WG 19K4901: Blue Color Missing

[WhereEaglesDare]

I have a StarGate Cabinet that was converted to Rough Ranger.
The gameplay has a bad yellow tint.

It is a WG 19k4901

Here it is with Red Down and Green Up

Here it is with Green Down and Red Up

When I adjust the blue nothing happens so there is no reason to post that picture.

Here it is tuned as well as I can get it.

This is how it should look.

I checked the cabling and I reseated the neckboard... any ideas? any help?

 

[edelgiud]

Check the Neck Board Transistor for the blue cutoff/gain....

 

[WhereEaglesDare]

Found that one of the transistors had a lot of flux built up on it so I reflowed all the transistors and cleaned them up some.


Q401
B 9.73 Typically should be 9.7
E 8.97 Typically should be 9.3
C 64.7 Typically should be 139

Q402
B 9.77 Typically should be 9.7
E 9.00 Typically should be 9.3
C 79.7 Typically should be 139

Q403
B 10.4 Typically should be 9.7
E 10.2 Typically should be 9.3
C 135.9 Typically should be 139

As you can see both Q401 and Q402 are reading low on the Collectors when both the Base and Emitter voltages should be within tolerance.

Ironically the Q403 is the only one with a Collector in tolerance and that is the blue out.

What do you think is the culprit?

 

[smalltownguy2]

Q401 and Q402 both look leaky. Swap with Q403 and see if the color problem migrates to another color. Do you have another neck board you can borrow parts from?

 

[WhereEaglesDare]

Okay I tested the blue line in the JAMMA Harness and it is good.

I OHMed out the input pin to the first contact on the chassis which is to R232, so it is going from the JAMMA Board to R232 on the chassis, so I know that is good.

I swapped red and blue and I still couldn't get any blue, but I was able to get the Red and Green Signals. If I pull the red splice open I get only green and no blue.

I went back and retested the transistors on the neck board and found that they are indeed within tolerance, when the gain is turned down.

It is safe to say that the problem is inside the monitor somewhere... unfortunately...

Back to the drawing board...

I'm thinking of swapping the transistors to see what will happen... **warms up iron**

 

[THE COUNT]

If you have another tube monitor that uses the same chassis, just swap chassis to determin if it's a tube issue. Otherwise, the only way of knowing is getting someone with a tube tester/rejuvenator to hook it up and check it out. If it is the tube, there is then the chance that a balance/cleaning or rejuvenation will fix your blue issue.

 

[pinbotler]

Blue Color Missing

Hate the missing color thing. Not sure if this will help but my G07 pacman was missing blue also, and B+ was a bit low. X901 or X902 was blown in the high voltage section and resulted in no blue. Not sure how they compare to the WG but might be something to keep an eye out for. Good luck!

 

[WhereEaglesDare]

Q401 and Q402 both look leaky. Swap with Q403 and see if the color problem migrates to another color. Do you have another neck board you can borrow parts from?

YOU ARE AWESOME.

HAHAHAHAHA ;D ;D ;D

Now I just need to order some replacement transistors (I'll go ahead and replace all three) and I should be in business!

Will follow up after I get the neckboard repaired, I'm also planning on ordering a cap kit.

 

[WhereEaglesDare]

BTW its a NPN Transistor 2SC2068LB
PN: 200x3206-800

and Mousr doesn't have either PN or Description on their site so its now time to decode this!

Anyone have any luck with this?

 

[Jeff F]

NTE378

NTE Search

 

[WhereEaglesDare]

So is the Part Number 200x3206-800 listed on the manual a Williams Internal Part Number? If not where do they get that number from?

 

[THE COUNT]

That no. crosses to NTE 376. Which you can get here.... http://www.parts-express.com/pe/showdetl.cfm?Partnumber=NTE376, here.... http://pickels.powerhostingusa.com/prod.itml/icOid/5194, or at Mouser.... http://www.mouser.com/ProductDetail/NTE/NTE376/?qs=JV7lzlMm3yIJHtr61Dwpew==.

 

[KenLayton]

MCM Electronics has the 2SC2068 transistors dirt cheap:

http://www.mcmelectronics.com/product/2SC2068