Need help with C128D (Black Screen)

[Popstar]

Here's what happened:

I turned on my 128D to test if the floppydrive was working and also to test my 'new' monotone monitor.
I tried it out (the 128) one week ago on my TV and it sort of worked, but not the floppydrive. The 64 mode worked fine, but again not the floppydrive.

The computer starts up just fine in basic with the ready screen and everything.
I haven't really tried a 128 before so to test the floppy I decide to go into C64 mode, which I know much better.
I type GO64 and Y and the screen turns blank... and continues being blank.
Since it is a different screen I never tried before I spent a lot of time messing with the screen before deciding it might not be the screen that's the problem.
I then turn off the 128 and turn it on again. Now the screen is just blank.
I connect the 128 to my TV and turn it on. Nothing but a black screen. (Not static, just black).

So: does anyone know what can have gone wrong with my C128D ? It seemed to 'die' the instant I tried to go into C64 mode.

Thanks for your time.

[Stephane Richard]

The C128 has 2 video modes, a 40 column display (using the same chip as the C-64 mode THE VIC-II ...and a VDC chip for an 80 column display.  

Perhaps you are just in the "other" video mode.  for fun try to press the 40/80 column key on your 128 keyboard (I believe the upper right corner group of 4 keys has that key.  you might need to press that key and the reset your 128.  Let me know if that worked (or not).

[hydrophilic]

If you have a black screen with both a TV and a monitor then it sounds like your Commie has died.  

However, it may be a bad power supply.  It supplies 9VAC and 5VDC.  The computer LED will light up when you turn it on if 5V is working, but it won't do anything else without 9VAC.

You would need at least a voltage meter to check that power is good.  If it is good, your Commie probably has a blown chip or maybe a crack in the motherboard...

Good luck!

[Popstar]

Ok, I forgot to say that I tried all the things I could come up with, like turning on the computer with 40/80 switched on and off, with caps lock on and off etc. and I even tried to disconnect the floppydrive and all floppydrive related hardware.
I also tried inserting a Final Cartridge III to force it to start up in C64 mode.
As for the power: When I turn on the computer, the power LED turns on (and stays on) and the drive LED turns on, there's a tiny audible click from the drive and the drive LED turns off. And that's it.

I do have a voltage meter, but I don't know how to use it except for using the beep to check wires.

[Mangelore]

Hi,

Do you have an IC extractor? If so, remove the SID chip (U9) and try powering up without it.

If that doesn't help, try reseating the ROM ICs: U18, U32, U33, U34, U35.

Failing that try swapping the two VIA chips (U1 and U4) around. Next step would be to remove them.

Check to see if any IC is hot after the C128D is powered up for 5 minutes or so.

Don't go playing around with the C128D power supply unless you know what you're doing.

Cheers
Mangelore

[Popstar]

I got the computer without SID chips, so it's not that.
Reseating the chips? Is that like taking them out and putting them back in?
Anyway, thanks for the answers, I will take a closer look at it when I get back home... And I won't start playing with the PSU, don't worry