Subj : Re: Advice on the best drive emulator?
To : All
From : Kenzo
Date : Sat May 07 2022 08:57 pm
On Saturday, May 7, 2022 at 4:43:36 AM UTC-7, Paul Förster wrote:
> Hi Kenzo,
> On 07. May, 2022 at 00:06:36 CEST, "Kenzo" <
[email protected]> wrote:
> > So my physical 1541 prevents the C128 from completing boot up when the drive
> > is powered on and serial cable connected. If I kill the power to the drive
> > while the 128 boot up is hung, the 128 completes booting. Same if I disconnect
> > the serial cable while the 128 is hung on bootup. And the drive does not
> > respond to load command, 128 reports drive not ready.
> >
> > I opened the drive case, board is internally very clean, and no burnt or
> > bloated caps. I am guessing one or more of the logic chips is bad. Looks like
> > the MOS chips are from 1984. I am using an aftermarket serial cable, the cable
> > pins look correct when compared to online pics, and continuity pin to pin on
> > each end is good. I guess these serial cables are supposed to be pin to pin
> > straight wired.
> >
> > If I get some ambition in the next few days, I will use my scope to check for
> > activity on the logic chips. My understanding is that with the scope ground on
> > a chip ground and scope lead on address or data pins, I should see high speed
> > voltage oscillation, indicating logic activity...
> >
> > Hate to give up on all my floppies, even if I pick up an emulator...
> The usual suspects are:
>
> 1. Bad power supply of the external drive.
>
> 2. If you have a 128D, you may have a drive number conflict. The internal
> drive is #8. If the external drive doesn't have some other number assigned
> (usually #9), then you will most likely experience exactly such symptoms.
>
> 3. The drive cable has a reset line (see below). Usually, it's wired through,
> but I have seen few few cables which have no connection there. Considering
> your described symptoms, it may make sense to try with a cable that does NOT
> connect the reset line. The downside is that pushing the reset button on the
> C128 or even powering it down and up again will not make the drive notice any
> change. If you want to reset the drive too, you'd have to do that separately
> then.
>
> Reset is on Pin 6:
> see
http://www.hardwarebook.info/Commodore_Serial_I/O
>
> Cheers
> Paul
thanks paul,
I also tried a commodore serial cable but still no luck for the first 1541 I tried. I had 3 other drives in storage which I retrieved and tested. A 1571, 1541, and 1541 II.
The 1571 won't power up but using the same power supply the 1541 II works fine. And the second 1541 also works fine. So I have two drives working, but not the 1571 yet.
And I had 4 computers in storage, a 64 and three original type128s. The 64 powers up, but composite connected monitor is blank. I have to do some research for that. Maybe the 64 does not output composite video?
The three 128s all work fine. Next I will try the two 1764 ram expansion modules. The one I have that was boxed comes with a commodore higher powered power supply. I will check the output voltages before powering up with it.
So now that I can read disks, I guess the next step is to clean and lube the drives, and then figure out a way to convert the physical floppies to .d64 files, since I don't expect the drives to work forever.
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