Poorly Rogers

martin213 · Post by **martin213** » Sat Oct 27, 2007 11:24 am

Hi All,

Rogers poorly

I switched my Cadet 3 power amp on a few days ago to be greeted with a hum/buzz on one channel. After removing all of the valves it is still present,but only on one channel.

Any ideas guys?

Kindest Regards

Martin

martin213 · Post by **martin213** » Sun Oct 28, 2007 8:11 pm

Help please

Post by **Nick** » Sun Oct 28, 2007 8:33 pm

When you say "removing all valves", does that mean you took them all out, turned it on, and it still buzzed?

Does it play music at the same time as buzzing? or is it only buzzing?

All I can suggest, is getting a circuit diagram, taking the bottom off, and measuring a few voltages to see if there are any differences between the channels.

Darren · Post by **Darren** » Sun Oct 28, 2007 8:33 pm

It's a bit difficult Martin, not much info for anyone to go on really?

Not sure I would want to power it up without valves. The HT may rise above the caps safety margins? I say may not will.

I would start by looking for loose connections and obvious physical damage to any resistors and caps.

Let us know you findings

martin213 · Post by **martin213** » Sun Oct 28, 2007 8:36 pm

[quote="Nick"]When you say "removing all valves", does that mean you took them all out, turned it on, and it still buzzed?

Yep

martin213 · Post by **martin213** » Sun Oct 28, 2007 8:44 pm

With all valves out,surely it must b the PS? But only 1 channel? Am i missing something?

martin213 · Post by **martin213** » Sun Oct 28, 2007 8:47 pm

Was working fine,no signs of any damage to components,fink Roger got the hump with me coz he knows i gonna replace him with Yarland ultimately

Post by **Nick** » Sun Oct 28, 2007 10:15 pm

Anyone got a circuit diagram?

have you a multimeter Martin?

pre65 · Post by **pre65** » Sun Oct 28, 2007 10:23 pm

Hi-see this link-

http://www.bassboy.com.au/getreel/class ... ircuit.htm

Post by **Nick** » Mon Oct 29, 2007 12:37 am

Thats a very useful link Phil, thanks. Ok, if it was both chans, I would suspect the rectifiers or caps in the voltage doubler, but its not, so I would check your voltages against the ones on the diagram and see where they differ.

martin213 · Post by **martin213** » Tue Nov 06, 2007 1:06 am

Thanks guys,
Having domestic issues currently,haven't the inclination to be bothered with it atm

Will report my findings in due cause.
Kindest Regards
Martin

martin213 · Post by **martin213** » Mon Nov 12, 2007 3:09 pm

Well,i decided to check some voltages today,but i didn't get the chance

Immediately i plugged it in,it threw the trip switch.......twice!!!

I have since checked between live and earth/neutral,a mere 14ohms,almost a direct short,yet all components look ok,and no smell of burning.

I hadn't tried the amp for about a week,the last time it just buzzed on one channel.

Any guidance would be appreciated.

Cheers

Martin

Post by **Nick** » Mon Nov 12, 2007 4:35 pm

between live and earth/neutral

Do you mean neutral is connected to earth?

It may be the mains TX thats gone...

martin213 · Post by **martin213** » Mon Nov 12, 2007 5:23 pm

Yes Nick, Neutral and Earth show to be connected,0 ohms,and 14 ohms from Live to Neutral/Earth. Are there any others checks i can do?

Cheers

Martin

Post by **Nick** » Mon Nov 12, 2007 5:37 pm

Looking at the circuit Phil posted both N and L should be floating. Maybe the first thing to do is to check if there is any obvious link between N and E.

audio-talk

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