Samsung HTP5044 power supply or main board

[DavidOH]

Re: Samsung HTP5044 power supply or main board

Is .01 a good esr for a 25v 680uf cap? (off the board) Just want to confirm I'm reading it right.

[awyatt2]

Re: Samsung HTP5044 power supply or main board

yes,esr is fine you probally need the xsus. i have a 5054 i need y main and buffers for. they are not cheap, prone to failure i found the parts that are bad but havent found a source for them yet.
when you fix one headed for the dumpster, it gives you a feeling you just cant describe.i just fixed a panny 50 for my daughter so she wouldnt be looking at a 32 thru next year.

[DavidOH]

Re: Samsung HTP5044 power supply or main board

I'm trying to trace the Ve/Vcc. Looks like the green caps are for the Vs which I have and the red looking ones are for the Ve which I don't. The number on the red ones is MPP225K/2H. I think they are part of the Ve. I'm not sure where to start.

[awyatt2]

Re: Samsung HTP5044 power supply or main board

a stupid question, have you checked all the fuses on the zsus? itried to find a service manual on it and cant. unless something is different here the voltages are made at the power board then stepped up or down on the zsus and ysus.have you checked all the mosfets on power board, also the to220 case diodes, surface mt or picofuses on the power supply

[DavidOH]

Re: Samsung HTP5044 power supply or main board

Yes, I checked the fuses with the power on. The main fuse and the pico closest to the heat sink read 207v on both ends. The pico next to the main fuse reads 4v on both ends. The service manual list 4 fets and 3 diodes to check. Before I take it apart to check those I'm going to touch up some soldier I don't like the looks of and try it. If nothing else I can get another board for about $45. So nothing to lose trying to fix this one first and I'm learning as I go.

[tom66]

Re: Samsung HTP5044 power supply or main board

More likely those caps are the energy recovery caps... they should measure from 25~75% of the Vsus voltage, varying with picture brightness.

[DavidOH]

Re: Samsung HTP5044 power supply or main board

After looking closer I'm not sure they have anything to do with the Ve. A lot of the fet legs don't have soldier thru the board. I'M going to resolder all of them a see what happens.

[tom66]

Re: Samsung HTP5044 power supply or main board

The energy recovery is called Vrc/Verc on Samsung.

Ve is used on X-main or sometimes Y-main to initialise plasma panel, on newer panels, to get low black levels. It is separate from the energy recovery circuit. The energy recovery circuit is used to reduce the power wasted by charging and discharging the panel.

[DavidOH]

Re: Samsung HTP5044 power supply or main board

Low Ve is the problem I have at the moment. Just need more to find out why its 4v instead of 94v.

[tom66]

Re: Samsung HTP5044 power supply or main board

Shorted Ve drive fets?
The Ve is imposed on the sus out using two MOSFETs in antiparallel.

[JeffJ]

Re: Samsung HTP5044 power supply or main board

yes,esr is fine you probally need the xsus. i have a 5054 i need y main and buffers for. they are not cheap, prone to failure i found the parts that are bad but havent found a source for them yet.
when you fix one headed for the dumpster, it gives you a feeling you just cant describe.i just fixed a panny 50 for my daughter so she wouldnt be looking at a 32 thru next year.

Ebay was the only place i could source proper FETS and buffer IC's for my 5054, don't know if you have checked.

[DavidOH]

Re: Samsung HTP5044 power supply or main board

Don't suppose there's an easy way to get the fets and heatsink off this board is there?

[awyatt2]

Re: Samsung HTP5044 power supply or main board

david, i use a weller pistol type solder gun and a solder sucker on the heatsink legs. the fets i use my vaccum solder station. i have never found an easy way to do it. lots of luck with it.

[DavidOH]

Re: Samsung HTP5044 power supply or main board

Well it's going to take more expensive equipment to get these fets off than I have. I'm going to damage the board with the heat if I havn't already. So I'm going to get a x-main board for it. You have to know when to keep trying and when to stop. It's time to stop.

[skidmark]

Re: Samsung HTP5044 power supply or main board

Before you get a main, pull the ymain and test the 88n30w fets for shorts as it's common for these to go together with a shorted upper buffer board

What's your methodology for pulling the FET's. Do you remove the whole heatsink, or painstakingly remove each MOSFET?