I have spent a considerable amount of time over the last couple of months restoring a very flakey Apple II plus motherboard to something approaching reliable operation. I expect that over the next few weeks, some final testing and debugging will resolve any possible remaining issues and I will be able to declare that the system is working completely reliably.

At the start of this effort, this particular motherboard occasionally worked properly, but never would stay working for long. In the past I had worked with other early rev Apple II motherboards that had similar intermittent issues and assumed that a lot of this intermittent behavior was due to connector issues, as reseating chips usually improved or at least changed behavior.

In the past those flakey boards have ended up on my spares pile, but I was determined to get this one working properly. Though I did encounter flaky sockets, I found many chips that had bad outputs, which made me wonder how the computer worked at all. Once I started finding and replacing these bad chips, the stability of the computer improved dramatically.

I have posted a youtube video that shows how I debugged one particular bad chip.

I’m restoring a very early Apple II plus in order to sell. I believe that this particular unit is a very unusual example of an Apple II plus, as it has the second style keyboard with “domed” power light.

The bulb in this power light was burned out, so I did some searching and found an exact replacement is still available.

The bulb on the left is the replacement and the one on the right is the burned out original. The bulb type is a #680 miniature bulb with a wire terminal base. You can find these bulbs for 31 cents each, plus shipping, at www.bulbtown.com. Here is a direct link:

https://www.bulbtown.com/680_Miniature_Bulb_Wire_Terminal_Base_p/680.htm

In case this link goes away at some point, here are the specs:

I’ve run this system over the course of many hours with the new bulb installed. The illumination is exactly the same as with an original bulb and there are no problems with the amount heat generated by the replacement bulb.

This lamp is only a replacement for the bare wire lead bulbs present in early keyboards, as later Apple II keyboards have a different style keyboard power lamp.

See my early Apple II keyboard page for more information on early Apple II keyboards.

http://www.willegal.net/appleii/early-a2-keyboards.htm

I had to create this to debug a Apple IIc alternate memory bank issue. The source has been added to my 6502 memtest page.

In the next day or so, I’ll be adding a youtube video to my channel showing the repair (but not the diagnosis).

The first video is an Apple IIc demo. Once I’m convinced it is 100% working, I’ll be listing this machine on eBay. I’ll be demoing other machines in the future. I’m starting with some machines I need to move out, since I need the space for future activities. Eventually I’ll be demoing some of my keepers like the SCELBI and Apple 1 clones.

I just ran across this old image that was used to make a poster for the first VCF that I had an exhibit at. Based on the date on the files, it looks like the poster was designed in 2008.

The main thing that struck me is that I can’t believe what I was thinking, selling those kits for only $349! You can’t imagine how much effort it took to gather together all the parts and then assemble kits. Eventually I gave up on the kit idea and just sold bare boards. All told, I think I sold something like 16 boards and kits and kept a couple of boards for myself. I made a little money on the project, but if you counted up the hours and calculated an hourly pay rate, it had to be way below than minimum wage.

You don’t find many electronics kits manufacturers these days. I think the main reason is that it is now actually cheaper to build an electronic item than package a kit.

I am sometimes surprised at how little money that some people ask for bare reproduction PCBs. Sometimes, I see people asking less money than what I paid for those PCBs. I suppose if you really dig around, you may be able to find a fab house in Asia that will make a PCB for almost nothing, but my investigations always showed that for larger PCBs and small runs, the most popular offshore fab houses, really weren’t that much cheaper than domestic ones. Thus, I always have my PCBs made here in the USA.