Recent content by JC8080

I have a working board with the RAM expansion. If you decide to base something on this design and run into a roadblock where having access to a working board would help, and you are in the US, let me know and I would be willing to loan it out for nondestructive reverse engineering.

Plus accelerators are hard to find, and expensive when they do come up for sale. The MicroMac Performer clone will work with a Plus, though it is more complex than using it with an SE, because the Plus does not have an expansion slot. Here is a writeup I did on a Performer clone build, I talk...

Have you tried the Plus keyboard on the 128k? Do all the keys on the 128k behave the same? I have never had one of those mice apart, but I would start by putting some deoxit into the switch contacts and see if that fixes the mouse. Definitely don't start looking for replacements yet.

If you haven't already, look at btbs other post where he links to his redrawn schematics.

Great work. Those schematics look nice, maybe there is hope for my Classic II after all!

Thanks for the info, I'll add those to my cart for my next order.

The caps on the analog board (power board) on those machines tend to leak badly. Look at the PCB at the base of the capacitors, you will likely see a pool of liquid electrolyte. The caps on the analog board are all through-hole, so they are easy to replace with some basic soldering skills. The...

Here is a link to a thread describing a similar problem with the clones, I don't think a solution was found in the thread, but you might want to post on that thread and see if anyone has updates with their situations. Here's a post I did about my original presto board and which drivers I used...

Unfortunately I do not. What are the symptoms of your faulty board? There is currently a mostly complete HyperDrive kit on eBay, though $550 + $50 shipping is a good chunk of change.

Does anyone have a cap list/cart for the ADP-17AB low-power AC adapter? I am putting in a Mouser order and don't have that particular PSU with me to open and look at the caps.

I had the same symptoms on a 512k. I checked continuity from where the keyboard connectors meet the PCBs on both ends, there were no breaks. I couldn't figure it out, the keyboard worked with another machine, like yours does. Someone suggested cleaning the keyboard cable jack with IPA. I blew...

Thanks for the pic. So your photo is before you removed the blob on side 1 of JB1? It definitely sounds like your 128k has been upgraded to a 512k. You would probably need to pull the expansion board off to tell if you have an actual 512k logic board, or if you have a 128k board that was...

I haven't used his service, but he has a good reputation, if I needed it done I would not hesitate to use his service. I've bought parts from him before, he seems like a nice guy.

Awesome, thanks for the update. A friend of mine just asked if I ever made progress with mine (I did not), this gives me some motivation to work on mine. Are your RAM chips socketed? I'm wondering if part of the problems I am having is due to poor connections in the sockets. Specifically...

Gotcha, thanks. I just wasn't sure if there were any ICs that are known to be prone to failure. Slightly related general question from a relative-newbie... What causes ICs to fail when there are no physical signs of damage or corrosion leaking into the body, and when they have not been zapped...