Apple IIgs with bad onboard ram?

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Apple IIgs with bad onboard ram?

Hey guys! I have been getting more and more excited about Apple IIs for a bit and I finally broke down and bought a IIgs on Ebay. It arrived and I set it all up and played with it a bit today. Turns out it is a Rom 01 with a 1Meg memory expansion card. As I played with it I noticed two things:
1) There is a line in the middle of this screen that shows up only when text or graphics other than the background color intersect it. It shows up on the RGB monitor as well as the composite port.

2) It crashes when loading some software.

 

I ran the CTRL+Option+Reset system test and it failed with:

02E00200

 

I take this to mean a memory error in bank E0.

I'm thinking that maybe the bad memory could be why there is a line in the screen (bad memory in the video section)?

 

Two main questions:

Do I try to get a full or partial refund on ebay? I'm tempted to ask for at least partial because it isn't in full working condition but I'm not sure if I should. In some ways it just seems like with equipment this old you get what you get.

If I want to fix it where do I go from here? I have to figure out which chip is bad and desolder it and replace it with a new one?

 

Thanks for your help!

 

 

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Bad RAM is not uncommon these

Bad RAM is not uncommon these days.  It is a pain, but it can be done to unsolder the bad chip(s), solder in a socket and put good chip(s) in.  3rd party diagnostics may be able to identify exactly which chip is bad so you don't have to do all of them.  I've never done that on a IIgs, but the procedure should be pretty similar to what it is on a //e.

 

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Thank you softwarejanitor I

Thank you softwarejanitor I am going to go ahead and undertake the replacement. Does anyone know how I can find out which memory chip to replace and more importantly where I can buy a compatible replacement memory chip (or 4)?

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Bank E0 indicates slow ram

Bank E0 indicates slow ram which is labeled on my board as "Standard Ram" correct? There are 4 chips in the standard ram section.

 

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I'm thinking of going with 4

I'm thinking of going with 4 of these and replacing all the "slow"/standard ram with them: https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&pa=41574&productId=41574

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JameCo is a reliable vendor. 

JameCo is a reliable vendor.  I used to buy a lot of stuff from them back in the 1980s.  Buy good quality sockets (machined), The easy way to remove the old chips is to cut all the pins and then remove them one at a time.

 

 

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The built in RAM is in banks

The built in RAM is in banks $00, $01, $e0, and $e1. Each of these banks is in 1 pair of the RAM chips. You should be able to determine which chip it is without replacing them all.

 

I don't know what the corresponding RAM chip is to the error you have but I am sure others here would know or it is in the hardware reference manual.

 

http://www.goldstarsoftware.com/applesite/Documentation/AppleIIgsHardwareReferenceManual.PDF

 

A quick guess would be the standard RAM, first chip since it's a low address $0200.

 

Now, of course you can always have other problems causing the RAM test to fail- memory addressing logic, damaged board, etc. but maybe you will get lucky.

 

Oh, and get that old battery off of there right now... It will eventually fail and leak.

 

 

 

 

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Great News!

So good news. I purchased replacement ram chips and sockets. My brother and I opened up the IIgs and replaced all four chips with sockets and then  inserted the new ram. It fixed the line in the screen and the system test now passes!  I ordered a replacement battery (mine is from 1986). It should arrive tomorrow and I can replace it too. Thank you guys for your help!

 

 

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