8mm Forum: Chinon 8000 lamp problem

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Posted by Stuart Reid (Member # 1460) on February 20, 2016, 03:34 PM:

Hi I have a Chinon Sound 8000 which is behaving oddly. When set to autothread the lamp lights dimly which is the correct behaviour, but when I switch to normal playback, or reverse playback the lamp goes out. Where should I begin my fault finding?

Posted by Janice Glesser (Member # 2758) on February 20, 2016, 04:39 PM:

Is this new behavior or is this a recent purchase where the projector came this way?

Posted by Steve Klare (Member # 12) on February 20, 2016, 05:23 PM:

I don't know these machines really well (or at all...), but if was was one of the ones I do know, the lamp would be controlled by a switch activated by a cam on the control knob shaft.

The one that works the projection lamp takes a huge beating because of the surge current when the lamp lights up from cold. (The dim pre-heat helps here)

One way or another some switch is supposed to be lighting that lamp, and either it isn't being told to switch, or it can't switch anymore.

In your case it sounds like it's supposed to select between a low voltage (dim) and a higher voltage (bright) and either the higher voltage isn't there (power supply problem or connection) or it isn't getting through (burnt switch contacts) so it's selecting between dim and dead.

-find that switch!

Posted by Andrew Woodcock (Member # 3260) on February 20, 2016, 06:58 PM:

There will either be a open or short circuit in the switch as Steve implies here. (Highly unlikely to be a short circuit issue or else you would continually be blowing the lamp fuse or main fuse).

Test what is happening here with a multimeter by testing the voltage to the lamp circuit in both primary and secondary knob positions.

You should be seeing 12 or 15vac in the secondary position but I suspect you will witnessing zero at the moment.

In the primary position, you will definitely be seeing some voltage here.

If you prove it is a faulty switch, then change the switch if possible with a close equivalent.

If you cannot find a fault with the switch then it will be mechanical wear to a cam lobe from the main switch to a micro switch or the likes.

Either way just trace the circuit with a multimeter doing a continuity test each step of the way from transformer lamp tappings right up until you reach the lamp terminals.

There is no quick fix solution here as this fault could be caused by many reasons. You just need to work out which from the information supplied here, what the problem is and then work out a feasible solution to the problem given that spare parts for this machine will be extremely difficult to come by.

Hope all of the advice here helps and good luck with it!

One thing you very quickly learn in the 21st Century dealing with vintage projectors and the likes, is that if you are not an electro mechanical engineer to begin with, you soon will be!

Posted by Steve Klare (Member # 12) on February 20, 2016, 07:17 PM:

I'd say there is some switching action here...just a lack of success!

It's getting it half right: it is de-selecting the dim voltage, but then what?

If it was a choice, I'd want a connection problem: replacing these switches is a bear of a job.

I did one on one of my Elmos about five years ago and it was a pretty solid three hours of work!

(-just quiet, patience and organization, really!)

Posted by Andrew Woodcock (Member # 3260) on February 20, 2016, 07:25 PM:

These type of issues are, as you quite rightly point out Steve, a real pain in the Butt!

Back then, everything was done (barring a few later models inc GS)
Electro mechanically. Ie a mechanical cam lobe hitting a micro switch typically to switch a heavy current circuit.

Wouldn't happen this way now of course, but at least this old fashioned method does bring about a certain degree of traceability unlike today's contactless way of switching and instant component changeout.

It's time consuming for sure and you do have to delve deep within the projectors innards but it is surprising just what you learn from just an exercise like this about our beloved machines.

"Character Building" as we say to our apprentices each time they point out there is a far easier "modern" way of doing certain electrical functions nowadays!

Yeah, but this one has worked for 50 years, has your modern one proved itself in the long term yet? We reply!
[Big Grin]

Posted by Pasquale DAlessio (Member # 2052) on February 20, 2016, 07:31 PM:

Well that's a switch! [Big Grin]

Sorry I just had to! [Eek!]

Posted by Andrew Woodcock (Member # 3260) on February 20, 2016, 07:34 PM:

I wouldn't expect anything less Pat! [Big Grin]

Might we just be taking this whole Filmie thing a little TOO serious for you? [Big Grin]

Posted by Stuart Reid (Member # 1460) on February 21, 2016, 02:09 PM:

Thanks for the advice guys, i'm going to get in deep with the meter when I've got a clear few hours.

Posted by Kevin Hassall (Member # 2352) on February 21, 2016, 03:26 PM:

Wow Andy you know your stuff buddy [Smile]

Posted by Steve Klare (Member # 12) on February 21, 2016, 03:40 PM:

"Meter" is the magic word here:

-all the difference between knowing what's going on and just shooting in the dark until you hit something.

Posted by Thijs de Kort (Member # 4897) on February 22, 2016, 02:08 AM:

Recently i had this exact problem with a Braun Visacustic 1000 there it was the combination of the lamp switch with the engine switch on at the same time, the lamp did on its own just not with the engine on as well. On that one i replaced the switches and it was fine. so as already said be aware of the switches. (and in my opinion especially of microswitches).

Posted by Andrew Woodcock (Member # 3260) on February 22, 2016, 05:29 AM:

Microswitches are as much a mechanical device as well as being an electrical switching device with delicate contacts.

It is therefore only to be expected that these do and will wear out over time. The good news is they are universally obtainable still, don't cost much to replace and are not difficult to refit just as precautionary measure to keep our machines in tip top shape.

The GS1200 I believe, is particularly prone to needing these changed out as they age. It is also a machine which uses more than most given all the non mechanical switching arrangement these and other machines like the Fuji SD used.

Soft touch keys began superceding mechanical linkages, cam shafts and rotary knobs by this era on some of the more sophisticated models.

With soft touch comes higher useage of components such as relays, solenoids and microswitches.

It is one of the reasons why projectors that are still heavily mechanical biased, such as an ST1200 remain generally in such good working order and therefore are popular among the masses. Far less electrical and electronic components to keep in good working order.

The same can equally be said for many traditionally built 16mm projectors. Simple in their design, but mechanically well built and therefore give excellent reliability results from what I hear.

When used in industry, parts such as micro switches, contactors and relays are referred to as F.C.P's
Meaning they are changed out on time cycle even when they still work. This is just to maintain reliability within the process by predicting when a "frequently changed part" will be coming towards the end of its life cycle.

[ February 22, 2016, 01:40 PM: Message edited by: Andrew Woodcock ]

Posted by Lee Mannering (Member # 728) on February 22, 2016, 05:37 AM:

Changed most of the micro switches in my workhorse Elmo last year as a precaution twas fun. [Eek!]

Sent you PM Andy

Posted by Andrew Woodcock (Member # 3260) on February 22, 2016, 05:46 AM:

Just replied thanks Lee. [Smile]

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