Re: VIC-1541 problem

From: Marko Mäkelä (
Date: 2006-12-12 22:29:56

On Tue, Dec 12, 2006 at 06:06:10PM -0300, Andrew Wiskow wrote:
> > I'd replace the UC1 (74LS14) and UD1 (7406).  The
> > newer (short) board
> > has similar inverters near the serial bus.  I don't
> > know of the 1541-II;
> > it might have these integrated in a big ASIC.
> > 
> I did try replacing the chip labeled as UAB1 on the
> board. UC1 and UD1 are the two small chips right
> "below" UAB1 if you're looking at the board from the
> drive opening.  They're non-socketed chips.

They're non-socketed, but small chips are easy to desolder.  If you want
to avoid any damage to the circuit board, cut the pins with wire cutters
and remove them one by one.  Grab the pin with pliers and heat it with
a soldering iron until it comes loose.

The 74LS14 and 7406 should be cheap and easy to obtain, so you can
blindly replace both chips.

> I think I'm probably better off just keeping this drive around
> as a large paper weight (and future use for spare
> parts) and getting a replacement rather than fix it.

Well, the main thing is that you don't throw it away.  For the record,
can you post the part numbers of the ROM chips?  I don't think that
this is a firmware issue, or I must have forgotten something.  The only
possible firmware problem I can think of is the timing of the ATN handshake,
but as far as I remember, it wasn't changed between the 1540 and the 1541.


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