Toshiba 32AV554D

[Davy]

Have this set dead with no standby light.... 4.9V at the output and 3 Volts coming back to the PSU.

From another post elsewhere, I posted here because I didn't want to hi-jack the thread, it was mentioned the 3 Volts is voltage protection, I'm pretty sure in this case it was stuck in standby.

I tried another 680uF on the 5 Volt rail still no light, so I checked the cpu crystal and that reads OK on the frequency counter.

I just can't see what the 3 volt does with no standby light and no main power 'relay activated',  this comes from the main board back to two or three smd transistors on the power board - apart from protecting the main power supply.

"Stumped"... what next? I appreciate any idea's or circuits, memory or cpu perhaps.

The power board is a Mitsumi SRV2169WW-f
Main board is Toshiba PE0630  V28A000

Dave

[Keith]

the STRF chip in the PSU can cause problems, but I would think you have corrupt flash boot loader data, you could try to find a file but probably best to replace the main board, but make sure you get the correct type, they are different depending on the make of the screen.

Keith

[Davy]

I get no communication at all. I get the 'Power ON' pulse when pressing the power button but still no standby light.... I even tried powering the 5V from an external source and changing the 5V decoupling capacitor, no hash on the supply at all.

I'll check the STRF chip just in case, thank you for your reply Keith.

Dave

[Keith]

Sounds like corrupt boot loader, replacement main board is the best option, if available

Keith

[watteau]

Hi,
IC150 corruption can give this problem,  pre-programmed IC's, CHS: E2P061 (SHARP DISPLAY), E2P060 (LG DISPLAY) - £5.50 + VAT,   also  IC151 can need replacing, E2P069 (BLANK), at the same time,  worth a try.
Regards

[Turnip]

Hi Watteau,

Had one in a while ago - a 555 with the same mainboard and stuck in S/by. Thought Eeprom, ordered one from ChasHyde then fitted it in the wrong place, not realising there were two Eeproms.

Upshot - Set was gifted by cust then found the Sharp screen MB version on Fleabay for a decent price - job done.

Note you suggest that other Eeprom is blank - wonder why ?

Thanks again John - Chris.

PS - Mention as other dorks like me might make the same error - Note, the S/by led was glowing B4 the MB replacement jobby.

[Davy]

No standby light whatever. I get all the command pulses from the tac switches so I reckon that clears the button panel problem even pulses from the IR sensor.

I've had sets with eprom problems and  the standby light illuminated one way or the other, maybe I'm getting misled because I thought this one blinked as they are booting?

I'm wondering if it's a 'power ON reset', a pulse at switch ON to start all the chips on a datum line for the boot sequence to begin.

Data seems to be coming out the eprom well, one of em' IC151... pointless just changing one, you can bet if you did that it would always be the other one.

Thanks for the replies anyway, don't see you before Crimbo all the best and have a great New Year.

Davy