Disassembling a Model 2

[Tibs]

I've been reading some on peoples restoration blogs on this one, and the project that Alphasite is working on got me thinking.

Assuming it gets here tomorrow in good condition, what gotchas are there on taking it apart and restoring this that would make me kick myself not knowing ahead of time.

I can see the video board high voltage is exposed, that looks like a fun place to put your hands when working on it. Have read how annoying it is to get to the power supply to replace the RIFAs.

I'll post pictures once its here, I made FedEx pack it and take full responsibility for getting it here, so we'll see how well that worked out.

 

[pski]

Whenever I get a Model II in the shop I always try to power it up and see what I'm in for. If you get really lucky and see "INSERT DISKETTE" you're halfway home! I do this before taking it apart so that I know what to focus on and to assure myself that I did not break it on disassembly. They are fairly easy machines to disassemble. Just take lots of pictures and do not rely on the manuals for putting it back together. No real gotchas that I can think of.

I'll elaborate a bit and throw in common issues you will encounter.

Power Supply. The A11080 standard MII PSU was marginal to start. It especially becomes an issue if you have more than the standard 4 cards. Check the voltages under load. This is easiest while the machine is still together but shorts may trick you. If you're lucky, you will have an A11081 or even better an A11082 which will run a full cage. Replace all the Rifas.

Black Screen. This could be about 100 different things including low voltages, CRT problems, analog video board, switches and issues with any of the cards. It is orders or magnitude easier to troubleshoot these machines when you have spare working cards. This is how the Tandy techs did it at Radio Shack back in the day. Swapping in working cards allows you to easily narrow down the issue to the affected card.

Floppy Not Working. This could be low voltages, the FDC board, the floppy board or the disk mechanicals. It is very typical to have issues with the floppy drive not working.

Keyboard. There's a 95% chance the keyboard will not work if it has not been restored. You will have to replace the foam pads as has been documented on this forum.

Wiring. The connectors to the keyboard and various cards other than the IDC ribbon connections will often have breaks that cannot be seen. Test them for continuity while moving the wires.

 

[Tibs]

So this is a good status? But there was an error DC when drive closed. No floppy yet to test.

And hoping the other box that is on a different truck has the darn keyboard....



I took the lid off and its relatively clean, just the 4 cards. I put it back on before the darn cat decided it was a good idea to jump in (some of you might think that is a good idea ). I'll check the power supply but I think its the -80 from memory. Other shipment has the diskettes.

 

[Tibs]

Other shipment didnt have diskettes, just binders, sigh. Keyboard still nowhere to be found by seller....gahhh.

 

[dittman]

How rare are the “Tandy II”-badged Model IIs?

You might try reseating the boards. I had to do that with mine. When I was working on mine and had the brace that secured the cards removed I had to reseat the boards fairly often. I guess they work loose due to gravity and vibration.

 

[pski]

How rare are the “Tandy II”-badged Model IIs?

As rare as a 3 legged ballerina. I've seen a few actually.

You might try reseating the boards. I had to do that with mine. When I was working on mine and had the brace that secured the cards removed I had to reseat the boards fairly often. I guess they work loose due to gravity and vibration.

Yes, that's one of the MIIs design flaws in my book. The cards are always fighting gravity.

 

[NeXT]

Does the model II not come with a retainer bar that holds the cards in place or was that added in a later revision?

 

[pski]

Does the model II not come with a retainer bar that holds the cards in place or was that added in a later revision?

It does have the bar. But when you're playing with it on the bench you typically leave it off for ease of access.

I have seen cards come unseated in these machines even with the bar attached. Granted these were a batch of machines that were rescued out of a garbage dumpster so they had a little bit of trauma.

 

[JonB]

So this is a good status? But there was an error DC when drive closed. No floppy yet to test.

Yes, you are in a good place, so far. Just need to get some boot disks. Machine looks pretty tidy too. Hopefully the keyboard will turn up soon!