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Topic: Bulb Issues
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John Whittle
Jedi Master Film Handler
Posts: 791
From: Northridge, CA USA
Registered: Jun 2003
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posted May 14, 2005 04:31 PM
quote:
So I turned the machine off and checked the bulb. I forgot to unplug the machine first, and as I began to loosen the bulb, I heard a pop and sparks flew. Now, there is NO sound, and the smaller, dimmer light under the sound head doesn't work.
Ok, back to basics. After you installed a new lamp the lamp and motor work but no sound or pilot light. One word of caution, when dealing with these projectors, they ARE wired differently for different markets to meet local electrical standards. An Eiki sold for UL/CSA won't be the same as one sold for the UK or Germany, so a schematic and especially fusing will be different. One Eiki, the SL series sold in the US has two fuses on the amp (exciter and amp), the same machine sold under contract to the US military has a detachable power cord and 2 ADDITIONAL fuses on the high and low side of the 117 volt line.
So back to your projector, most machines use an auto-transformer for the lamp since a traditional transformer would be way too heavy to provide the amps at the low voltage, but there are windings for the various other voltages. So we need to get back to the multimeter and see if you have an AC voltage for the amp coming off the transformer and then trace it. It's very likely that a diode could have blow in that instant you heard the pop since the projector was plugged in anything is possible including feeding the high side of the lamp to the chassis and the voltage could have exceeded the input diode on the amp card capacity.
Also, if the projector has a speed control card for the motor, is that running properly? Do you have both speeds? Are the accurate? It could have been a victim of the same thing or if it's ok, then the problem is just on the amp card. Of course many US projectors just used induction constant speed motors and belt changes since the company didn't have to deal with various voltages or Hz rates that were necessary to accommodate in other parts of the world.
I have an Eiki SNT which was built for the international market so it can be switched between 220/117 and 50/60 hz with switches and a motor pulley change. It's wiring is very different from the normal US sold product. (On the other hand, the EX6000 pedestal xenon machines were all built for 117/220 and the supplied pulleys were 50/60 hz).
John
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Bill Parsons
Film Handler
Posts: 66
From: Brookland. UK
Registered: Jul 2004
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posted May 15, 2005 10:27 AM
Michael and everyone else!
I wish I lived nearer to you Michael, I would be round with a test meter to help you out! Kev passed on the diagram to me to have a look at, it is not clear to me looking at the rather poor copy of the diagram what happens to the lamp common (return) it may well do as Rick suggests, it does appear to be rather an odd arrangement to me, but it does make sense to start at beginning and check the AC into the bridge and DC out, there are only two bridge recs, the one you are looking for is drawn as two double diode units (in one block) wired together in a bridge, that is if we have the correct diagrams for the model you have! Also it is worth checking the underside of the boards for burnt print, this is a strong possibility, you could even have a damaged output ic,it is unfortunate but you do need a bit of technical knowledge to get to grips with this type of fault.
Apologies if I have been over ground that has already been covered, one thing this is certainly creating some interest on the forum, we may end up not talking to each other, but it’s all interesting stuff.
Bill.
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Rick Skowronek
Expert Film Handler
Posts: 120
From: Marietta Georgia USA
Registered: May 2005
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posted May 15, 2005 11:20 AM
Kevin,
I re-read my post and it does look like I'm a getting testy with you which absolutely was not the case. The more input the merrier. In electronics, as you know, there can be many possible causes to one symptom and certainly a bum rectifier is possible. I was just trying to give, from my perspective and with literally thousands of hours of troubleshooting complex electronics, my best possible theory considering the wiring diagram provided by Mike. It's typically not very likely, though not impossible, for a short circuit spike to get past a close-by ground. The bridge rectifiers in my past experiences can usually take a substantial overload before failing.
That said, without either of us having access to the machine and being able to physically measure anything we're all giving it our best "guess".
Last, just to help Michael, the small black object in his picture of the motor board next to the blue capacitor is a bridge rectifier. I believe from the schematic supplied by Mike that it's the rectifier for the motor voltage. Note: the value of the filter cap on the schematic is 1000uF for the motor. The value of the blue filter cap in his picture is that value. The schematic shows that the filter for the electronics is 4700uF. My deduction was that the bridge and filter for the electronics is on the big sound board under the motor board since the 13.5 VAC is shown connecting directly to the sound card.
One last thing, Michael, if you do pick up an inexpensive multi-meter available at Radioshack to check voltages, just be very careful where you stick their probes. Having done it myself more than once, it's easy to wipe out another component by the probe slipping and shorting something else out.
Good Luck and many apologies again for my Post, Kevin. Wasn't meant to come off sounding harsh and would never want to alienate anyone and especially one with all your experience with these oldies but goodies.
To John Whittle, I agree it's clear that the unit Mike Peckham has is "more" protected than the one Michael is troubleshooting, unfortunately. Just a quick answer on the motor it is a DC unit with tach/generator feedback to a motor control IC. If you need or wish better, clearer shots of the wiring diagram and schematic, I have those that Mike was kind enough to forward to me.
Rick
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Topic Closed
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and giving me another project to do...which I'm finally getting around to now. Having just re-read the whole thread from the beginning, I'm now armed with a wealth of info and some good starting places to check out with a multimeter... A few questions I do have, though:
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