Commodore 1541 runs continuosly

[Desperado]

Hi guys!Can someone help me with my Commodore 1541 drive?
When i turn on, he runs continuosly and the two led lights (green and red) are always on
I tested 6502, the two 6522 and ls14 and are good....

what could be the problem please?
Thanks!

 

[VintageVic]

It can be a wide range of things.
How did you test those chips ? On another working drive ?
I assume, they were socketed. Sockets can be oxidized. Even if chips are ok, bad contacts
to sockets can be the cause.

Are you familiar with Ray Carlsen's work? He has listed possible symptoms for each chip,
just google for it and check it out, it is valuable read in fixing 1541 drives.

Edit:
UB4 rom fails rather often and worth to check if you have a working drive.

 

[Desperado]

Ok thanks!
Tomorrow i ll looking for ub4 and i ll try change it

 

[Ruud]

I tested 6502, the two 6522 and ls14 and are good....

The 7406 near the LS14 is another good candidate for causing the problem.

 

[Desperado]

The 7406 near the LS14 is another good candidate for causing the problem.

Hi,i changed the 7406 with a new 74ls06 but it's the same...
i suspect rom 901229-05.....it's possible burn bin file in a 2732 eprom maybe?
Thanks!

 

[VintageVic]

I recently made EEPROM and tested that it does work. Also EPROM works,
but of course you need programmer and socket adapter.

Did you have another drive to test your ROM chip there ?

 

[Desperado]

I recently made EEPROM and tested that it does work. Also EPROM works,
but of course you need programmer and socket adapter.

Did you have another drive to test your ROM chip there ?

No unfortunately no...
but i have eprom programmer...
2732 eprom it's good ?

 

[VintageVic]

from a quick google check I assume 2732 eprom is a 4kb rom ?

901229-05 is 8kb rom chip. You will need at least 8kb eprom. 2764 eprom should do fine.

Check this out for suitable socket adapter:
https://ist.uwaterloo.ca/~schepers/roms.html

However, if you do not have a working 1541 drive, you cannot really reliably check out
the chips on your 1541 drive. In my opinion, you will have to be a bit lucky to fix it.
It would save a lot of effort to check out your existing chips on a working drive.

What if you believe that you put new working chips to the drive, but if in fact even one
is failed chip, you will end up replacing all the chips and the drive will remain dead.

 

[Desperado]

Hi guys, i ve bought a new 901229-05 original rom but nothing change
How can i do please?

 

[jafir]

There is some good info here: http://personalpages.tds.net/~rcarlsen/cbm/1541/

There is even a file of symptoms to components.

 

[austfox]

Have a look at a few videos involving 1541 repairs on Adrian’s Digital Basement on Youtube. Step by step guide, but most importantly explains why he is checking each IC etc.

 

[rittwage]

The ROMs do go bad more often than the other chips, at least in the old days when they weren't so old. Now, it can be most any other chip with a problem that causes that. Motor running constantly and lights on just means it never booted.

Fortunately (sort of) it should be pretty cheap to buy a whole spare 1541 board by itself. Most Mitsumi/Newtronics heads have open coils (dead, unfixable) so there are a lot of orphan logic boards out there. Heck, if you are in the US, I can send you a tested one for $25 + shipping - just send me the dead one back.