HPT5054 Buffers...

[mmartell]

I think it's ok to run the set with either of the upper or lower buffers (or both I guess) uninstalled, is that correct ?

Also what do you use in place of the epoxy after reinstalling the buffer ic ?

I opened up the back of this set and fired it up with an audio disc on input one and cycled through the inputs until I heard sound. Was looking at the back of the set and noticed the led on the upper buffer board. Ok that's probably good. Then another led lit beside it.

Then a third.

THOSE AREN'T LED's !!!

Jumped up to pull the plug, sound was still audible so I think I might still be ok so wanted to test the lower buffer and pull the bad ic(s) off the upper buffer board to see where I'm at hence the two questions above.

[mmartell]

Re: HPT5054 Buffers...

So I installed the lower buffer only and powered on with and still no picture. I expected to see a pic on the lower half of the screen, only got a few occasional flashes of lines near the center. The lower buffer still measures good as per the tests posted here and elsewhere.

Next I'm going to remove the faulty ic on the upper buffer and install both back. Should I expect anything or is my Y Sustain suspect ?

[tw2005]

Re: HPT5054 Buffers...

As far as I know you will not get a picture with lower only on this set. I have seen a youtube of somone identifying and removing the shorted buffer IC/s on the upper and hooking them up and getting a picture assuming your ymain is still intact and not blown by the shorted upper which is usually the scenario with these.

[splitcrete]

Re: HPT5054 Buffers...

If your Y-MAIN has a green light it has a fault, and will take out the buffer ICs again.

[mmartell]

Re: HPT5054 Buffers...

If your Y-MAIN has a green light it has a fault, and will take out the buffer ICs again.

I will check for the green light. When functioning normally there is no light at all ?

[freakaftr8]

Re: HPT5054 Buffers...

I worked on a few the sets and I believe you will see a background with the lower buffer only connected the lines are seen the top of the screen Is the bottom of the no signal jumping around is lying you're seeing with only the lower buffer connected in the center of the lower part of the screen what to do that possibly take a picture and post it.

Try hitting the menu button with just the lower buffer in place

[tocold4u2]

Re: HPT5054 Buffers...

I was just tinkering with 2 of these sets...u can have just upper buffer in and have half a pic as long as your y main or x main is good. i had a lower buffer in and had half the pic but the picture was all. messed up cause the wro.ng buffer board

[mmartell]

Re: HPT5054 Buffers...

I worked on a few the sets and I believe you will see a background with the lower buffer only connected the lines are seen the top of the screen Is the bottom of the no signal jumping around is lying you're seeing with only the lower buffer connected in the center of the lower part of the screen what to do that possibly take a picture and post it.

Try hitting the menu button with just the lower buffer in place

What do you mean by background ? I did hit Menu button - saw nothing on screen.

[freakaftr8]

Re: HPT5054 Buffers...

Is the sceeen lighting up at all? If so ysus board should be ok

[mmartell]

Re: HPT5054 Buffers...

I was just tinkering with 2 of these sets...u can have just upper buffer in and have half a pic as long as your y main or x main is good. i had a lower buffer in and had half the pic but the picture was all. messed up cause the wro.ng buffer board

So I should expect to see half a pic with the lower buffer provided the Y and X Sustains are functioning correctly.

Will strip the upper buffer of its bad ic and reinstall both just to confirm further problems with my Y Sustain or other. Cheers.

[mmartell]

Re: HPT5054 Buffers...

Is the sceeen lighting up at all? If so ysus board should be ok

Oh, no it's not, save for the random noise generated midway on the panel where the upper and lower buffer trace lines would meet.

[freakaftr8]

Re: HPT5054 Buffers...

I meant if it day a dull Grey raster with no mal discharge noise it should be ok . Check all big mosfets on ysus if you suspect that it is bad

[mmartell]

Re: HPT5054 Buffers...

All five fets on the one heatsink test shorted on-board. Kinda odd as neither fuse is open unless there is a shorted component in parallel with all five ?

I need to know the proper way to read the voltages va, vs etc.. I measured 15v on Vcc pin at ysus with with ysus/buffers disconnected and nada on the other pin I think was Vs ? Shit can't remember atm

[tw2005]

Re: HPT5054 Buffers...

All five fets on the one heatsink test shorted on-board. Kinda odd as neither fuse is open unless there is a shorted component in parallel with all five ?

I need to know the proper way to read the voltages va, vs etc.. I measured 15v on Vcc pin at ysus with with ysus/buffers disconnected and nada on the other pin I think was Vs ? Shit can't remember atm

Most likely the 88N30W FETs? Sometimes you get lucky and not all will be shorted but you won't know until you pull them off one by one . One bad one will short the whole bank out in cct.

I never had and fuses gone on the 3 I did. Just those FETs and a replacement upper buffer board. From memory I think I had 1,2 & 4 shorted FETs on the 3 different TVs.

[mmartell]

Re: HPT5054 Buffers...

Yes those ones and the k2...

[mmartell]

Re: HPT5054 Buffers...

Scratch previous post about VS and VA power supply outputting good voltages. Still need to trace down shorted components on VSUS.

I've removed the ic from the upper buffer - not too brilliantly haha but will order another ic anyhow and have a go.

Is there a common compound that can be used to insulate the pins from arcing/shorting ?

[mmartell]

Re: HPT5054 Buffers...

Got the heatsink off (what a bitch!)

One shorted 88N30W, one shorted K2837 and one shorted B20NK50Z surface mount FET.

I've read about a surface mount ic possibly going bad as well or should I be alright replacing just those components ?

[mmartell]

Re: HPT5054 Buffers...

D5302 is shorted and D5501 is testing like a diode in both directions. Wtf does that mean and does anyone have any idea of the values of these two diodes ?

[mmartell]

Re: HPT5054 Buffers...

D5302 is NOT shorted, it tests fine when pulled out of circuit. It looks like it is in parallel with a 15ohm resistor.

Could someone explain what purpose a diode might do there if the current is just going to go around it through a low ohm resistor ?

[mmartell]

Re: HPT5054 Buffers...

I ordered a kit from SJ for the Y Sus and they sent 5N3011's in place of the 88N30W's I have on my board. Are these compatible ? I've had a look at the datasheets but have no idea how to compare them and which stats are critical.