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Thread: Commodore MMF 9000 / SuperPet 9000 Monitor problem: Help needed!

  1. #11

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    Hello

    When you switch on the PET do you get the usual ‘chirp’ sound ?

    If so, do you have an eprom programmer ?

    Dave’s comment about typing on the keyboard to check if the flashing cursor block moves along the screen is a good start.

    Then, my opinion would be take look at the eprom labelled UA3 (this is the character rom) and see how it compares to the master rom file that can be found on Zimmers.net (I can point you to the right page if you need). Of course I would also try re-seating the eprom in case there is a bad connection and also use a multimeter to check for ‘continuity’ between the eprom and socket.

    The lines on your screen, shown when in 6502 mode, are what you would get if this rom was not present... so I think it could be good to check if the eprom has gone bad.


    Where in the world are you located ?

    Andy

    Quote Originally Posted by ZapdoZ View Post
    Forgot to post the photos in my last reply sorry
    Attachment 49133Attachment 49134
    Last edited by AndyG; November 3rd, 2018 at 03:00 PM.

  2. #12
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    2,064

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    AndyG - not quite true in my mind...

    The fact that you get a blank square exactly where the cursor may be throws slight doubt on this to my way of thinking. This is further supported by the mixed solid and blank blocks when in 6809 mode.

    I think we have some problems with moderating posts at the moment - so can I suggest that ZapdoZ tries to get his post count up to about 10 - when (hopefully) the moderators will let him roam freely and we won't start to get confused...

    I think there are a few outstanding things for ZapdoZ to try and report back...

    I wasn't particularly interested in the flashing cursor moving - but more on the effect of storing various different characters into the video RAM to see what appeared on the screen.

    Dave

  3. #13

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    "When you switch on the PET do you get the usual ‘chirp’ sound" - Yes i do get the sound. But only in 6502 mode

    "If so, do you have an eprom programmer" - I don´t think so, but i got some EPROMs for The MMF

    "(I can point you to the right page if you need)" - Yes please. I dont find it XD

    "Of course I would also try re-seating the eprom in case there is a bad connection and
    also use a multimeter to check for ‘continuity’ between the eprom and socket.
    "
    - So I removed the EPROM from the socket and I noticed three pins where cut of / bent.
    Can that be the problem? But how do i test the continuity between the socket and the eprom?
    There are no areas to test at the socket!

    "Where in the world are you located ?" - I live in germany. I said that before but the post didn´t go online for whatever reason


    "I think we have some problems with moderating posts at the moment - so can I suggest that ZapdoZ tries to get his post
    count up to about 10 - when (hopefully) the moderators will let him roam freely and we won't start to get confused...
    " - Yeah that would be helpful

    Ok so BASIC is working good i think. When i type something and hit the return key, my cursor jumps down the lines you usally get
    with a syntax error. But no Text on the screen.

    IMG_20181104_085222.jpg

  4. #14

    Talking Thank you all!

    Thanks for all the replys!

    I replaced the EPROM with a working one and the computer starts perfectly!

    IMG_20181104_113558.jpg

    The brightness controls are really buggy, but i can live with that

    Thank You all!

    -ZapdoZ

  5. #15

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    Excellent !!! Glad you got it working. Is the replacement character rom a normal 8032 version or superpet version ?

    I guess I am asking what happens when you flick to 6809 mode (a normal character rom will just be the solid lines you showed for the 6502.)

    I am still a little worried about the “smoking” comment .... do you know where the smoke may have been escaping from. Back of the monitor for example (does not point to the problem but may help) ?

    I guess we can wait we learn what happens when you switch to 6809 mode .. (the pet doesn’t chirp when you go to 6809 mode, but you should get the usual menu and a solid non blinking cursor block.

    Is the keyboard working also (the ........3333 - is that what you typed or how it boots up?)

    More questions I know

    Andy


    Quote Originally Posted by ZapdoZ View Post
    Thanks for all the replys!

    I replaced the EPROM with a working one and the computer starts perfectly!

    IMG_20181104_113558.jpg

    The brightness controls are really buggy, but i can live with that

    Thank You all!

    -ZapdoZ

  6. #16
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    2,064

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    Moderating the posts do suck a little - but I prefer that the moderator's deal with the spam rather than us. Thanks moderators!

    With those three pins being bent/broken indicates to me that someone has tried to 'repair' the system before and they have removed the character generator and installed the IC wrongly (possibly damaging it in the process).

    Those three damaged pins are pin 1 = Address line 7, pin 13 = Data line 3 and pin 24 = +5V! No wonder the machine wasn't working...

    There is a brightness control on the rear of the monitor. Failing that, I seem to remember similar monitor faults being posted, diagnosed and fixed on the Commodore section of VCFED. In your case, however, I would recommend seeking a local T.V. repair company. The schematics for the monitor are available over on Bo Zimmer's website.

    Agree with AndyG - I would checkout all of the keys etc. in 6502 mode first and then see if the 6809 processor works next.

    Have you replaced the character generator with a stock PET 8032 variant or a SuperPET one?

    Good going though.

    I am also concerned about reports of smoking. Keep an eye, ear and nose open for signs of any smoking. If detected, switch off instantly, disconnect from the mains and try and quickly locate what component(s) were in distress. Use all of your senses - visual, touch (heat) and smell. On the main board, the most likely culprit(s) would be the voltage regulators or bridge rectifier(s). After that, it could be the transformer or from somewhere in the monitor.

    Don't go anywhere near the insides of the monitor - high voltages are present.

    Dave
    Last edited by daver2; November 4th, 2018 at 12:55 PM.

  7. #17

    Default

    do you know where the smoke may have been escaping from. Back of the monitor for example (does not point to the problem but may help) ? - It came back from the monitor.

    I guess we can wait we learn what happens when you switch to 6809 mode - Nothing happened - I hope we can fix that.

    Is the keyboard working also (the ........3333 - is that what you typed or how it boots up?) - The keyboard is fine. Some keys need more pressure to trigger but it works. The ........3333 was a test by me. I connected some random input & output lines of the connector to test.

    Have you replaced the character generator with a stock PET 8032 variant or a SuperPET one? - I don´t know. The chip ist labeled MOS 90I640-0I 498I.

    Keep an eye, ear and nose open for signs of any smoking. - I know that. I am really careful when powering old machines on

    Don't go anywhere near the insides of the monitor - high voltages are present. - I know that too

  8. #18

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    OK - MOS 901640-01 is the correct Character ROM. Did you burn this as an EPROM or did you have the actual CBM Chip in a box ?

    If the Keyboard works have you tried out any programs ?
    Do you have a floppy disk drive or PetSD to test programs etc. ?

    If all OK then when you switch to 6809 you say nothing happens.... Do you mean it simply freezes or does the screen get cleared with a solid non blinking cursor ?

    The top board on your SuperPet is the 64k Memory board. The board below contains the 6502/6809 chips and also EPROMS. The fact the PINS on the character ROM were bent I wonder if someone has also looked at other parts of the motherboards.

    Schematics can be found on Zimmers.NET : ftp://www.zimmers.net/pub/cbm/schema...PET/index.html

    My opinion (), the next steps require more in depth investigation which means removing boards. Only if you are comfortable doing this, I would be to power up the Superpet in 6502 mode and first just check the voltages on the voltage regulators on the top board (left side of the board, mounted on heat sinks, near the capacitors) which is the 64k memory board. One should output -5V (U61, 7905), the other 5V (U24) and the other 12V (U19).... I just read off the U numbers from my top board. I mention this as the voltage regulators on the SuperPET'S can fail from the research I had done (they can be flaky and mine had a failing 12Volt one which caused some hard to diagnose random memory issues)

    I would then remove the memory board - be very careful removing the ribbon cable as it will be stiff and you could bend some of the pins!

    The SuperPet should boot happily into 6809 mode without the board present - it's just you cannot do anymore other than switch to 6809 mode and display the Waterloo microsystems menu.

    I would then Inspect all the EPROMS and also 6809 CPU to see if there are no bent pins etc..... also check the voltage regulators on that board (think there are 3 5V regulators from memory)

    Post photos of the SuperPET with the memory board removed so we can see the middle board ..... (I hope the smoke is to do with a component on one of these boards failing.)

    The EPROMS on the second board are 2532 in all sockets apart from E

    Andy
    Last edited by AndyG; November 8th, 2018 at 11:20 AM.

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