8mm Forum: Debrie D16

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Posted by Terry Sills (Member # 3309) on May 01, 2014, 04:01 AM:

I just got my Debrie out for a run and it has developed some problems. Firstly there is crackles and pops from the speaker. also when I turn the motor on there is loud hum from the speaker and the sound volume is very low. Can anyone suggest what is wrong and how to fix it?

Posted by Paul Mason (Member # 4015) on May 01, 2014, 06:00 AM:

Terry,
It sounds very like the problems I've had with several GB Bell & Howells (630, 636 and 640). The amplifier probably has multiple problems. The capacitors start leaking i.e. breaking down giving hum, resistors go high resistance and the valve gains reduce leading to low or no volume. The best answer is a complete rebuild of the amp particularly the capacitors. I hope I'm wrong but good luck in fixing anyway.

Posted by Terry Sills (Member # 3309) on May 01, 2014, 06:23 AM:

Paul
Yes that sounds very feasible. I see that you live in Hampshire (not too far away from me) so do you know anyone in the area with the expertise to rebuild it? It's not something I would undertake myself.
Terry

Posted by Paul Mason (Member # 4015) on May 01, 2014, 07:04 AM:

Terry, I'm afraid I can't help much. Rebuilding the amp by replacing the capacitors with modern ones is feasible for anyone handy with a soldering iron - not me I'm afraid. I tried a chap I found on the internet 10 miles from me who repaired guitar amps who had my removable B & H amp for 5 months. Through lack of time or interest he didn't get very far - too small and fiddly for him maybe. I gave up on my 50s Bell & Howells and paid Kevin Brown Cine Repairs of Nottingham to restore my 644. He does electronics and did a good job. You could try Bill Parsons in East Sussex or KW Technical Services in Luton but I've not used these people.

One other option if you don't mind losing the original amp is to install a new solid state pre and power amp with a new power supply and exciter lamp supply. You also need a photo diode or photo transistor - a fiddly installation job. This is probably easier and cheaper than a rebuild.

Posted by Terry Sills (Member # 3309) on May 01, 2014, 09:11 AM:

Thanks Paul. Thats given me food for thought.
Terry

Posted by Terry Sills (Member # 3309) on May 04, 2014, 10:13 PM:

Having just remembered that I have a manual for my D16 I discovered the problem. Nothing to do with the amp! Just needed a new PEC. A lesson to be learned here. Always check the simple things first. Sound is now fine. Unbelievable!

Posted by Paul Mason (Member # 4015) on May 05, 2014, 07:00 AM:

Great news Terry. It's not always easy to check the PEC if you haven't got a spare. Is that what you did?

Posted by Terry Sills (Member # 3309) on May 05, 2014, 08:02 AM:

Paul I just replaced it as I have one or two spares. How do you check them?
Terry

Posted by Paul Mason (Member # 4015) on May 06, 2014, 03:14 AM:

I've never had a spare PEC to try unfortunately. They don't seem plentiful from vintage valve sellers. You can get an idea of the state of the actual amp by plugging in a suitable microphone. I was sure my Bell & Howell amps were on their last legs when the sound output was so poor.

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