1978 Commodore PET project

[BrackenFix]

Originally Posted by ScottishColin

The code I used to test the IEEE488 port is in this book:

http://www.primrosebank.net/computer...8_Bus_text.pdf

The testing Appendix starts at page 181 of the book and the code is on page 184.

It'll be easier if your tape drive works so you can type this in and save it on a cassette rather than having to type it in each time, so the focus on the tape drive is probably the right thing at the moment.

Colin.

That's fantastic, thank you.

Really looking forward to doing the tape deck

[SiriusHardware]

BF, I've now had the opportunity to watch your video linked to in post #175 properly from beginning to end.

I think your soldering skills are a lot better than you modestly made out, or you are just intuitively good at it because many people would have ended up chewing, burning or blistering the PCB if they tried to use your approach, but you did it all very carefully and patiently and it all worked very nicely.

The conventional sockets which you worried might not be the right type are perfectly OK, some people do prefer the turned-pin / machine pin type which are superior in most respects but they are very difficult to remove from double sided PCBs without damaging the board. I generally feel that on double sided PCBs, conventional sockets are better because you can replace them quite easily, more than once if necessary.

I notice you were concerned that quite a few of the pads of UE7 seemed to be connected together, if you were to look at UE7 on the circuit diagram you would see that quite a few of the pins of UE7 are indeed connected together in pairs, so you may find it useful to get a little bit more into reading and understanding circuit diagrams.

I'm enjoying watching you work through these problems and it will be interesting to see how the tape deck goes, hopefully any problems there will be more physical / mechanical than electronic.

[ScottishColin]

Agreed.

The way I worked through a new socket was to get the old one one, the new one in and then do some continuity checking using the schematics so I can make sure that each pin was connected on to the 'next' IC as appropriate, using my meter.

I did this before I inserted a new chip/turned on to make sure that at least the socket was sound electronically.

I got quite good at it after a while...

Colin.

Originally Posted by SiriusHardware

BF, I've now had the opportunity to watch your video linked to in post #175 properly from beginning to end.

I think your soldering skills are a lot better than you modestly made out, or you are just intuitively good at it because many people would have ended up chewing, burning or blistering the PCB if they tried to use your approach, but you did it all very carefully and patiently and it all worked very nicely.

The conventional sockets which you worried might not be the right type are perfectly OK, some people do prefer the turned-pin / machine pin type which are superior in most respects but they are very difficult to remove from double sided PCBs without damaging the board. I generally feel that on double sided PCBs, conventional sockets are better because you can replace them quite easily, more than once if necessary.

I notice you were concerned that quite a few of the pads of UE7 seemed to be connected together, if you were to look at UE7 on the circuit diagram you would see that quite a few of the pins of UE7 are indeed connected together in pairs, so you may find it useful to get a little bit more into reading and understanding circuit diagrams.

I'm enjoying watching you work through these problems and it will be interesting to see how the tape deck goes, hopefully any problems there will be more physical / mechanical than electronic.

[BrackenFix]

Originally Posted by SiriusHardware

BF, I've now had the opportunity to watch your video linked to in post #175 properly from beginning to end.

I think your soldering skills are a lot better than you modestly made out, or you are just intuitively good at it because many people would have ended up chewing, burning or blistering the PCB if they tried to use your approach, but you did it all very carefully and patiently and it all worked very nicely.

The conventional sockets which you worried might not be the right type are perfectly OK, some people do prefer the turned-pin / machine pin type which are superior in most respects but they are very difficult to remove from double sided PCBs without damaging the board. I generally feel that on double sided PCBs, conventional sockets are better because you can replace them quite easily, more than once if necessary.

I notice you were concerned that quite a few of the pads of UE7 seemed to be connected together, if you were to look at UE7 on the circuit diagram you would see that quite a few of the pins of UE7 are indeed connected together in pairs, so you may find it useful to get a little bit more into reading and understanding circuit diagrams.

I'm enjoying watching you work through these problems and it will be interesting to see how the tape deck goes, hopefully any problems there will be more physical / mechanical than electronic.

That is very kind of you to say, I promise my first proper soldering was done for my first channel video a couple of months ago.

I completely agree I need to learn to read circuit diagrams.

[BrackenFix]

I finally got time to clean and service the datasette this weekend.

I also tested the keyboard and loading of programs and am very pleased to say it all worked perfectly.

Phew!!!!

As always, you have all been amazing.

All that is left is to clean the chassis, really.

That being said, the text on the screen kind of shakes. Not blurred, more like it is moving a few pixels all the time.

I'll look at that next I think

Here is a video. Including the part where I found the source of the tape rattle.

https://www.youtube.com/watch?v=0y59aqTT1vA

[SiriusHardware]

Well done on getting so far so fast with so little trouble.

I've only been able to skim your latest video so far because I am about to go out for the day but I have to say the display looks rock steady to me in the segments I looked at. If the display is occasionally shifting up or down by a line or two it may just need a small tweak to the hold controls in the monitor, but don't go there until we have a better understanding of what you feel the problem is.

[BrackenFix]

Ill try to get a better video of the movement

[BrackenFix]

Well, I think it is all done.

All cleaned up, tested and working

Thank you all from the bottom of my heart for all your help. I will no doubt be back soon with questions and info on my next project.

I fancy fixing another vintage computer as soon as I can get my hands on one

[ScottishColin]

Good job. Where did you find your PET as a matter of interest?

And did you text the IEEE port with the code mentioned in post 178?

Colin.

[BrackenFix]

My father in law bought it new in 1978. Was in his loft for 25 years and he offered it to me.

I did indeed type out that code, saved to tape too. Said all was ok. (Heart then End of Test)

[SiriusHardware]

Glad it is all sorted, if you ever have any other interesting items like that to fix, you know where to find us.

[BrackenFix]

Oh trust me, I will be back.

Looking for a C64 now, had one as a kid so why not!

[BrackenFix]

Thank you again everyone, you have all been amazing

[ajgriff]

Another PET lives on! Very well done and thank you for keeping us informed throughout.

Alan

[ScottishColin]

All sorted then.

I think mine was kept in a shed, or perhaps at the bottom of a swimming pool.

Lofts are good.

Colin.

Originally Posted by BrackenFix

My father in law bought it new in 1978. Was in his loft for 25 years and he offered it to me.

I did indeed type out that code, saved to tape too. Said all was ok. (Heart then End of Test)