K4600 short in degauss circuit?

DeLuSioNaL29

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Hi all,

My K4600 series monitor (K4606) is popping the 1.5a slow blow fuse on the bottom of a Galaxian cab. The inline fuse on my chassis is fine. If I disconnect the power to the monitor the fuse in the cab is stable and it plays blind.

[Disclaimer: I received the game like this, apparently some water leaked onto the top of the cab and the owner turned it on and he saw a "flash". It's been sitting for a year unfixed so it's completely dry. I picked it up "as is".]

Again, the game plays blind if I disconnect the monitor's power cable and replace the 1.5a fuse on the bottom of the cab. So it's definitely a short somewhere with the monitor.

I have a hunch it may be a short in the degauss coil. Anyone have any pointers on how to test? I will probably disconnect it from the chassis to see if it works minus the degauss function.
(I may be wrong here though) (See pic below that I stole from Tighe's thread here: https://forums.arcade-museum.com/showthread.php?t=319272 )

What I've done so far: Cleaned the chassis. I did a full re-cap kit, re-flowed everything while I was at it. Changed B+ filter cap. Changed ceramic axial cap at C621. Changed Black level pot.
Left the 2SC1893 HOT "as is" along with the 2SC1106 voltage regulator (didn't have those on hand, they are on the way in the mail).

Thoughts?

Jason
 

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Last edited:
Hi all,

My K4600 series monitor (K4606) is popping the 1.5a slow blow fuse on the bottom of a Galaxian cab. The inline fuse on my chassis is fine. If I disconnect the power to the monitor the fuse in the cab is stable and it plays blind.

[Disclaimer: I received the game like this, apparently some water leaked onto the top of the cab and the owner turned it on and he saw a "flash". It's been sitting for a year unfixed so it's completely dry. I picked it up "as is".]

Again, the game plays blind if I disconnect the monitor's power cable and replace the 1.5a fuse on the bottom of the cab. So it's definitely a short somewhere with the monitor.

I have a hunch it may be a short in the degauss coil. Anyone have any pointers on how to test? I will probably disconnect it from the chassis to see if it works minus the degauss function.
(I may be wrong here though) (See pic below that I stole from Tighe's thread here: https://forums.arcade-museum.com/showthread.php?t=319272 )

What I've done so far: Cleaned the chassis. I did a full re-cap kit, re-flowed everything while I was at it. Changed B+ filter cap. Changed ceramic axial cap at C621. Changed Black level pot.
Left the 2SC1893 HOT "as is" along with the 2SC1106 voltage regulator (didn't have those on hand, they are on the way in the mail).

Thoughts?

Jason

Sounds like the monitor needs work honestly. Did you try the monitor in another game (make sure it has an isolation transformer)
 
Yeah, I was thinking the same thing. I think it's this one... I need to check when I get home, not positive on that one.

J
 

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  • Degauss plug.JPG
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Just wanted to follow up on this. It was a short in the degauss circuit. I unplugged the degauss connector from the chassis. It didn't pop the fuse and the monitor fired up (no picture but that's another story).

I took apart the whole degaussing circuit. Re-taped the coil with electrical tape all the way around. I figured it was hitting the chassis somewhere. Re-flowed the resistors and diodes and plugged it in. Fired it up and it no longer pops the fuse in the cab.

But after a full re-flow and cap kit, it's still behaving the same where I only get 73vdc on the B+ test point. Aargh. Back to square one. The flow chart says to check TR501 and TR502. Can do this without unsoldering them? Same question with C608 & C605?

Thanks!

Jason
 
Just wanted to follow up on this. It was a short in the degauss circuit. I unplugged the degauss connector from the chassis. It didn't pop the fuse and the monitor fired up (no picture but that's another story).

I took apart the whole degaussing circuit. Re-taped the coil with electrical tape all the way around. I figured it was hitting the chassis somewhere. Re-flowed the resistors and diodes and plugged it in. Fired it up and it no longer pops the fuse in the cab.

But after a full re-flow and cap kit, it's still behaving the same where I only get 73vdc on the B+ test point. Aargh. Back to square one. The flow chart says to check TR501 and TR502. Can do this without unsoldering them? Same question with C608 & C605?

Thanks!

Jason


if you have a transistor tester that is designed to test them in circuit you can but if your using a meter you will have to pull them and the caps you can desolder on leg and test.
 
Thanks! I took a look and it turns out I already swapped both Caps (B+ cap too is one of them) and TR502 as well.
However, I did not swap TR501 (equivalent is 2SC1815), so I might as well swap it out if I need to remove it. But I don't have those in stock. I just ordered 10 on mouser so I have them for the future.

I'll report back, but I'm pretty sure that's the problem.

Jason
 
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