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Graphics 808 scan switches.

 
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Sat Nov 08, 2014 10:03 pm    Post subject: Graphics 808 scan switches.

Help needed as per subject line.

Pj was previously set up for ceiling/front projection. I now have it on the floor/front but need to switch the scan switches properly. I didn't read the manual right and made a botch. I managed the vertical switch change but I only realised afterwards that I hadn''t switched the horizontal switches correctly. I only switched one of the tubes - I'd forgotten there was one switch for each tube and didn't follow the manual correctly. Big error on my part. I powered up but the pj seemed to keep trying to sync and then quiting to standby or something. I switched the pj off, studied the manual, realised my mistake and put the switches back.

Could I have done damage by having one of the scan switches in and two of the switches out on the horizontal deflection? I.E. one of the tubes was reversed on the horizontal scan.

I can currently only get tube output by putting the switches back in "ceiling/front" position. Hoping it's just dirty switches, I've "exercised" them quite a bit but need to get some canned air on them tomorrow. Hope I've not killed something like the horizontal board - support and parts for these things is nonexistent in the UK. Embarassed
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Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC

TV/Projector: All of them!

Posted: Sun Nov 09, 2014 1:55 am    Post subject:

Nope. no way to damage the set, but you're probably right, the switches may be oxidized. Compressed air won't do anything, get a can of control or contact cleaner.

Don't mess with the switches with the set powered up, or you'll nuke the tubes. You should be able to flip one switch at a time to see which one causes the set to act up. I've got the switches if you need them.
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Decibel



Joined: 31 May 2007
Posts: 904
Location: Roma - Italia

Posted: Sun Nov 09, 2014 8:15 am    Post subject:

You can check the functionality of the switch with a tester.
I have an extra switch and I'll describe the connections soon.

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Domenico (Barco fan!)
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Sun Nov 09, 2014 11:45 am    Post subject:

Many thanks Curt for your advice. Before I spend more money on contact cleaner am I alright to squirt in some Isopropyl Alcohol and try that first? Just glad I haven't killed anything. I've been getting all sorts of symptoms in everything but front/ceiling. It's a nice clean set but having a switch stuck in one position all the time is probably gonna cause problems in the long run. Wouldn't think of switching the switches with the set on but thanks for the warning anyway.

Thanks Domenico for your support. I'm normally fine using a multimeter/tester but my back is really slowing me down at the moment as working on these things require a lot bending over when they're on the floor. Look forward to the further details.

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Simon
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Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC

TV/Projector: All of them!

Posted: Sun Nov 09, 2014 2:56 pm    Post subject:

Usually a few presses of the switch cleans the contacts. Isopropyl won't do anything. While I've cleaned scan switches in the past, it's because it's preventative maintenance, not because a switch had a fault.
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Sun Nov 09, 2014 4:21 pm    Post subject:

OK thanks Curt - I hear you. I'll try and have a play with things soon (exercise those switches) and look out for some contact cleaner if need be. Servisol super 10 is affordable in the UK. Caig Deoxit is sparse and/or very expensive.
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Sun Nov 09, 2014 6:03 pm    Post subject:

Good news! Did some testing - the vertical switch certainly wasn't working as got nothing out of the tubes when I tried again with it. I exercised all four switches 20 times each and then set them for front/table. Success! I'm used to doing this on old hi-fi equipment but this pj being so clean I didn't think it would be an issue. I know these machines are designed robustly so I figured the switches must be idiot proof if setup incorrectly (which I certainly think I did at first). Seems the £95 I paid for this machine is going to be worthwhile after all.
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Simon
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Wed Nov 12, 2014 1:33 pm    Post subject:

Bad news! The switch exercising only worked once. Projector is still back to only happy with ceiling/front.

So which end/side/top or bottom of the vertical switch is best to spray the contact cleaner using a straw? I would think top and both ends but I don't know where it will get in best.

Not looked at where to squirt the horizontal switches yet because they're under the width coils. Is the board with the width coils just secured with the top screws?

I assume all these contact cleaners are non-conductive and I can power the machine straight on again?
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Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC

TV/Projector: All of them!

Posted: Wed Nov 12, 2014 3:01 pm    Post subject:

Get a can of DeOxIt made by Caig. It's the only thing I use now.
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Wed Nov 12, 2014 4:40 pm    Post subject:

Cheers Curt. I know it's good stuff it's just so expensive in the UK, like £15, three times the price of something like Servisol Super 10. I will look into it again and see what version of DeOxIt I need - there seems so many.

Any, more affordable, contact cleaner suggestions from others, specifically for the UK?

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Simon
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Wed Nov 26, 2014 7:10 pm    Post subject:

Okay couldn't warrant the cost of DeOxit so went for Servisol Super 10. It seems to get relatively good reviews in the UK. Anyway it hasn't altered anything.

Not sure where I'm supposed to spray this stuff to best get in the switches. I sprayed it on top and hoped it would find it's way inside then I exercised the switches.

Anyway as it goes I think the front two horizontal switches work. It's a combination of the back horizontal switch (the bigger of the three horizontal switches) and the vertical scan switch which cause the tubes not to fire up aside from a dull glow at the tops or the bottoms of the tubes when you look in the lenses.

As far as using a continuity tester goes. I'm pretty sure it is but - is the motherboard double sided?

Domenico, you suggested you had a description of the schematic for the switches. Have you still got that so I can test with my multimeter?

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Simon
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Tue Dec 02, 2014 6:14 pm    Post subject:

From this thread: https://www.curtpalme.com/forum_archived/viewtopic.php@t=36346.html

I pulled this quote (7 posts down):
Quote:
No bent pins, it appears to have been a dirty scan switch as I called Tom and he suggested cleaning them and possibly using some tape to hold them in position, I blew them out with some compressed air the some precision cleaner and air again reinstalled the cards and now it's staying on.


Clutching at straws here. What does Tom mean by "using some tape to hold them in position"? They stay in position if the mechanism is working don't they? Does he mean hold them in at their deepest point before they click back? Is this safe to do or will my set go bang?

I would get the continuity meter on there if I was in better health and could bend over - soon maybe.
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Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC

TV/Projector: All of them!

Posted: Tue Dec 02, 2014 6:28 pm    Post subject:

The spring on the V switch has a tendency to pop off the mounts. That kills the locking action of the switch. That's when you use painter's or electrical tape to hold them in place, as most sets are permanently installed, and you never need to change the switch.

I now have enough spare switches so I replace them, but back in the day I did the tape thing a few times, as the switches weren't available.
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Tue Dec 02, 2014 7:59 pm    Post subject:

Thanks Curt for clearing that up. So it's only when the locking action of the switch is dead due to faulty spring action. Well it's worth a check before I do the continuity tests.
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Simon
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Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC

TV/Projector: All of them!

Posted: Tue Dec 02, 2014 11:05 pm    Post subject:

Whatever you do, don't wiggle or touch the switch when the set is on! you'll burn a line into each tube.
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cosaw



Joined: 08 Mar 2006
Posts: 164
Location: Nottingham, England

Posted: Wed Dec 03, 2014 8:56 am    Post subject:

Thanks Curt, I hear you.
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Simon
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