Image Map Image Map
Results 1 to 8 of 8

Thread: Please help me revive a Pet 2001!

  1. #1
    Join Date
    Sep 2009
    Location
    Cambridge, England
    Posts
    23

    Default Please help me revive a Pet 2001!

    Hi all! I hope you can help me.

    I thought I should try and revive my beloved 2001. It's been a talking point in my office for ever, but it hasn't been turned on for over 10 years - last time I tried it appeared to be dead, and fear of electrocuting myself by touching the wrong part of the CRT has meant it's mothballed ever since.

    Well, today I changed the fuse, plugged her in - and, oh my god, the screen lit up! I was expecting a big bang and smoke. So now I'm sitting here looking at a screen of gibberish (see picture), and I'm wondering what to do next - can anyone help?

    I'm not a hardware person, and my only diagnostic tool is a multimeter, but I'd love to get it working again! It's got a nice clear, sharp screen, and gibberish gives me hope there's something alive in there.

    Many thanks in advance,

    Tony
    20140904_152708.jpg

  2. #2
    Join Date
    Dec 2005
    Location
    Toronto ON Canada
    Posts
    6,685

    Default

    The first thing is to rotate it upright; they don't like to work on their side

    No fear of electrocuting yourself unless you take the cover off the back of the monitor.

    Undo the two screws if necessary and lift up the 'hood' ('bonnet' if you're in the UK), prop it up and tell us what the assembly number is (along the right edge near the front).

    You might try (with power off) pushing down on all the socketed chips (not too hard) to make sure they're properly seated, and pushing them back and forth (along the long axis) in their socket to break any oxidation.

    With a little luck that'll do it.

    Good luck.

    BTW, please put your location in your profile.

    mike

  3. #3
    Join Date
    Sep 2009
    Location
    Cambridge, England
    Posts
    23

    Default

    Hi! Location set (hello from Cambridge, England), computer turned the right way up! (no idea why it got turned, I'll watch out for that in the future).

    So ... I opened her up, and blimey, it's filthy in there - see attached. I pushed down on all the socketed chips, turned it on, and wow, she lives again! I wish I'd known it would be this easy years ago - these things are built like tanks!

    I do have a couple question I hope you all can help me with:

    1. Should I resist the temptation to clean the motherboard? It's working, and I'd like to keep it that way, but I wonder if that might be better in the long run.
    2. All the 2001s I see online have black cassette drives, but mine is beige, and a slightly different design. Is this something that was replaced later in its life, or did it come like this?
    3. I'd like work out how old this computer is - what should I look for to help me date it?
    4. I'd love to load some software onto it, but I don't think I can produce a tape (and I'd be surprised if the tape drive still works). Can I use an external sound source?

    Many many thanks in advance!
    20140904_155656.jpg

  4. #4
    Join Date
    Feb 2009
    Location
    Southern California, USA
    Posts
    2,315

    Default

    Quote Originally Posted by minty View Post

    1. Should I resist the temptation to clean the motherboard? It's working, and I'd like to keep it that way, but I wonder if that might be better in the long run.
    A little cleaning is OK, but don't use water. Water vapor is the enemy of printed wiring boards. Can you get some very pure isopropyl alcohol? Unfortunately many like to put their board in the dishwasher and the boards will come out looking beautiful. But ask an Electronics Reliability Engineer and he would say that unless you put the board quickly afterwards into a thermal-vaccuum station for 20 hours of high heat and high vacuum to dry and outgas the water vapor and contaminants, you just took years of life off the board.

    Also perhaps you should not use high pressure air to blow out the board as it create thousands of Volts of static electricity. If the ICs were soldered into a board with an internal copper ground plane, it would easily handle it as the large area of the plane would dissipate the static voltage, but I just found out the Commodore main board does not have a ground plane.

  5. #5
    Join Date
    Dec 2005
    Location
    Toronto ON Canada
    Posts
    6,685

    Default

    Hello Tony; welcome and congratulations! You are now a qualified PET technician

    I'm not quite as anal as Dave about compressed air so if it's just dusty I'd blow out the dust with compressed air or the outlet of a vacuum cleaner, assisted with a stiff brush. Standard procedure both in my hobby and also professionally (But I assume no responsibility).

    There were at least three different internal tape drives used in the PET and yours is one of the two later ones. It's hard to date PETs accurately, but your best bet would probably be the date codes on the ICs; beside the 74xxx and 65xx numbers you'll probably find at least one other four or five digit number probably starting with two digits in the 76 to 78 range and the latest one of those would be close to the week in which it was manufactured. Any number higher than 78 or 79 probably means that the chip was replaced, although you'd likely see evidence of it being resoldered. Of course the serial number would give you a relative indication.

    That looks like the 320008 board; is it? Also, tell us at least one or two of the numbers on the 24-pin ROM chips in row H; different revisions of BASIC had different issues.

    Try typing in a little program, saving it to the cassette and loading it back in; you never know...

    Unfortunately, without spending a little money there's no easy way to load in a program other than typing it or getting a tape from someone. Also, whether you can use a disk drive or one of the modern solid state emulators depends on the ROM version (see above).
    Last edited by MikeS; September 4th, 2014 at 01:29 PM.

  6. #6
    Join Date
    Feb 2009
    Location
    Southern California, USA
    Posts
    2,315

    Default

    Quote Originally Posted by MikeS View Post
    Hello Tony; welcome and congratulations! You are now a qualified PET technician
    I agree. Anybody that posts on the Commodore Forum would have been offered a job at Commodore as a top gun designer.


    I'm not quite as anal as Dave about compressed air ...
    Well thanks for the complement, Mike. Everyone knows that all good engineers have strict anal personalities!

  7. #7
    Join Date
    Feb 2009
    Location
    Southern California, USA
    Posts
    2,315

    Default

    Quote Originally Posted by minty View Post
    4. I'd love to load some software onto it, but I don't think I can produce a tape (and I'd be surprised if the tape drive still works). Can I use an external sound source?
    A member of this forum tezza has done a lot of work on creating cassette files for the PET. I found this link which may get you started. I'm sure somewhere he has written more about this. It uses things like TAP and WAV files and the VICE PET Emulator that runs on a PC.

    http://www.classic-computers.org.nz/...r-download.htm

  8. #8
    Join Date
    Dec 2005
    Location
    Toronto ON Canada
    Posts
    6,685

    Default

    Quote Originally Posted by dave_m View Post
    A member of this forum tezza has done a lot of work on creating cassette files for the PET. I found this link which may get you started. I'm sure somewhere he has written more about this. It uses things like TAP and WAV files and the VICE PET Emulator that runs on a PC.

    http://www.classic-computers.org.nz/...r-download.htm
    Hmm... It looks like Tez doesn't actually say that he created a working cassette without going through a C64; the thing that complicates the issue a bit on commodore machines is that the tape drive is (sort-of) digital.

    But I'd give it a try; I do seem to recall duplicating PET tapes with 'normal' audio equipment so it oughta work once you get the levels etc. right.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •