Defective Commodore 64?

[Noah98]

I received a Commodore 64 through ebay today and I believe it is defective. I've attached a photo of the boot screen which only renders garbled text. Any thoughts?

[awhite2600]

Looks like bad RAM. Could also be a problem with a data or address line between the RAM and the video chip.

 

I'm not much of a hardware guy so not sure what you might be able to do to fix it. Hopefully another member here can offer some advice.

[Keatah]

I am an expert at Apple II repair and used to know C-64 stuff. I kinda got away from that and remained focused on the Apple series.

 

But the info in post #2 is an excellent place to begin. If you can get some freeze-spray component cooler and blast those chips briefly, you might get lucky and locate the bad part without electronics knowledge.

 

Otherwise you'll probably need a 'scope to look at address & data lines. Failing that, it's going to be block-diagram guessing and process of elimination.

 

Have you tried loading anything? Blindly of course.. And if so how is the sound?

What about cartridges? How's that working?

Edited July 18, 2013 by Keatah

[98PaceCar]

My first guess would be the power supply is flaky (a lot of them are), but it could also be U5 (character rom).

 

More information here: http://personalpages.tds.net/~rcarlsen/cbm/c64/c64-ic.txt

[Noah98]

Thanks for the info! I sent it back to the ebay seller, and purchased another one. Hopefully this one works fine.

[Noah98]

My second C64 from ebay was DOA even though the seller swears it worked befor shipping

 

I replaced the fuse and reseated the chips, but still dead. It's not worth the money to replace the chips that may be defective, or even the power supply too. Oh well, another return to ebay...

 

Are the "breadbox" models prone to failure? The two I had looked immaculate and had the original boxes, but were still dead. I bought a bunch of game cartridges on ebay and still can't secure a working system! Are the 64c models made better?

[Galeforcerm]

I thinks its a crap shoot with all of them. I've thrown away more c64s than any other system. Both breadbox and c64c. I think bad power supplies kill them.

[RickR]

I thinks its a crap shoot with all of them. I've thrown away more c64s than any other system. Both breadbox and c64c. I think bad power supplies kill them.

 

I second this. I must have bought six before I found one that worked perfectly. In many cases, it seemed like one of the RAM chips was bad. It's one more reason why I don't really like the C64 now, after having drooled about them as a teenager. Although i still own one.

[Noah98]

3rd one from ebay has a bad power supply and looks pretty rough! Meanwhile my 800 XL, XEGS, and Ti 99 4/a are all working just fine...

 

I wanted one of these so bad when I was a kid, but settled for a Ti 99 4/a instead. Now I'm starting to think that the C64 isn't worth the trouble investing in...

[Keatah]

I had two defective c64 consoles back then, and I don't know how many 1541 drives blew up on me.

 

Have you thought about enjoying the 64 through emulation?

[Noah98]

Was able to cobble together two broken C64's to make one functional one. Hope it's worth the hassle!

Edited August 2, 2013 by Noah98

[R.Cade]

For sheer volume of software, there is no better 80's computer.

[Keatah]

For sheer volume of gaming software, there is no better 80's computer. Fixed that 4 u.

[Keatah]

Was able to cobble together two broken C64's to make one functional one. Hope it's worth the hassle!

 

We shall see!

[+grips03]

Was able to cobble together two broken C64's to make one functional one. Hope it's worth the hassle!

 

have you purchased a Ultimate 1541 II? Makes playing C64 games very easy

[Noah98]

 

 

have you purchased a Ultimate 1541 II? Makes playing C64 games very easy

 

I was thinking about buying something like this:

 

http://rover.ebay.com/rover/1/711-53200-19255-0/1?ff3=4&pub=5574883395&toolid=10001&campid=5336500554&customid=&mpre=http%3A%2F%2Fwww.ebay.com%2Fitm%2FC64-SD-card-SD2IEC-SDrive-1564-card-interface-Commodore-1541-emulator-%2F111133787686%3Fpt%3DUS_Vintage_Computing_Parts_Accessories%26hash%3Ditem19e0170626

 

Is this basically the same thing?

[+grips03]

I was thinking about buying something like this:

 

http://rover.ebay.co...=item19e0170626

 

Is this basically the same thing?

 

I think U1541II has higher compatibility, but I've not tried the SD card, lemon64 might know

[R.Cade]

I was thinking about buying something like this:

 

http://rover.ebay.co...=item19e0170626

 

Is this basically the same thing?

 

No, those are nice and work well, but don't handle disk images with special loaders, which is a LOT of them. That device emulates something like a CMD hard disk, while the 1541U emulates a floppy drive.

[Hatta]

The SD2IEC devices do support floppy images, and act like a floppy drive for the most part. You will encounter incompatibilities with copy protected disks and some fast loaders, but a lot of stuff has been cracked too. If it works in VICE without true drive emulation turned on, it should work on an SD2IEC/uIEC type device.

[TMR]

A C64 disk drive is, essentially, a computer in it's own right with a 6502, some RAM and I/O chips and most of that just isn't simulated by the SD2IEC-based hardware; anything that relies on that hardware to change how data is transferred in some way attempts to dump drive code to the RAM and falls on it's backside.

 

The 1541 Ultimate 2 and Turbo Chameleon both emulate the drive far more fully and, although they are expensive, you also get other features for that money such as cartridge emulation for fastloaders (so no rooting around on eBay for an Action Replay or Final Cartridge) or EasyFlash and support RAM expansion up to 16Mb (which is utilised for caching of game data by some cracked games, significantly speeding loading up to almost cartridge speeds...

[Noah98]

The 1541 Ultimate 2 looks amazing! Is it really $200 though?

[R.Cade]

The 1541 Ultimate 2 looks amazing! Is it really $200 though?

 

Really more like $160, but yes.

[Noah98]

 

 

Really more like $160, but yes.

 

Where could I buy one for $160?

[R.Cade]

They are 119.96 EUR (including shipping) which is $160 USD. You will have to wait until the next batch is built.