Rescue Tron! - WG19k4906 Repair

[RetroJames]

I pulled the monitor from Tron, a WG19k4906.

[Ken Layton]

This chassis is well known for many numerous bad solder joints particularly around the outer perimeter of the board and the horizontal output transistor. Definitely put in that capkit as bad caps will cause it to appear not powered up.

[RetroJames]

Bah -

Well, the first attempt was fruitless.  I installed the capkit only.  Did not yet resolder the rest of the chassis components.

I go a brief sizzle sound, and little else.  No glow in the neck, nothing.

I was able to feel static discharge on the face of the tube.

I suppose I need to start working the wg19k4900 troubleshooting flowchart.

Rats.

[RetroJames]

I had a little time to look through the manual and flowchart.  One of the first items to test according to the flowchart is:

"Check the regulated power supply at resistor r503...terminal closest to the fuse should read +130vdc"

So my question is, I am assuming that I place the red test lead on my VOM on the r503 terminal closest to the fuse as directed...where though do I place the common lead?

You can see the flowchart and the manual here (  http://home.earthlink.net/~rescuetron/  ) in today's post or in the "Pictures and Documents" section in the sidebar.

[Ken Layton]

Black lead goes to frame ground. Meter should be set to DC volts.

[RetroJames]

Following Randy Fromm's wg4900 flowchart, I tested the voltage output by the chassis resistor, R503. It should read +130VDC. Bad news is that it does not, coming in at between +160VDC and +168VDC. Good news is I am one step closer to finding the problem. Next I need to examine a jumper wire and some traces, but I need to remove the chassis for that. I will let it sit over night (baby is asleep so best not discharge now) and take a look-see tomorrow.



Also, anyone have a Radio Shack Multimeter #22-168?

I cannot find my disk with the logging software and need a friendly download.

[RetroJames]

grrr....I love it when you make a nice long post and then loose it on error...here we go again...


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So next steps and results are:

- Examine the jumper wire J33 as well as other jumper wires on the 130VDC trace. (Done and look visually intact and ok)

- Inspect chassis for bad solders and or hairline cracks in pcb, (done and looks ok, have not resoldered anything yet.  )

Measure voltage at the metal case of Q352, the transistor on the side of the chassis closest to the HV unit.

Question:  I am a bit confused by the statement, "Measure the voltage at the metal case."  Does this mean that my red lead will go on the metal housing on the outside of the chassis with the COM lead to the chassis frame?

Is it that white compound that unsulates the frame from the metal case?

In the pic below you can see the transistor, Q352 in the yellow box to the right.

[RetroJames]

A step in the right direction tonight.

[MonitorGuru]

Tearing is usually along the top edge of the monitor (by the anode wire) caused by too strong or too weak of a sync signal or dried caps or off adjustment horizontal frequency coils. It is about a 1-1.5" line that is clear but just angled 45 degrees over that space. (Early 80's RCA TV's used to do this when connected to VCR's due to sync issues, and is one of the things that MacroVision on VHS Tape/DVD causes to the video output by playing with the sync. Also called "Flagging")


Bleeding is closer to the problem you are experiencing. It can be caused by:
- Focus control spun way out of correctness
- Drive/Screen controls turned up way too high

It may also be affected to some degree by bad caps (but you replaced those) and an out of alignment horizontal coil, but again, then you normally get sharp, but "raked" bits running diagonally across the whole screen.


The 3 images and rolling show that your vertical circuit is out of whack.   Does the vertical hold adjustment do anything? Is it jumpy?  Shoot some contact cleaner on the back of the pot while turning it (with the monitor off) and see if that helps, try the other vertical controls.

Remember: Tron/MCR games use an interlace mode instead of non-interlace. This drives the monitor a lot differnetly than other games.   I would try connecting a non-interlace output game to the monitor and see if you can stablize the image that way first...  Then attempt to get Tron to work.   Doublecheck sync wire outputs/etc... But I'd try to connect the monitor up to another game that you have first if you know the other game is good and it is standard NI output.  That way you can narrow down things more.

[Ken Layton]

Black Level Control is set too high for the smearing colors problem.

[RetroJames]

Guys thanks for all the input!

I put the chassis back in and started working through the settings, here are the results -

Blurry Picture

- Duh, adjusted focus got better - Fixed

3 images

- Tweaked vert hold and black - Fixed

Horizontal bleeding

- I started with the black, this helped a bit, then tweaked the drive.

[Ken Layton]

That long line at the edge of the picture is a Tron game program problem. Midway issued a service bulletin a long time ago about that. Their "cure" that was suggested in the bulltin was to crank the vertical size control just enough to put that line outside of the monitor mask.

[RetroJames]

That long line at the edge of the picture is a Tron game program problem. Midway issued a service bulletin a long time ago about that. Their "cure" that was suggested in the bulltin was to crank the vertical size control just enough to put that line outside of the monitor mask.

I seemed to remember seeing that line before on Tron.  Guess I still have a few of those brain cells left from the early 80's after all.

Someone told me the discoloration could be degausing (though this monitor has the auto degauss, or the rings might have moved.  Does that sound correct?)

[Ken Layton]

If you have a discoloration problem I would always start with a good manual degaussing first before doing anything else. there could be a problem with the yoke sliding out of adjustment a little bit or the convergence rings getting bumped out of position. Sometimes the purity magnets on the convergence rings lose their magnetism (get weak).

[RetroJames]

If you have a discoloration problem I would always start with a good manual degaussing first before doing anything else. there could be a problem with the yoke sliding out of adjustment a little bit or the convergence rings getting bumped out of position. Sometimes the purity magnets on the convergence rings lose their magnetism (get weak).

I took a high res pic of the glue glob (what is left of it) on the rings.  It soes not appear to me that they have moved, at least the two rings in each pair have not moved independantly of thier pair members, though the pair to the far right may have moved in relation to the others to the left.

Take a look and let me know if you see anything obvious.  I am headed out now to get the bits I need to finish the rest of the adjustments.

[RetroJames]

I ordered a degaussing coil today.  I will try to remove that spot as soon as it arrives.

[RetroJames]

Degaussing didn't really clear up the discoloration and I find I probably need to replace the vert hold / dampner pots as I am having an intermittent vert hold problem.

[Ken Layton]

Two possibilities on the discoloration:

1) The metal frame of the monitor has become magnetized (just keep degaussing with the manual degausser once or twice a day for several days). Remember that a degausser is an intermittent duty device. No more than two minutes on and then at least 30 minutes off before using it again or else you'll burn it up.

2) The yoke has slid back from the 'bell' of the picture tube slightly or the purity ring assembly has lost some of it's magnetic strength.

[RetroJames]

Will do on the degaussing routine. 

On the bell slipping, is there a way to confirm/discount that? 

Re: The purity rings, if that is the case I assume nothing can be done short of replacing the yoke correct?

FYI: Here are some other shop notes I posted on the blog...all kinds of new and continuing issues.  I should be pretty good at this once this thing is fixed! Whew!


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Monitor
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1. Degaussed the monitor as instructed, one time for about 2 min.  I will be checking to see if I should try again or for a longer period.  I was doing this to try and eliminate a spot in the upper right hand corner (when vertically mounted) that appears to have washed out color.  It isn't really that bad, but if it is fixable I would like to do so.  I think you can see the discoloration in this pic, upper right corner.



2. I suspect I have a vertical hold issue.  When I started the monitor it was rolling again.  I barely touched the horiz hold and it stopped.  A few min later it started again and it took a bit longer to stop, this time playing with the vert hold and the vert damp.  I suspect I should just go ahead and replace all the pots.



3. One issue I was having was that the monitor would reset (power down and up again) if the ac cord was bumped.  I picked up a replacement connector and reterminated the connection.  This issue is fixed.



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Controls
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4. I also reterminated the molex-type connector for the joystick trigger.  For the most part this worked though there were a couple of instances in the test mode in which it did  not appear to work.  I will need to watch this.

5. Controls overall - Right now the joystick is as I found it minus the trigger repair.  This thing will need to be rebuilt.  It feels choppy, response is poor, and there were times it did not appear to make proper contact.  Also, even though my CP is latched down it is moving all over the place.  Not sure if there is some rubber missing or what, but it needs to be secured properly.



6. I noticed in the test mode, in the controls menu that when I tested the spinner there was a stripe of static on the screen.  I did not notice this in gameplay, so I will just keep an eye on it.

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Sound
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7. In the test mode, I think in the self diagnostics, I got a "Sound Interface Error" error.  The sound was working so not sure what this means.

8. In the test mode / sound test - all effects sounded great except two of the music items.  I think it was the "success" and "fail" music.  Anyway, these two had noticable static on the line wheras others did not.

[Ken Layton]

In regards to the yoke slipping away from the picture tube's bell, loosen the yoke clamping screw and try pushing it forward toward the 'bell'. Warning: You'll have to do it while the power is on! High voltage present! Wear leather gloves and have a helper watch the picture as you move the yoke. This is easiest to adjust when the game is in a monitor test pattern screen displaying a solid red screen.

In regards to the purity/convergence rings: you don't replace or even fool with the yoke when this assembly goes bad. The purity rings are made of a ceramic magnet which can lose magnetism over time or someone may have bumped/moved the adjustment tabs on it.

[RetroJames]

When adjusting the yoke, what size hammer is recommended?

[MonitorGuru]

I usually use a 3# dead blow sledge myself

[RetroJames]

Arrrggg - After a completely frustrating afternoon tying to troubleshoot the monitor, and eventually cracking two of the light covers in the process, I am finally giving up on this piece of crap. I will not suffer another round of eBay sales so tonight I decided to do the honorable thing and put this game to rest, internals and all.

RIH you piece of junk.

Pics of the demise: http://home.earthlink.net/~rescuetron/

[Daniel270]

Please say it's  April Fools!!!!   

[BUCKETHEAD]

Looks real to me! 

[Chris]

Nope... sideart in the flaming pic isn't the same as the sideart in the original pic.  Good gag, though!