Commodore 1084S repair question - UK Vintage Radio Repair and Restoration Discussion Forum

naujoks · 9th Feb 2024, 12:33 pm

I have a Commodore 1084S-P1, which increasingly was having picture and sound distortions, which I was able to fix with friendly pats on the back of the monitor. So I thought "cold solder joints!" and set up touching up some joints.
On reassembly, the picture would was somewhat fuzzy and had distorted colours. I noticed that by touching the push buttons at the back to select COMP/SVIDEO etc, the picture would change and flickers, so I gave the buttons a blast with contact spray. Since then, the picture has disappeared altoghether (I can get a perfect picture using the RGB port), wiggling the buttons makes it show a few coloured bars, but that's it.

So is it all down to the push buttons? Can I get replacements for them somewhere? I'd like to bridge the contacts in the meantime, also to see if that actually fixes the picture, but the switches seems to have 6 contacts and I haven't been able to find a nice scan of a schematic for the 1084S-P1, so I have no idea which contacts to bridge. I don't use the COMP, only the chroma/luma SVIDEO.

Any advice is gratefully received!

G6ONEDave · 9th Feb 2024, 3:27 pm

If the switch is arranged as 2 rows of 3 pins making 6 pins in total, then it is a 2 pole change over type. The 2 pins nearest to the button and circuit board edge are 2 fixed poles and connect to the middle pair of pins when the switch button is outwardly positioned. When the switch button is pressed inwards, then the middle pair of pins make contact with the 2 pins away from the circuit board edge. They disconnect from the 2 pins nearest the circuit board edge.

With the power off it might be worth trying some more switch contact cleaner and operate the switch 10 to 20 presses. Then let the cleaner dry off before powering up the monitor again.

Dave

naujoks · 9th Feb 2024, 5:04 pm

While poking around in the monitor I since discovered by chance that one of the RCA sockets had a cracked solder pad. I fixed that and now the monitor is working again. Thanks for your advice though, that is interesting and good to know anyway!

9th Feb 2024, 12:33 pm	#1
naujoks Diode Join Date: Aug 2023 Location: Berlin, Germany Posts: 5	Commodore 1084S repair question I have a Commodore 1084S-P1, which increasingly was having picture and sound distortions, which I was able to fix with friendly pats on the back of the monitor. So I thought "cold solder joints!" and set up touching up some joints. On reassembly, the picture would was somewhat fuzzy and had distorted colours. I noticed that by touching the push buttons at the back to select COMP/SVIDEO etc, the picture would change and flickers, so I gave the buttons a blast with contact spray. Since then, the picture has disappeared altoghether (I can get a perfect picture using the RGB port), wiggling the buttons makes it show a few coloured bars, but that's it. So is it all down to the push buttons? Can I get replacements for them somewhere? I'd like to bridge the contacts in the meantime, also to see if that actually fixes the picture, but the switches seems to have 6 contacts and I haven't been able to find a nice scan of a schematic for the 1084S-P1, so I have no idea which contacts to bridge. I don't use the COMP, only the chroma/luma SVIDEO. Any advice is gratefully received! Last edited by naujoks; 9th Feb 2024 at 12:57 pm.

9th Feb 2024, 3:27 pm	#2
G6ONEDave Octode Join Date: Dec 2019 Location: Owston Ferry, North Lincolnshire, UK. Posts: 1,704	Re: Commodore 1084S repair question If the switch is arranged as 2 rows of 3 pins making 6 pins in total, then it is a 2 pole change over type. The 2 pins nearest to the button and circuit board edge are 2 fixed poles and connect to the middle pair of pins when the switch button is outwardly positioned. When the switch button is pressed inwards, then the middle pair of pins make contact with the 2 pins away from the circuit board edge. They disconnect from the 2 pins nearest the circuit board edge. With the power off it might be worth trying some more switch contact cleaner and operate the switch 10 to 20 presses. Then let the cleaner dry off before powering up the monitor again. Dave __________________ Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica)

9th Feb 2024, 5:04 pm	#3
naujoks Diode Join Date: Aug 2023 Location: Berlin, Germany Posts: 5	Re: Commodore 1084S repair question While poking around in the monitor I since discovered by chance that one of the RCA sockets had a cracked solder pad. I fixed that and now the monitor is working again. Thanks for your advice though, that is interesting and good to know anyway!