8mm Forum: Another Eumig S940 problem

This is topic Another Eumig S940 problem - now its the amp! in forum 8mm Forum at 8mm Forum.

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Posted by Phil Slater (Member # 2388) on October 01, 2013, 04:00 PM:

Day 2, and my newly aquired Eumig S940 has developed another, potentially more serious problem. Am I just unlucky or am I jinked?
Everything was fine on day 1 - great picture, superb sound,, then today when I switched it on it made a loud crackle and then nothing from the amp, not even a hum.
On inspection with the cover off I discovered that the amplifier fuse had blown so I put a new one in. now I'm just getting all sorts of loud crackling and buzzing when I switch on. It's so loud I have to switch it off immediately.
I'm hoping it's fixable

Posted by Phil Slater (Member # 2388) on October 02, 2013, 02:02 AM:

Does anyone know what the problem might be? Thanks

Posted by Maurice Leakey (Member # 916) on October 02, 2013, 02:29 AM:

Could be a switch problem caused by oxidisation of contacts. Quite often the record switch gives a problem.

Operate every switch there is several times including the sliding controls.

I hope it helps.

Posted by Maurizio Di Cintio (Member # 144) on October 02, 2013, 07:38 AM:

Not so easy on the 940: switching from playback to record mode and viceversa is achieved by means of electronic circuitry, not mechanically: there is no actual switches inside the machine like the ones you find in the lesser 9xx Eumig Series, the commutation takes place inside some microchip.

Posted by Martin Jones (Member # 1163) on October 02, 2013, 08:15 AM:

"today when I switched it on it made a loud crackle and then nothing from the amp, not even a hum." indicates to an engineer that a definite fault has occurred in the electronic circuitry resulting in, probably, a fuse failure.
You have confirmed that diagnosis; replacing the fuse has restored some life, probably because whatever was damaged was damaged badly enough as to become "open circuit" and no longer able to blow the fuse.

That is a VERY simplistic explanation, but what it infers is that
it is unlikely that anything you might do manually to the machine will help to cure your problem. My opinion is that the problem will need to be diagnosed and sorted by a qualified audio engineer equipped with proper diagnostic tools.
Sorry to be a wet blanket!
Regards,
Martin

Posted by Maurice Leakey (Member # 916) on October 02, 2013, 08:59 AM:

The consensus of opinion is not good.
As the Eumig was bought on eBay perhaps contact with the seller should be sought to seek a part refund for repairs to the projector, not forgetting the defective lens with its broken pin.

Posted by Lee Mannering (Member # 728) on October 02, 2013, 09:39 AM:

Sadly microprocessor failure has become common over the years within a 940 and although a gorgeous machine when working they are effectively a dead machine when this component goes. I’m hoping it turns out to be something else in Phil’s 1982 ish machine as this particular component is no longer available new. It wont be the first time a 940 owner has tried to find a microprocessor either I can vouch for that. It’s all a bit like that amp block within the Elmo GS1200 all over again.

Posted by Maurice Leakey (Member # 916) on October 02, 2013, 10:02 AM:

It would be interesting to know how the eBay item was phrased by the seller. Was this the projector, by any chance?

http://www.ebay.co.uk/itm/Superb-EUMIG-S940-SOUND-PROJECTOR-Super-8-Inc-Mic-Reel-Case-etc-VGC-GWO-/151126120576?nma=true&si=3NH4%252BDmxEnXOMuzEW2qL%252BLGaplQ%253D&orig_cvip=true& rt=nc&_trksid=p2047675.l2557

If it is, it seems that the seller has little knowledge of the item, viz, large spool queried as 600' whereas we can all see it's a 800'.

I once bought a projector from UK eBay and there were great problems right from opening the box. Finally my service engineer prepared a detailed quotation and the seller paid for the repairs.

Posted by Phil Slater (Member # 2388) on October 02, 2013, 11:33 AM:

Maurice,
Yes that was the one. The seller told me before he shipped it that the on off switch wasn't working, ie it was permenantly on, and he had installed an inline switch on the mains cable. I negotiated a partilal refund for this. I'm just wondering whether operating that switch had anything to do with it, such as causing a power surge.

It still works as a silent machine, with the amp fuse removed. Does that sould like the chip has failed? If so, what are the chances of finding a new chip?

I will probably get it checked out, just incase it turns out to be something more simple to fix.

Thanks to everyone who has respond so far. If anyone has any further thoughts, please let me know.

Posted by Robert Crewdson (Member # 3790) on October 02, 2013, 12:49 PM:

From all the problems I have been reading about Ebay lately, it seems the best place to buy a projector is from a dealer such as Paul Foster / CHC.. You might have to wait a bit to find a suitable projector, but at least you can trust the sellers description. Hailsham Camera Centre also have projectors in all gauges.

Posted by Maurice Leakey (Member # 916) on October 02, 2013, 02:04 PM:

Phil

Whilst the seller does/did have one other projector for sale he certainly doesn't seem to be a "cine man", as such.

I quote from part of his sales patter:- "........it is in excellent condition and is working very well......" Well, that certainly doesn't seem to be the case. I would return it and ask for a full refund (get the lens back first.)

I agree with Robert, eBay is now such a mine-field for the sale of projectors that it is much better to buy from an acknowledged dealer. Yes, I have bought films and a projector from Hailsham Camera Centre, their manager (Robert) is a great guy.

Posted by Paul Browning (Member # 2715) on October 02, 2013, 03:02 PM:

Phil, I had this on projector a while back, where the replaced fuse as you say in the amplifier stage kept blowing when you replaced it, I thought it was the power supply to this stage( the bit that changes it to dc), not that either. Its something that draws enough current to take out that fuse when switched on?. The output stages of an amplifier have transistors to drive the speaker or speakers on anything audio, and my guess is its one of them that's failed, in my case this was shorting one of the pins on the transistor to ground taking the fuse out. I feel sure someone on here could tell you more, perhaps martin who's already chipped in here, as a tele repair man retired, he's trained to component level testing, could tell how to safely test it.

Posted by Maurizio Di Cintio (Member # 144) on October 03, 2013, 02:48 AM:

Honestly I can't understand why the main chip in this model should fry and at the same time, a fuse should blow: couldn't it be a (minor) electrical failure of the sound circuit input? Perhaps the current rectifier? In any case I think what should be done is find a qualified technician with the proper schematics of this (so complicated) machine. It might be some not so difficult to come by component...

Posted by Martin Jones (Member # 1163) on October 03, 2013, 03:40 AM:

Thank you, Paul.
Yes, I probably could, because I've actually done it before...

Not long after I joined this Forum I helped someone (nameless!) to repair the amplifier of a 926. Because of the complexity of doing it, and because he was located elsewhere in the world, it was done through a very large number of emails containing photographs and detailed step by step instructions, .

I had a circuit diagram and another board of the same type, he had a soldering iron and solder and a Multirange meter, both of which he said he could use. And he was sure he could follow my remote instructions (he was a trained medical practitioner in a surgical discipline).

The faulty component was traced by a logical step by step series of measurements on the board with no power applied, involving isolating sections of the circuit in turn, then individual components in turn. Fortunately it didn't take long to find the fault which was fortuitously early in the very long series of tests envisaged.
The process was assisted by the owner following my instructions TO THE LETTER, no variations or short cuts on his part... and EVERY measurement or observed effect reported back before a further instruction was sent.
The spare was obtained and fitted... and the board worked first time.....BUT! After refitting, it didn't work! Out it came and the answer was obvious. Yes, the gentleman could use a soldering iron, but his soldering skills were sadly lacking when it came to electronic circuitry! Bad joints, lifted printed wiring, all disturbed and damaged when replacing the board.

There's no way that can be dealt with at a distance. I offered to repair the board at no charge if he could send it to me, but I heard no more.

The moral: to repair an electronic item you require the Knowledge, tools, skills to use them properly, the relevant information and the ability to interpret it properly. And it helps to be able to remove and replace boards without causing further problem! There are MANY competent amateurs (that's how I started and I am almost exclusively self taught on the practical side) but you need to know who they are, which is why I would always recommend using a professional with a good track record.
There are a number of people on this Forum who will agree with the foregoing... and agree with my position on such remote repairs.
Regrettably, I would NEVER repeat that kind of exercise! And although I have on occasions repaired members' machines in my own workshop my advancing years are affecting my best tools (My eyes and my fingers) adversely. These days I only try to please the wife!
However, advice is still available.
Regards,
Martin

Posted by Lee Mannering (Member # 728) on October 03, 2013, 04:54 AM:

In a search for parts for you Phil I have also turned up a 900 series 1.3 13,6mm lens in original working order pin etc. I'll keep looking. [Cool]

Also another Eumig stereo amp for spares only which may come in handy

One amp now sold. One left.

[ October 04, 2013, 04:24 AM: Message edited by: Lee Mannering ]

Posted by Phil Slater (Member # 2388) on October 03, 2013, 10:30 AM:

Thanks Lee. I'll keep you posted on developments.

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