|
Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
|
Thread Tools |
27th Sep 2022, 10:19 pm | #141 |
Octode
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,762
|
Re: 1978 Commodore PET project
Wait until you open it up. This is what was inside my keyboard (although the closer keys of your keyboard may save you from this).
Colin. |
28th Sep 2022, 1:49 pm | #142 | |
Tetrode
Join Date: Sep 2022
Location: Newton Abbot, Devon, UK.
Posts: 75
|
Re: 1978 Commodore PET project
Quote:
I removed UC6 and UC7 and the screen was the same |
|
28th Sep 2022, 1:57 pm | #143 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,583
|
Re: 1978 Commodore PET project
Shows that the PIAs aren't causing the problem thus eliminating them from our enquiries at this stage. Worth doing as it's a quick and easy check.
Alan |
28th Sep 2022, 2:32 pm | #144 |
Tetrode
Join Date: Sep 2022
Location: Newton Abbot, Devon, UK.
Posts: 75
|
Re: 1978 Commodore PET project
Absolutely, took 2 minutes and that included 30 seconds trying to move the heavy lump
|
3rd Oct 2022, 11:37 am | #145 |
Tetrode
Join Date: Sep 2022
Location: Newton Abbot, Devon, UK.
Posts: 75
|
Re: 1978 Commodore PET project
Sorry for the radio silence.
I have got the keyboard working now and the 3 replacement chips have arrived. Just deciding the best way to swap the chips so will report back soon |
3rd Oct 2022, 11:50 am | #146 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
|
Re: 1978 Commodore PET project
Well done on the progress with the keyboard.
If in doubt, snip the legs off the original ICs high up next to the body of the chip, remove the body and then desolder and remove the individual pins. There are still plenty of chips around but you only have that one 40+ year old mainboard, so not damaging it is your main priority. Suggested order of replacement was (I think) UE7, UF7, UF9 replacing only one at a time and trying the machine again after each chip change. |
3rd Oct 2022, 12:04 pm | #147 | |
Octode
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,762
|
Re: 1978 Commodore PET project
When I was at this stage, I carefully used a hobby 12v drill and a metal cutting disc to cut each leg off as high as I could. A careful hoover to suck up any metal shards was required to make sure I had left nothing to short anything else. This seemed (to me) to exert less pressure on the pads on the motherboard than snipping each leg.
I guess we all have our own ways.... Colin. Quote:
|
|
3rd Oct 2022, 12:20 pm | #148 |
Octode
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,762
|
Re: 1978 Commodore PET project
|
3rd Oct 2022, 12:36 pm | #149 | |
Tetrode
Join Date: Sep 2022
Location: Newton Abbot, Devon, UK.
Posts: 75
|
Re: 1978 Commodore PET project
Quote:
Using paper was a great tip |
|
3rd Oct 2022, 12:52 pm | #150 | |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
|
Re: 1978 Commodore PET project
Quote:
As for exerting force on the pads while trying to cut the legs, that's why the advice is to cut them high up, not low down next to the PCB. Most electrical / electronics side cutters are too clunky and the ends of the jaws too thick and blunt to slip into the gap on either side of an IC pin, that's why I keep mentioning 'cuticle nippers' which are essentially a miniature version of the same thing. |
|
3rd Oct 2022, 12:56 pm | #151 | ||
Octode
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,762
|
Re: 1978 Commodore PET project
I am certainly no expert on this, but it worked for me and seems to be the least abrasive to start off with.
Colin. Quote:
|
||
3rd Oct 2022, 12:56 pm | #152 | ||
Octode
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,762
|
Re: 1978 Commodore PET project
I got lucky then.
Colin. Quote:
|
||
3rd Oct 2022, 1:26 pm | #153 | |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
|
Re: 1978 Commodore PET project
Quote:
On a more serious note the use of a rotary tool also poses the risk of generating static as well, I honestly would not do it that way myself. |
|
3rd Oct 2022, 1:48 pm | #154 |
Tetrode
Join Date: Sep 2022
Location: Newton Abbot, Devon, UK.
Posts: 75
|
Re: 1978 Commodore PET project
Will just be such a shame to damage the old chips. Granted they are possibly broken anyway but still a shame.
Leave it with me, I'll have a ponder |
3rd Oct 2022, 1:49 pm | #155 |
Octode
Join Date: May 2012
Location: Perth, Scotland
Posts: 1,762
|
Re: 1978 Commodore PET project
|
3rd Oct 2022, 2:26 pm | #156 | |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
|
Re: 1978 Commodore PET project
Quote:
As you currently don't seem confident about removing ICs in one piece, your choices would seem to be, wait until you do feel confident (maybe when you've had a bit more practice with your desoldering gun) or play it safe and cut up one or two possibly blameless ICs in order to not damage the PCB. You don't actually have to make that decision now, sleep on it for a week or a month if need be. |
|
3rd Oct 2022, 2:52 pm | #157 |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,583
|
Re: 1978 Commodore PET project
What about the de-soldering tool?
Good work on the keyboard. Well done. Alan |
3rd Oct 2022, 2:59 pm | #158 |
Tetrode
Join Date: Sep 2022
Location: Newton Abbot, Devon, UK.
Posts: 75
|
Re: 1978 Commodore PET project
|
3rd Oct 2022, 3:02 pm | #159 |
Tetrode
Join Date: Sep 2022
Location: Newton Abbot, Devon, UK.
Posts: 75
|
Re: 1978 Commodore PET project
I have loads of tapes for when I can test them at least
Including one called Cosmic Jailbreak (proper Commodore one) |
3rd Oct 2022, 5:43 pm | #160 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,814
|
Re: 1978 Commodore PET project
I remember back when I was doing mobile phone repairs (19 years ago!!) we had a special soldering iron for replacing solder on ribbon cables, specifically the ones on Nokia 7650’s, it was a Metcal thing that had 2 elements which went into a single inch and a half long wedge shaped tip, I think one of those, or even 2 of them would make removing IC’s intact a lot easier.
Regards Lloyd |