Toshiba 57H83 dead set part NLA

[Jeff Rigby]

Got a 57H93 HD Toshiba top end 2003 set in for service and it's DEAD.

Have Tritronics talk to Toshiba and get clarification. They will do the
research for you and see if the X version is available or if they will be
getting more of them. I have run into several long term backorders with
Toshiba in the last couple of years...DCUs, Hyper Modules, and FBTs.

You might try posting on sci.electronics.repair, the TechData forum, or
the TechAssist listserve. Someone on one of those might have a scrapper
but I doubt it. Probably the only reason one of those would be trashed at
this point would be the same reason you have.

Have you isolated everyting else on the data bus(es)? See if things start
coming up? Usually not much detail on the communication between chips in
many sets these days, so sometimes you just have to divide and conquer...

Sounds like you have all the documentation, right?

Leonard

I think I have all the documentation, and you are right...can't tell what
the MPU is looking for, no documentation on it's internal logic.

On previous chassis (H83) there was no ATSC digital module with the scine
circuitry. The MPU didn't have the extra serial data port that talks only
to the digital board. There were two serial data lines that talked to other
processors in the set and even if the serial data line was blocked by being
held low or high the MPU would boot and indicate by flashing the power on
led it's status and sometimes what circuit had the problem. That was a
useful feature. It seems that feature was not implemented for the data line
to the digital board and it's so critical that they have no recovery option
if the digital board doesn't talk to the MPU. The last is a guess.

As for the digital module, there is no documentation for that and the serial
data line between the gemstar module and digital (scine) board is dedicated.
My only hope is to check the digital board for obvious problems internally
like power and data lines critical to the main controller in the digital
board.