Vic 20 Black screen

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Darbyram
Vic 20 Newbie
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Location: United Kingdom

Vic 20 Black screen

Postby Darbyram » Tue Sep 26, 2017 9:32 am

Hi there my vic 20 has just died with black screen, before that it had crashed in a game. the led lights up when i power in on.
Cant start the cassette deck with shift-runstop. sometimes when turning it on and off i get a screen full of garbled characters. any thoughts?

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srowe
Vic 20 Nerd
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Re: Vic 20 Black screen

Postby srowe » Tue Sep 26, 2017 12:38 pm

Welcome to Denial.

Ray's excellent diagnostic document is a good starting point

http://personalpages.tds.net/~rcarlsen/cbm/vic20/vic20.txt

There are a number of possible causes:

  • CPU
  • VIC
  • RAM
  • Address line buffers

Are any of the chips in your system socketed? If they are it's an easier task to swap in known good replacements.

Darbyram
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Joined: Tue Sep 26, 2017 9:25 am
Location: United Kingdom

Re: Vic 20 Black screen

Postby Darbyram » Tue Sep 26, 2017 12:53 pm

Thanks just looked at the guide. i have just left it on the black screen with led on for about 20 minutes and it turned itself off??

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srowe
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Re: Vic 20 Black screen

Postby srowe » Tue Sep 26, 2017 1:45 pm

By "turned itself off" do you mean the power LED has gone out? That would suggest the fuse has blown or there's a more fundamental issue with the power supply.

Darbyram
Vic 20 Newbie
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Joined: Tue Sep 26, 2017 9:25 am
Location: United Kingdom

Re: Vic 20 Black screen

Postby Darbyram » Tue Sep 26, 2017 2:17 pm

Yes the LED light goes out and screen turns to static like it does when you switch it off

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srowe
Vic 20 Nerd
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Re: Vic 20 Black screen

Postby srowe » Wed Sep 27, 2017 12:58 am

Check the clip that holds the fuse within the VIC, it might not be making a good contact.

Which model do you have? The original two pin or the CR with the round DIN socket?

Darbyram
Vic 20 Newbie
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Joined: Tue Sep 26, 2017 9:25 am
Location: United Kingdom

Re: Vic 20 Black screen

Postby Darbyram » Wed Sep 27, 2017 6:14 am

Fuse and folder ok, its the round DIN type

Edit..just ordered a new board that's been tested and a decent price :D

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beamrider
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Re: Vic 20 Black screen

Postby beamrider » Wed Sep 27, 2017 9:21 am

Are you using an original PSU? If so that could have fried it...

Darbyram
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Joined: Tue Sep 26, 2017 9:25 am
Location: United Kingdom

Re: Vic 20 Black screen

Postby Darbyram » Wed Sep 27, 2017 9:54 am

yes its an original wedge one..how do i go about testing it?

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srowe
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Re: Vic 20 Black screen

Postby srowe » Wed Sep 27, 2017 1:00 pm

Do you have a multimeter? I'd be careful about plugging a new board into a suspect PSU. You should have a steady 5V DC off pins 4 & 5, 9V AC off pins 6 & 7.

http://sleepingelephant.com/denial/wiki/index.php?title=Power_Supplies

I'd check the voltage while plugged into the current board, if it's producing too high a voltage it might have damaged some chips already.

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beamrider
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Re: Vic 20 Black screen

Postby beamrider » Wed Sep 27, 2017 1:11 pm

I think the general consensus is not to use those PSUs without replacing or upgrading them.. Even if it tests OK at the moment, it's quite likely to fail in the future. Also I've heard it said that the voltage over-supply can be sporadic so might be ok when you check it but spike at other times.

See this thread...a similar thing happened to me.

viewtopic.php?f=11&t=8318

Darbyram
Vic 20 Newbie
Posts: 6
Joined: Tue Sep 26, 2017 9:25 am
Location: United Kingdom

Re: Vic 20 Black screen

Postby Darbyram » Wed Sep 27, 2017 2:04 pm

Cheers guys. don't have a multimeter. I have ordered another PSU that's been tested

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beamrider
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Re: Vic 20 Black screen

Postby beamrider » Wed Sep 27, 2017 3:46 pm

As mentioned if its an original one there is no guarantees it won't spike. Need a modern PSU to be safe or get a "saver" device to connect between the PSU and the computer.

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Floopy
Vic 20 Enthusiast
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Re: Vic 20 Black screen

Postby Floopy » Wed Sep 27, 2017 4:37 pm

It's the BSoD, :lol:
(Black screen of death)
-Floopy

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Mike
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Re: Vic 20 Black screen

Postby Mike » Thu Sep 28, 2017 5:33 am

Darbyram wrote:i have just left it on the black screen with led on for about 20 minutes and it turned itself off??

What did you expect? That the initial damage inside your VIC-20 would repair itself?

don't have a multimeter.

Then buy another set of working VIC-20 and PSU on ebay.

Using either a defective VIC-20 (with internal shorts on the voltage rails or within ICs) or a defective PSU (with overvoltage due to a defective voltage regulator) is likely going to take the other, functioning unit with it.

If you don't own a multimeter, you have no way to zero in on the originally defective part.


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