8mm Forum: GS1200 Speed Control

This is topic GS1200 Speed Control in forum 8mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=003275

Posted by Graham Ritchie (Member # 559) on November 28, 2007, 03:41 PM:

Last night I was using my spare projector "it has not been used for a while" and noticed that when switching to 18 fps it would not run at that speed, tried moving the speed control and ESS switches a number of times with no success, however later I found that by moving the ESS switch just slightly to the right of Normal "the centre" the projector would run at 18 fps and for the rest of the night it ran fine at that speed, however back to the "centre" nothing, well I was thinking would it be better to replace the switch rather than trying to work some CRC into the contacts, any advice would be great.

Graham.

Posted by Kevin Faulkner (Member # 6) on November 28, 2007, 04:40 PM:

Dirty switch contacts. The position you found was probably a point where the contacts were still clean. I would try some switch cleaner first as that will probably cure it. You are going to have to remove the rear cover anyway so why not give that a go first which easier in the long run than having to remove the board etc to allow you to replace the switch.

Kev.

Posted by Graham Ritchie (Member # 559) on November 29, 2007, 12:59 AM:

Thanks Kev
I removed the rear cover, and gave the ESS switch a good clean with CRC contact cleaner while moving it a number of times from one side to side to work it in, I really thought that this should do it, but it did not work, bit surprised, the projector runs fine at 24 fps but I still have to move the switch just of to the right from the normal position for it to run at 18 fps the projector does run in the normal position but I think its 6fps or something like that, the clean should have done the trick, what do you think?

Graham.

Posted by Kevin Faulkner (Member # 6) on November 29, 2007, 10:31 AM:

That definitely sounds like the switch has given up the ghost. Yes with no connection you would get the 6fps.

Looks like you will either have to remove the switch and try to open it carefully to see what gives or try and get a replacement which might be difficult now.

Wittners in Germany did have some of those panels complete and at real knockdown prices.

Kev.

Posted by Graham Ritchie (Member # 559) on November 29, 2007, 01:42 PM:

Kev
One thing I did notice that there seemed to be a hard grease deposit on the contacts that were visible and so I used some CRC Electra-clean first, which removes grease, before finishing with contact cleaner, so its still possible that this stuff that was used on the switch from day one has gone hard on the contacts further inside "just a thought" I was also wondering about the possibility of a dry soldered joint on one of the terminals on the switch, well next week I will pull it apart and hopefully get it fixed, Kev, thanks for your help and will let you no the outcome.

Graham.

Posted by Graham Ritchie (Member # 559) on December 03, 2007, 01:18 PM:

Hi Kev
Well I havent been very sucessfull with this problem I removed the board that was the easy bit, and looking at what is involved in getting the switch apart [Eek!]

made me think that I better be right, that the problem is the switch, so I gave a further extensive clean with CRC contact cleaner at the same time working the switch many times, after this I checked it with a multi-meter checking the resistance of the switch etc and over the complete board, so far I cant see anything wrong, everything seems to be doing what it is supposed to do, I re-installed the board and the projector is up and running but still only at 24fps but no 18fps. [Frown]

Kev, is there anything else that I should be looking at in the control circuit?.

Thanks Graham.

Posted by Kevin Faulkner (Member # 6) on December 06, 2007, 11:32 AM:

Graham,
I have just studied the circuits and would suggest that you check the following points.
The ESS Switch, The speed selector switch. The left hand pot on the small speed control board as this could be open circuit. The rear connector on the speed control board and make sure the connections are ok under the main board. Last check round the female connectors from the board with the switches on which you have pictured and check their male counterparts on the main board.

As the 24 FPS is ok I'm certain it has to be one of the items above. You seem to be getting a lack of continuity between the speed selector switch and the left pot on the speed control board.

Kev.

Posted by Graham Ritchie (Member # 559) on December 07, 2007, 02:18 AM:

Kev
Thanks for your help, I hope to get more time over the next few days and will check out everything that you have suggested and will let you know how things work out, much appreciated.

Graham.

Posted by Graham Ritchie (Member # 559) on December 10, 2007, 02:10 AM:

Hi Kev
Fixed [Big Grin]

....the reason, I dont no, [Confused]

last Friday I prodded all over the place with the multi-meter in particular checking continuity between the left pot and the ESS and speed selector switches, everything seemed fine including all the connectors at the back of the board, I checked everything you mentioned. I gave up at this point and left the projector at work, told the weekend projectionist he was welcome to give it a go { he has just completed an electronics course} just the thing to put some of that theory to work, anyway got a call the next day the projector is running fine switched it on and it worked, although I am happy with the result it does not answer "the why" so today I again removed the rear board and sprayed a small amount of CRC2-26 into both the switches its supposed to improve electrical properties, penetrates and most importantly lubricates, as the CRC contact cleaner I had used earlier had removed any lubricant that was originally inside both switches, and as a result made the switches hard to move, using CRC2-26 did the trick, with a final clean with contact cleaner over the entire bottom board including all the connectors, [Roll Eyes]

what a story eh!, well I ran the projector constant for 8 hours today at both 18fps and 24fps, tried to make it fail, it ran with no problems, [Smile]

thank goodness.

I can only guess that the prodding on Friday might have done something, a loose connection or a poor joint somewhere, I dont no, also the grease used on the switches may have dried hard over the years, causing a poor contact its all guess work, one thing is for certain most mechanical/electrical components need to be used and the GS1200 does not like to sit around and gather dust so this machine is going to get a lot more use [Wink]

its been an interesting experience.

Graham.

PS. Just a word of caution to anyone out there who is thinking of using elecrtical cleaners, there are some that effect certain types of plastic [Eek!]

and some that are flammable so be carefull what you use.

Posted by Kevin Faulkner (Member # 6) on December 10, 2007, 05:53 AM:

Thats good news Graham although it would have been good to know what the cause was.

Every time I use my GS Xenon I move all the switches and use the record controls. This helps to keep the switches clean.

Kev.

UBB.classic^TM 6.3.1.2