Hi Guys, I have a Mitsubishi VS-50705 rear projection TV. It's about 5 years old and has served me very well. The other night, I came home and turned it on, then it shut itself off. When I press the power button now, I hear a relay click, the Program Timer LED lights briefly, and it turns itself back off without generating any audio or video. When I first plug the set in, the LED flashes
3 times. Can anybody give me any direction on fixing my baby? Any information is appreciated...
The 3 flashes of the led when you plug the unit in is the microprocessor initializing.
This unit has an error code diagnostics.
On the front panel of the unit press and hold the INPUT and MENU buttons at the same time and hold them down for about 5 or 6 seconds. The unit should activate it's error code mode.
The led will flash count the number of flashes. It will then pause for
1/2 or 1 second. The led will flash again count the number of flashes. The unit will repeate this for about 5 or 6 times.
You now have the two digit error code. The first time the led flashed is the first number of the error code, the next time the led flashed is the last number of the error code.
Thanks for the reply on this, I appreciate your advice. I did have an error code #22 flash from the LED. I had a tech out today and he told me that the convergence IC's (STK392-110) had failed and caused a diode (D522) to short out. I found the IC's online for around $10 and plan to replace them and the diode myself. Any thoughts on this? Does his diagnosis make sense? From your experience, do you think replacing the IC's and diode should cure the problem? Any input is appreciated...
I work on lots of these and I happen to own the 60" version of this set. I don't have the schematic, training info, or notes handy, so my memory may be a bit off, but this is what I can recall on these.
The 2-2 error code is a short detect on the low voltage supplies. Most often this has been due to a coolant leak in the vicinity of the 9V regulator on the signal board.
A 5xx numbered component in a Mits is, IIRC, in the deflection stage. If a failure in a convergence output were to cause a problem it would be in the
9xx numbered parts in the PS. It is rare on these for convergence output failures to cause anything other than open fuses or open chokes in the supplies to the outputs. I'd be surprised if what the tech told you about the output causing that diode to short is accurate.
When these ICs fail, it is almost always one channel of one chip that goes and the set rarely shuts down. You may not have an output problem at all. The ICs that you will get for $10 may be suspect. We have seen problems with the STK392-110 from many vendors. There are upgraded versions of this chip numbered STK392-150 and STK392-180. I would recommend buying them only from distributors that sell parts from the major suppliers like Toshiba, Hitachi, or Panasonic, from a handfull of very reputable distributors of original Sanyo (the OEM for all the TV makers) chips, or directly from Mitsubishi. Last I checked, Mits was still supplying the -110 and the price on the upgraded versions was best from Hitachi and Tochiba.
Before doing anything, I would get to the bottom of why the diode is bad, if it really is. Pull it out and check it yourself. If you can't do that you need to get a tech who is very familiar with THESE sets to do the service. I would also check the boards very carefully for coolant, as leaks are actually very common in these units. It can be very hard to detect unless you know where and what to look for.
After you change convergence outputs, if you need to, there may be significant alignment to be done. If you have not done it on these sets before it can be tricky in some cases. Unlike many techs, I generally change only the bad chip on these, not both, and upgrade to the -150 or -180.
The input at pin 46 of IC700, is the SHORT line is connected to the 5V Standby Suply. Under normal conditions diodes D979 -( SW12V), D973 - (SW5V), and D511 -(SW34V) are reversed biased and pin 46 is High as monitored by pin 46. If there is a short on one of the Switched Supplies that diode is forward biased pulling pin 46 LOW. The Micro then turns the set off.
Pin 46 of IC700 , also monitors the Horizontal Output transistor, Q5A00 and the Horizontal Yoke current. R566 is the ground return for both and if the current gets to high Q533 is turned on pulling pin 46 LOW. The Micro will turn the set off.
Excessive voltage can be caused by a leaky Horizontal Output, shorted Yoke or a large current drain on the Convergence plus and minus 24 volt supplies lines.
When I work on a VZ7 chassis that shutdown at power up and the self diagnostics indicate's a Short Protect error code -22, I first check Q5A00, and C557. If Q5A00 is bad I'll check Q533, R567 and R566. If all is good I go to the Switched Supplies and hope for a short day.
Cape Cod stated the tech that came out found a bad STK's and D522. This diode is on the plus or minus 24 volt supplies lines. So D522 may have caused the Short Protect error code. I don't have anything to say bad about any Tech. I know how hard it is to try and make a living repairing TV's. The good old days are no more.
I post messages here to try and help others. I read the messages here to attempt to learn. If you are not open to something new what's the point.
Actually, you are correct that the STK failure could cause D522 to fail. I did not recall that the VZ7 has a scan derived supply to the outputs rather than off of the main convertor where diodes would be numbered differently. I stand corrected.
Could someone get back to me with a value or part number for diode D522? The tech took mine with him and now I don't know what to replace it with. Thanks again...
Just fixed a JVC version of mitsubishi VZ7 (NV-55D500) a via for 5V standby went open (coolant ate the conductive paint) so micro lost the
5V and successfully fixed but chassis didn't respond yet my brain didn't realize that chassis is mitsubishi and was trying to use JVC remote to operate it and couldn't.
Got into tail-chasing mode, chase chase and chase. So put on thinking cap and search mode: I happened on a control panel stashed in junk drawers and wired it in. Works. Then showed my boss the result and he go "OH, that's mitsubishi". !! I fished out a universal remote and programmed it. Works! Grrr.
Thanks Again TJ, Do I understand that the NTE506 is a valid alternate to the FR155? I'm having a difficult time finding someone who will sell me a single FR155 and may have to substitute. Of course, if anyone has a spare FR155, I would be glad to take it off their hands... :-)
OK Guys, I'm back to the drawing board on this. I replaced the STK IC's and the D522 Diode. I buttoned the set back up and turned it on. It worked fine for about
2 minutes, then something happened. The convergence suddenly was all over the place and there was a bad pincushion problem (none of the colors converged properly and the picture was bowed in from all sides). I suspect the new IC's may have failed after about 1 or 2 minutes in the circuit. Anyone have any new advice for me? Is there something that could be causing the STK's to fail? It was really nice to have my TV back for a couple of minutes, but would really prefer a more permanent repair. As always, any help is appreciated.
OK, I've calmed down a little since cursing out my TV. Let me more clearly review the situation. After thinking about what happened, I must say I'm not absolutely certain that the video was right when I turned the set on. I think it was, but I was just watching it out of the corner of my eye as I buttoned the set up. Anyway, I got the STK's from this place:
formatting link
I got lazy and used the old heat sink grease on the new IC's. There was a lot there and I pressed it on well, but if I had it to do over again, I would have regreased them. They don't seem to be getting that hot right now, but then again, maybe they aren't healthy anymore. I dunno, I'm just getting frustrated and I miss my TV. Can someone HELP? :-(
Well if you left the old compound on that's the problem.. You have to clean the old off and put new on.. Maybe now you have blown a fuse also close to the STK,s
Does it look like a quality part? It's supposed to be from Sanyo, which I understand is OEM for Mitsubishi. Would failure of the STK cause the symptoms I'm describing (pincushion and bad convergence)? Is there a way to verify that the parts are bad before I replace them again? Just a thought, but is it necessary to adjust convergence and pincushion after replacing the STK's? (What I'm seeing isn't just because I replaced the IC's, is it?) I have a feeling I'm gonna end up doing as you suggested and re-replacing the STK's (with new grease this time). Jeez, and I had the Jenna Jameson fleshtone test media all warmed up too. Life just isn't fair. :-(
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