8mm Forum: B&H Humming but no tune

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Topic: B&H Humming but no tune

Robert Pitman
Junior
Posts: 24
From: Wales, UK
Registered: Mar 2007

posted April 08, 2008 06:39 PM

Wow its been a year since I last revisted. Why do I get the film bug at this time of year?
Looking for some advice on a B&H TQIII green [spew][/spew]. The sound suddenly stopped working and now I got a constant hum from the speakers that is not effected by volume or tone controls.
Disconnect speaker sound goes.
Exciter lamp lit fine.

Thanks in advance,
Rob

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Why do transformers hum?
Because they don't know the words.....

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Simon McConway
Phenomenal Film Handler

Posts: 1085
From: Doncaster, UK
Registered: Jun 2004

posted April 09, 2008 02:39 AM

You need a new amplifier board. Contact Gordon Ogbourne. Email me and I'll send you his details. smcconway at hotmail. com

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John Whittle
Jedi Master Film Handler

Posts: 791
From: Northridge, CA USA
Registered: Jun 2003

posted April 09, 2008 09:41 AM

If you have an amp schematic you can probably track this down. To me it sounds like an open cap or dried out cap. Don't know the cross between the US and UK models but some were tube some where hybrid (part tube part solid state) and some were solid state. If it's the third you also could have a bad transistor.

Since your problem doesn't change with the volume control or tone control, it's possible it's toward the final driver end of the amp and not the preamp section. If it were earlier, then turning down the volume control would remove the hum.

Good luck, don't know how hard it is to work on these if you require an extender card or if you have to have a bench with various power input and tests. Or you could just replace the amp as Simon said. Extra parts machines (especially ones with broken helical gears) are great cheap sources for parts.

John

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Dan Lail
Film God

Posts: 2110
From: Loganville, Georgia, USA
Registered: Jun 2003

posted April 09, 2008 11:27 AM

Robert! John is right. I have a couple of B&H projectors in running condition plus three junkers I bought very cheap just for parts. Sure saves a lot of headaches when somethng fails or breaks. Some people give these non-working projectors away.

A replacement sound board here in the US costs around $125.00 plus shipping. The working ones in my junkers cost next to nothing.

Good luck. [Smile]

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Robert Pitman
Junior
Posts: 24
From: Wales, UK
Registered: Mar 2007

posted April 09, 2008 02:13 PM

Thanks everyone for the pointers.
Guess I really gotta decide which way to go on this.
It's not my main projector, but I'd still like to get it going again. If only just to get some peace in the garage while the kids are ripping the house apart [Smile]

Rob

--------------------
Why do transformers hum?
Because they don't know the words.....

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted April 20, 2008 04:49 PM

This will be one of the all semiconductor versions. If you look in the Manuals section on the left I'm sure you will probably find a service manual to download for your machine.

As John says it will be in the output stage and more likely a dried up capacitor.

Kev.

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GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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