Commodore 128 help?

[chaoticjelly]

Hi guys,

 

I just got a Commodore 128 today, apparently rare as Hen's teeth, very very cheap, I was wondering could anyone please help me with it? I've never owned one before. I connected it all up, it's similar to the Commodore 64, but when it's all plugged in, all I get on the TV is a black screen, and nothing happens...

 

Any ideas?? is this fixable?

 

Thanks in advance!

 

Not sure if you have Commodore's in the USA?

[Trooper]

Hi!

 

I don't really think the 128 is that rare, it's of course rarer than the 64 but not insanely rare.

 

About your problems, have you checked that it's not just a dead RF cable, you should get some kind of picture but I guess it could be totally broken.

 

Does the powerdiod come on or is it all dead? Could be just the PSU that's gone if it's totally dead, otherwise I'd guess the RF unit's busted.

 

I hope this is of any help to you.

 

Cheers!

 

Troop

[chaoticjelly]

Hi Troop

 

Thanks for the reply man!

 

I've tried different RF cables, and I've tried the one that I've just had my Atari 520 ST E working on, and it's still the same

 

The power light comes on bright and shining red.. you have to wiggle the bit that plugs into the C-128 around a bit though, I think the wire is loose in the end it looks slightly damaged, but when the power is on, there's no picture it's just all black and slightly fuzzy no writing or anything..

 

I looked on a C-128 website, and it suggested it could be any or all of 6 chips/roms on the mainboard, or the power supply unit..

 

Dont have a spare.

[Trooper]

Ok, well if you get power to the machine which it certainly indicates by giving you the bright red light I think it's either the RF unit or, like you said yourself, one of the chips on the board.

 

I don't own a 128 myself only a bunch of 64's but aren't many of the chips the same as the ones in the 64? If so you should be able to get one or more 64's and exchange the chips from them. This of course is if it's not one of the 128 specific chips that have died but it might be worth trying since a 64 can be had for almost no money today.

 

Cheers!

 

Troop

[Clock]

I used to have a 128, but can hardly remember much about it. It does sound like the RF modulator or something on the main board has gone kaputt. Although I'm no expert on these m/c's

[chaoticjelly]

EXCELLENT idea trooper thank you so much!

 

I do actually have four! commodore 64's lying around, so I may just do what you suggested! will the chips just pry out or something? or do I need special tools

[Ze_ro]

Careful about transplanting C64 chips into a C-128, as some of the chips are different and might not function properly... the differences are often minor though, so you might be safe. If you still can't get it to display anything, you should make sure that the 40/80 key is up... you can't display 80 columns on a TV, only on an RGB monitor.

 

--Zero

[chaoticjelly]

Yeah the key is up...

 

Someone who used to service Amigas told me to try a load command, and if the tape drive runs, then the RF unit is the thing that's buggered..

[Trooper]

will the chips just pry out or something? or do I need special tools

 

Well, if you're lucky each chip sits in a socket in which case you can get them out by using a small (read tiny) screwdriver and pry a bit on each end until it loosens. Be extremely careful not to bend the legs of the chip though, this is very easily done while performing this operation.

 

However, if you're unlycky the chips are soldered directly to the mainboard in which case you'd have to unsolder them using a soldering iron. When doing this it's even more important to be careful and make sure you don't put to much heat on the legs of the chips since this will fry them faster than an egg in hell.

 

Try opening all of your 64's to see if you don't have one where the chips sits in sockets instead of being soldered directly to the board.

 

HOWEVER! I don't guarantee in any way that this will fix your problem, it's just my 2 cents.

 

And Ze_ro is of course right in saying that you should definetely be careful when swapping chips between the machines, however I THINK it shouldn't be any problem as long as you just switch the chips that are the same on both machines.

 

Hope this helps at all, like I said I'm no service technician.

 

Cheers!

 

Troop

[chaoticjelly]

Well the guy who used to repair Commodore Amiga's said they are soldered in.. I think I'll just leave it.

 

I tried loading a tape, but nothing happens, so I suppose some chip on its mobo is shot.

 

I think I'll just use it as a big paperweight

[Trooper]

Well the guy who used to repair Commodore Amiga's said they are soldered in..

 

The ones in the 128? Because I have a lot of c64's and almost all of them have different revisions of the motherboard and some have all the chips soldered to the MB, others have all the chips in sockets and som of them have about 50/50 soldered/socketed.

 

Would be a damn shame to use it as a paperweight

 

Cheers!

 

Troop

[Chris++]

It couldn't hurt to try forcing the computer into C-64 mode while you're powering up. If the C-64 screen comes up just fine, then at least you've narrowed it down to one of the chips exclusive to the 128.

 

To try this, do the following: With the computer off, hold down the key with the Commodore logo on it (lower left corner). Now make sure you're still holding it down as you turn on the power. Wait a few seconds before releasing the key. Usually, this forces it into C-64 mode. If this still doesn't work, then yeah, slowly type LOAD "$",8 and hit the Return key, and see if the drive starts spinning.

[lhfreak]

I was gonna say the same thing as Chris++.......try to boot it in c64 mode....Do you have it hooked to a tv or a monitor? I recall having this problem once and it had something to do with the 80 col mode......check the 40/80 col button on the keyboard......sorry thats not too helpful, but at least try to boot it in c64......after all that is what you'll most likely use it for anyway......(The only game I ever had for the 128 exclusivley was Beauacracy by infocom.....wish I still had that sucker!!!)

[Ze_ro]

Another thing you might want to try is to attach a disk drive, and then hold Shift and hit Run/Stop. On the C128, this will attempt to load and run the first program on the disk, so if the disk drive spins, then you're probably right about the RF modulator (On the C64, this same action will trigger a Tape load instead... although without a display, you will see no confirmation that it did anything in C64 mode).

 

If that's the case, you might want to find a video cable for the computer to avoid using the RF modulator entirely. The C128 can use the same Luma/Chroma/Audio cable that the C64 uses, so that's a definite option (At least, this is the case in North America). You can also try using a DB-9 cable to plug it into a digital RGB monitor like the 1902 (although these monitors aren't terribly easy to find unfortuntaely). If you're not getting a picture through the RF though, then it's probably unlikely that you'll get anything through composite either... could be a problem with the VIC-II chip that handles the video signal (it's worth mentioning that the RGB output uses a different video chip, which is possibly undamaged in your unit).

 

One more option is to open up the machine and try to re-seat all of the socketed chips (if any). Over the years, they can sometimes corrode enough that the connection is no longer good... just pry them up a bit on each side and push them back down. A cruder method is the 4" drop that I've seen in various Atari ST FAQ's... lift the computer about 4" off the table and drop it. The force of the impact may reseat the chips, and is unlikely to break anything... although I'd still recommend the more careful approach

 

--Zero