Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

[Michale32086]

I came across an older Hitachi...

It's old and it's heavy... Don't want to put much work/$$$ into it..

http://sjfm.us/temp/42EDT41A.3gp

If it's just the ZSUS board, it might be worth fixing... If it's possible/likely other boards are bad, not so much..

What's the chances of me actually getting lucky here??

[freakaftr8]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

That kind of looks like a YSUS issue to me. How is vscan? Is it stable while its doing this?

[tom66]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Agreed on Y-sus fault. I believe these sets use Vw for Vscan and Vy as Vy, though I have not worked on one for a long time...

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

I just knew it wasn't my day to get lucky..

I gots to pick up the wife from work in about 20 mins..

I'll get it on my bench first thing in the morning and check the VS..

Thanx for the input.. Very much appreciated..

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

What the hell, I have at least 20 mins

Here's what I have accessible on the YSUS...

VSCW, VY and V-SETUP

I am assuming the VSCW is the VS/VW..

I also assume it matters what side of the resistor I clip on the + probe??

[tom66]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Is this an LG panel inside?

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

LGE PDP 040228
Model 42V6

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

That's the part number on the YSUS board..

[tom66]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Voltages will be measured across those resistors.

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

I knew that..

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

VSCW started at 121v at power up, then gradually went down..

VY started at -76v at power up and gradually went up..

The Label says VS 160V...

[tom66]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Ignore polarity for most power supply testing.

Hypothetical example. Power supplies generally have a polarised output capacitor and an output rectification diode on the transformer side.

So, what would happen if the supply had -200V on it instead of +200V? And this was somehow a continuous operation. Three things:
a) the diode would be rapidly damaged by the capacitor discharging
b) the capacitor would violently bulge and vent. The chemical reaction inside the capacitor vents hydrogen peroxide which really stinks up the place.
c) the transformer, driver FET and control logic would probably emit the magic smoke, which would stop them working (as electronics work on smoke - if the smoke leaks, they stop working)

I'm assuming that none of these have happened. If so, ignore polarity for now.

[tom66]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Vs != Vscw.
I have not seen a Vs that low before!, sure it's not 180V?

[freakaftr8]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

sounds like the low vs causing the picture to momentarily want to drop out. Try with Y & Z boards disconnected from power supply does the power supply maintain vs and what is the voltage?

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Had to leave the unit at the shop... I'll jump on it first thing in the AM, EST.... I'll also confirm the VS stuff....

Thanx for all the input.. I'll follow up...

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Ignore polarity for most power supply testing.

Hypothetical example. Power supplies generally have a polarised output capacitor and an output rectification diode on the transformer side.

So, what would happen if the supply had -200V on it instead of +200V? And this was somehow a continuous operation. Three things:
a) the diode would be rapidly damaged by the capacitor discharging
b) the capacitor would violently bulge and vent. The chemical reaction inside the capacitor vents hydrogen peroxide which really stinks up the place.
c) the transformer, driver FET and control logic would probably emit the magic smoke, which would stop them working (as electronics work on smoke - if the smoke leaks, they stop working)

I'm assuming that none of these have happened. If so, ignore polarity for now.

Yep, haven't seen any evidence of this..

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

OK, measured VA and VS off the connectors coming from the Power PCB..

VS shows 192V

VA shows 65.6V

Both are in keeping with the tag on the display...

VS=190V

VA= 65V

[tom66]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Is Vs stable when picture glitches? Check on Y-sus and Z-sus too - could be bad connection.

[Michale32086]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Seems to be stable. Holds at 192v +/- a volt or so...

Both Y and Z show stable 192 +/-

[tom66]

Re: Hitachi 42EDT41A Glitzy Solarizing- ZSUS??

Worth checking other voltages then and see if they drop out, including Va.