Denial

Sorry for the delay. I've been helping a friend who lost her house in one of the LA area fires.

I basically left what works alone, and moved on to other projects. I never did easily find what the issue was.

Joe

I haven't done a thorough test as of yet. But I do intend to try both CP tester styles all on of my VIC's and post results.

Merry Christmas!

Joe

FINAL UPDATE: I replaced the Zener Diode, and it made no difference. So I replaced the two transistors at Q3 and Q4 at the same time (just to not do one, test, then do the other in case the first failed). And now the diagnostics pass the Cassette Test with a "OK". Good thing too! I haven't...

I just did another test measurement on a different VIC-20 (CR version). The voltage on the cassette edge connector 3 stays close to zero before the cassette port test is run, and then it goes to 5 volts during the test. On the system with the false BAD test result, the voltage hovers around 4 to 5 v...

I need to acquire some replacement parts for a VIC-20 (two prong power) board. Of the items that I need to acquire and replace is the transistor at Q4, the transistor at Q1, and the Zener Diode at CR1. I'm trying to resolve a false "BAD" result that is appearing during diagnostics, even th...

UPDATE: I spoke a little too soon. It turns out that some of the VIC-20's work with the cassette harness that does not have the 27ohm resistors, while others need the harness with the 27ohm resistors. I still have one VIC-20 two prong system that can't pass the test regardless of which harness I use...

I can hardly wait to see one in person!

Great work!

Joe

I found a solution to the problem with the cassette diagnostic harness. The harness that would give me false BAD test results has the following design: cassette.jpg The harness above works fine on CR VIC-20's, but not with the original (two prong power) design VIC-20's. I found Ray Carlsen's hand dr...

Never mind!

Found it!

http://sleepingelephant.com/~sleeping/i ... hp?t=10360

Joe

I know that I've seen somewhere the ROM for the VIC 20 diagnostics that was modified to continue past any errors. I don't know if I already have a copy of it or not. But I can't find the website where I found it before.

Does anyone have this ROM link?

Thank you!

Joe

Last week I found this YouTube video on building a low cost VIC-20 two-prong power supply. The video is from 5 years ago. https://www.youtube.com/watch?v=W3WDOUbzKZM I was able to zoom in on the part of the video that shows the power adapter. It's has the following markings: Model #: K10145WHGN-1 Vo...

Thank you for the reply. I think I'm going to try Ray Carlsen's design while using a breadboard to host the harness wiring connections, including the resistors. I have a few cassette port connectors that I can put to use as well. With this configuration, I can swap out resistors quickly if I need to...

Before I go off on an exploration of my other two-prong VIC-20's for a potential answer, I was wondering if anyone has had the following issue: I have two two-prong power supply VIC-20's I'm working on. They both boot just fine. When I run the diagnostics on both of them, I get a BAD result for the ...

I have two Plus 4 computers. The one I recently acquired on ebay had a bad PLA, so I ordered a modern replacement. I received it over the weekend, and installed it today. The Plus 4 booted up with no blank screen like it had before. But when I try to use a cartridge or try the keyboard, neither work...

Another update: - The shield has been cleaned and re-soldered to the main board (with the paper insulator between the two). - I have not been able to recreate the initial issue with inserting a cartridge since cleaning/lubricating the cartridge port (twice) with Deoxit. The system still passes all o...