Modifying "old" 4600 chassis to support horiz. centering

[KenLayton]

Updating this thread.

If you have one of the earlier P317 boards which does NOT have the horizontal centering parts installed, here are the parts to buy so you can add them to your board:

VR202: Horizontal Centering trimpot, 10k vertical mount style, use Jameco Electronics # 94714

http://www.jameco.com/webapp/wcs/st...Id=10001&ddkey=http:StoreCatalogDrillDownView

C204: Ceramic disc capacitor, 680pf, use Jameco Electronics # 2162732

http://www.jameco.com/webapp/wcs/st...Id=10001&ddkey=http:StoreCatalogDrillDownView

VR201: Black Level trimpot, 2.5k vertical mount style (most boards had this type), use Jameco Electronics # 35503

http://www.jameco.com/webapp/wcs/st...Id=10001&ddkey=http:StoreCatalogDrillDownView

 

[joeycuda]

Updating this thread.

If you have one of the earlier P317 boards which does NOT have the horizontal centering parts installed, here are the parts to buy so you can add them to your board:

VR202: Horizontal Centering trimpot, 10k vertical mount style, use Jameco Electronics # 94714

http://www.jameco.com/webapp/wcs/st...Id=10001&ddkey=http:StoreCatalogDrillDownView

C204: Ceramic disc capacitor, 680pf, use Jameco Electronics # 2162732

http://www.jameco.com/webapp/wcs/st...Id=10001&ddkey=http:StoreCatalogDrillDownView

VR201: Black Level trimpot, 2.5k vertical mount style (most boards had this type), use Jameco Electronics # 35503

http://www.jameco.com/webapp/wcs/st...Id=10001&ddkey=http:StoreCatalogDrillDownView

Thanks Ken... I'm going to print this out as this is good info to file away.

 

[RobMcRaf]

Thanks for all this info!

Got about 6 4600's resurrected this year and am going to try to get the mods done to all of them for full adjustibility. I hate not being able to adjust monitors.

Ironically, the best working 4600 chassis I have is the earliest made one with no apparent mods or hacks.

 

[RobMcRaf]

Connector nomenclature - thread resurrection

So, I found Ken's details about the variations of the interface cards online: http://www.ionpool.net/arcade/tech/19K4600_pinout.txt

This explains that the P317 (which I have) includes the "highly desirable" horiz centering pot. However, I was a little disappointed when I discovered that my pot didn't effect the image at all.

It turns out that the P317, while presumably "compatible" with every version of 4600 main PCB, isn't "supported" by every 4600 main board--including mine. I dug up every 4600 schematic I could find (which turned out to be only 4 different versions). Two of them show "older" interface cards (P313, in the K4616A/4666A schems, and P305 in the K4606 schems), and two others show the P317 (4625/4626/4675 and 4625A/4626A/4675A).

On the "newer" main boards (which aren't identified differently, that I can tell), pins 1 & 2 of P202 are connected to each end of R635; of the "older" main board (including mine) those two pins are only connected up into an unpopulated area of the PCB. Also different: R635's value changed from 12K to 6.8K, and an add'l 6.8K resistor (R652) is added between R635 and P607.

So, I decided to modify my main board to support the P317 adjustment pot. I jumpered from P201 pin 1 to P502 pin 7; and from P201 pin 2 to the opposite side of R635. I swapped in a 6.8K 1/2W for R635. Finally I replaced jumper J19 with another 6.8K 1/2W resistor.

Works like a charm. Can now adjust horizontal position. Thought I'd share in case anyone else with an "old" 4600 main board ever had a P317 interface board in it and couldn't figure out why the adjustment didn't do anything (I know, slim chance...)

Sorry for the thread revival, but when mapping out what you did on a set of schematics, I have one question (am looking at schematics for the 4601, 4603, 4653, 4604, 4602 & 4625,4626, 4675, 4676):

"I jumpered from P201 pin 1 to P502 pin 7" - Did you mean P302 vice P502? It would make sense and I can't find a P502.

Also worth noting (and it may have been said before) that P201 and P202 are incorrectly swapped on the drawings for the manuals that cover the 4601, 4602, 4603, 4653, & 4604. They list the P202 as having pins 1-6, and P201 as having pins 7-12.

Thanks!

 

[videogameattic]

Hey Guys,

I'm a newbie to Arcade repairs and I'm terrible with schematics. Anyway I have the old K4600 that has the old P313 board (I believe). This is in a Galaga cab that was gutted, nothing was left in this cab but the monitor. Sooo I decided to try one of these Game Elf 412 in 1 boards. Yeah, they're crap I know, but anyway, I've had beef with this monitor since I got it. I re-capped it and re-soldered it which fixed the issues with it shorting out, but of course it doesn't have the horizontal position adjustment.

Do you guys have a step by step on what I need to do for this? There are no raster jumpers and it's the board that has the black level towards the back of the board. Forgive me if the details were already posted, I'd just like to put all of this together.

 

[Smart Bomb]

any hacks to get the vertical positioning to move over about two inches?...the pins to adjust the vert. position barely moves the screen...nowhere near enough to center it. I sent it off to get converged by a tv repair shop....they converged it but its way off to one side by inches....and instead of hot gluing rings in position they super glued them....those rings aren't ever moving....but now my screen if offset.

 

[KenLayton]

Bumping this thread. Should be a sticky thread in my opinion.

 

[Jamesv833]

Bumping this thread. Should be a sticky thread in my opinion.

I agree, I had an issue with one of my chassis and didn't know it was due to the older rev. till I found this thread. Pretty much all of your posts should be a sticky as well. Lol.

 

[DarrenF]

I hope I set this up right:

http://s1106.photobucket.com/albums/h365/dgfinck/

So, apparently sometime between 2011 and now, photobucket lost my pictures, and this link is now bad. Bastards.

Luckily, I think I still have the photos in question. See attached. My K4600 is gone, but not forgotten.

 

[cpyne]

Great writeup.

When making this mod, should the horizontal and vertical raster position jumpers be added too? Or does it not matter? My board has the connection posts, but no jumper wires.

 

[cpyne]

I just did this mod on my K4635, but I'm not getting a picture at all now, just a wavy bar on the left side of the screen. I didn't see this specific model mentioned in the thread. Does anyone know if this should work for all 4600 models?

UPDATE - Works great! I had made a simple mistake and mixed up my sync and ground wires