Mitsubishi Convergence issue

[RaiderRC]

I just signed up on this forum and couldn't find my exact problem. I have a convergence issue. I have the bow tie effect on all colors, and i can't change the convergence in any such manner. I turned the TV on for a few minutes and the STK chips don't feel hot at all. I did replace them anyways no to avail. So i am guessing they are not getting any power. I checked all the fuses, and they are all good. The ones on the power board and convergence board.

I plugged the power cord directly into the convergence board to try and get readings from the 24V and -24V but i couldn't get a reading. Can anyone point me in the right direction of where i should be looking to see what i need to replace? It's happening to both IC so... any suggestions?

[lcaillo]

What do you mean by plugging the power cord directly into the convergence board. Sounds like you may be getting into dangerous practices and need to be very cautious! Don't try anything that you are not sure about!

If you are not getting power to the convergence ICs but the set is running, you almost certainly have something open, either a fuse, circuit trace, resistor, or coil. What model?

[RaiderRC]

Its the WS 55857. There was 120volts at that point so I was trying to isolate just the convergence board from the rest of the power board. The power at the convergence chip is the same at the diode.

[RaiderRC]

So i found that the STK's are getting 24V but they are not getting hot at all. So i am guessing that means they are not working. Where do i go from here? I would assume the chips are not fried because I am getting no convergence adjustment at all.

[lcaillo]

Where are you measuring the +/-24V? On the pins of the ICs?

I still do not understand what you did with the power. The a.c. line goes into the power board which is where the convergence ICs are found.

At this point one would need to refer to the schematic and make some checks of what is the condition of the power supplies, convergence mute, convergence signals, etc. This is where the skills of an experienced tech become necessary and may be beyond the capability of most DIYers.

[RaiderRC]

Okay so i traced everything down. I think the Conv-Gene board isn't getting power or isn't working. Does anyone know what pin takes in the power for that board. I turned the TV on and checked for voltages at the Conv-gene board but i don't know which ones are actually sopose to get power.

I am getting .7V at pin 2 on the stk's so i assume thats within range to turn them on correct?

anyone with a schematic of a WS-55857??? RaiderRC@aol.com can i barrow

[RaiderRC]

What the heck is going on? Anyone have any ideas?

[lcaillo]

Probably a loose connection. You need to be very careful. This could be a loose high voltage lead and you could get into a dangerous situation or do some serious damage to the set. I recommend that you have a professional deal with it at this point.

[RaiderRC]

I appreciate the tip look for problems on the power board aka disregarding the take it to a pro.

[RaiderRC]

Sorry i don't much like professionals because its their job. Most of them don't care like i would, or want to take the time to trouble shoot. Like this TV it's a pain.

I did find out something though. I found out where the squiggly lines are coming from. I took out the Conv-Gene board and turned the TV on... the crazy lines are gone. As i turned the TV off i walked to the back of the TV and a little spark flashed on top of the white connector. I guess I know what to try and replace. Does anyone have any kind of schematic for the Conv-Gene board

Mitsubishi WS-55857
CONV-GENE
935D5230

anyone?

[lcaillo]

I am a professional. There are many of us that take pride in our work and give our clients the best value possible. We do not get rich in this profession. A true professional takes each repair seriously and completes it correctly with the right parts at a fair price. A hack just doing a job may be common, but is not a professional. Your suggestion that because someone does something for a living he/she will not take care in the work is incorrect and unfair, at least in the case of a professional. Personally, I find it offensive. Perhaps it was just recless posting.

My position is this: I do not mind sharing tips on routine repairs that DIYers can accomplish easily and safely on a symtom-repair basis. I do not hold someone's hand through the troubleshooting process nor go did out a schematic and trace down information that I do not readily have in memory. An experienced tech brings much to a repair problem like this that cannot be communicated effectively nor efficiently to a novice or DIYer. Anytime someone seems to be digging a hole deeper or getting into areas that they do not understand, the responsible way to respond is to recommend having a professional proceed.

I already take enough heat from other professionals for sharing what I do here, and spend a very large amount of time on it. I get paid nothing for my time here. I do not apologize for what I do for a living and do not apoligize for setting limits on how much help I will provide online. Ingrates push those limits lower and lower. I know a number of techs who have given up on helping people online because of attitudes like yours about "professionals." You have every right not to use a professional if you choose. You have every right to your opinion Please do not insult those of us who give so much to help people. At least not here.

As for your current problem, you should specify which connector you are talking about if you want an answer. "The white connector" could mean many. If you saw a spark after you turned it off the most likely thing is a bad connection or cracked solder joint. If it was at the connector to the convergence generator with it removed, you likely have some damage, as there should be no place for current to flow with the board removed. The information you give does not suggest what needs to be replaced.

I have schmatics for most sets, but I cannot share them because of contracts with manufacturers that prevent this. Professionals abide by such contracts. You are likely to find the manual somewhere online if you search, either for free or for a small fee. You can also buy it through Mitsubishi parts. Several places to look are in the stickies for the Manufacturer and Vendor Reference Information forum.

[RaiderRC]

If anyone still cares. I tracked down the problem. IC7A00 - P22 isn't putting out 3.8V its only .11 which i am guessing the conv-gene board is relaying. Anyways does this mean the entire board is messed? Can i just get a new chip or does anyone know where the input is to control that pin?

[lcaillo]

That may be a problem, but I have never seen IC7A00 defective. Every time I thought I had a problem there it turned out to be a related part or a bad connection on the board. I would be verifying the low voltage supplies. The filter caps on those secondary regulators are alwasy suspect.

[RaiderRC]

One of the tracers wasn't letting power through. Couldn't get a connection between one of the resistors and the IC7A00. Soldered a jumper wire to try and see if that would fix it. Looks like the problem was with coolent on the signal board.

Turned the set on heard a pop then turned off. All the fuses seem to be okay. Turned the set back on no picture, no menu, but do have sound. Tried the diagnosis menu/input and i'm getting blink 1-2 so it seems to check out fine. Any suggestions lcaillo? Back to the convergence IC's? Can the convergence IC's cause the set not to come on?

[lcaillo]

If you have had coolant on the board you have a situation that is well beyond the degree of help that can be afforded in a forum like this. Every connection and trace in the areas that have had coolant on the board is suspect and repair can be a very tedious and difficult process. With a double sided board like this one, the feed through holes are often a source of problems with coolant leaks. Most experienced techs beg off on these repairs and will not even attempt them. I fix about 90% of them and the rest are unrepairable.

The first part of these repairs is to map the area with coolant very carefully. Next you have to clean the coolant thoroughly. The smallest amount of residue wil eventually cause corossion. It is best to wash the board in isopropanol then run it through a dishwasher with a dry cycle. Then you have to start checking every component in the coolant area previously mapped and every connection and trace. Any feed through that is damaged needs to have a wire placed through the hole and solderred on both sides.

This is tedious and deliberate work that requires patience and diligence.

[RaiderRC]

Do you know of where i can get a new signal board? For my model WS-55857

[RaiderRC]

My question still is. Would the IC's cause a situation where the tubes will not power on?

[lcaillo]

Mitsubishi is the only source for new boards. They are likely out of that one, but you can check. Typically if an IC was causing shutdown you would not get a 1-2 code. That code indicates that your problem is not a protection issue but the se is not starting properly. It is pointless to try to troubleshoot a set with a coolant problem until that is fixed properly. You can check with PTS for rebuilt boards. They may have them available.

[RaiderRC]

Well I am trying to get back to the original point when i first got the TV, bad convergence picture. Seems like im going in reverse. Thanks for your help though. Whos PTS?

[RaiderRC]

New problem developed. I am only getting 16V at the ends of the 2 large diodes, on the convergence board. Can you think of any problems off the top of your heard that wouldn't get me 24V at these diodes?

[lcaillo]

OK, let me say this again. It is pointless to continue until you repair the coolant damage on the signal board. You will continue to chase your tail until you do as I suggested. I have probably fixed more sets with coolant damage than most techs and I simply will not attempt to troubleshoot them until following the procedure outlined above. This is as far as we can go to help you here. I will not continue to talk you through this repair. If you have something to contribute to the forum, you are welcome, but we have gone far beyond what is practical with this repair.