Weird VIC-20!

[DoctorSpuds]

Ladies and gentleman of the retro computing world... this VIC-20 makes absolutely no sense. It seems to be a bit of a Frankenstein's monster, it has the wrong badge and keyboard type for the model number board (1001006 REV 3), it has a PET style keyboard with mustard function keys, with a silver (not rainbow) VIC-20 badge while the serial number sticker is for a VIC-1001. Clearly the keyboard has been replaced at some point, what really confuses me though are two of the chips on the board, they are a dark grey color with a plaque for the chip type and number, but here's the kicker the pins are gold. Could this have anything to do with the serial number, which to date is the lowest I've seen (102640). Here's a link to a VIC-20 serial number registry (currently mine is at the top) https://cbmvic.net/registry/all, you'll get more detailed info there. Here's some pictures for you to mull over, any help or info at all would be appreciated. It was owned by a fairly prominent journalist (I will NOT tell you his name), so it may have been a 'review computer' sent to him by Commodore, but there would likely be something in or on the case/board saying that. Also I have no means of powering it on yet, seeing as I don't have an a/c adapter that fit's nor do I have the proper video cables.

 

Help, please

Edited August 29, 2018 by DoctorSpuds

[Mayhem]

That's a very old 6502 there! To me, it looks like the bottom half of a VIC1001 and the top half of an early US VIC-20.

[DoctorSpuds]

That's a very old 6502 there! To me, it looks like the bottom half of a VIC1001 and the top half of an early US VIC-20.

 

It's a pity that it's mismatched, but the main thing I'm confused about is the two chips, I've only ever seen chips like that on prototype or lab copies of video games.

Any info would be highly appreciated.

[carlsson]

Aren't those what are referred to as "ceramic" as opposed to "plastic"? Yes, those mainly appear on prototypes or very early production machines. I may have a few of varying models, though not commonly seen. I believe there was someone who posted pics of a very early production C64 with such kind of chips too, so this may very well have been an early production VIC-1001 which got a new upper case in order to launch a review sample of the VIC-20.

 

However as noted in another thread, the VIC-1001 was introduced in October 1980, the VIC-20 was announced in January 1981 with expected delivery by March, but still by May or June it was a rare find even on the US market, with supply trickling out by the early fall, around the same time the first batches of PAL models hit the European markets. Unless the VIC-1001 exclusively used ceramic chips, one would have thought that a pre-launch VIC-20 built from a production model 1001 to have plastic chips as it had gone so long between October 1980 and Feb-Mar 1981.

[DoctorSpuds]

However as noted in another thread, the VIC-1001 was introduced in October 1980, the VIC-20 was announced in January 1981 with expected delivery by March, but still by May or June it was a rare find even on the US market, with supply trickling out by the early fall, around the same time the first batches of PAL models hit the European markets. Unless the VIC-1001 exclusively used ceramic chips, one would have thought that a pre-launch VIC-20 built from a production model 1001 to have plastic chips as it had gone so long between October 1980 and Feb-Mar 1981.

 

I have done many google searches to find the same model board as the one in my VIC, and only one of the pics I've seen have the ceramic type chips, and it's got an even lower serial number than mine (101516), very interesting since most boards I've seen, even from VIC-1001's don't have the ceramic chips, (perhaps they were using up old stock?). Again, since this was previously owned by a journalist it isn't too far fetched to think that Commodore swapped the keyboard on an early VIC-1001 they had sitting around for an early PET style VIC-20 keyboard and shipped it off as a review machine, at least I hope that's what they did, since it makes for a far better story.

 

Last Minute Addition: After doing more googling I have found that the strange object at the center top of pic 4, is a bridge rectifier (MDA970-1, m7732), for converting AC current into DC current, does this mean my machine has a built-in power adapter? Because I have two pin power cables that would fit the plug, but I don't dare power the machine up for fear of destroying it. I have not seen this on any of the board I've looked at which leads me to believe this was added by the previous owner, is it safe to power on?

Edited August 30, 2018 by DoctorSpuds

[carlsson]

Yes, all the early VIC-20's take 9V AC input, in the range of up to 2-3 ampere. Not until the VIC-20CR version with 5-pin DIN input, they took the dual voltages of 9V AC + 5V DC.

 

However, as noted it has a rectifier which means it will be alright to power with 9-12V DC if the power supply can deliver enough amount of ampere/watt. It is due to part of the power supply is inside the computer it runs so hot.

[DoctorSpuds]

Yes, all the early VIC-20's take 9V AC input, in the range of up to 2-3 ampere. Not until the VIC-20CR version with 5-pin DIN input, they took the dual voltages of 9V AC + 5V DC.

 

However, as noted it has a rectifier which means it will be alright to power with 9-12V DC if the power supply can deliver enough amount of ampere/watt. It is due to part of the power supply is inside the computer it runs so hot.

 

I have located a snag... The fuse is blown... I think the guy I bought it from just used a 2 pin plug that goes directly to the mains like what you find with stereo or radio equipment, I'll need to get a new fuse before I do anything, thankfully they're incredibly cheap on ebay.

[carlsson]

Ouch! Let's hope the fuse blew before something else blew if you feed 115V into equipment expecting 9V.

[DoctorSpuds]

Ouch! Let's hope the fuse blew before something else blew if you feed 115V into equipment expecting 9V.

 

From the looks, and smell of it, only the fuse blew. I've done my fair share of chip/board frying and this doesn't have the "melting circuit board/internally dying chip" smell. If it did I wouldn't have bought it.

[Mayhem]

My VIC-1001 and PAL revision A C64 both have ceramic chips in them iirc. Certainly in the case of the latter, the early VIC-II chips were made in ceramic before swapping to more heat tolerant plastic type.

[Jacklyn]

Out of curiosity...I have a VIC 20 in the box with everything original. I would like to sell it and you guys obviously know a lot more about these than I do. Can you Gentlemen tell me what the value is on this? Serial # P1691266

[markx999]

Perhaps it was modified from using the Katakana special characters to using the PETASCII graphics characters