Samsung

**Tek2k9** · **03-15-09, 02:53 PM**

Hello Fellow Shackers,

HISTORY:
I got this set used and with damage to (2) 3.9 Ohm resistors and a blown 3.5 Amp fuse. No convergence!

After talking with the guy I got it from, he said that the STK's had been replaced with good quality STK's. The guy he had replace them did excellent solder work. STK392-040

I spent a good bit of time reading up on these set's and decided to attempt a repair. I replaced the (2) resistor's and the fuse. everything else looked fine....popped it all back together...fired it up and it was working great.

Noticed that after a week of use it started to develop some distortion at the top of the screen but would only do this after an hour of use. as time has gone on the distortion had got worst. with the exception that if switch to HD 1080i there was no distortion at all.

Now the red has lost convergence. I pulled it apart again and only problem was a blown fuse. I figured that the stk had gone thermal and blew the fuse as protection. I haven't ordered anything yet, but I have removed the STK's from the board to replace. the compound on them was way to much (no metal contact at all). I did remember the guy I got it from saying "that you should gob it on really thick" which didn't make much sense.

I have read a very good post on here about heatsink compound. It backs up what I always knew.

I'm about to buy some STK's and want to replace with original STK's. I'm thinking that the original's are STK392-020's 5amp and the 040's are 7amp which makes me believe that it would put a strain on other components as they would draw more current.

Anyone know what the original STK's for this set are?

Also thinking of putting some 22pin sockets in to make a future replacement easier. and adding externally powered fan to both heatsinks.

Let me know what you guy's/gal's think!

Tek2k9

**lcaillo** · **03-15-09, 08:53 PM**

It does not matter. Use the STK392-040. The current rating is the maximum current that the chip can output. The amount of output will depend on the load and the drive. The -040 is a direct replacement for the -020 & -010, with higher power and wider bandwidth.

The problem may be setup. I have found on some Samsungs that there is excess drive at the edges or excess d.c. offset. I have had to start from scratch and do a complete geometry and convergence setup. Start by measuring the d.c. offset at the inputs to the amps with the chips removed.

**Tek2k9** · **03-22-09, 09:11 PM**

Thank you for your reply.

This brings up another question. Is this adjustment you speak of something that is changed in the setup menu or do I need to make this adjustment on the actual power board?

I relayed your reply to my friend (the rocket guy) and he said that I might need an ocilliscope which he has and can loan to me. but we would need the schematic which I have ordered.

I stopped by the TV repair place and chatted with there lead tech (owner) and he said that there was a 4 month back-up on all repairs. so it wouldn't hit the bench for 4 months. He also told me the STK392-060 was the best chip for the job. I tried to find this chip and could only find one source and hardly any documentation on this one. no specs either.

I could post a picture of the screen if that would help....it's not the best picture but you can see this distortion I mentioned above.

I guess most of what I said in my first post was answered, So thank you for your time and response.

**lcaillo** · **03-23-09, 05:45 AM**

Eerything is done from the remote in the service menu except mechanical position of the yokes, electrostatic focus, and G2 control.

You don't need a scope to check the dc offset nor to do a service reset. It is useful to see if you have convergence control with the chips out if you need to do that.

**Tek2k9** · **03-23-09, 04:24 PM**

Thanks.....I'll post back my results once completed. got everything ordered, just waiting for the arrival.

**Tek2k9** · **04-14-09, 01:50 PM**

Hey Folks,

Got everything in. Installation went smooth. Perfect focus errors (no sensor data).

I have control of all guns, So making adjustments is possible (still need to setup my jig).

I went into service mode to look at geometric and noticed some things were really out of spec.
after setting them back, I need to adjust the rotation of the screen, a little counter clockwise...anyone know what nemonic this is?? I found the HS (H-Shift) need some tweaking also. The picture is shifted to the right about an inch.

So all I need now is the (Rotation) figured out. Any clues. Here Is a list of defaults and the setting before I adjusted anything.

ITEM: RANGE: INITAL DATA EEPROM MINE
VS 0-255 ID=110 55"=100 M=158
VA 0-255 ID=120 55"=120 M=115
HA 0-255 ID=84 55"=80 M=60
HS 0-127 ID=90 55"=90 M=101
VLO 0-125 ID=0 55"=0 M=80
RDR 0-63 ID=20 55"=38 M=15
GDR 0-63 ID=20 55"=32 M=20
BDR 0-63 ID=20 55"=22 M=18
RCT 0-63 ID=31 55"=8 M=0
GCT 0-63 ID=31 55"=20 M=252 *wacked
BCT 0-63 ID=31 55"=5 M=16
SBT 0-63 ID=15 55"=28 M=19
CON 0-15 ID=7 55"=5 M=8
DCT 0-3 ID=2 55"=3 M=2 * wacked
RCO 0-100 ID=100 55"=100 M=40
GCO 0-100 ID=100 55"=100 M=60
BCO 0-100 ID=20 55"=20 M=55
BPO 0-255 ID=160 55"=160 M=161

I've listed only the ones that were different than my EEPROM default setting and noticed two off them really wacked.

Any one know what controls Rotation?

Thanks, Tek2k9

**lcaillo** · **04-14-09, 01:53 PM**

What do you mean by out of spec? The settings on your set should not be expected to match any particular defaults. That is why they are there, because you have to adjust it to get the proper geometry and convergence. You adjust what you need to get the result that you want.

**Tek2k9** · **04-14-09, 05:39 PM**

ok...thanks.

I ment adjusted away from default

and this one wasn't even in range GCT 0-63 ID=31 55"=20 M=252

I just need the one for Rotation as the whole screen is tilted now....even before i changed any settings

thanks, tek2k9

**Tek2k9** · **04-20-09, 12:50 PM**

Got it sorted out. Picture looks great!

After making my alignment grid... and adjusting convergence...needs no rotation.

Thank you, lcaillo, for your help!

**Tek2k9** · **06-22-09, 12:05 PM**

It lasted about a month....now its back like it was before replacement parts.

I have discussed it with my wife and she's opt'ed for a new flatscreen LCD.

So now it a basement project....I think it is the power supply not sending the correct voltage.

Now to move the set from upstairs to downstairs and over to the bench in the workshop.

Thanks for your replies.

Advertisement