CurtPalme.com Home Theater Forum

[atty]

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Replaced the convergence IC's about two months ago, and I thought I had raised this old box from the dead, but suddenly no video, no sound. Front panel LED is steady red, but DP06 red LED on DEF. board is blinking. Four out of the five green LED's are lit. The dead one is, according to the board DP19, but according to the schematic DP19 is not an LED.

The start relay is clicking on OK when the power button is pushed. No chirping sounds. +28V and -28V are both +80V. In fact on both sides of the four lit green LED's, I'm showing 80V. I made sure that my ground lead to the multi. is in fact on circuit ground (not chassis ground) for the measurements.

This one has me talking to myself.....well, more so than usual. Any ideas would be appreciated.

Update: OK, the second thing to go is the eyesight. The fifth green LED that did not appear to be lit was covered with that waxy stuff put on circuit boards to hold wires in place. Somebody got a little frisky and covered the fifth LED. Once that was cleaned off, then they all appeared to be the same. THEN, once the sun went down, it was apparent that NONE of the five green LED's are lit. Maybe I should start doing my troubleshooting in the dark. So far the results are the same.

[timbo]

It is my understanding that oftentimes when the ICs are replaced it is important to replace the applicable resistors.

I've heard of instant failure of the ICs when the resistors have been neglected and I've also heard of your situation.

Problems can occur with poor quality aftermarket ICs.


One resource that has been mentioned with authentic Sanyo ICs and resistors (correct for Hitachi) is
tvrepairkits dot com.

I certainly am no expert. I'm just repeating what knowledgable folks have passed along.
When the day comes for me to do the repairs for myself, I hope I'll be able to get it right.

[atty]

Thanks for the response. Actually these IC's were replaced with a kit from Tvrepairkits, as well as the resistors. With the number of posts regarding subsequent failures shortly after replacement, I'm wondering if a shorted convergence IC could throw the DEF power supply into protect mode.

On that note I'm contemplating another replacement just to see if I can change the symptoms. Aside from all the soldering, it's worth a shot since this board is no longer available anywhere I can find.

[macgyver655]

If you still need help with this then post back and I'll post some info.

[atty]

Any help would be appreciated. Managed to get the Def. Board out and ran some measurements from convergence IC ground to the pins, and they appear to be about equal, so I'm not thinking I had a recent failure of the newly installed IC chips.

I'm still in head scratching mode.

[macgyver655]

Here's a couple things to check:

1: I attached a service bulletin. Download it a check that. Let me know when you have it as I probably wont leave it posted.

2: Here is a list of common failure parts. Check them for open or short.
D907, Q777, Q657, EP98, Q401, D441, DH41, IH02, QH01, C655, IP05, IP06, DP05, DP39 and IP01.

If Q777 test bad dont just replace. Post back. There is an update.

3: If all these test good then follow this test. Observe the 5 green leds, turn tv off then turn it back on. All 5 leds should come on and then go off. Observe which led goes off first and post back that info.

[atty]

Thanks very much for the post. I have the download safely tucked away.

If I remember correctly Q777 is the horiz. output xistor, and it did check out. Even removed it from the board to make sure. This, of course, was all before I removed the def. board from the cabinet, so I remember how much fun it was to get it back in.

I'll check the other components and post back. Right now NONE of the five LED's are lighting up....at any time.

I appreciate your help and interest.

[macgyver655]

If none of the green leds are coming on even if for a second or 2 on startup then you probably have a problem on the hot side of the power supply. What relay are you hearing click? Id location.

Test DC voltage at connector PQD1 pins 1 and 2. Should be a couple hundred VDC. Test EP91 for open.

[atty]

The normal start relay sound is heard. Normal click.

I'll have to get it back together for a voltage measurement.

Are you talking about a failure on the power supply board, or the high voltage section of the Def. Board?

[macgyver655]

[atty]

You have given me quite a bit of homework to do. When I get through with a static check on your list of components, I'll get this thing back together and give you a voltage reading on PDQ1 and 2. As I recall from my "in cabinet" tests, EP91 was OK, but I'll give it another look.

I have this "gut" feeling, which is worth nothing of course, that the flashing DP06 is indicating a short condition rather than an open component. Not sure why I say that, and I'm probably wrong.

[macgyver655]

[macgyver655]

[atty]

I'll get this thing back together and give you some voltage checks and a relay location.

[atty]

I forgot to mention.....one of the biggest problems that I have had so far is finding the correct ground for both voltage and resistance measurements. It appears to have five or six different grounds depending on the circuit, i.e. all have different logic grounds, but no common ground. Since we're working primarily on logic circuits, I assume the old chassis ground is out of the question?

[atty]

OK. All components mentioned have been checked statically, with the exception of those on the audio board, i.e. Q401 and D441.

Reinstalled the Def. Board. Voltage between PQD1 and 2 is 164VDC. While I was there, I checked the 5VDC, 9VDC, 12VDC Standby, and 33VDC. All within range. These were read off of PQS2, PQS1, and PQD2. I found no EP voltage protects open.

Since we're getting 164V to pins 1 and 2 of PQD1, I guess I need to start chasing voltage on the primary and secondary of TP91. We still have no lights on any of the five green LED's. IP01 is starting to look like a prime candidate.

I appreciate your hanging in there with me.

[atty]

Forgot to mention the relays. S901, S902, S903 are all energizing on the power supply board when the power button is pressed.

The operating voltages on IP01 are as follows:

#1 165V
#2 0V
#3 0V
#4 0V
#5 19V
#6 .9V
#7 .9V

Not surprisingly I have nothing on the secondary side of TP91 as measured from ground on PQD2 (pin #2). No 130V, no 28V, no 13V, and of course, nothing on the five green LEDs to ground.

I'm going to make some comparison voltage checks on the STR-M6811A on the Power Supply board to see if perhaps IP01 is our culprit.

[macgyver655]

So far I'm in agreement. Those number on IP01 dont look good. Make sure to test surrounding components.

[atty]

Oddly enough, I don't get a lot of difference on the Power Supply STR-M6811A which appears to have no problems:

#1 160V
#2 0V
#3 0V
#4 1.5V
#5 23V
#6 .16V
#7 2V

Granted, the power supply is under no apparent load since I don't have anything happening on the Def. Board, but it's certainly not drastically different. The Service Manual wants #5 on the Def. Board 6811A to be at 21 - 25. While I'm at 19V, I wonder if that is a significant difference, once again considering I have no load?

Thanks for checking in.

[macgyver655]

Sorry I dont have more time to give you a hand with this. Just to much going on right now. Pin 5 may need at least 21v in order to oscillate and 25v would shut it down. The easiest may be to just swap those STR's and see what happens.