8mm Forum: What could this modification be?

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Posted by Stuart Reid (Member # 1460) on April 17, 2016, 08:25 AM:

So, I'm looking to get this Elmo HiVision SC18 back up and running because I have quite an affinity for them, it was the first projector I truly desired when I was about 14 but could never afford one! I picked this one up from Mr. Guest last week and I'm ready to get to work on it, but what on earth is this modification supposed to be? I'm wondering if it was some sort of sync unit connection? Anyone throw any light on it?

So as you can see, there's a male 2 pin plug which has been soldered to the PCB above the mains transformer, and a matching female connector directly soldered to the internal speaker. I haven't powered the machine up yet as I wanted some advice and ideas first.

EDIT: This has also been fitted with a 24v 200w bulb, not a 12v 100w as per the usual spec.

Posted by Steve Klare (Member # 12) on April 17, 2016, 11:47 AM:

The black plug looks like some kind of power connection, given the style of the wiring and connecter and the fact that it's running up to a fuse panel.

It could be associated with the lamp swap: maybe this is how you choose the lamp voltage, then again that socket connected to the speaker deepens the mystery.

-it's almost as if there is some piece missing in the middle: something that takes power from the fuse panel and outputs a signal to the speaker. (or maybe takes the audio signal off the speaker and processes it and sends it somewhere else.)

It doesn't make sense for the black plug to ever meet the white socket. -that would be quite loud...and then quite silent!

I hope there isn't live voltage on those two pins flapping in the breeze: that's asking for trouble!

I'd only plug this one in with that black plug insulated and monitored with a voltmeter: maybe figure out what it's up to.

I'd also look in the lamp circuit wiring for a plug/socket pair of the same type.

Posted by Rob Young. (Member # 131) on April 17, 2016, 01:36 PM:

Stuart, with greatest respect but under what circumstances and instruction did you buy this?

It look s a complete maze of er, post manufacture wiring.

You need to be really careful with this kind of stuff.

Seriously.

Posted by Stuart Reid (Member # 1460) on April 17, 2016, 02:24 PM:

Hey Rob,
It was knowingly bought as spares or repair, and the more I look at it the more I think it'll be just spares.

Posted by Pasquale DAlessio (Member # 2052) on April 17, 2016, 03:36 PM:

OK my turn! I think the white that is soldered to the speaker is for an extension speaker.

The black may have been for a remote of some sort. For example, a remote switch to lower the lamp voltage.

Either way the two do NOT belong together. I agree with Steve. I would definitely insulate the prongs. But I would also take a voltage reading to see if it is live.

The two plugs do not belong together.

Have fun!

PatD

[ April 17, 2016, 06:21 PM: Message edited by: Pasquale DAlessio ]

Posted by Steve Klare (Member # 12) on April 17, 2016, 06:48 PM:

The extension speaker idea is a possibility.

The problem with doing this is there is no cutoff of the internal speaker when an external one is plugged in, and the two speakers at the same time could overload the amp.

-doesn't mean nobody'd try it! You see all sorts of unlicensed surgery on these machines!

I bet this machine has the DIN external apeaker jack with speaker cutoff like the STs and GSs do. Maybe the guy had a massive stash of these other jacks and wanted to use them.

Posted by Pasquale DAlessio (Member # 2052) on April 17, 2016, 09:13 PM:

I just figured it out. The white plug connects to the Flux Capacitor!!

Posted by Stuart Reid (Member # 1460) on April 18, 2016, 04:06 AM:

Steve, the DIN socket is still there, and still connected. Obviously a standard DIN connection just didn't cut the mustard for our intrepid hacker!

Posted by Andrew Woodcock (Member # 3260) on April 18, 2016, 04:15 AM:

As Steve says Stuart, don't plug white to black whatever you do!!

If you plug this projector in, the first thing you need to establish is what voltage is present at the 2pin black plug connector.

I cannot imagine, what the intention of this "flying cable" ever was, given that it comes directly off the transformer and has no fuse protection in circuit from what I can see of it.
Whatever it was used for, it needs disconnecting from circuit and then try to ensure the original circuit path remains as was after desoldering.

Presumably the white speaker connector was somebody's attempt to get an external speaker connection or a line level input into something? It's all wrong either way.

Posted by Maurice Leakey (Member # 916) on April 18, 2016, 07:25 AM:

quote:
This has been fitted with a 24v 200w lamp, not a 12v 100w as per the usual spec

Stuart

Are there two transformers for this projector, if not, how is the 24 volts supplied?

Posted by Stuart Reid (Member # 1460) on April 18, 2016, 07:39 AM:

Therein lies the confusion, Maurice. Perhaps the flying lead was to connect the lamp to another transformer? Anyway, I'm hoping to remove all extraneous cabling at the end of the week as I'm flying abroad for work tomorrow and won't get a chance to look at it.

Posted by Steve Klare (Member # 12) on April 18, 2016, 08:06 AM:

The other transformer is often external. If you mind your phasing you can even get away with adding a second transformer in series with the internal one. It can be smaller/cheaper than a single transformer powering the lamp alone.

(If that's the case here the lamp will not light. All the voltage will show up across those two disconnected pins.)

I don't think this machine is beyond rehab: a little judicious unsoldering to get rid of all the Frankenstein stuff may work wonders!

Posted by Andrew Woodcock (Member # 3260) on April 18, 2016, 08:17 AM:

Here here.

Posted by Mathew James (Member # 4581) on April 18, 2016, 08:18 AM:

I agree with Steve. Just unsolder the rogue cabling, and then try it as per normal. I would swap to a normal bulb as well of course...

I totally have always wanted this little unit and have kept an eye on it on ebay for some time.... I think it is very worth trying to get it going, safely!!! Cool Machine!

Posted by Steve Klare (Member # 12) on April 18, 2016, 08:47 AM:

Maybe start with removing that external speaker spigot: I'd say we are unanimous this is good for nothing and removing it won't hurt anything.

(Projector repair by committee!)

The other one may actually be broken into the circuit and require some kind of a jumper in place to bring the lamp back to life. (That voltage measurement and observation of the lamp is a big clue here.)

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