Cbm 8032 capacitor

[Lololobolosse]

Let's just take stock of where we are now.

1. You have the correct DC voltages measured on the PET main logic board.
2. You have the replacement CPU installed correctly in IC socket UB14.

Are there any IC sockets without any devices fitted into them. This doesn't denote a problem - but it will be useful to know.

If I understand your last post correctly - you do have an oscilloscope? If this is correct, do you know how to use it? There are some relatively simple checks we can do with the oscilloscope to see if the CPU is actually running...

If you didn't ground yourself properly - there is nothing you can do about it now I am afraid...

Dave

There is no missing IC but i don't know how to use an oscilloscope does it can check if the new processor is broken ?

 

[Lololobolosse]

Let's just take stock of where we are now.

1. You have the correct DC voltages measured on the PET main logic board.
2. You have the replacement CPU installed correctly in IC socket UB14.

Are there any IC sockets without any devices fitted into them. This doesn't denote a problem - but it will be useful to know.

If I understand your last post correctly - you do have an oscilloscope? If this is correct, do you know how to use it? There are some relatively simple checks we can do with the oscilloscope to see if the CPU is actually running...

If you didn't ground yourself properly - there is nothing you can do about it now I am afraid...

Dave

And does the fact that the computer have boot up one time but not another time

 

[Lololobolosse]

Can help us now ?

 

[daver2]

>>> There is no missing IC.

I would have thought there should be at least one missing IC on the circuit board if memory serves me correctly (unless you have something non-standard plugged into your board). Perhaps a general photograph of your whole board taken from directly above if possible.

>>> but i don't know how to use an oscilloscope does it can check if the new processor is broken ?

We may be able to do this - depending upon what is wrong with the machine. We can teach you... What oscilloscope do you have (manufacturer, make and model) so we can download the manual?

>>> And does the fact that the computer have boot up one time but not another time

So this is very useful information. When did it last boot up correctly?

Dave

 

[Lololobolosse]

>>> There is no missing IC.

I would have thought there should be at least one missing IC on the circuit board if memory serves me correctly (unless you have something non-standard plugged into your board). Perhaps a general photograph of your whole board taken from directly above if possible.

>>> but i don't know how to use an oscilloscope does it can check if the new processor is broken ?

We may be able to do this - depending upon what is wrong with the machine. We can teach you... What oscilloscope do you have (manufacturer, make and model) so we can download the manual?

>>> And does the fact that the computer have boot up one time but not another time

So this is very useful information. When did it last boot up correctly?

Dave

Im going to take the picture and the seller told me it turned on one time but not another

 

[Lololobolosse]

Here is the picture and i spotted ud12 is missing but the seller didn't touch the computer so i think it's normal

 

[daver2]

Excellent.

I forgot you had a Universal PET board - so the CPU should be fitted to UB14.

UD12 should be missing. This is expected. However, I see that UD11 has something non-standard fitted! EDEX is an enhancement to BASIC that added some new commands.

I wouldn't really trust anything the previous seller stated to be honest.

So, what oscilloscope have you got to move forwards?

Dave

 

[Lololobolosse]

Excellent.

I forgot you had a Universal PET board - so the CPU should be fitted to UB14.

UD12 should be missing. This is expected. However, I see that UD11 has something non-standard fitted! EDEX is an enhancement to BASIC that added some new commands.

I wouldn't really trust anything the previous seller stated to be honest.

So, what oscilloscope have you got to move forwards?

Dave

Actually someone is goign to give me one in a couple of days and i will be back when i got it

 

[daver2]

Ok,

I await developments...

In the meantime, I would suggest some Internet reading about taking simple measurements using an oscilloscope. I know that the Tektronix website has some good online training documents, and they are in different languages as well (but not Italian for some strange reason)...

Dave

 

[daver2]

You can still perform some valuable testing with your trusty multimeter in the meantime.

Firstly (as I now know you have a universal PET board) can you double-check the orientation of your CPU with the image below. The CPU should be UB14. Please notice the orientation of the semicircle notch in relation to the voltage regulators (e.g. VR3). I think I can see from your previous photographs that it is inserted correctly though. Always worth double checking these things though...

With the black (negative) lead of your multimeter connected to the negative (0V/GND) lead of the large external capacitor - and your multimeter set to read DC volts (5V or so full scale) measure the voltage at the following pins of the CPU (UB14). Noting that pin 1 of the IC is immediately to the LEFT of the semicircle notch as shown in the image below.

Pin 2 - RDY.
Pin 4 - /IRQ.
Pin 6 - /NMI.
Pin 7 - SYNC.
Pin 38 - SO.
Pin 40 - /RESET.

Report the voltages back please.

Dave

 

[Lololobolosse]

You can still perform some valuable testing with your trusty multimeter in the meantime.

Firstly (as I now know you have a universal PET board) can you double-check the orientation of your CPU with the image below. The CPU should be UB14. Please notice the orientation of the semicircle notch in relation to the voltage regulators (e.g. VR3). I think I can see from your previous photographs that it is inserted correctly though. Always worth double checking these things though...

With the black (negative) lead of your multimeter connected to the negative (0V/GND) lead of the large external capacitor - and your multimeter set to read DC volts (5V or so full scale) measure the voltage at the following pins of the CPU (UB14). Noting that pin 1 of the IC is immediately to the LEFT of the semicircle notch as shown in the image below.

Pin 2 - RDY.
Pin 4 - /IRQ.
Pin 6 - /NMI.
Pin 7 - SYNC.
Pin 38 - SO.
Pin 40 - /RESET.

Report the voltages back please.

Dave

When i turn on the cbm with pin 40 to ground it boot up with a strange screen making a sound that looks like a error code but not when pin 40 is to ground and
5v pin 2
5v pin 4
5v pin 6
10v pin 7
Nothing pin 40

 

[Lololobolosse]

You can still perform some valuable testing with your trusty multimeter in the meantime.

Firstly (as I now know you have a universal PET board) can you double-check the orientation of your CPU with the image below. The CPU should be UB14. Please notice the orientation of the semicircle notch in relation to the voltage regulators (e.g. VR3). I think I can see from your previous photographs that it is inserted correctly though. Always worth double checking these things though...

With the black (negative) lead of your multimeter connected to the negative (0V/GND) lead of the large external capacitor - and your multimeter set to read DC volts (5V or so full scale) measure the voltage at the following pins of the CPU (UB14). Noting that pin 1 of the IC is immediately to the LEFT of the semicircle notch as shown in the image below.

Pin 2 - RDY.
Pin 4 - /IRQ.
Pin 6 - /NMI.
Pin 7 - SYNC.
Pin 38 - SO.
Pin 40 - /RESET.

Report the voltages back please.

Dave

View attachment 1245560

It did not do that when pin 40 is not on my multimeter to the capacitor

 

[Lololobolosse]

And i got the oscilloscope its an old tektronix 2200 and if you could help me find the manual in english or french that would help me

 

[OldPETGuy]

Did not find a tek 2200, but did find the tek 2205.

Bama Manual Archive

Hope this helps.

Fred

 

[daver2]

Pins 2, 4 and 6 look OK (i.e. they are not causing us any problems).

You haven't checked pin 38 as I asked you to do. Could you do that please.

Pin 7 also looks partially suspect. Can you recheck this pin also? I do suspect what is happening - but let's be sure.

I am not sure what you are saying about pin 40 (/RESET) though. This is a key pin of the CPU for the operation of the machine - so this needs to be right.

Is the value HIGH or LOW? You can check if the pin is HIGH by measuring the voltage from 0V/GND to the pin itself. However, you can check if the pin is LOW by connecting the RED lead of the multimeter to the +5V supply of the logic board and taking a reading of the voltage on the pin using the BLACK lead of the multimeter. Report the reading back.

Dave

 

[daver2]

Could you also post a photograph of the front and rear of your oscilloscope - so we can see what a 2200 actually has (if we can't find the correct manual).

I have found a 2201... Unfortunately, the numbering system doesn't quite follow the path that the 2201 is a slight improvement in some way over the 2200...

Dave

 

[Lololobolosse]

Pins 2, 4 and 6 look OK (i.e. they are not causing us any problems).

You haven't checked pin 38 as I asked you to do. Could you do that please.

Pin 7 also looks partially suspect. Can you recheck this pin also? I do suspect what is happening - but let's be sure.

I am not sure what you are saying about pin 40 (/RESET) though. This is a key pin of the CPU for the operation of the machine - so this needs to be right.

Is the value HIGH or LOW? You can check if the pin is HIGH by measuring the voltage from 0V/GND to the pin itself. However, you can check if the pin is LOW by connecting the RED lead of the multimeter to the +5V supply of the logic board and taking a reading of the voltage on the pin using the BLACK lead of the multimeter. Report the reading back.

Dave

Pin 7 is 1v
Pin 38 2v
And pin 40 is -0.40v with measuring from gnd to pin 40

 

[Lololobolosse]

And here is the pictures of my oscilloscope

 

[Lololobolosse]

Pins 2, 4 and 6 look OK (i.e. they are not causing us any problems).

You haven't checked pin 38 as I asked you to do. Could you do that please.

Pin 7 also looks partially suspect. Can you recheck this pin also? I do suspect what is happening - but let's be sure.

I am not sure what you are saying about pin 40 (/RESET) though. This is a key pin of the CPU for the operation of the machine - so this needs to be right.

Is the value HIGH or LOW? You can check if the pin is HIGH by measuring the voltage from 0V/GND to the pin itself. However, you can check if the pin is LOW by connecting the RED lead of the multimeter to the +5V supply of the logic board and taking a reading of the voltage on the pin using the BLACK lead of the multimeter. Report the reading back.

Dave

I checked a 3rd time pin 7 and it's 1.5v

 

[Lololobolosse]

Pins 2, 4 and 6 look OK (i.e. they are not causing us any problems).

You haven't checked pin 38 as I asked you to do. Could you do that please.

Pin 7 also looks partially suspect. Can you recheck this pin also? I do suspect what is happening - but let's be sure.

I am not sure what you are saying about pin 40 (/RESET) though. This is a key pin of the CPU for the operation of the machine - so this needs to be right.

Is the value HIGH or LOW? You can check if the pin is HIGH by measuring the voltage from 0V/GND to the pin itself. However, you can check if the pin is LOW by connecting the RED lead of the multimeter to the +5V supply of the logic board and taking a reading of the voltage on the pin using the BLACK lead of the multimeter. Report the reading back.

Dave

And i tried to turn the computer with pin 40 to ground like when it did the patern on the screen and the error tone i think but nothing i think it just happenned like that