Home Theater Forum and Systems banner

1 - 8 of 8 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Greetings,

I have spent the last hour or so trying to get up to speed on this forum by reading old posts, Great site!

My set tries to power up for 3 seconds then shuts down, code is 2-2. I have read other posts with the 2-2 code and just want to confirm the correct procedure here. I have tested all pico fuses and none are open. I'm pretty sure I have located the convergence ICs, they are the 2 big honking ICs on the big heatsink at the extreme rear of the center board, right?

So a logical next step would be to unsolder and remove the convergence ICs and see if the set powers up?

Thanks in advance for any advice.
 

·
Plain ole user
Joined
·
11,121 Posts
Correct. Have you read the convergence repair sticky?
Posted via Mobile Device
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
Thanks for the quick reply. Yes I have read the sticky convergence thread.

Well, I un-soldered both the convergence ICs and I have the same symptoms: 3 second power on, then shuts off, 2-2 code. Re-confirmed continuity through all fuses.

Is there anywhere easy to go from here or does it get too complicated for a DIYer? Would a bad flyback transformer cause this symptom?

Thanks for the help.
 

·
Plain ole user
Joined
·
11,121 Posts
One of the supplies is low to get a 2-2 error. Measure them.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #5
Thank you. I am trying to do my homework so as not to be a pest, but I am in unfamiliar territory here.

My IC is a STK394-250. I looked at the data sheet. It appears I am looking for +38V and -38V at pins 4 and 5, with respect to ground at pin 1. I assume I have 3 seconds to measure this before the set shuts down. Does this sound like a proper way to measure the supplies?

Again, thanks for the help.
 

·
Plain ole user
Joined
·
11,121 Posts
The various supplies are usually have labelled test points on the board. Check all of them. Yes, you will need to be quick.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #7
I found 3 test points on the far right board. 12V which measures 4.5V even with the set off. 10V which measures 2.2V for a second and 111V which measures about 11V for a second when powered up.

I found 3 test points on the middle board. 12V on one side of a diode which I get nothing at (well maybe .5V), and +24V and -24V. +24V measured about 3.3V for a second, and -24V measured -5.5V for a second when powered up.

I'm using a pretty cheap digital meter, but I have no reason to question it's accuracy. It appears my voltages are all too low.

This TV was a freebie, but I really enjoy fixing things. If you think this is going to quickly get me in over my head, just say so and I'll junk the TV and move on to the next project. I actually own a 'scope but have had no real training in how to use it properly.

Thanks again for the help so far.
 

·
Plain ole user
Joined
·
11,121 Posts
Some meters are not fast enough to measure the voltages coming up. I use the peak hold feature on my fluke and can get them. I suspect that your meter is too slow as it is unlikely that all of them are low. If they are all low, you have a regulation problem with the main power supply. That is possible, but not likely. I would be looking at the voltages with a scope to see what they are doing, but you may not see them well without a storage scope.
 
1 - 8 of 8 Posts
Top