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Mac Classic Expansion board?

S

snadol

6502
Hi there,

First post, so please forgive me if I put this in the wrong spot or something.

There seems to be an expansion board on top of my Classic and I need to get the main board out because I need to clean the capacitors. I got this maybe a week ago and I'm having an issue where the screen displays a checkerboard. I've looked online, and come up with: "take the main board out and scrub it with a toothbrush and soap. Wash and let dry.". I am trying to take the main board out to do that but this expansion board is in the way. It is on top of the main board, looks like it has more RAM, and connects to my main board with the floppy drive connector and another one in the back. The board has text that reads, "Quesse Computer Co Copyright 1991". The floppy drive then connects to a port on it. So I have 2 questions. What is the board, and how do I get it out?

I can send a picture of the board if you'd like, but it's kind of hard to see so it would be a bad picture. Let me know if you need it!

Thanks!

 
Last edited by a moderator:
That's a ram expansion board. Just gently rock it back and forth and pull it up. I have no idea why the floppy would be connected though?

Also, don't just wash it. Recap it too.

 
I wonder if it's some kind of accelerator? Please take pictures and post it so we can see what you are talking about

 
It says Total Systems Gemini Classic on it. The Gemini Ultra is listed as discontinued for the mac classic here.

EDIT: Also, is it ok to have only 3/4 sticks of RAM on the expansion board?

EDIT 2: I removed the expansion card and the checkerboard pattern went away... didn’t even touch the main board. Why?

 
Last edited by a moderator:
It's likely something is screwy with the expansion board. It's unusual, but accelerators are known to become faulty with age sometimes.

If you decide you don't want to mess with it, let me know, I'll take it off your hands. I'd be interested in working on one of these to understand better how they work in the Classic.

 
Last edited by a moderator:
snadol said:
Hi there,

First post, so please forgive me if I put this in the wrong spot or something.

There seems to be an expansion board on top of my Classic and I need to get the main board out because I need to clean the capacitors. I got this maybe a week ago and I'm having an issue where the screen displays a checkerboard. I've looked online, and come up with: "take the main board out and scrub it with a toothbrush and soap. Wash and let dry.". I am trying to take the main board out to do that but this expansion board is in the way. It is on top of the main board, looks like it has more RAM, and connects to my main board with the floppy drive connector and another one in the back. The board has text that reads, "Quesse Computer Co Copyright 1991". The floppy drive then connects to a port on it. So I have 2 questions. What is the board, and how do I get it out?

I can send a picture of the board if you'd like, but it's kind of hard to see so it would be a bad picture. Let me know if you need it!

Thanks!
Click to expand...
Deed breathe!

 
It won’t work with three RAM sticks. You need four sticks of the same size.

Also there should be jumpers somewhere to set the RAM speed and amount.

Accelerators with extra RAM usually need an auxiliary power supply as well when used in the Classic.

 
Not too big of a deal if it's missing though. You can throw in a cheap small 5V power supply and bolt on the appropriate cable.

You gotta be careful though, the pinout on the 4 pin power connector of that accelerator is not your standard PC floppy drive power pinout. It has two 5V and two ground pins.

The accelerator in my Classic came without a power supply as well but I wired up a chinese eBay PSU in series with the mains switch on the analog board so it turns on together with the Mac itself. Works like a charm.

Power connector on mine is different but the accelerator itself looks pretty similar:

View attachment 11068

 
I have an extra power supply, it's screwed in next to the main one. It has those little tweezer things that are connected to the resistor on the main power supply. It's output plugs into the red/orange power port on the accelerator. The floppy plugs in here on the connector above that in the picture.

untitled (9).png

 
Was the FDD plugged into that connector when you opened it up? That I've not seen on any accelerator. Video card interface seems more likely unless there's a connector for it underneath the power connector. Could you take a high resolution pic of the board to upload?

 
The floppy connector is just a passthrough. It plugs into the logicboard underneath.

PowerCache adapter for the Classic does the same.

 
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