GS1200 Xenon Lamp

[Joel Bleakley]

Hello Guy's I've recently picked up a GS1200 Xenon for only $305 US which I think is a steal. It is faulty however. That of course doesn't worry me in the least since I'm an electronics repairman by trade. I've been doing projector repairs for about twenty years now. I was on this forum only briefly about 15 years ago but been quiet since then. In the coming weeks and months I'll be posting some updates on the restoration for those that are interested. It is currently a japanese 100 volt unit which I was contemplating getting the transformer rewound until I remembered the Xenon models have the mains run into the lower PSU for the lamp as well. If anyone needs any electronics advice I'm happy to help. Greetings from Oz! Joel.

[Burton Sundquist]

Welcome back Joel! looking forward to your updates!

[Stuart Budd]

Looking forward to the faults you find! Fixing something is always rewarding. I have the standard GS1200. Our enviroment for electroics is the killer. Oh and contacts. Yep, any tips and tricks and fixes and the list goes on...
Best of time (you won't need luck) on you project.

[Joel Bleakley]

Hello All, I've got an update on the GS1200 Xenon project. If you see the attached pictures you notice the odd looking power connector. I could have went to the trouble of sourcing a cable for that connection however I'd rather have the standard IEC power connection so I don't have to worry about compatibility in the future. You'll note I've swapped it in the lower image. It looks a bit ugly since the shapes of the two connectors were quite different so I'll need to pretty it up in the future but it will do for now while I assess the machine and find what needs fixing. According to the sales report the take up went in the wring direction and the rewind was not working. As for the direction I found a transistor under the flywheel shorting out a diode. I straightened that up and I don't think any lasting damage has been done. The motors all seem to be running in the correct direction. In fact I only found two/three major faults.
They are the Xenon lamps tries to strike and you can see it flickering on/off and the exciter arcing however it won't fully turn on. I'm not too stressed out about that yet since the main happy news is that it's not blowing fuses and all the main chunky high voltage/current and power transistors all seem to be intact. I suspect it's either due to worn worn and tired electrolytic capacitors in the Lamp power supply and oscillator circuit or perhaps a difference in supply frequency from 50hz to 60hz but all that needs further investigation. I'll possibly be looking at refreshing a lot of the main electrolytic capacitors throughout the unit anyway but I'll see how enthusiastic I am.
The other main faults or fault is the take up and rewind arms don't turn despite the motors actual running. At least if you look at the back of the motors inside you can actually see them both running fine. The arms don't. I took a look at the belts inside and they seem fine. That's as far as I've got. I'm tired now from having to file and drill out the back to mount the new power socket. I also had to drive around getting it. I'll post more updates as they come to light. If anyone knows what the deal is with the motors not engaging the arms I'd love to know since I've never come across that fault before. Either way I'm sure it won't bee too hard to figure out. I've also included in the pictures for those curious a picture of a Japanese fuse section to highlight the absence of the voltage selection block. Normally on most GS1200 units right there is the block where you adjust for 110/120 to 220/240 volts. On the Japanese this is missing and the mains goes stright into the transformer windings. I've also found out the Xenon models lamp Power comes of the Mains directly. If you adjust the selector voltage on the Projector there is a seperate adjustment in the lamp power supply box that sits under the unit. Cheers all, Joel.

[Stuart Budd]

You've inspired me to sort the pilot/play LED.
Sometimes you need a little break.
Those caps will be interesting to follow you replace. That short, maybe just a hand fiddling about!
Till your next post

[Joel Bleakley]

Hello All, Just another Update on the xenon. I found the fault with the rewind and take up arms. It seems someone has been working on this projector before. I've found the Gear for both were on the wrong side so in other words they were swapped. As a result of this one of them has been damaged. I've ordered two from Van Eck so I'll have them soon. It will be interesting to see how the rest of the projector operates since that will be the first time I get to take a deeper look. It also came missing the lens, but I have a standard GS1200 also so I'll just borrow the lens of it to do the test. Not sure how much money I want to spend on this until I get a better idea of it's condition.

[Clive Carmock]

I also have a GS1200 Xenon - UK model. It still has it's original Toshiba Xenon lamp. At times it can be problematic to strike. I have found that if I attamp a strike for 3-4 seconds and then switch off, wait a moment and try again repeating this it will strike. I think this helps ruiase the temperature of the lamp a little, and that makes it easier to strike.

Good luck with the repair - it's a fine machine when in good running order.

[Joel Bleakley]

Here we go so more updates on the GS1200 Xenon project and these are cool. In this shot we see the two damaged gears for the arms.

[Joel Bleakley]

After that and while I'm waiting for the new ones from Van Eck I started on the Lamp circuit. This time on the PSU that sits under the projector. In the shot attached I show the tool I use to remove the pin from the Molex connector which plugs into the switching CCT board inside the Projector. For those that don't know the PSU underneath is not the entire CCT for the lamp. In the other pictures you can see me change the three Electrolytics for the oscillator CCT.

[Joel Bleakley]

Finally the exciting part is that this has restored the lamp functionality. Although I'm not finished yet. I still would like to change the bigger 220uf 200 volt capacitors in the bottom. More importantly I want to tackle the switching PCB the sits inside the Projector that connects to the Chunky 2SC2650 switching transistor. That comes next.

[Stuart Budd]

That must have been a good feeling having a complicated lamp strike up. CCT is, as with the other topics, a tad over my head. Thursday's lesson, which I missed!
Trying to find a way of helping and all I have is my interest and support.
Out of interest, you may not have run film yet. Another thread relating to image stability:
https://8mmforum.film-tech.com/vbb/f...stable-problem
Wear on the gate film pressure guides! With the arm gears broken, maybe a high mileage machine and worth a look. Wounder if filling with solder may help if needed.

[Lee Mannering]

Only thing I ever did was to replace and align Xenon lamps in my GS Xenon machines since the 80s. Other than that looked after machines seemed to have been trouble free other than one exploding lamp in front of 200 people at a film festival reported on the old forum. Oh those were the days projecting to a big audience and all that Kodachrome.

[Greg Perry]

Joel,
These repairs you are making to your GS1200 Xenon are brilliant! Thanks for sharing these pics, and the info with the rest of us.

[Joel Bleakley]

Hey Guys, Thanks for the support. I'm waiting on parts at the moment but I'm sure it won't be too long since I have some updates. An interesting thing is that this projector came without a lens. As such I was open to a few ideas. I was going to wait until it was fully up and going but I got excited and ended up ordering a schneider 1.1 with an adapter. I'll be interested to see how that compares to the stock elmo 1.1. I see this has been a talked about topic on the forum. The other thing I was curious to ask the more experienced xenon lamp users was about the lamps end of life and indicators. Hearing your story Lee is a bit daunting. I have heard stories before and was curious if this was how they always go? Is there a way to avoid such explosion?

[Joel Bleakley]

Here we go some images of the first run. In my excitement I forgot to take some pictures of the install of the two cogs. They have fixed the problem and I can announce the Projector is up and running. I've included some shots of the projector running a test film of Butch Cassidy & Sundance. This is a 2 track mono film. That is there is a mono track on both stripes of the film I use to test stereo projectors. I do have a stereo film of Romancing the Stone but I'm not running that through yet. I still haven't finished replacing the capacitors in the lamp cct but seems running not too bad despite this. There is a flicker on the high setting indicative of power supply ripple but nothing that can't be fixed. I want to give the film path a thorough cleaning before I go any further. But the first test run looks good. Note the Red film with the xenon lamp. I might take a screen shot of the same film with the standard GS1200 just for giggles.