Toshiba 32HFX73 Help

[brodek]

Hi All having a bugger of a time with this set. I've owned her since new and I would really like to get this working again. Set is completely dead. When you plug it in you get two quick clicks. The power relay pulls in and drops out instantly. The 5V_1 or standby power is good. I confirmed the set is going into protection as I removed the "power" pin to the AC input board and the set powers up...kinda. I have a raster, the top of the vertical is down by about 1/3 and the horizontal is a little "wonky" in the middle. I disabled the protect out from the vertical board and the set still shuts down. So I believe that leaves the over current/xray protection for the 133V feed to the flyback. The 133V to the flyback is solid (when you disable the protection) I also checked a number of other voltages from the flyback like the + and - 15V that feeds the vertical they all seem good. One thing of note. When it does power it's garbage on the screen. No response to any buttons/menu from the front or remote. So it I started to suspect something in the signal board? Anyone have any experience with one of these sets? I tried to post the schematic but it was too large a file.

[Doug]

So sets powers up.on plug in.
So u don't have to push power button to turn it on.
Maybe micro issue. Check the 5v there also check see if any
Noise on the 5v line at the micro

[brodek]

Hi Doug. The set was completely dead to start. Just two quick clicks. It only powers on when I pull the "Power" signal to the AC input board. Then the set powers up when you plug it in. The power line has multiple input's "ored" in. So the vertical protect can shut it down, over current on the 133V to the Flyback, and power off from the micro all go into the one line. As such when you pull that connection the TV comes on as soon as you plug it in. I'll try putting a scope on the 5V standby to see if there is more ripple than there should be. Any other quick tricks to see if the micro itself is bad?

[brodek]

Posting some snapshots of the schematic for reference.

[Doug]

Issues I had with noise wasn't from the power supply but the osc frequency was on the 5v line at the micro.
If the issue was the set would not come on .
from a cold start,not shutting down from being on
Then I would just heat up the board with an hair dryer.
Then plug it in.if it works then freeze mist will help find the issue
What year is that set

[zeno]

Force on, run 15 secs. see if hoz out transistor gets hot.
If it does its almost always the flyback. If not things can really
get deep

73 Zeno
LFOD !

[brodek]

I have already run the set for probably 10-12 min all in (forced on). Nothing is getting too hot and I didn't let any magic smoke out. So hopefully that's a good sign for the horizontal. All signs are seem to be pointing to the micro issue. I need to find some time to drag the scope out and poke around to see if it's the micro itself or something connected to it like the oscillator or one of the supply voltages. Also looking for noise as noted earlier. Hopefully I can find some time this weekend to mess with it further. I tried to look around for a replacement micro. Doesn't seem to be anything available. Any ideas where I might score one if it turns out that's what quit?

[Doug]

Do you know what year that set was made?

[zeno]

A few things you may look at....
Go into service menu & write down all the numbers.
Compare to the manual, some are set to feature level per
model. Others are true adjustments.

Had several Sonys that the tuner/IF assy shorted at the data line.
Gave all sorts of strange symptoms. None of the IC's were getting
data to load up. So check the DATA, CLOCK & ENABLE lines
for clean wave forms. Activity usually in bursts but sometimes
only on key press.

Its not rare for Eproms to go corrupt.

Zeno

[brodek]

Hi Doug the set was made in 2003

[brodek]

Hi Zeno. I can't get into any menu options when I force power it on. I attached a picture of the screen when I force it on. I initially suspected something in the vertical but since there is zero response to any controls including the remote I'm starting to suspect the micro or something related as Doug is suggesting. I will try to take some scope shots of the 5V in, clock, and the SCA, SDL lines to see if there is any activity. Probably won't get to that till this weekend. Thanks to everyone for all the support/ideas.

[brodek]

Raster when I force on.

[brodek]

Ok so I got the scope out. Gotta bring the equipment to this beast as it weighs like 200lbs. In any case. Got a good clock (see attached)

Also got activity to the eeprom SDA0 and SCL0 images attached. This traffic lasts for one or two seconds after power on then stops. (possibly as expected)

I also checked the external I2C bus SCL1 and SDA1. Constant activity here but a steady pattern which without a decoder I'm thinking could be external devices just monitoring the bus?

I also checked for noise/clock on the 5V it was totally rock solid.

Also checked for activity from the remote (pin 1) and the remote is sending activity through there as well.

So it looks like the micro isn't completely dead. Any other ideas on what else to look at?

I'm going to poke around the protection circuit just a bit more to rule that out 100%

[Doug]

So scope your 133 and your 15 volt supplies and any other.
I don't have any manual on that.
Would like to see more schematics. Between the power supply and the deflection circuits
Doug

[brodek]

Attached are the schematic snapshots as requested.

I also verified 100% that the set is NOT going into protection. In the OCP_Protect snapshot I checked on the cathode of the SCR and it's zero volts I would expect 5 volts if there was any kind of protection going on here. So I must conclude the micro is keeping the set off for some reason?