Samsung LN32B530P7F PSU issue

[OldTecho]

Re: Samsung LN32B530P7F PSU issue

Hi everyone,

I also have on/off problem with Samsung LN32B530P7F; but it has nothing to do with PSU. It is not the CAP's either but in the function control board on the right side. Problem solved.

When I read B4ndit problem, I believe it in the hot side of PSU. Did you finally fix that ? May I help ?

[b4ndit]

Re: Samsung LN32B530P7F PSU issue

OldTecho, I know my problem is the PSU because I don't even have standby voltage.

I ordered all the parts last week and the last of the parts were delivered Friday. I am planning on performing the repair today.

I ended up purchasing three zener diodes (one is a spare), two IC's (one is a spare), and enough capacitors to recap the PSU to make the shipping costs worthwhile (added one spare of each kind, filter cap not being swapped). For all these parts, I ended up spending around $22.

I plan on swapping out the two zener diodes, CM808 capacitor, and the IC first. This should tell me if the issue has been fixed. If it has fixed the problem, I might just recap the board as well since I have the parts.

[b4ndit]

Re: Samsung LN32B530P7F PSU issue

Just swapped out CM808, the IC, and the two zener diodes with the new parts.

Didn't get any magic smoke or anything, but the TV still does not work. The symptoms have not changed at all, so I believe the problem is somewhere else on the PSU.

I have no idea where to look right now as I've tested most of the major components on the board and can't find anything wrong.

[OldTecho]

Re: Samsung LN32B530P7F PSU issue

B4ndit,

I just got home and sorry to hear your problem has not changed. Review your testing conditions; I feel little strange.

For now:
First make sure your meter is good ( not intermittent) by testing something with known values. After that, neg meter lead, hook to neg of CP815 for hot side, ( Neg meter lead, hook to neg of CM867 for cold side). With your PSU diagram, you should have high voltage at CP815 or fuse FM802S then at UM801S pin 1 . ( If no high voltage, check fuse FS901A and BD801S.) I assume you replaced UM801S; check pin 4 for roughly some voltage around 15-35V ( I am guessing) .

[OldTecho]

Re: Samsung LN32B530P7F PSU issue

Under normal condition, power cord plug in, power off :
16Volts at CM876/ CM881, no 13 volts , no 5 volts at CNM802
5volts at CM852, 5volts standby at CNM802 pin 3.

You once wrote no 5volts standby at CNM802 pin 3, but do you have 16Volts at CM876/ CM881 ? if not go back to hot side.

Did you check RM869 .3 ohm
It bothers me when you have .6 volt at CM804 . Therefore no voltage goes thru QB801, to UP801S pin 8

[OldTecho]

Re: Samsung LN32B530P7F PSU issue

Edit:
It bothers me when you have .6 volt at CM804 . Therefore no voltage goes thru QB801, to UP801S pin 8 and UB802 pin8

[b4ndit]

Re: Samsung LN32B530P7F PSU issue

Thanks for your help OldTecho. I'll do some more diagnosing after work today.

I plan to check the voltages at the points you mentioned and also double check the capacitors and diodes to make sure I didn't miss anything the first time.

[b4ndit]

Re: Samsung LN32B530P7F PSU issue

Sorry, had a couple late nights at work.

I measured from the positive side of CM881 and CM876 to the negative side of CM867 and got 1.2VDC both times.

0VDC from CM852 (pos) to CM867 (neg).

I suppose this means I should be looking at the hot side?

[OldTecho]

Re: Samsung LN32B530P7F PSU issue

Go back to hot side, reread post #24, #25 and #26.

[OldTecho]

Re: Samsung LN32B530P7F PSU issue

When I ask you to check voltage @ CM881 to confirm the problem is not on the cold side (No standby 5.3V) .

You must have some kind of voltage for three IC to run. CM804 must have slightly higher voltage compares to CM808; NOT 0.6V like you said .

[budm]

Re: Samsung LN32B530P7F PSU issue

So are you still getting fluctuating voltage on CM808 (on post 5) of 9~15VDC?
And what resistance do you get on Zener ZM801?