What failures have you had?

[mrr19121970]

I know @Ken strongly disagrees. Buying on eBay as 'untested' really is a synonym for 'i took a dump on the mainboard' and fried chips - buy from me and it's now your issue.

I read Ray Carlson's trouble shooting guide, his 'top 5' list seem to be KERNEL, VIC-I, ROM and VIA. I wanted to hear from others also what their issues have been. This is what I've seen so far:

9v machine
Switch issues
Fuse holder
VIC-I

CR machine
6502
VIA1
char ROM
(yet to be diagnosed issue, resolved by resetting a few times - eslapion suggests the reset electrolyte)

[srowe]

Both the KERNAL and BASIC ROMs in my original 2-pin VIC were faulty when I brought it out of storage.

The other original 2-pin I bought on eBay was functional (and used to diagnose the issues with my first VIC).

[Boray]

A: 9V Vic: Rectifier desoldered itself from heat problems causing humming in the sound while using tape, and burning the fuse. The problem probably started by that the heat sink for the rectifier was a bit loose. I have changed the rectifier and actually moved it (and the regulator) outside of the computer.
B: 9V Vic: The color yellow turns gray without a heat sink on the vic chip.
C: CR Vic: Keyboard totally unusable before it was cleaned inside. A logic chip was bad and had to be replaced. Tweaking the picture screws was necessary.
D: CR Vic: Keyboard totally unusable before it was cleaned inside. Tweaking the picture screws was necessary. The picture is a bit too grainy and probably needs a S-video mod.

...and that's all of my vics so 100% needed some kind of repair.

[srowe]

I forgot about the keyboards, both the VIC and C64 I bought off eBay needed the contacts cleaning.

[mrr19121970]

Well I got a gold label NTSC VIC-20 9v today. Other than having to:

. vacuum clean the inside (full of fuzz balls)
. fudge abit with a 'eurostecker' and a 9v AC transformer (it is completely different to the Euro 9v connector)
. really force the on-off switch (it was really stiff)

I was amazed it worked.

[R'zo]

I had to replace a via chip when I got my vic (2-pin) a little over a year ago.

[RobertBe]

Several keys not working on the keyboard...

Truly,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm

[joshuadenmark]

MOS 6502 - pin corroded, replaced chip.

[mrr19121970]

I think on Saturday I had (self inflicted) 180 degree bend on pin 17 of a NTSC VIC-I. Funnily enough it still worked. Careful work with the tweezers returned it to the correct position. POT X, what is it? Something for paddles?

[srowe]

POT X, what is it? Something for paddles?

Yes, POT X and Y can be attached to variable resistors and give a reading between 0 and 255. They are used for paddles and analogue joysticks. I remember hooking mine up to a light-dependent resistor, my VIC had a 'eye'

[Muzz73]

My VIC's have been very reliable over the years, but I have had a few bumps along the way...

Original VIC:
Voltage regulator that kept popping fuses

CR VIC:
6502
6560-101
Bad resistor in audio circuit

I also had a a component in one of my external RF modulators go kaput, but that's not necessarily a VIC-20 problem...