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    Teamwork! Nice picture... It is interesting...

    Teamwork!

    Nice picture...

    It is interesting that both Q1 and Q2 had failed... almost as though someone had used a faulty datasette and tried it on both cassette ports on the PET - bang, bang......
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    Transistor Q1 appears to be dead. Either that,...

    Transistor Q1 appears to be dead.

    Either that, or something on the PCB is dragging the signal down to 0 Volts.

    Remove transistor Q1 and test it on your multimeter with the hFE function. It is...
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    So, because UE16 pin 10 is changing state based...

    So, because UE16 pin 10 is changing state based upon the state of the PLAY key on the dataset, I suspect Q1 is possibly dead.

    With no keys depressed, can you measure the voltages on the c, b and e...
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    >>> but if i press Play i have 0V!!! Don't...

    >>> but if i press Play i have 0V!!!

    Don't sound surprised, this bit seems to be working OK!

    Can you next check the voltage on pins 13, 14 and 10 of UE16 (Q2T2222 transistor array) relative to...
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    That's OK. I wanted to see that at least one side...

    That's OK. I wanted to see that at least one side has the +9V on it...

    What about the UB12 pin 19 test results? These results will affect the voltage reading on the other side of R48.

    Dave
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    That’s fine. That’s what I was expecting... ...

    That’s fine. That’s what I was expecting...

    Can I ask you to measure two more points with your multimeter please.

    First off can you measure the voltage on both ends of the resistor R48 (15k) to...
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    Excellent. Next, multimeter positive lead to...

    Excellent.

    Next, multimeter positive lead to J3 pin 3 (cassette motor) and multimeter negative lead to J3 pin 1 (0V).

    With no cassette keys pressed you should read 0V. With the PLAY key pressed...
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    Looks a little bit low to me. One of the fingers...

    Looks a little bit low to me. One of the fingers could be dirty perhaps? But there is at least some Volts...

    Next, connect your multimeter positive lead to J3 pin 2 (+5V) and your multimeter...
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    That’s good to know. Do you have a 0V rail as...

    That’s good to know.

    Do you have a 0V rail as well?

    Measure the voltage between J3 pin 1 (0V) and J3 pin 2 (+5V).

    Dave
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    >>> unfortunately this problem it's...

    >>> unfortunately this problem it's intermittent.....sometimes cursor stops blinking and sometimes run correctly...

    Ok, but you know what to look at and post when it next occurs. If the problem is...
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    So, after that distraction... What we still...

    So, after that distraction...

    What we still need is a further oscilloscope trace (with the same oscilloscope configuration) of CPU pin 4 when your cursor stops flashing to compare the previous...
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    Darn, spoke too soon! Ahead of you on this...

    Darn, spoke too soon!

    Ahead of you on this one...

    Check my post back in #229 for a suggestion...

    It sounds like you have something that is temperature dependent. A hair dryer and a can of...
  13. In post #13 you say you had an oscilloscope trace...

    In post #13 you say you had an oscilloscope trace that was indicating +/- 1V and was expecting +/- 5V.

    I am expecting a value from 0V to +5V...

    I would also like to see the timebase on your...
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    >>> Finally 8032Sk it's ok!! Great news,...

    >>> Finally 8032Sk it's ok!!

    Great news, another one rescued!

    >>> Thank you very much for the precious help you gave me!!

    No problem.

    Of course, when you had my PETTESTER installed you...
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    I’m with glitch on this one, you shouldn’t need...

    I’m with glitch on this one, you shouldn’t need to take the disk pack apart to clean it - unless you are not using the correct cleaning equipment.

    I have taken a donor pack apart before now (I...
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    Didn't even know that project existed. Thanks for...

    Didn't even know that project existed. Thanks for the pointer though.

    If I had known a while ago - I would have yet another project on my rather large pile!

    I still might obtain a copy of the...
  17. No problem. Glad to be of help. An...

    No problem.

    Glad to be of help.

    An interesting set of issues to learn from!

    Dave
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    Excellent. You might want to check pin 4 of...

    Excellent.

    You might want to check pin 4 of the CPU with your oscilloscope with the cursor flashing normally to get a ‘feel’ of what the interrupt pin ‘looks like’ under normal circumstances.
    ...
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    I get the impression that we are trying to solve...

    I get the impression that we are trying to solve too many problems in one go. We are following one problem and then we get another thrown into the mix.

    Can we get the alignment of the picture on...
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    I am not still 100% happy with the outcome so...

    I am not still 100% happy with the outcome so far.

    I too am still suspect of the E400 rail.

    I am also still suspect that we found two dead 'fusible' resistors and no reason why they had gone.
    ...
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    Yes, you can see it on the PETTESTER diagnostic...

    Yes, you can see it on the PETTESTER diagnostic screen as well. I thought that one was OK until I went back and had a look.

    This is what Dwight has been saying - the photograph needs to be framed...
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    The first picture (that will drive Dwight...

    The first picture (that will drive Dwight insane...) is most likely a faulty monitor circuit somewhere.

    The second picture is most likely a faulty PET logic board.

    Dave
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    Just edited my previous post with that...

    Just edited my previous post with that information... It is in the manual as well :-)!

    Dave
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    OK, So, this is the problem with 'vintage'...

    OK,

    So, this is the problem with 'vintage' equipment. It can just fail for no reason - and (as you have just seen) can also fail when you change something. I suspect you have some poor contacts...
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    It depends upon whether the OP still has the...

    It depends upon whether the OP still has the BASIC ROMs in or my PETTEST ROM. Hopefully, the standard ROMs.

    Just checking, but did you install the video RAM in the right way round?

    You should...
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