Wednesday, January 27, 2010

A14F Rectifier Diode

I've received quite a few emails on where to find the A14F rectifier diode, and my answer has always been:

It turns out doesn't have them and I do not know where to find them -- if anyone does, please let me know. (I obtained my A14F in a trade for a 2519N with an Apple 1 owner who has long since, sold his board, and I have lost contact with him, so I'm not sure of the source).

Wednesday, January 13, 2010

News tidbits

If you are interested in obtaining your own Apple 1 reproduction kit, you might want to check out to see Mike's progress on the Apple 1 he is reproducing. Hopefully we'll all be able to purchase boards and kits soon!

I was also informed today that Cameron C. is starting a new community for Apple 1 enthusiasts : Cameron is still working on the site but stay tuned.

There are 2 guys working on wire wrapped Apple 1s.

I am working on short videos of my progress -- although my camera sucks, I'll see what I can make available (probably on youtube because of blogger's video size limit).

Second PCB Bug

Mike Willegal had posted a question on awhile ago for someone to check/verify that pin 12 of the Address Decoder / 74154 was connected to ground. From the scans he was working with, he found that pin 12 was not grounded. I checked the board that came with the kit and could see visually, that pin 12 was grounded. At the time I assumed there was nothing wrong with the non-kit board I have, but I assumed wrong. Earlier this week I removed the DIP socket where the 74154 resides, because I wanted to check for solder-bridges under the DIP. I then placed multimeter leads (set to Ohms) from pin 12 to ground and verified that pin 12 is not connected to anything.

I resoldered a new DIP socket, and added a jumper from pin 12 to the ground side of the closest ceramic capacitor. Unfortunately, I am still picking up a 1+ volt signal on ground... more to come on this when I know more.
BTW, it appears at quick glance that the schematics omitted showing GND on each component.

Friday, January 1, 2010


For all of those who purchased an Obtronix board (not the kit) on ebay several years ago, there is a bug on this board. I can't say we all have the same board, but the board I have is missing a trace on D7 (74161) from pin 7 to pin 10. This bug was causing characters to repeat after a reset. I soldered a jumper wire across these pins, and the repeating chars stopped. This bug was found by Mike Willegal ( I verified these pins were not connected by using a multimeter.