With datasheet for PCM56P DAC ICs, I see why I'm not getting all the
signals, some partials, some totally off and some are flatlined, only
two out of six were outputting correct signals for convergence amp
ICs. All six of DAC ICs are getting data, clock and enable signals
from T7K64 IC with own EEPROM.

Do I go with replacing PCM56P DACs or this T7K64 IC (SMD square IC)?

Do anybody else see high failure rate on PCM56P ICs it is DAC by
burroughs brown.

Cheers, Wizard

Just a shot, but have you tried powering up the set with the
convergence outputs disconnected and then entered the convergence
service mode and performed an all reset to default settings to
reinitialize the eeprom? If the eeprom somehow became corrupted, this
might fix the problem.


Also is the convergence module getting all the correct signals from the
mainboard?

FYI: Toshiba's replacement part is the entire convergence module and
that was what we always replaced. They required it under warranty as
the early versions had an engineering defect and needed modified.



Jason D. wrote:
With datasheet for PCM56P DAC ICs, I see why I'm not getting all the
signals, some partials, some totally off and some are flatlined, only
two out of six were outputting correct signals for convergence amp
ICs. All six of DAC ICs are getting data, clock and enable signals
from T7K64 IC with own EEPROM.

Do I go with replacing PCM56P DACs or this T7K64 IC (SMD square IC)?

Do anybody else see high failure rate on PCM56P ICs it is DAC by
burroughs brown.

Cheers, Wizard

On 9 Jun 2005 21:22:58 -0700, wrote:

Just a shot, but have you tried powering up the set with the
convergence outputs disconnected and then entered the convergence
service mode and performed an all reset to default settings to
reinitialize the eeprom? If the eeprom somehow became corrupted, this
might fix the problem.

Good point, problem is I don't have service manual and getting it is
has to figure into estimate which will jack up from 300+ to over 450+
and may scare customer off. Do you have steps or info to send to me
by email to do the convergence job or reset?


Also is the convergence module getting all the correct signals from the
mainboard?

Yes, it is, communicates via serial bus ATE, data and clock. and one
I2C.

FYI: Toshiba's replacement part is the entire convergence module and
that was what we always replaced. They required it under warranty as
the early versions had an engineering defect and needed modified.

Ooh. What is the early and late version of this module part numbers
on it so I can tell apart on one I have now.

Cheers, Wizard

Looks like you need the service manual. I don't have access any
longer.
Back in 2002 I was full aware of the problems Toshiba was having with
the convergence modules in those sets, and they were paying for a lot
of out of warranty replacements at that time. I was probably doing 1
or 2 per week with this failure for about 1.5 years back 3-4 years ago.

You did not answer the question of whether it was getting all the
correct signals.
I2C and data buses and power is only part of it, what about the pulses
from the vertical and horizontal circuits?

Add this web sites home page to your favorites:
http://www.eserviceinfo.com/equipmen...Toshiba_2.html
The tz50v51 service information should give you the basics on getting
into the convergence mode and doing a reset, if your set has additional
screen modes 480p, widescreen, etc, you will need the full service
manual on how to get into each mode to adjust the convergence.

FYI if this fixes the problem, you also need to buy the screen overlay
(or make one) for each mode to do the geometry adjustments. Same would
go if you could have replaced the main PLC/EEProm ic in the module. I
am not even sure you can buy that part from Toshiba individually,
certainly buying it generically won't work as it won't have any of the
programming information preloaded.

This is one set that it would probably be much less expensive having a
Toshiba Warranty authorized servicer repair as they should already have
all the overlay jigs and service manual on hand. This is your first
Toshiba RPTV from that era with a convergence module issue? Given the
high failure early on, I would bet that any Toshiba authorized servicer
that does any kind of volume for them has all the jigs and information.