Beaulieu 708 no sound....help!!

[Mark Barton]

Hello all. My newly acquired Beaulieu 708 not only looks in terrific condition but loads, plays and offers a brilliant bright sharp picture but...no sound. On power up you can hear the speaker make a ZZZSSSSTTT sound, but with a sound film, and all switches in the correct place, no sound, nothing. Even in stop and you rotate the volume dial you cannot hear a hum from the speaker, absolute zippo. Can any of you kind souls offer me a solution? Thank you in advance. Stay safe all.

[Steve Klare]

To me it sounds like a bad connection between the amp and the speaker. The "ZZZSSSSTTT" sounds as if the amp is getting power and may be trying to break through. It could mean something like there is a speaker cutout for something like a headphone jack or an external speaker jack that's oxided-over or just plain open circuit even when the jacks aren't connected. Even with a really sickly amplifier, you often get hum.

I'd try plugging into those jacks and then listen if the sound comes through them. I had an "accidentally silent" machine like this once. When I tried this the sound came through the headphones. When I unplugged the phones it came through the speaker too.

Maybe if you look at the speaker connections and try to find some kind of jack and plug disconnect. If so, disconnect and clean the pins and sockets.

(Oxidation is without Mercy! )

[Mark Barton]

Thank you Steve, Ill give that a try. Cheers

[Lee Mannering]

Yes worth connecting a external speaker eliminating the 2 pin din plugs for the speaker. Those plug sockets can go faulty having a make and break contact inside them.
If it not that may be a switch which tuns on the sound or perhaps the record button. Worth giving that a push a few times.

[Brian Fretwell]

I remember some plus (RCA Audio?) has a spike that scratched the centre pin when inserted to remove any oxidation, so someone appreciated the problem.

[Steve Klare]

The problem usually is worse when there is no mechanical activity. For example, where I work we have a couple of hundred power supplies mounted in closed equipment racks and operating 24/7/365. Their input power is turned on and off remotely. Unless something goes wrong these things can go several years without a human ever touching them.

After we were operating about three years, all of a sudden they started to go flaky: pulsating on and off when we just wanted "on"!

Long story short was there is a front panel on/off switch. It has a wiper to clean its contacts, but that only works if a human being physically operates the switch on a regular basis.

Step one: Turn off all the power, get everybody in Engineering (There are like 500 switches and only 20 of us!) to run to the racks, open the doors, find each switch ("off, on ,off, on, off, on ,off, on, off, on"), slam the door and move on to the next.

We installed gold contact switches when we could, but until then this crazy exercise quieted things down.


In our world, a projector sitting on a shelf for 20 years is exactly the same thing!

[Mark Barton]

Hi All, cleaned the outputs/spk, demagged the head, contact cleaned the internals. Still zippo, awwwhhh!

[Steve Klare]

Hi Mark,

OK, we need to dig deeper. So, THE problem is your speaker isn't getting any power. So far we tried to look at the connections between the sound circuitry and the speaker: no dice.

Before I begin, full disclosure: I've never stood in the same room as one of these, but at the end of the day all the manufacturers of the same devices tend to do things the same way. (I know for a fact they take each other's stuff apart! I've been there when they do it.)

Let's assume the sound circuitry isn't getting power and that's the reason the speaker isn't either.

Find a pretty populous board inside that the speaker wire connects to. Look for components that look overheated and tracks that are melted or anything that looks like a fire has swept though.

I'm hoping you are comfortable with a voltmeter. Look for the biggest capacitor on the board: this is where the sound circuit's power supply is. Be careful here: we're going to work live! Plug the machine in and turn on the sound. Poke the two terminals of that capacitor and observe the DC voltage.

Numbers like 12V, 15V and 24V are fine. Negative voltages are fine too: you just need to switch probes! What we don't want to see here are things like Zero, .5, 3: basically any number far less than 10V. These have to be wrong because it's not enough voltage to drive a speaker.

At least this gives us some facts about what's going on.