Non-working Commodore PET 3016 - Page 10 - UK Vintage Radio Repair and Restoration Discussion Forum

SiriusHardware · 21st Jan 2021, 4:11 pm

Power on, black lead on known 0V, meter in voltage mode, what voltage do you see on pin 40 of the 6502?

ScottishColin · 21st Jan 2021, 4:15 pm

4.963v

ScottishColin · 21st Jan 2021, 4:19 pm

Another quick question - I do not have a chip in UD5 and the BoM gifs I have indicate there should be something in there.

What I do have is a spare 24 pin chip with no markings which was never in the PET while I have had it. Should there be anything in UD5?

SiriusHardware · 21st Jan 2021, 4:33 pm

_Reset input state looks normal so it's odd you don't seem to have activity on the low address lines.

I'll have to wait until I get home before I can answer your question re: UD5 (technically at work just now). Anyone else?

ScottishColin · 21st Jan 2021, 4:42 pm

Hm. On the actual schematics (page 4), UD3, UD4 and UD5 are all marked as 6332 (SPARE), so I'm not sure there should be anything. Anyone's help appreciated.

Mark1960 · 21st Jan 2021, 5:00 pm

Might be worth checking the markings on the 6502 in case it has been swapped at some time in the past for a 65C02.

Check the voltage and if any frequency on 6502 pin2 RDY and pin 7 SYNC.

If no frequency measured on address lines pins 9, 10 and 11, what voltage is on those pins?

You could also check for frequency and voltage on any of the other address lines, pins 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25. Note if there is a frequency the voltage doesn’t really help, but if there is no frequency we might see what address the 6502 is stuck at.

ScottishColin · 21st Jan 2021, 6:26 pm

I'll check the voltages/frequencies as above - thanks Mark.

fyi, the scope I ordered two days ago from China has just been delivered....

SiriusHardware · 21st Jan 2021, 6:37 pm

That's pretty good isn't it?

Can you link to a page showing the model you have (not on ebay if you can avoid it, but maybe you can find the same model on Amazon or elsewhere?). If we can see what you have it will help us to be more specific when asking you to make measurements.

If you are feeling lucky try using it to look at all the 6502 pins Mark suggested (as well as measuring for frequency and possibly voltage).

ScottishColin · 21st Jan 2021, 6:48 pm

Here it is. It's quicker than posting a letter to my Dad in Norwich....

https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1

I need to install software on a PC and learn how to use it which I'm looking forward to so I'm doing the install right now and a bit of Youtubing to educate myself.

SiriusHardware · 21st Jan 2021, 7:10 pm

Looks potentially very useful, especially with that logic analyser capability. I hope yours did come with probes. It looks like a possible clone of the 6022 Mark mentioned so maybe Mark already has a good idea of how to drive one of those?

ScottishColin · 21st Jan 2021, 7:40 pm

Lots and lots of probes

SiriusHardware · 21st Jan 2021, 8:52 pm

In particular, I meant the 2 * scope probes as they might be expensive to buy separately if you didn't get them with the unit.

A good 'First look' would be that 1MHz signal we spent all that time looking for on UG5 pin 7. Now you'll finally be able to see what it looks like.

Mark1960 · 21st Jan 2021, 9:01 pm

Quote:

Originally Posted by SiriusHardware

Looks potentially very useful, especially with that logic analyser capability. I hope yours did come with probes. It looks like a possible clone of the 6022 Mark mentioned so maybe Mark already has a good idea of how to drive one of those?

No, I just picked that as a preference over the toy kit that colin originally considered. I had looked at the specs when I was looking for a scope last year, but went for siglent 200mhz dual channel instead.

ScottishColin · 21st Jan 2021, 10:30 pm

post #186

measured with my new meter (not the scope)

No frequency on any pins

Voltage on all pins (12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25) between 3.1-3.3

Colin.

Mark1960 · 21st Jan 2021, 10:36 pm

Did you check pin 2 and 7?

ScottishColin · 21st Jan 2021, 10:48 pm

Attached is a photo of the 6502.

Neither pins 2 nor 7 of the 6502 had frequencies

Pin 2 voltage 5.073V
Pin 7 voltage 0.134V

ScottishColin · 21st Jan 2021, 10:51 pm

No frequencies on pins 9, 10 or 11

Voltages:
Pin 9 - 3.56V
Pin 10 - 3.56V
Pin 11 - 3.57V

Mark1960 · 21st Jan 2021, 10:58 pm

Also still worth checking the markings on the 6502, just in case it has been swapped at some point.

If RDY is held low, that might explain why the address lines are held high with no activity.

As you have clock input and output on the 6502, but no address activity, if sync is also no activity and RDY is held high, then I would suspect a faulty 6502, but you should verify the previous measurements with the scope first.

I think the pet should be using one of the original nmos 6502, rather than the later 65c02, but that should be verified first by someone thats more familiar with pets.

SiriusHardware · 21st Jan 2021, 11:10 pm

Mark, are you still having difficulty viewing the circuit daigrams online or was that just on one particular device? If you can't view them at all I can try grabbing them and emailing them to you.

This is where I wish my Sybex 'Programming the 6502' wasn't buried in the garage. It's probably been nibbled away to nothing by Silverfish by now.

I'll have a look to see where the input to RDY comes from on this system.

ScottishColin · 21st Jan 2021, 11:11 pm

The 6052 has

MOS
MPS6502
3979

markings on it.

21st Jan 2021, 4:11 pm	#181
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Non-working Commodore PET 3016 Power on, black lead on known 0V, meter in voltage mode, what voltage do you see on pin 40 of the 6502?

21st Jan 2021, 4:15 pm	#182
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 4.963v

21st Jan 2021, 4:19 pm	#183
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 Another quick question - I do not have a chip in UD5 and the BoM gifs I have indicate there should be something in there. What I do have is a spare 24 pin chip with no markings which was never in the PET while I have had it. Should there be anything in UD5?

21st Jan 2021, 4:33 pm	#184
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Non-working Commodore PET 3016 _Reset input state looks normal so it's odd you don't seem to have activity on the low address lines. I'll have to wait until I get home before I can answer your question re: UD5 (technically at work just now). Anyone else?

21st Jan 2021, 4:42 pm	#185
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 Hm. On the actual schematics (page 4), UD3, UD4 and UD5 are all marked as 6332 (SPARE), so I'm not sure there should be anything. Anyone's help appreciated.

21st Jan 2021, 5:00 pm	#186
Mark1960 Octode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 1,294	Re: Non-working Commodore PET 3016 Might be worth checking the markings on the 6502 in case it has been swapped at some time in the past for a 65C02. Check the voltage and if any frequency on 6502 pin2 RDY and pin 7 SYNC. If no frequency measured on address lines pins 9, 10 and 11, what voltage is on those pins? You could also check for frequency and voltage on any of the other address lines, pins 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25. Note if there is a frequency the voltage doesn’t really help, but if there is no frequency we might see what address the 6502 is stuck at.

21st Jan 2021, 6:26 pm	#187
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 I'll check the voltages/frequencies as above - thanks Mark. fyi, the scope I ordered two days ago from China has just been delivered....

21st Jan 2021, 6:37 pm	#188
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Non-working Commodore PET 3016 That's pretty good isn't it? Can you link to a page showing the model you have (not on ebay if you can avoid it, but maybe you can find the same model on Amazon or elsewhere?). If we can see what you have it will help us to be more specific when asking you to make measurements. If you are feeling lucky try using it to look at all the 6502 pins Mark suggested (as well as measuring for frequency and possibly voltage). Last edited by SiriusHardware; 21st Jan 2021 at 6:42 pm.

21st Jan 2021, 6:48 pm	#189
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 Here it is. It's quicker than posting a letter to my Dad in Norwich.... https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1 I need to install software on a PC and learn how to use it which I'm looking forward to so I'm doing the install right now and a bit of Youtubing to educate myself.

21st Jan 2021, 7:10 pm	#190
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Non-working Commodore PET 3016 Looks potentially very useful, especially with that logic analyser capability. I hope yours did come with probes. It looks like a possible clone of the 6022 Mark mentioned so maybe Mark already has a good idea of how to drive one of those?

21st Jan 2021, 8:52 pm	#192
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Non-working Commodore PET 3016 In particular, I meant the 2 * scope probes as they might be expensive to buy separately if you didn't get them with the unit. A good 'First look' would be that 1MHz signal we spent all that time looking for on UG5 pin 7. Now you'll finally be able to see what it looks like.

21st Jan 2021, 10:30 pm	#194
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 post #186 measured with my new meter (not the scope) No frequency on any pins Voltage on all pins (12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25) between 3.1-3.3 Colin.

21st Jan 2021, 10:36 pm	#195
Mark1960 Octode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 1,294	Re: Non-working Commodore PET 3016 Did you check pin 2 and 7?

21st Jan 2021, 10:48 pm	#196
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 Attached is a photo of the 6502. Neither pins 2 nor 7 of the 6502 had frequencies Pin 2 voltage 5.073V Pin 7 voltage 0.134V Attached Thumbnails

21st Jan 2021, 10:51 pm	#197
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 No frequencies on pins 9, 10 or 11 Voltages: Pin 9 - 3.56V Pin 10 - 3.56V Pin 11 - 3.57V

21st Jan 2021, 10:58 pm	#198
Mark1960 Octode Join Date: Mar 2020 Location: Kitchener, Ontario, Canada Posts: 1,294	Re: Non-working Commodore PET 3016 Also still worth checking the markings on the 6502, just in case it has been swapped at some point. If RDY is held low, that might explain why the address lines are held high with no activity. As you have clock input and output on the 6502, but no address activity, if sync is also no activity and RDY is held high, then I would suspect a faulty 6502, but you should verify the previous measurements with the scope first. I think the pet should be using one of the original nmos 6502, rather than the later 65c02, but that should be verified first by someone thats more familiar with pets.

21st Jan 2021, 11:10 pm	#199
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Non-working Commodore PET 3016 Mark, are you still having difficulty viewing the circuit daigrams online or was that just on one particular device? If you can't view them at all I can try grabbing them and emailing them to you. This is where I wish my Sybex 'Programming the 6502' wasn't buried in the garage. It's probably been nibbled away to nothing by Silverfish by now. I'll have a look to see where the input to RDY comes from on this system.

21st Jan 2021, 11:11 pm	#200
ScottishColin Octode Join Date: May 2012 Location: Perth, Scotland Posts: 1,804	Re: Non-working Commodore PET 3016 The 6052 has MOS MPS6502 3979 markings on it.