Commodore 1581

[Retrofan]

Hi:
I've recently bought a 1581: http://www.ebay.es/itm/181428785792?...84.m1439.l2649

I would need some help to repair it.
The symptoms are:

- The power led light constantly flashes.
- The lector head doesn't move at all even inserting a floppy disk
- The spindle is spinning all the time from power on.



Edit: Now also tested with a working Power Supply from a 1541-II.

Edit 2: It seems the motor that moves the lector head is dead, so I will try to find another floppy drive. This is a Chinon F354E

[Jope]

Any A500, A1000, A1010, A1011 drive will work as a replacement.

[demolition]

Originally Posted by Retrofan

Edit 2: It seems the motor that moves the lector head is dead, so I will try to find another floppy drive. This is a Chinon F354E

Did you try turning the motor manually? It can seize when sitting still over a long time. I once 'fixed' a floppy drive simply by turning the motor manually.

[Retrofan]

Thanks both. Yes, I even opened that side of the floppy drive. One of the metal sheets (attached to the motor) that moves the lector head was out or I moved it out (almost sure) of its support, but after mounting it all again (I think that right) there is no change. I think the motor doesn't work, I don't feel it running with my finger. I can not see it working because it has to be closed to be connected.

I will try to find the same unit, Chinon F354E just in case, and I will look for the jumpers to be in the same position if I find one.

Edit: I will look for more A500 models.

[Overdoc]

One question:

1) Does the led only flash after you tried to access the disk in the drive, for instance via LOAD"$",8 ?
Or
2) Does it also flash right after you have turned on the drive ?

In case of 1) the problem could be the drive. Any Amiga drive will work. Also, PC drives will work with a little modification on the cable, but you will probably not find a drive where the eject button fits the hole in the case.

In case of 2), the 1581's RAM or parts of the ROM maybe bad. The ROM goes thru a self test upon startup, which checks the RAM and also parts of the ROM. The number of long/short flashes will tell you which of the 2 is bad.

[Retrofan]

Thanks for the question Commodore Collector . Afortunately it's only case 1; it starts flashing when I run the commands to load something. I'm after an A500 unit, but I will have to wait some more days for an auction to finish.

Edit: Now I've got a Chinon FB-354

[Retrofan]

I've received the new drive and I've had to change the ribbon cable orientation as they are different:



So this is how I've left it just twisting the ribbon:



But the power led light starts flashing right after writting LOAD"$",8 on the Commodore, just like before.

EDIT: PFFF... The power on button was a bit hard to push, and now, the third time I use it in doesn't work anymore; it doesn't change position, so now I've got to find a 6 pins power on button for it

Looks like this http://detail.1688.com/offer/1192088422.html , but I can't order from there.

[Retrofan]

Well, it has been some months, but today I've looked again to my 1581.

I've fixed the button. Just a bit of ISP alcohol and a bit of silicone grease and much of pressing it on and off with pressure and now it's ok again.

If you think why a power on button gets stuck in my opinion there are two ways:
- It is too old and shit happens
- It had too much voltage or an incorrect one Edit: too much current 'cause a short.

I think it's the second. You know that I changed the floppy unit, but although it has to be compatible, it has the floppy ribbon cables the way round:

http://hostthenpost.org/uploads/0b7d...4b559edf8b.jpg

So I need a crossed ribbon cable, don't I?

[Hewitson]

Originally Posted by Retrofan

- It had too much voltage or an incorrect one.

Nah no way. Most switches are capable of handling at least mains voltage.

[Retrofan]

I say that because a month ago I was connecting a switch at home for the air extractor in the bathroom and I put the cables the way round. The fuses blown, but the switch got stucked. I opened it and it was stucked because of the heat produced.

[Hewitson]

That's because you caused a short circuit which made way too much current go through it! Nothing to do with voltage.

Sorry but with your lack of electrical knowledge you shouldn't be wiring things up to the mains.

[Retrofan]

Of course I know it was a short in this last case, I just didn't express right that in my phrase (my bad), and the unit was working (light on) so there wasn't a short there. And yes, I will keep wiring and fixing things like always . If I ask here is because I don't know about everything and it's hard to write in english when I have to search for translations like fuses blown when we don't call it like that here anymore, we say the diferential jumps as we don't use fuses since many years ago.

I just ask if the ribbon needs to be crossed, that's all.

Edit: It seems it doesn't. Well the thing is that the ribbon I tried has the connectors the way round than the original (or having them the same way, the red line on the other side), but I've got another longer ribbon that lets me connect it right.

The new floppy drive behaves just like the former: the stepper motor doesn't move even moving it to a side of it first, and the rest of symptoms.

Edit: I've ordered a JiffyDos for the 1581 to see if it's the DOS ROM chip U2 (CBM 318045-01) that's bad.

Edit: I haven't received it yet, but I'm almost sure it isn't the problem. Well, I don't mind to have a faster JD chip either .
I've been messaging with the master among masters, Ray Carlsen and he has been so kind...

I sent him a video and it seems the problem will be U4 or U8 (the controller or it's interface to the mechanism, U8 is an interface IC and U4 is the mechanism controller IC). I've got U4 already desoldered now and my replacement (very hard to find) is on the way.

You have to know that my U4 is the very suspicious WD1770 that Commodore was offering -after some problems- to replace for free to 1581's customers at that time. They changed it with the 1772.

Thanks a lot Ray, you are a legend to fix C64's and related.