Topic: Defective (original Irem) R-Type  (Read 19539 times)

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Offline Elgen

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Defective (original Irem) R-Type
« on: March 24, 2011, 08:04:42 AM »
Hi

I'm new here on the board.
My name is Elgen (aka Morten irl };-D), and I've been messing with arcade for about 5 years now.
I've done only very simple repairs like changing a capasitor or resistor, patching a broken circuit or IC-leg ect.
I have to say, that when I found this board, I was impressed; it's a gold mine of repair logs, truely inspiring };-P

Well now for the issue:
I have an R-Type (original Irem).
All the sprites display well, the controlls, gameplay, and sound is also good.
But the backgounds is all messed up. There are big rectangular patches of striped and solid goo, and there is white vetical stripes on the whole screen.
See video here: http://www.youtube.com/watch?v=If9BXlpWDz0
I'm suspecting this could be a RAM issue, but I don't know much of these things (yet?!).

Well bottom line, I've desided, that I want to give it a try at repairing it, but where do I start?
I've been through the standard things:
- Checking for physical damage.
- Taken the 3 boards apart cleaned all connectors putting it back together.
- Had all socketed IC up, cleaned legs and sockets and reinserted them.
Still the same. As said before I've never done REAL repairs of arcade, but I've got the tools (scope, multimeter, soldering iron etc.), I'm real handy, and I'm a fast learner when it comes to technical stuff (bordering autistic };-D).

Do any of you have any clue as to where I should start with this one?

I will ofcause post all progress here on the board };-D

Hope some of you will be willing to help a repair-n00b out.

PS. I've build my SuperGun/TestRig myself; you can see how that went by here (all comments in Danish, sorry): http://www.facebook.com/album.php?aid=110508&id=1390686556&l=d171261ea5
« Last Edit: March 24, 2011, 10:03:39 AM by Elgen »

Offline Panther

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Re: Defective (original Irem) R-Type
« Reply #1 on: March 24, 2011, 08:50:13 AM »
Welcome to RCM Elgen,

Can't help with the arcade board, not got a clue with that type of thing.

Hope you manage to get it fixed, I'm a BIG fan of R-Type  ;D

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #2 on: March 24, 2011, 09:01:40 AM »
I was kind'a hoping for Womble to make his entre in this thread };-P

Offline AndyRCM

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Re: Defective (original Irem) R-Type
« Reply #3 on: March 24, 2011, 10:02:08 AM »
Yeah either Womble or Porchy . . . they both know their stuff! ;)

A

PS - Welcome Elgen
"I could see the faces of those who led pissing themselves laughing" - Funeral Pyre by The Jam

Offline porchy

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Re: Defective (original Irem) R-Type
« Reply #4 on: March 24, 2011, 11:12:55 AM »
i had similar problem with my m72 version of x-multiply (should be same hardware IIRC), mine had a couple of corroded tracks to one of the srams on the address lines

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #5 on: March 24, 2011, 11:15:13 AM »
So you suspect it be a problem related to RAM also?

Offline porchy

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Re: Defective (original Irem) R-Type
« Reply #6 on: March 24, 2011, 11:17:54 AM »
possible but could be logic or ROM issues too.
Ive had several Irem boards in my collection and the M72 boards have all had corroded track problems.
Are all of the ROMs originals? If one has been swapped for an eprom (27c301 is mostly compatible) then a slight mod is required.

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #7 on: March 24, 2011, 11:34:05 AM »
Well, I AM a total n00b to this, so where are the srams located on the board, and what kind of tests should I conduct?

Offline porchy

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Re: Defective (original Irem) R-Type
« Reply #8 on: March 24, 2011, 11:56:11 AM »
Not sure on the location of the rams on that board as I don't have one anymore. I'll check on my m81 board and see what type is used on that, although they may also be different types on yours.
As for checks, have you done visual checks for track breaks etc? Maybe do some continuity checks.

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #9 on: March 24, 2011, 12:08:42 PM »
Hmmm, well for visual, best I could, but I'll give it another round again };-D

Offline porchy

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Re: Defective (original Irem) R-Type
« Reply #10 on: March 24, 2011, 12:31:20 PM »
The RAMs on my M81 board are:
MB8464 (28pin)
or
TMM2018 (24pin)
or
PD4364 (28pin)

Womble did a great post a while back on RAMs, Its a recommended read.
http://retrocomputermuseum.co.uk/forum/index.php?topic=2331.msg27493#msg27493

Offline Womble

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Re: Defective (original Irem) R-Type
« Reply #11 on: March 24, 2011, 12:42:10 PM »
Evening all! Could you post some high resolution photos of the board, if you can manage it so I can read the chip markings I should be able to point you in the right direction. Nearly midnight here so just about logging off.

I had forgotten my RAMble post :)
Sic Transit Gloria Atari

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #12 on: March 24, 2011, 01:03:31 PM »
I'm at work atm (UPS! hope my doesn't look over my shoulder };-D) and will be working late (present time + about 6 or 7 hours), by I will try to post hi-res (best I can) pics of the board; I have a iPhone4 as my only taking-a-picture-device, is that hi-res enough u think?

Offline porchy

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Re: Defective (original Irem) R-Type
« Reply #13 on: March 24, 2011, 01:26:14 PM »
IPhone should be plenty good enough, hardest part will be a steady shot.

Offline Elgen

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Re: Defective (original Irem) R-Type
« Reply #14 on: March 24, 2011, 01:28:17 PM »
I'll do my best };-P
« Last Edit: March 24, 2011, 01:34:34 PM by Elgen »