8mm Forum: Bauer T610 hum

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Posted by Sam James (Member # 477) on September 28, 2019, 02:18 PM:

Hi all,
Got her out for an evening of Tom, Jerry, Stan and Ollie (albeit for the first time in 18 months) and can only just hear the soundtrack of a number of titles at full volume over the inevitable booming hum that goes with that. Same thing with 6 ohm hifi speakers connected (which I know is too high). So there is sound, but only audible at very high volume accompanied by loud hum. I've looked back through the forum and can't find exactly the same symptoms, but apologies if it's been covered. Help or advice would be very gratefully received, particularly by cross 5 year-old son.
Thank you
Sam

Posted by David Roberts (Member # 197) on September 29, 2019, 02:54 AM:

Ive had numerous Bauer 500/600 projectors over the years,and they have all had some audible hum through the speaker.In fact,this is the one aspect of these machines that I don't like.
It sounds like yours is far worse,and I would be interested to hear if anyone has any suggestions to reduce the hum.
Mine still hum through an external amplifier,when connected via the din socket on the back.

Posted by Ken Finch (Member # 2768) on September 29, 2019, 09:05 AM:

I have one of these and do not get any loud hum from it and output the sound through my audio video amp. via the external amp socket. It sounds as if you may have the DIN pins wired wrongly as the socket is for input as well as output to the external amp. But if you are also getting hum from the external speakers it must be a problem within the projector amplifier as the hum sounds like mains hum. I am not an electronics expert so it may be worth getting it checked out by someone who is. Ken Finch.

Posted by Mike Spice (Member # 5957) on September 29, 2019, 09:44 AM:

Is it a hum, or a buzz, there is a distinct difference.

Either way a machine of that age will have leaking capacitors these days.

A buzz would indicate capacitor problems in the PSU and a hum might indicate a capacitor going to ground in the amplifier is leaking.

Posted by Leon Norris (Member # 3151) on September 29, 2019, 10:22 AM:

Mike, machines like this have to be played! If you let them sit for a long time you will start to have problems! I have a Bauer T610 myself! Try spraying the record button with contact cleaner! Work it in there real good then try it! Also I have heard this a lot about machines being stored away for a long time. Now listen to this if you don't plan on using your machine for a good while than just take it out and run it for at least five minutes. Than put it away! Do that at least once a month! I was told that from Elmo!

Posted by Mike Spice (Member # 5957) on September 29, 2019, 10:31 AM:

Leon I quite agree about running machines from time to time.

Very sensible from a mechanical point of view.

But.... Given the age of all our machines, capacitors are leaking today, nothing can prevent that, it's age and cheap paper/wax capacitors do not stand the test of time like a mechanical part might do, and capacitors play a unique role in keeping things quiet, so when they leak, which most of them are now doing, it can be buzzing or humming.

The same with amplifiers, radio sets tv sets and record players of that era.

Posted by Leon Norris (Member # 3151) on September 29, 2019, 10:57 AM:

Mike, your right ! With age things can happen! Now sometimes the record button can stick! That will cause a hum or buzz problem!
So just spray those switches! It does help!

Posted by Tom Photiou (Member # 130) on September 29, 2019, 11:37 AM:

I also have one of these machines, i have a,(and still am) an Elmo man through and through. The sound that belts out of the 1200HD's far outways the Bauer in volumn and with no hum or hiss no matter how how.

I dont know if this will help, i am still learning about the Bauer T610 but i know this is a common set of capacitors thats sold as a kit

https://shop.van-eck.net/PA-0003.html

Posted by Sam James (Member # 477) on September 29, 2019, 12:37 PM:

Thank you all and you're right, of course, I shouldn't have left it sitting in a cupboard for so long. The sound was beautiful before, both internally and via external speakers but now it is only audible at full volume by which time the accompanying hum is pretty unpleasant. On your suggestions I will roll my sleeves up and attempt to replace the capacitors via the kit listed. Do I need to be a technical whizz or am I likely to be breaking out in a "I've no idea what's going on", Danger UXB style sweat?

Posted by Mike Spice (Member # 5957) on September 29, 2019, 01:51 PM:

Capacitors can store a nasty charge for many many weeks, so be aware that you could get a hit if you catch the end of a cap and the chassis..

I found a youtube video to teach me how to make a capacitor discharge lead to keep me safe from shocks... cost $5 to make

Youtube has some great videos for capacitor discharge and removal.

Never short a PSU cap to earth to discharge it, use some kind of resistance.

That's where a capacitor discharge lead can be of help.

Capacitors do have a legend on them to make sure they go in the the right way round (polarity) so again, a bit of googling on capacitors wouldn't go a miss.

If the projector has been powered up recently then the caps will certainly have a charge in them than can make you jump should you happen to catch the wrong contact and touching a chassis.

It's not complicated but basic soldering skills are essential, so again, you could youtube some soldering videos and practice on some odds and ends before delving in to the projector.

It will make a huge difference to any machine from the 50's 60's or 70s to be re capped today.

Not long agao I had a laptop PSu fail so I ripped it apart to just have a look inside.

Silly me, four days later picked it up and it happened that my hand touched the underside of the board and holy hell, did I get a hit.... caps can be quite nasty left charged up.

not so much the 35v amplifier caps, but any cap can make you jump if you catch it on a bad day with a hand in the wrong place.

common sense, steady hand. Discharge caps if you can to be on the safe side.

As for soldering, a nice hot iron, let it get hot, a damp cloth to clean the tip, and tin with solder.

Don't use a massive iron, you are not doing a BBQ...25w max, better with a 15w iron.
Apply as little heat as possible, look for a nice shiny joint in the new caps on the circuit board.

cloudy dull joints will eventually become brittle and crack and go dry.

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