Film-Tech Forum ARCHIVE: Strong SPA-7 fried

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » Strong SPA-7 fried

Author

Topic: Strong SPA-7 fried

Ian Price
Phenomenal Film Handler

Posts: 1714
From: Denver, CO
Registered: Jun 99

posted 01-11-2002 06:12 PM

There is a previous thread titled Strong SPA-7 Frailer that I started. In that case the problem was an old switch that had failed. Now that very same SPA-7 automation has failed in a more spectacular way.

First the automation didn't work. So we checked the fuses and found one that was fried. It was the one right next to the power supply (3A 125V). We replaced that and turned the unit on. There was a buzzing sound and we switched it off again. The fuse wasn't blown so we turned the unit on to see if we could diagnose the problem. The failsafe wasn't on; it has a red light when it is in failed mode. Then we looked at the automation board again and it was smoking around the power supply, so we switched it off again and pulled the fuse. We are running in manual for now.

My next step is to contact my supplier and see if I can still get that board. Perhaps Pat Moore has a suggestion.

Meanwhile, do you have any suggestions?

| IP: Logged

Jerry Chase
Phenomenal Film Handler

Posts: 1068
From: Margate, FL, USA
Registered: Nov 2000

posted 01-11-2002 06:28 PM

Just one comment based on computer experience after lightning strikes. Once one component in a circuit has failed it can stress other components beyond their limitations even though those might last for a short while longer. I have no idea what the cause of the buzzing sound was, but I would suspect a bad bridge or power transformer that shorted windings? Beyond that, I'm out of my league and am equally interested to learn what the gurus have to say.

| IP: Logged

Ian Price
Phenomenal Film Handler

Posts: 1714
From: Denver, CO
Registered: Jun 99

posted 01-11-2002 06:44 PM

My Cinema supplier doesn't sell that automation. He threw a monkey wrench in my thinking by suggesting that the buzzing sound might be a relay being confused. He suggested that the failsafe might be sending an errent signal back to the automaion.

The failsafe is a Strong FP-350 optical failsafe and proximity cue detector unit.

Having him say that just complicated the whole thing. We'll see what Strong has to say on Monday.

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 01-11-2002 07:47 PM

I have had a voltage regulator fail on them

| IP: Logged

Pat Moore
Master Film Handler

Posts: 363

Registered: Mar 2000

posted 01-11-2002 08:56 PM

Ian;

I'm not the tech guru type guy, but it sounds like the power supply section of the automation has a severe problem. Look for shorted diodes in that area -- there will be four diodes that make up the rectifier bridge. There's also a capacitor of some kind in that same area, and I think there is a voltage regulator as well as Gordon says. I'd bet on the cap first, then the diodes -- failures there could have taken the voltage regulator as well. Check the foil traces in that area too -- something should look cooked. I doubt if it has anything to do with the failsafe, but you can disconnect it easily enough to prove that idea.

What failed before on this guy? Could there be a relation between the two failures?

We do still support the automation, but that might mean replacing the full board.

Good luck...

Pat

| IP: Logged

Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001

posted 01-11-2002 09:07 PM

SPA-7 ... This is likely a power supply problem. Unfortunately Strong supplies the most useless drawings ever for the SPA-7. The power supply (and a LOT of other stuff) isn't there at all.
I think Eprad made the thing, maybe they can help if you need info. If this is a wall unit it's not bad to work on, the X-90 console mounted ones are a bear.
The power supply is fairly simple. The buzzing suggests AC is getting through the supply (this makes the DC relays buzz) so probably a diode or bridge has failed. If you can tell what was smoking that will be a good clue.
It's unlikely that the cue/failsafe is the problem, but who knows? Try disconnecting it.
Be careful working in there, it switches 120VAC for the motor, lamp, and changeover and possibly a slide projector too. If it's an X-90 then turning off all the breakers except main and "automation" should remove all 120 (except the automation itself) but I wouldn't bet my life on it...
If it is a power supply failure, the electronics are fairly robust and shouldn't have failed. The power supply parts are all standard stuff (except the transformer) available at Radio Shack type places. Hope for the best! If some of the main circuitry has failed, most of the tricky stuff uses programmed logic chips that will only be available from Strong.

| IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.