360K Read ok, 720K Disk offline

Rookie (28)

04-08-2011, 22:28

After changing the 360k original drive out of the vg-8235 for an old pc FDD, the loading process of a game on a 360k formatted disk is fine.

But strangely games on 720k formatted disks refuse to load, I get "disk offline" or "disk offline in 10" errors...

Any clues?

The wiring on the main disk cable has been changed, 2 points have been soldered on the back of the mainboard (just in like bas-ditta's pdf tutorial) and the PC FDD has been modified to DS0 ( default A: instead of B: ).

I don't know what to do next, could it only be the disks? Then why does the one disk load fine with 360k and shows "disk offline" with 720? I don't get it..

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By boss_msx

Champion (415)

04-08-2011, 22:43

Did you replace the diskrom IC?

By s0ph0r

Rookie (28)

04-08-2011, 22:45

Nope, since for reading only the original diskrom should be fine, shouldn't it?

By boss_msx

Champion (415)

04-08-2011, 22:53

I don't think that's true. You should ask Bas the same question and he will probably sell you the diskrom...;-)

By Daemos

Prophet (2051)

05-08-2011, 00:37

There is indeed a difference. The original diskrom only supports 720Kb for external drives. You will have to change the diskrom.

By s0ph0r

Rookie (28)

05-08-2011, 07:46

Okay, I will change it. Hopefully bas has some left for me.

How do I put that chip out and the other in? Is it soldered or something? Do I have anything to be aware of?

By boss_msx

Champion (415)

05-08-2011, 09:55

Bas has instructions on his site how to do it.

Use a low voltage, small solder-station.

First cut all pins from the excisting IC, then use a TIN remover and remove all loose pins on by one as well as the TIN left in the holes. Put the IC Socket (pins) on the holes of the old IC and solder the pins to the board from the backside. Then gently plug the IC in the socket.

By jalu

Master (158)

05-08-2011, 21:40

For as far as I know, all VG8235s already have the DiskROM in a socket. So exchanging it is quite simple.

By Repair-Bas

Paragon (1170)