Voltages are fine 12v 24v 5v 3v no drops stable.

I sugges is eeprom so i ordered eeprom to see if its fix this issue

Tv cuts off then trys to start again and that constantly never stops trying

 

I sugges is eeprom so i ordered eeprom to see if its fix this issue

What makes you think that will work? There are so many things that will cause the computer to abort a start-up. I would not assume the EEPROM is the issue unless I had supporting data.

 

I found some source

Is one same brand just dif in inches had same issue but replacing eeprom fixed issue so that can be the problem.

Im not loosing anythig if its not fix it i can return it couse its claims as replacment fix eeprom corruption auto constant restart

 

You lose warranty if you fiddled with the TV.

 

Tv has no warranty so dont care

 

Please note the capacitor mounted horizontally under a part of a heatsink(has the RoHS sticker on it I think). This should be around 220uf 400vdc(maybe 250v if USA) and is the main working capacitor in this power scheme ;o) I also noticed a small 22uf cap and one I couldn't see a value near it, but the output filter caps do look ok with no plastic shrinkage to the tops, which is a sure indicator of internal heating(increased current/power losses) and degrade from there. Suspect values of 22uf, 33uf, 47uf capacitors, as in my 35+yrs repairing electronics, I have found these odd values to be challenging to component makers over the years, and fail much more often than standard values like 1uf, 10, 100, and I know it sounds odd, but we replace these values for quality sake in many items. Also, check for solder connections, and the boards plugging into this module play a role in it's operation. good luck!

 

Please note the capacitor mounted horizontally under a part of a heatsink(has the RoHS sticker on it I think). This should be around 220uf 400vdc(maybe 250v if USA) and is the main working capacitor in this power scheme ;o) I also noticed a small 22uf cap and one I couldn't see a value near it, but the output filter caps do look ok with no plastic shrinkage to the tops, which is a sure indicator of internal heating(increased current/power losses) and degrade from there. Suspect values of 22uf, 33uf, 47uf capacitors, as in my 35+yrs repairing electronics, I have found these odd values to be challenging to component makers over the years, and fail much more often than standard values like 1uf, 10, 100, and I know it sounds odd, but we replace these values for quality sake in many items. Also, check for solder connections, and the boards plugging into this module play a role in it's operation. good luck!

These days most TV PSUs have a PFC front end - basically a boost converter with no reservoir electrolytic between it and the mains rectifier, in UK sets the reservoir between the PFC and the B+ line tends to be rated about 450V.

There's usually a film cap across the bridge rectifier to eliminate mains hash, but the current is drawn in pulses at the switching frequency, that way the average current draw follows the value of the sinewave - instead of blips of current to top up the reservoir at each AC peak.

 

These days most TV PSUs have a PFC front end - basically a boost converter with no reservoir electrolytic between it and the mains rectifier, in UK sets the reservoir between the PFC and the B+ line tends to be rated about 450V.

There's usually a film cap across the bridge rectifier to eliminate mains hash, but the current is drawn in pulses at the switching frequency, that way the average current draw follows the value of the sinewave - instead of blips of current to top up the reservoir at each AC peak.

with respects....
The PFC has found little sympathy in the electronics industry and makes little sense on small internal power supplies, except to add part counts and expense. PFC does come into play when items will be consuming large loads, but not in the treadmill industry. There is also no boost(buck boost, charge pumps) incorporated into a harsh environment such as the noisy motor circuits, which have extreme varying current loading, and would be simply over-engineered. This PSU takes Main voltages, rectifies them thru a single 50A full wave bridge, thru a control relay in some cases, or an SCR, then to a pwm operated Hi-power Hexfet which drives the motor windings ;o)

 

with respects....
The PFC has found little sympathy in the electronics industry and makes little sense on small internal power supplies, except to add part counts and expense. PFC does come into play when items will be consuming large loads, but not in the treadmill industry. There is also no boost(buck boost, charge pumps) incorporated into a harsh environment such as the noisy motor circuits, which have extreme varying current loading, and would be simply over-engineered. This PSU takes Main voltages, rectifies them thru a single 50A full wave bridge, thru a control relay in some cases, or an SCR, then to a pwm operated Hi-power Hexfet which drives the motor windings ;o)

AFAIK; only PSU higher than 50W are required to have PFC - most "harsh environment" stuff tends to be motors etc with purely reactive power factors - there have been regulations about those for years; such as PFC capacitors to compensate for the inductive ballast in florescent lights.

 

The OP has reported finding target voltages in the PSU, so why all the continued talk about the power supply? The problem is likely elsewhere.
Happy to be proven wrong..

 

The OP has reported finding target voltages in the PSU, so why all the continued talk about the power supply? The problem is likely elsewhere.
Happy to be proven wrong..

I suggested quite aways back to suspect possibly one of the backlight inverter transformers could have shorted turns - there was actually some mention of the set conking out about the point it tried to fire that bit up.

Shorted turns on one of the CCFL transformers isn't exactly unlikely - which may or may not have killed it's driver MOSFETS.

These sets usually have extensive safety shutdown circuits, so a fault in one CCFL channel may shut down all the others.

 

I likewise suggested the backlight inverter in #14. I guess it's semantics - I don't think of that as part of the power supply per se.
I guess we'll have to wait and see how the OP's EEPROM experiment goes first, before he turns to the other suggested issues.
Are we certain yet whether this is an LCD or a CRT?

 

I likewise suggested the backlight inverter in #14. I guess it's semantics - I don't think of that as part of the power supply per se.
I guess we'll have to wait and see how the OP's EEPROM experiment goes first, before he turns to the other suggested issues.
Are we certain yet whether this is an LCD or a CRT?

Its led lit lcd

 

Do you ever see the backlight turn on during startup?

 

Yes back light turns on for few secs then tv cuts off and trys to start again

 

Humor me, change the main storage cap, 220uf, 250+v for $3 and test. I have seen this more than once. You can also borrow a hair blower, heat that cap up, power up the unit, and watch it fail, but, I too have been wrong, but I make a living repairing electronics, so I would be starving if I was too off base ...

 

Humor me, change the main storage cap, 220uf, 250+v for $3 and test. I have seen this more than once. You can also borrow a hair blower, heat that cap up, power up the unit, and watch it fail, but, I too have been wrong, but I make a living repairing electronics, so I would be starving if I was too off base ...

Its often worth checking whether electrolytics get hot, a sure sign of high ESR losses - but be careful with PSU primary side electrolytics; the aluminium can might not be isolated.

The negative end of the bridge rectifier isn't ground - it swings negative to the peak value of the AC in!

 

Its often worth checking whether electrolytics get hot, a sure sign of high ESR losses - but be careful with PSU primary side electrolytics; the aluminium can might not be isolated.

The negative end of the bridge rectifier isn't ground - it swings negative to the peak value of the AC in!

Very true! All Off-line switching power supplies, or SMPS are HOT grounded, and many use voltage doublers which requires 2 large capacitors with an intersection connection tied to an ac line component, allowing this reference to swing +/-60vac, resulting in doubled voltage found at V+ and V- respectfully...ty, nice point to bring up!

 

Hi reveived part soldered on tv was dead no mark off life at all.

Soldered old one back tv up und running again

That strange

Thanks everyone for help

 

Huh? So you de-soldered the EEPROM, replaced it, that didn't work, you put the old one back, and now it's working?

Cool.