We’ve recently acquired a pair of non-functioning Commodore VIC-20 and are looking at fixing them.
Overall condition
The boards are both somewhat clean, and visual inspection does not reveal anything weird. No missing chips, no lifted pad. No bodge wires. Except that one of the boards has had its game port replaced in the past, but not with a correct right-angled board-mounted one, rather with a set of wires.
While we applaud the resilience of whoever fixed this, we will likely replace it with a more appropriate part.
Square 2-pin power supply?
When bidding on this specific set of VIC20s, we thought we’d be powering them with our trusty modern Keelog (no affiliation with wereallgeeks) replacement Commodore 64 Power Brick. But something we didn’t notice in the auction that was crystal clear when we got them, is that it won’t be possible.
Both VIC-20 boards are of the original, 2-pin power connector, with only 9VAC power input, power conversion being done onboard. These are the early types VIC-20s, often gold or silver labels, and perhaps maybe even a PET keyboard. The PCB was designed in 1981. Latter, reduced cost versions VIC-20 used the same connector and power brick as the Commodore 64.
The power brick on these early VIC-20 were 9VAC to 10VAC at 3A or 30VA. With a square connector. They sometimes pop on auction sites, but pricing is ridiculously high for just a power transformer. Readings online on atariage or other forums demonstrate the connector itself isn’t exactly easy to locate either.
Bypass the AC and power them with DC?
The same forum threads shows there are people who simply power those VICs with DC power – sometimes using the onboard power conversion trough the original connector, using the unmodified power circuit; and sometimes bypassing it with alterations to the circuitry; either with the original connector or an added one.
But starting from an unknown board, it may be a better idea to begin with proper AC power and diagnose the whole thing. Alterations may come at a latter date.
So, the hunt for a power solution begins.
Nest step: VIC-20 repair log #3 – Power tests
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