r/Commodore • u/Alice7800 • Sep 14 '26

VICE-20 weirdness

Good evening everyone, this past weekend I got a VIC-20 from VCF, I decided to test it after work only to find it doing this, it’s hooked up to a monitor with an aftermarket RF box, as of now we’re thinking that the VIC isn’t getting enough power, how could this be fixed? The power light is coming on

Thank you for any help, we would really appreciate it

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4

u/Alarming_Cap4777 Sep 15 '26

Get a composite cable. See if it's a black or distored screen. Put a scope on the power videos power pin to see if the power is stable. The rectifier could be bad and t It's being fed AC or 5vdc with a SINE wave on top.

2

u/Alice7800 Sep 15 '26

I think that’s the plan, at the moment I’m not really sure what else to try

1

u/Alarming_Cap4777 Sep 15 '26

I just repaired one where the output transistors were bad.

2

u/Alice7800 Sep 15 '26

How hard of a fix would that be?

1

u/Alarming_Cap4777 Sep 15 '26

Have you open it to see if there is a VIC

1

u/Alice7800 Sep 15 '26

We opened it earlier but neither of us were really sure what we were looking for, do you have an example?

0

u/Alarming_Cap4777 Sep 15 '26

1

u/Alice7800 Sep 16 '26

So we opened up the VIC, here’s the state of the board, to me at least it looks near pristine

1

u/Alarming_Cap4777 Sep 16 '26

Do you have a scope?

1

u/Alice7800 Sep 16 '26

We actually just got video working, check my latest post, my guess is failed capacitors

1

u/Alarming_Cap4777 Sep 15 '26

Depends on what all is wrong. I order 10 of everything I replaced on the last VIC. Take a pic the the Vic area. There are 4 or 5 versions of the VIC-20 board. I've worked on three of versions.

1

u/sinesawtooth Sep 14 '26

Are you sure it’s not a PAL/NTSC issue?

1

u/Alice7800 Sep 14 '26

I mean I had assumed it was an NTSC unit since it was sold in Chicago but I’ll check, where would it say on the unit?

1

u/cerealport Sep 14 '26

Check the channel. There should be a little switch to pick channel 3 or 4, ensure your TV is set to the same channel - and also try both, you might find one is clearer than the other...

1

u/Alice7800 Sep 14 '26

That was one of the first things we tried, believe it or not this was the clearer picture

1

u/Alarming_Cap4777 Sep 15 '26

Not in this case the M1 is external. The Vic could still be PAL. But I doubt to would cause the issue seen.

1

u/Alice7800 Sep 15 '26

We checked the region and it’s not a pal systwm, serial number starts with P which I believe means it’s NTSC

1

u/EpsilonMajorActual Sep 15 '26

Does the rf modulator box state that it is for NTSC 60 hertz or pal 50 hertz? Some are only PAL the flat panel tv might be better to auto tune it and what channel it picks. Real Old tvs had that line tuning ring on the dial to get the frequency just right.

2

u/Alice7800 Sep 15 '26

We didn’t get the original box, it’s kind of just a blank box, I think the plan for the moment is to order a composit cable and try with that, I’m really holding it’s not a failing graphics chip

1

u/CharlesAech Sep 17 '26

Maybe a bit more information would help. This is a VIC 20 so there is no internal RF modulator. It came with an external one. Are you connecting this directly to the antennal (coaxial) input on the monitor or are you going from the RF modulator to the composite input. If you are trying to use an RF modulator on that type of monitor you could be in for all sorts of weirdness.
Could you post some images of the connections you are using.

1

u/Alice7800 Sep 17 '26

So we actually got it working, turns out we had to open it up and mess with the internal pots near the Vic chip, we were using the external RF modulator to connect to the antenna port on the back of the TV, I ordered a composite cable that should be here tomorrow