby 5V.
So I decided to go without series bulb. ... opss! Something is now
tripping down the SMPS after few milliseconds.
To better trace the problem I connected a bulb in place of the HOT:
140V in perfect as they are +20 and -20 and 13V ... confirming the
SMPS is properly working. Turning the 140V trimmer effectively
regulates B+ as expected, letting me argue that the SMPS' regulator is
also working properly .
Suspecting something in the HOT circuit I replaced the two (damper?)
diodes, the resonating cap, checked resistors .... without any
result.
Turning back to the series bulb arrangement, the circuit doesn't trip
working as described before... but with further testing I noted that
sometime the signal @ the HOT's collector is somehow irregular.
Sometime it shows a third irregular swing in the middle of the main
two.. -> checked EAST-WEST correction circuitry... it seems ok.....
Ahhhh! HELP!!
..