Spy Hunter Monitor Problem - WG4900 - Intermittent Vertical Collapse

[RetroJames]

Been fixing my upright Spy Hunter, nearly everything is working correctly ...

Now the only issue left (i think) is the monitor.

Works mostly, but it seems after it warms up for a bit it get's flaky in that -

The left side of the screen "folds" and about 1/4 of the image on the left disappears. Some on the right disappears as well, like the image gets thinner but seems to only "fold" on the left.

The border is then a bright green line on that left side. (hence the "fold")

I'm unsure as to what type of monitor it is, but here are some pics of the chassis etc.

I'll have a screen shot of the issue shortly.

Hoping someone can help me id the chassis / monitor and even better have a suggestion as to which component(s) on the chassis might be the cause of this behavior.

[grantspain]

wells gardner 4900 i am sure,it would benefit from a cap kit

[RetroJames]

wells gardner 4900 i am sure,it would benefit from a cap kit

You are correct and I think it has a synch problem as noted in Randy's flowchart.

I'll post results once I make the repair. Thanks!

[RetroJames]

Cap kit didn't fix it though it did get rid of a little wave that was going on. Colors look better.

vert synch issue still there. I did not check the solders on that circuit, dummy. Rushing to try it out.

In other news I learned the outlet I have been using has an open ground.

After playing the game and seeing the issue again I was going to pull the chassis again and resolder everything on the very synch circuit.

I wired a ground wire from the monitor frame to the outlet. Then used a discharge probe, wired its ground to the monitor frame. Got the probe near the anode cap and heard a little bzzzzzzzzz.

Not even touching, just close.

The probe has a meter on it and it was reading about 5000 volts just getting the probe near the cap's leads.

I decided .. hey, maybe I'll just check that outlet for ground before I go further ... sure enough, no ground.

I was within a hair's breath of becoming a light bulb I think .. or sending a few thousand volts through anything connected to a ground strap in the machine ... eep.

- also found a looses wire in from the sound board to the amp, causing a coupld channels to fade in and out.

- Also the steering is still funky. Works great nearly all the time, but every once in a while you fire up the game and the steering is totally wacked. A restart usually makes it go back to normal. Likely need a new pot after all.

Done effing with it today.

=================

Here are pics of the issue

[Kevin Mullins]

"Wiggle" the pots and see if the image jumps in and out from good to bad.
(vertical size, vert position, SCREEN, etc)

[RetroJames]

"Wiggle" the pots and see if the image jumps in and out from good to bad.
(vertical size, vert position, SCREEN, etc)

Did, no noticeable shimmy or change. Difficult though with SH, hard to do the "reach around."

[Ken Layton]

Vertical Dampening (V Damp) adjust.

[RetroJames]

Vertical Dampening (V Damp) adjust.

Did, any fix is temporary, the condition returns after 10 - 15 min. 

[Ken Layton]

Replace BOTH vertical output transistors with brand new ones.

[RetroJames]

Replace BOTH vertical output transistors with brand new ones.

That appears to be - (from the wg4900 manual)

Ref No. ** Part No. ** Description
------------------------------------------------------------------
Q302 ** 200x3207-306 ** Transistor (NPN) 2SC2073LBGL2

Q303 ** 200x3207-306 ** Transistor (NPN) 2SC2073LBGL2

I'm having a heck of a time finding these online or in-town (Atl). I am searching using the code in the description, so far no luck.

[grantspain]

ummm,ebay-i found about 6 listings
also if you are in the states then just use the nte cross reference to find your equivilent
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/69d5aa3584d015ce85256e780056e56f?CreateDocument

[RetroJames]

This may be them?

http://www.therealbobroberts.net/parts.html#semiconductors

2SC2073 Used as vert outputs & more   $2.00

[RetroJames]

I'm trying to locate them locally, I'd like to try this today if possible.

Would Fry's have something like this?

The local store has two of the NTE375 transistors in stock>


That cross-ref brings up this (and thanks!)

http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf

2SC2073LBGL2

Replace part....            With NTE part....                                             
2SC2073LBGL2         NTE375                                                   

[Ken Layton]

The only numbers that are important are 2SC2073.

NTE 375 is also what I have used as a replacement. Worked perfectly.

[RetroJames]

The only numbers that are important are 2SC2073.

NTE 375 is also what I have used as a replacement. Worked perfectly.

Good deal. Fry's had two left and I just picked them up. Will effect the repair later today and see where I'm at. Thanks so much for all the advice!

[Ken Layton]

In my case the bad transistors were testing good all the time, even when out of circuit. So I replaced them anyway with brand new ones and that fixed it.

[RetroJames]

In my case the bad transistors were testing good all the time, even when out of circuit. So I replaced them anyway with brand new ones and that fixed it.

So these guys are screwed to a metal bracket on the PCB, and there is some sort of white glue or dope or something between them. Do I need to replicate that substance or can I just screw the new ones to the same spot?

Having a hell of a time getting one of the screws off. 

[RetroJames]

In my case the bad transistors were testing good all the time, even when out of circuit. So I replaced them anyway with brand new ones and that fixed it.

So these guys are screwed to a metal bracket on the PCB, and there is some sort of white glue or dope or something between them. Do I need to replicate that substance or can I just screw the new ones to the same spot?

Having a hell of a time getting one of the screws off. 

Ok, success .. BUT ...

That putty has me puzzled.

Also, I noted that the transistors came with small plastic backings and a rubber grommet.

Should the backing be installed between the frame and the component and should the grommet be installed ..

- between the frame and the plastic?

- between the plastic and the component?

[grantspain]

the putty as you put it is heat sink compound(like on a pc cpu fan)
basically you should always clean off the old and put some new on whenever changing a component of this nature-if you do not do this then the life span of the transistor will be affected badly
the plastic sheet should go between the transistor and the metal heat shield and the grommet goes through the component fixing hole from the front of the transistor

this is basically isolating the transistor from the heat shield electrically as the transistor fin is also used as collector

sometimes it is not needed and other times it is-normally you just do whatever is installed(as long as that was correct in the first place of course)

[RetroJames]

 
Ok, been on and played for about 20 min or so at this point .. loooooooking good!

[Ken Layton]

If you don't put a smidge of that white silicone heat sink grease on the replacement transistors, they will fail soon from overheating. You can buy the heat sink grease at Radio Shack (# 276-1372) for about $3 for a small squeeze tube.

[RetroJames]

If you don't put a smidge of that white silicone heat sink grease on the replacement transistors, they will fail soon from overheating. You can buy the heat sink grease at Radio Shack (# 276-1372) for about $3 for a small squeeze tube.

Gah.

does it need to be between the transistor and the plastic or the plastic and the metal .. or both?

[Ken Layton]

Both. A thin film is all you need on each surface.

[RetroJames]

Both. A thin film is all you need on each surface.

Ok will do. The game ran for about an hour, hope the plastic is still in tact.

[RetroJames]

Ok, I think this operation is a success! Picked up the heat sink compound this morning. I was able to get the plastic back out, and slurry a bit of the goop on both sides for each component.

Everything is looking very, very, good!

Thanks again Ken and Grantspain .. great help and advice! Much appreciated!

[Ken Layton]

Keep playing it. You've probably got it licked.

[grantspain]