Denial

Hi, I have a "new" 1541 and when connected to the Vic 20 it powers up normally: the red led stays on and then it turns off, while the green one remains lit. I can hear the motor spinning while the red led is on. The problem is that whenever I issue a command from the Vic, for example the usual LOAD"$",8 (the same happens increasing the number) all I get is the "DEVICE NOT PRESENT" error, with no additional sign of life on the serial bus. I've read on the website of Ray Carlsen that probably (as suspected) the 6522 are the problem.

In case anyone has some 6522 as spare parts available, in order to fully bring to life again this cool drive of the past, please just PM about the details.

Thanks.

Here are a couple of photos of the baby for reference:

Since the disk drives stops spinning and the red LED goes off (the green one is the power so it always stays on as long as the drive is turned on) then the problem seems more likely to be with the VIC-20.

Replacement 6522 ICs are still being made and can be purchased from Mouser (www.mouser.com) look for part W65C22N6TPG-14.

Both the VIC-20 and the 1541 drive use the same type of chip for communication but there are a few logic ICs between the 6522 and the cable so these may be at fault too.

Hi,
I'm supposing that you can try it with a C64 or VIC20 that have the serial port well working.
The two 6522 have different business: one work with serial port, the other with mechanics.
Try to swap the two 6522, if the problem will change (serial link ok, but foult on other functions) the problem is the 6522, else the oter 2 chips that work on serial line are: UA1 (74LS14) and UB1 (7406)

Ciao,
Presuppongo che tu possa provare con un computer la cui porta seriale sia sicuramente funzionante (o non puoi escludere che il difetto sia nel computer...).
I due 6522 hanno mansioni diverse e solo uno gestisce la porta seriale: scambiali e se il difetto alla seriale soparirà allora il problema era il 6522 (avrai altri difetti, ovviamente, ma non sulla comunicazione seriale).
Se nulla cambia allora gli altri 2 integrati che lavorano con la seriale sono UA1 (74LS14) and UB1 (7406)

Se poi ti serviranno integrati da sostituire io posso vendertene.

Thank you both for your answers!

I did the following testing

1. C64 + 1541: same exact symptoms as the Vic 20: green led stays on (power), red one turns on at startup, then goes off; "DEVICE NOT PRESENT ERROR" after LOAD"$",8 (,9 etc) with no further red led nor motor activity

2. Tried a 1541-II with both the Vic 20 and the C64, using the same serial cable: both of them can work with no problems with this other drive: they load the directory info and the programs.

3. swapped the two 6522 on the 1541: symptoms remain the same as in #1

What do you think guys?

P.S. @MCes: piacere di sapere che c'è un altro "italico compatriota" che ancora non conoscevo

The other 2 chips that work on serial line are: UA1 (74LS14) and UB1 (7406),
I think that you have to replace them!

P.S.
Il piacere è reciproco!

MCes wrote:The other 2 chips that work on serial line are: UA1 (74LS14) and UB1 (7406),
I think that you have to replace them!

UD1 is another 7406 which can also be at fault.

If I read well the right electric diagram of yours drive here:
http://www.zimmers.net/anonftp/pub/cbm/ ... 5_Jan).pdf
The only ICs that manipulate the serial signals are:
UC3 6522
UA1 74LS14
UB1 7406
UD3 74LS86

(UD1 is another 7406 that seems used only to drive step-motor and to drive the "ACTivity red led")

P.S.
on the hidden side of the card: check the welds of serial connectors....
(or use the other serial connector to test the drive activity.....)

Thank you!

I have a multimeter and even an oscilloscope available: I will try to understand which kind of measurements I can do then, before buying parts that maybe are not involved. Your tips are immensely welcome since this is not my usual activity! (boom!)

Thumbs up, cheers
Enrico

MCes wrote:If I read well the right electric diagram of yours drive here:
http://www.zimmers.net/anonftp/pub/cbm/ ... 5_Jan).pdf
The only ICs that manipulate the serial signals are:
UC3 6522
UA1 74LS14
UB1 7406
UD3 74LS86

You're right!

MCes wrote:The only ICs that manipulate the serial signals are:
UC3 6522
UA1 74LS14
UB1 7406
UD3 74LS86

So, being just these the "usual suspects" maybe it's better to get them as a replacement instead of investing time on the testing side.
Has anyone all of them as spare parts to sell and send me?

Thanks again MCes and eslapion

my opinion: check the drive with serial cable plugged into second drive connector,
if it don't work: swap the 6522, if failure will change the problem is the 6522 that was in UC3, else replace (in this order) UB1 (and test the drive), UA1 (and test the drive), UD3.

you can immediately swap the serial connection and the couple of 6522 without buying anything.....

Ok, so I will have to buy UB1, UA1 and UD3, since I've already tried the second connector and swapped the two 6522.
Unfortunately those chips aren't socketed as the two 6522, so desoldering-resoldering time is coming
Thanks for your help!
Enrico

I think you may try the 6522 in a VIC-20 to be sure they are good.

Did you try accessing it as device 9, 10 or 11 (instead of just to make sure someone didn't cut a trace to change the device number on it?

PhotoJim wrote:Did you try accessing it as device 9, 10 or 11 (instead of 8 ) just to make sure someone didn't cut a trace to change the device number on it?

I have to admit this may be a good idea.

Whenever I had UA1, UB1, UD3 or one of the 6522 faulty on a 1541, the drive would detect it and go on ESOD (endless spin of death). This one does not.

However, the photo on the OP shows 2 device number jumper discs intact.

Sidenote: watch out for smileys...