Mitsubishi WS-55511 Problem

**falcon935** · **07-16-07, 09:16 PM**

I'm not too sure of the history of this set as it was just given to me broken. When I asked what went wrong, all I got was "it doesn't work." I don't have the money to have a Tech look at it, so I'm on my own here. I'm looking at a WS-55511 that powers up for 3 secs, then powers down. This can be done with the front panel and the remote. The only blinking light is within the first 70 secs. of plugging it in. And I was told that was normal.

After getting the error codes, it came up with "22" (Short Protect) . The DM board is fine. I examined all the boards and the CRT's for obvious shorts/leaks, blown fuses/links and came up empty.

I have the service manual and have checked most of my voltages and seem to think the problem is in the power board.

I have "some" experience with PCB's.

Any ideas on where to start looking for short?

**lcaillo** · **07-17-07, 06:20 AM**

First thing to check are the fuses on the PS secondary. 2-2 indicates a problem in one of the low voltage supplies, most likely the +/- 24 volt lines that feed the convergence outputs and the vertical output circuit. If you find a blown fuse, you have a good clue regarding the area with a problem. Most likely the convergence output stage.

**falcon935** · **07-17-07, 06:40 PM**

hello,

After further inspection/tests, I believe that I have a blown convergence IC. Most posts point for two IC's. I only have one. STK393-110. The 12 - 3.9ohm 2w resistors around it are reading around 2.3ohms. I think they may be bad as well. The 2 Pico fuses feeding that circuit (+24/-24) are open also.
So, with that said......what do you think? Think we have the problem cornered?

Should I order the IC, the resistors and the fuses?

BTW, thanks for your help. I really appreciate your time.

**lcaillo** · **07-17-07, 07:35 PM**

Quote:

falcon935 wrote:

hello,

After further inspection/tests, I believe that I have a blown convergence IC. Most posts point for two IC's. I only have one. STK393-110. The 12 - 3.9ohm 2w resistors around it are reading around 2.3ohms. I think they may be bad as well. The 2 Pico fuses feeding that circuit (+24/-24) are open also.
So, with that said......what do you think? Think we have the problem cornered?

Should I order the IC, the resistors and the fuses?

BTW, thanks for your help. I really appreciate your time.

Don't bother to measure the resistors until you remove the output IC and disconnect the lines to the convergence yokes. Also realize that there may be resistors in parallel. I do not recall on this model, as convergence failures are relatively rare on these. Get the IC from a reliable vendor such as B&D or Acme. You can find listings in the distributors thread in the Manufacturer and Vendor Refererence forum. It is very unusual for both the + and - supply fuses to open. This would lead me to suspect the convergence output, as it is the one thing that uses both supplies. Pull the chip, install the new fuses, then fire it up and see if they remain intact. If they do then the chip is the problem. If they blow again, there is something else going on.

**falcon935** · **07-20-07, 05:53 PM**

I ordered the parts today (chip and extra fuses). I should have them Wed. or Thursday. So you're saying I should put the fuses in first without the chip to see if they blow again. If they don't blow, the chip was the culprit. If they blow again, there is a short somewhere else. Will the set run w/o the chip in it? Will there be some kind of picture?

I'll post back when I put the new parts in.

**lcaillo** · **07-20-07, 05:55 PM**

Yes the set will run without the IC. Be sure to check the resistors carfully and make sure that you don't damage any traces at the chip. Where did you order the part from?

**falcon935** · **07-20-07, 06:42 PM**

I have my solder sucker ready have done some PCB soldering/de-soldering in college.

I'm gonna take the resistors out and check them individually.

I got the parts from http://www.bluestar-online.com/STK39...stk393-110.htm.

**lcaillo** · **07-20-07, 07:52 PM**

No need to take them out. Just unplug the connections to the convergence yokes, and with the chip OOC verify that they are not open. Any that are heat stressed should be changed.

I hope that youget a good part. I am not sure who that vendor is and what kind of rep they have, but at that price I would be willing to bet that the part is coming from somewhere that is not an actual Sanyo distributor. It is likely a cheap copy. Most of the reputable vendors who only sell original SAnyo chips are charging over $20 for that one. Many, many techs have learned the lesson on these STK chips, that one should only buy the original parts that come through distribution that can be traced back to Sanyo.

When you run the set with the output IC removed, BTW you will see the pix with no convergence correction at all. It will be curved on all sides and the images will be offset from each other.

**falcon935** · **07-23-07, 09:47 PM**

-UPDATE-

Parts came today. Installed fuses and re-installed board to check for further shorts. The TV came on. Removed board and installed new convergence chip.....
IT LIVES!!!

Thanks for all you help.

**lcaillo** · **07-23-07, 09:52 PM**

Congrats! Who did the parts come from?

**falcon935** · **07-24-07, 05:08 AM**

www.bluestar-online.com

Ordered Friday and they arrived Monday.

**lcaillo** · **07-24-07, 06:56 PM**

Is that who actually shipped it to you? They look like a typical internet front end for multiple distributors.

**jtaylor** · **01-02-08, 05:48 PM**

Quote:

falcon935 wrote:

-UPDATE-

Parts came today. Installed fuses and re-installed board to check for further shorts. The TV came on. Removed board and installed new convergence chip.....
IT LIVES!!!

Thanks for all you help.

Hi everyone. I too have found the same two fuses blown and have ordered the STK393-110 and pico fuses. Do you have any instructions on how to remove the board from the chassis? I have pulled the whole projection system out the back, thinking I would do the work with the board installed, but if it's easy to remove, it'd be easier to get at that heat sink the STK is stuck to.

My biggest worry is the board-to-board connectors. Looks like one end is soldered into one side, then a 'V' strain relief, then the other end of the ribbon cable is a connector of some sort. Does that connector lift straight up? Or does it pull toward the other board? I don't want to screw up the connector - as that would then take me much longer to repair...

Thanks for any advice...

Regards,

jt

**lcaillo** · **01-02-08, 05:50 PM**

If you have the chassis out there is probably no reason to remove the board to change the IC.

**jtaylor** · **01-02-08, 05:56 PM**

Hey now, that's what I wanted to hear!!!

Is there anything that works better than another at cleaning up the heat sink compound? Alcohol? Just a dry rag?

Thanks.

**lcaillo** · **01-02-08, 06:05 PM**

I use paper towels and a scraper to clean off the dried part. Alcohol will not cut it.

**jtaylor** · **01-05-08, 08:50 AM**

So, after thinking about how my convergence IC got fried, I started thinking about something I did several months ago. My 55511 has color adjust buttons inside the front grill, under the removable front panel. Also there is some form of electronic focus. Of course I had to go and mess with them. I got the colors pretty much back to normal looking, but didn't know if the levels were set correctly.

What's the easiest way to set the colors back to where they should be?

I noticed that the TV seems to self-adjust to some degree. I'm worried about having the levels too high - which might cause damage? Are there specific voltage levels I can check somewhere

If it ain't broke, don't mess, right?

Any suggestions or helps?

I think there may be a DVD I can get that will help me adjust the colors, right?

**lcaillo** · **01-05-08, 12:22 PM**

If the color looks good, your adjustments will not do any damage. The set does have an auto bias circuit to balance the output. There is a procedure to set the screen voltage using a scope, but if you turn it up until you see retrace then back about a quarter turn then tweak for best gray scale you will be close.

This has no effect on convergence failures.

**jtaylor** · **01-06-08, 10:41 AM**

THANK YOU!

A big thanks for your help here on this forum - especially to "lcaillo" and "falcon935". I received the new parts for my Mits WS-55511 yesterday, pulled the board out, removed the old parts, checked the resistors and diodes to make sure everything else looked ok, installed the new parts, put it all back together and wha-la, it works! In fact, the color looks better than it has in quite some time. Cost me about $50, but I bought duplicate parts to protect me from myself... %)

I scribed a line around the STK393-110 on the heatsink before removal, based on someone's suggestion in the past, so I could line the new one up before installation.

I took the time to hone the back of the STK393-110 part and heatsink to ensure a good, close fit and better heat transfer. The back of the STK393-110 was definitely not flat. It was slightly concave, so the middle would not have fit snuggly had I not performed the honing.

Installation of the fuses was straight forward, but I installed the STK393-110 a little unconventionally (in my opinion). First I reinstalled the board back in the chassis with the fuses replaced, then I mounted the STK393-110 to the heat sink with as little grease as I could get away with and still cover the back of the part, then carefully put the STK393-110 leads through the board as I installed the heat sink back on to the board. After mounting the heatsink and making sure the part leads all lined up - and that I hadn't missed any of the pins, I flipped the chassis forward (removed the the set) and soldered the part in place from underneath. Cleaned up residual flux with a swab or two of rubbing alcohol.

Also thought that the inside of my set looked like it had been worked on before - or maybe upgraded before it had been sold to me? Weird. I bought it new from Ultimate Electronics here in Plano, TX.

Thanks again for building my confidence that I could do this fix. Makes me feel real gooood!

PS: I've been in this discussion and one on techlore.com, sorry for duplicating this message in both places... I started posting over there first, so kept it alive too. I really got the "beef" to fix my TV on this forum from those mentioned above.

Thanks again!

**Abe** · **05-21-08, 03:46 AM**

Hope your set is still working good, I'm about to perform the same repair and would like to know if you replaced the IC and the resistors while leaving the board in the chasis. I am hesitant to take the board out for fear of breaking something.

**jtaylor** · **05-21-08, 11:50 AM**

Hi Abe. I ended up taking the board out of the chassis so I could see what I was doing. I didn't feel like there was much chance of breaking anything. Worried a little bit about the ribbon cable connections, but that all disconnected easily. You might want to take some notes about what you disconnect to make sure you get everything hooked back up.

I replaced the fuses and removed the STK393-110 with the board out. Then, put the board back in to install the STK393-110 with the heatsink.

Let us know how you make out.

jt

Advertisement