Toshiba RPTV, need info on 1222 jungle (rainforrest) IC

[bharat]

Does anyone have datasheets for this IC?

On my Toshiba 61A61 RPTV, nothing was coming out of 1222 IC and there
was no audio or video. So I replaced the IC. When I powered the TV
on, I heard a crackle (not too loud but enough to tell me something
happened). Upon checking, I found that audio was working fine but
video was still out. Further checking revealed that pin #22 (it is
labelled as 9V(DEF) on schematic) is internally shorted to the ground.
When I disconnect the pin from the board, I see 9V on the node as it
should. Because that pin is shorted to ground inside the IC, can't do
much but to replace it again.

what is causing this? I ordered another IC but am afraid to install
it as same thing may happen again....Everything else looks good. All
voltages coming out of power board are what they should be (except all
voltage associated with H.out).

Thanks for any help with this one.

 

[JURB6006]

That is strange, but I'll tell you this much, if you heard the crackle, it has
or had HV. This is inconsistent with the deflection Vcc being shorted out, the
TA1222 is addressable I think and as such probably provides the H drive.

Re check this, recount off the pins, something is amiss. Even though it is
possible the set doesn't use the deflection portion of the IC for deflection,
it probably needs it for blanking and BGP generation.

Typically a jungle IC either runs off the SMPS or has a trickle startup ckt
then is powered by the H out ckt once it is up and running.

In either case, if you actually confim the IC to be shorted (sounds like you
have) it must've taken a shot of too much voltage.

If you DLed the print, I wish you would send it because I lost my gooood
Toshiba link in a HD crash . (don't post it to the NG)

If you bought it look around for the internal details of that chip.

Perhaps that crackle was not HV ?

Anyway, on point, frequently the deflection Vcc in a jungle chip is usually
simply regulated by an internal Zener. This allows them to simply use a
resistor from main B+ to start it. If you apply a strong supply of a voltage
higher than the rated max, it usually shorts that Zener out.

Perhaps the next time you might want to supply the 9V externally, but I think
at first power up you should set your scope to free run mode and use it as an
extremely fast voltmeter.

To be continued.....

(my mouse just locked up, gonna reboot)

JURB

tab,tab,tab>send, Alt,O ,O Ctrl+Esc ^, ^, Enter.