WK 19k4951 on the fritz

[heaton84]

Hey all, I'm new here and hope someone can help me out.

I inherited an arcade game with my house. The cabinet reads "Video Victor", but I can't find anything on it or any markings indicating what game is in the cabinet.

Anyway, when I first powered this thing on I had no juice out of the isolation transformer, so I replaced it. Now I have sound if I hit enough buttons, but no video. Instead of a picture, I get a bright greenish yellow screen with slightly brighter lines zigzagging through it. I found the repair manual for this monitor, and have read about a repair flowchart but can't find one. I'm new to monitor repair, but I know the basics of what the electronic components do. I've tried all the trimming knobs I could find... blackness, brightness, red/green/blue intensity, and red/green driver adjustment. Nothing has any impact on what is displayed aside from the sizing and positioning controls.

Where should I go from here with it?

[heaton84]

Sorry, I meant WG, not WK. Gotta learn to really double-check what I type before hitting Post.

[Kevin Mullins]

First thing to know is whether or not the game actually plays properly "blind". (ie. without a monitor)

This way you know whether to start with the monitor or the game pcb/power supply.

From the sounds of your description of the display on screen..... the monitor is probably "working" but the video signal going to it is not correct or working.

Does the game pcb have any markings on it?
Does it have a standard switching power supply in it?

Where does it say "Video Victor" on the machine?
Any manufacturers markings?

[SirPeale]

Post a picture of the machine.  You know the old saying about 1,000 words and whatnot.

[heaton84]

Alright then, here she is. Sorry about the bad quality. I'm stuck with the camera phone until I can find where I hid my digital camera.

The banner lit by a worklight (no appliance bulbs on hand)


Side of the game and a bit of my hand


The screen I am greeted with and can't seem to change


No identifiable markings on the board other then "Sun Microsystems Corp". I hunted all over the entire thing. No clue as to what game this is. 

[heaton84]

Ok then, it's definitely either the monitor or the JAMMA board. Is there any easy (read: cheap) way to test the monitor to see if it is in fact good? I don't have any other boards around. I have a few spare PCs and have heard that one can drive a monitor from a VGA card. Any suggestions?

[Kevin Mullins]

Pretty positive it's NOT the monitor.

That looks like a game pcb or power supply issue.

I would first try re-seating any and all wire connectors and removable chips.
(unplug and plug right back in)
Careful not to break any chip legs when pulling and re-installing them.

I'm curious as to what kind of power supply that has.

Can you get a pic of the insides?
And a pic of the game pcb itself? (might be a bootleg board)


Definitly an oddball, I haven't found anything on the web about that one.

[heaton84]

Pretty positive it's NOT the monitor.

That looks like a game pcb or power supply issue.

I would first try re-seating any and all wire connectors and removable chips.
(unplug and plug right back in)
Careful not to break any chip legs when pulling and re-installing them.

I'm curious as to what kind of power supply that has.

Can you get a pic of the insides?
And a pic of the game pcb itself? (might be a bootleg board)


Definitly an oddball, I haven't found anything on the web about that one.

Here's a shot of the board...


Checking the connector pinout again, it's definately not JAMMA. Some sort of 36-pin thingamabob. I'll try reseating the chips and see if that helps. I'll also try to jot down some voltage readings and see if I can't get that power supply model (it's a pain to get to). Only ID marks on the board other then Sun's name is TVX-3(A) with an expansion marked "TVX-SI".

Update: Power supply is a TEC-1000. Just remembered my multimeter is still out on loan... I'll have to get that back to check voltage levels. I did manage to identify two Z80 processors and one AY-3-8910 sound chip on the board. This may not be the right forum to ID the board, but now I'm curious as to what's in those chips!

[Kevin Mullins]

I always like a good hunt to figure out the unknown. 

There's a few of us on this forum that still mess with that old school technology.

 

[D_Zoot]

I'm 99% sure it's Route 16, marketed by Centuri, the boards were manufactured by Sun.  The TVX-3(A) marking is the giveaway as to what it is.




D

[Kevin Mullins]

Definitly matches one Route 16 board pic I found.
And the cabinet style looks to be right as well.
Good call D_Zoot !!

But curious where the "Video Victor" part comes in.
It was obviously in that machine at some point. (the control panel has been modified)

Route 16 Manual
Route 16 Pinout
Should be able to do a quick voltage check on the power supply with the schematics in the manual or the pinout fond on Crazykong.
A quick look at the schematics and it looks like it'll run off a standard switching power supply if need be.

Should be interesting to see which game actually comes up when you do get it to go.
The roms appear to be labeled like the Route16 board, but the Video Victor stuff is odd.

[heaton84]

Yup, found a video of this game on youtube. That's the music I hear after I mash the buttons.

Now to figure out why the video isn't working...

[Kevin Mullins]

I'd start with the re-seating and cleaning of chips.
Then swap the two Z80 cpu's around.
Follow the sync line back to see what chips are inline with it.

Heck... just make sure it's connected to the monitor properly. 
K4951 Manual

[qrz]

check ur green output xistor for a collector/emitter short . check this with pwr OFF
if ok , u may have  a heater/cathode short on the crt . (cathode voltage below 60v ) check with pwr ON, no signal
a single gun h/k short may be negated by isolating the filament winding.

qrz

[Mauzy]

NOT the PCB. I had an incredibly similar problem (see here : http://forum.arcadecontrols.com/index.php?topic=74524.0) And I ran three diff. PCBs through it and got the same thing. Mine just needs to warm up and it will stay on long enough for a 210K game of Galaga 

My monitor was also a WG, but it is a 19K7201

[heaton84]

Alright, got my multimeter back!

Collector to emitter on Q402 seems fine, no short there.

Swapped the Z80's to no avail.

Sync line on the monitor runs into the negative lead of a 16v 100uF capacitor on the mainboard. I've read on the monitors that cap kits are occasionally needed. What do you guys think about swapping out the caps? Or should I go qrz's route and isolate the heating filament?

[qrz]

what is the collector voltage of green drive xistor ?? (pwr on )
still leaning towards a hk short


qrz

[Kevin Mullins]

Just unplug the video input...... screen should go black.... if it still looks the same then you have a chassis or tube problem. (i.e. H to K short, etc)

Number one thing is to get the game board to run and operate first. You should be able to flick the coin switch, press player 1, and it should run. With or with out a monitor you should have proper game sound and be able tell that a game is in progress. (playing blind)
I wouldn't jump to diagnosing a monitor if it is still uncertain whether the game board is working properly.

"have sound if I hit enough buttons" to me doesn't mean the game is working properly.

Have you measured the power supply lines?

[heaton84]

Just unplug the video input...... screen should go black.... if it still looks the same then you have a chassis or tube problem. (i.e. H to K short, etc)

Ah ha! I have tried that one already, still a bright green screen. Sounds like it might be a heater/cathode short then. How would I verify that?

[Kevin Mullins]

OK, then ignore most of what I just said.   

Is the neckboard marked somewhere near the neck pins H H KG KB KR G1 G2 or something like that with one letter corresponding to each pin of the socket? If so , remove the neckboard from the tube and ohm between the pins on the tube for KG and either of the H's.

Compare those readings to the KR and KB.

[heaton84]

OK, then ignore most of what I just said.   

Is the neckboard marked somewhere near the neck pins H H KG KB KR G1 G2 or something like that with one letter corresponding to each pin of the socket? If so , remove the neckboard from the tube and ohm between the pins on the tube for KG and either of the H's.

Compare those readings to the KR and KB.

Without the neckboard I get an open circuit between KG and either R. Perhaps there's not enough voltage in my multimeter to punch through whatever is shorting?

I did check the voltages of KR, KG and KB with the CRT on. Here are the results:

Between KR and H: 10VDC
Between KG and H: 8VDC
Between KB and H: 90VDC

Which confirms that the guns are in fact firing I guess.  Question is, are any of these questionable?

*edit* I wonder if it would be easier to hunt down a 19" TV and swap the tubes (note I have never attempted this)...

[heaton84]

Alright, I pulled Q402 (green drive transistor) just to rule that out. Still had the greenish yellowish picture so that rules out a bad signal... it's gotta be in the tube from what I gather.

I went around and measured all tube pins to ground, and here is what I found...

GI @ 0VDC
KG @ 10VDC, slowly climbed to 20VDC while I went around and measured everything else
G2 @ 307VDC
KR @ 10VDC
H (both) @ 0VDC ()
KB @ 86VDC

I fail to understand why both heating elements are at 0VDC... I thought it ran at 6V?

[Kevin Mullins]

You need to measure the H's together..... not to ground for the heater voltage.

Without the neckboard I get an open circuit between KG and either R.

You meant H right? 
Ohm    H + KG 

Do the same check for H + KR and H + KB

[heaton84]

You need to measure the H's together..... not to ground for the heater voltage.

Without the neckboard I get an open circuit between KG and either R.

You meant H right? 
Ohm    H + KG 

Do the same check for H + KR and H + KB

Yes, H. For some reason I keep wanting to call it R.

When I ohm it without the neckboard, I get an open circuit. Which doesn't make sense.

[Kevin Mullins]

When I ohm it without the neckboard, I get an open circuit. Which doesn't make sense.

Well, that's the way it should be..... open.

Do all the color guns show open?

[heaton84]

When I ohm it without the neckboard, I get an open circuit. Which doesn't make sense.

Well, that's the way it should be..... open.

Do all the color guns show open?

Yes, they're all open.

The only difference between the CRT and the neckboard is that I read 35Kohm between KR and KG, but open circuit to KB.

[Kevin Mullins]

You're showing some odd results in relationship to the problem showing on screen.
I try to think of tests that the average joe can try at home due to the lack of specialized equipment. (including myself) Usually things are shorted or they're not. If you disconnect the video signal.... and none of the color transistors are shorted and none of the color guns are shorted.... then there should be nothing on the screen.

About the only other thing I can suggest as far as the tube itself is concerned is to call around some old timer tv repair shops and see if they have, and know how to use, a tube rejuvinator. It will not only test the tube guns, but can possibly clean or revive them if they aren't too far gone. It's never 100% guaranteed that it will work and might possible to more harm depending on the condition of things. But at this point you have nothing to loose on that tube.

[heaton84]

You're showing some odd results in relationship to the problem showing on screen.
I try to think of tests that the average joe can try at home due to the lack of specialized equipment. (including myself) Usually things are shorted or they're not. If you disconnect the video signal.... and none of the color transistors are shorted and none of the color guns are shorted.... then there should be nothing on the screen.

About the only other thing I can suggest as far as the tube itself is concerned is to call around some old timer tv repair shops and see if they have, and know how to use, a tube rejuvinator. It will not only test the tube guns, but can possibly clean or revive them if they aren't too far gone. It's never 100% guaranteed that it will work and might possible to more harm depending on the condition of things. But at this point you have nothing to loose on that tube.

Agreed, hence my statement that the open circuit seemed strange. The only thing I can think of is that it's not an full-on short... but close enough that when the tube voltage is applied it can jump the gap.

Not sure if I'll keep at it or gut the cabinet and MAME it at this point. I might try tapping on the neck some more with it turned face down. What's the word on brick-dropping if I manage to break the tube and short stuff out?

[qrz]

ur voltage readings do coincide with an hk short on the green gun . however , the 10v on the red cathode is also a problem.  note: voltage measurements should be referenced to "cold" gnd.
i'd "lift"  the  the red cathode and remeasure the collector voltage of red drive xistor. ( ok if high)
 if low, there may also be a hk short on the red gun 
 a single gun hk short is easy to negate......but multiples...., likely gonna take a diff crt.   hint , watch for a thrown out 19" tv .   the price is right   

qrz

[heaton84]

Ok, I may get the boot for asking this, but I've got nothing else to lose on this project.

Would anyone happen to know a good tutorial on isolating the heater? A picture of the winding on the HT transformer would be great.

Alternatively, since this thing is shot, what about using the HT to blow out the short? Worst case is I trash the tube even worse. I've read you jumper the two heater elements together to keep it from opening up. I have no high-voltage caps around. Another alternative is a 9kV neon sign transformer that maxes out at 30mA.

[qrz]

to isolate crt filaments , one must wind a new secondary coil on the flyback.
start with a 2- 3 foot piece of 22ga ( i prefer stranded ) insulated wire.
thread wire thru the exposed core . pull till have equal lengths ..
loop one end of the wire thru the core again - parallel to the first - pull tight.
repeat till 3 complete turns have been made .   note : approx 2 volts per loop
twist the wire a few times close to the core . this will help secure the wire position on core .

on crt socket , disconnect both filament leads. connect one end of new winding to a fil lead .
connect the other end to the other fil lead via a 2 ohm 2 watt flameproof ( metal oxide or ceramic)
resistor. ( surge protection/fuse )
this removes the ground loop caused by the orig fil winding being referenced ( tied) to ground.
the cathode short still exists , but no longer affects tube parameters

qrz

[heaton84]

Well, I tried isolating the heater. It fired up nicely, but still presented the same problem. Must be a different sort of short. 

I think I'm going to gut the cabinet and put an old PC running Tyrian in there. 

[qrz]

ok, remove the green output xistor and pwr it up .
 if u have no green , the xistor may be breaking down under voltage . ( high leakage current at applied voltage )
 could test xistor by substituting red/blue or just replace
most video output (drive) xistors will have a ECBo of 300v.

qrz
 

[heaton84]

ok, remove the green output xistor and pwr it up .
 if u have no green , the xistor may be breaking down under voltage . ( high leakage current at applied voltage )
 could test xistor by substituting red/blue or just replace
most video output (drive) xistors will have a ECBo of 300v.

qrz
 

Thanks for the suggestion, but I already tried that one ( http://forum.arcadecontrols.com/index.php?topic=75061.msg779377#msg779377 ). Still a bright green/yellow. I've given up on it and already gutted the cabinet. Route 16 doesn't look that fun anyway. The cabinet will make an awesome home for a DOS system running Tyrian. 

[qrz]

sry, didn't reread prev posts 

since isolation didn't help, the only thing left --BINGO! Either that, or I was attempting to say "before" but it was too many letters to type-- replacing the crt would be the socket .
many crt sockets have an integrated spark gap that have been known to develop corrosion and then short...

in fact , had two in the last month.... though, still not a common failure .

qrz