Philips 2b chassis and my mind sanity

[Emanuele Girlando]

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!!

..

 

[Emanuele Girlando]

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!!

.

Has anybody out there suggestions about how to disable protections in
the 2b chassis?

 

[[email protected]]

On 19 Mar, 00:45, "Emanuele Girlando" <[email protected]>
wrote:

A Philiips 2b or not a 2b?

Has anybody out there suggestions about how to disable protections in
the 2b chassis?

Unfortunately no. My tv chassis knowledge is far too out of date. I
did once replace the whole smps though, that got round all protection
issues. Just used lightbulb dropper, rectify, smooth... But you cant
do that sort of thing nowadays.



NT