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VIC20 cartridge slot not working

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I purchased a commodore vic20 and after replacing the large capacitor that had some damage it turns on to basic and will play cassette tapes however it will not read cartridges. I have about 20 cartridges so i dont think they would all be bad. I also cleaned the cartridge slot and dont see any visable damage. I tried a basic code of FOR A=0 TO 40:PRINT PEEK(8192+A);:NEXT which gave me a bunch of 32's whether or not a cart was inserted, not sure what that would mean though lol. Not sure how to go about diagnosing the cartridge slot im just starting on learning how to diagnose and repaire things so my experience and ability is limited though i do want to get better at it. Any help would be greatly appreciated, thanks!


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At the risk of stating the obvious.... are you certain you are pushing them in fully?  The VIC cartridge slot is very tight, the cartridges need a good shove to push them all of the way in.   Far more than for an Atari or the later C64.


If you are certain they are fully in, the obvious suspects is the +5V line (Pin 21).  There are multiple GND points on the slot.   As a test you might ground the reset line and see if that resets the VIC. 

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  • 2 weeks later...
2 hours ago, impactlapod said:

@oracle_jedi yeah it's assuredly shoved all the way in ;) I've made sure of that and with multiple carts. When you refer to +5v line (pin21) that's on the cartridge connector right?

Yes,  might be simplest though to take the case off a cart and then measure across one of the chips. 


Pin X is the reset line.   Ground that and the VIC should reset.



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