Help!! Silent WAD 300B PSE

[Greg.]

So Guy, what happened?

[John Caswell]

I will be sorting it today.

John

[Guy Pettigrew]

Originally Posted by John Caswell

I will be sorting it today.

John

That's what I like--a positive attitude!

Yup, Dr John will be looking at it this morning and working out what's gone wrong.

One or other of us will report back later.

See you at 11.00, JC.

Guy

[Richard]

That's good, John's your man if it's involved
There're quite a number of things it could be which really aren't that serious now you've established the OP stage is alive.
It's a little unusual in having a separate HT supply for the ecc82 for instance which would account for it if it failed.
You would find these things or other problems almost certainly with a voltage check so I guess you've decided not to do it yourself.

[Guy Pettigrew]

Yes indeed, Richard, not going to try to diagnose it myself. I've learnt over the years that my diagnostic skills are appalling! My repair skills are fine, though, once the problem has been found.

Speed and a reliable identification of the problem is important at the moment. A friend is due to visit on Tuesday, so I'm hoping today's detective work by John, followed by a quick order for whatever the amp needs, will mean it's back up and running for Tuesday.

Guy

[John Caswell]

All sorted,
0.47µF PIO s/c on g2 of 6AU6, temporarily put an orange drop in its place.
Bit ashamed took me 10 mins to fix it

John

[pre65]

I often advise friends to use an expert when things go wrong.

Some may charge a higher than usual hourly rate but most often find the problem a lot quicker.

Bravo Dr John.

[Guy Pettigrew]

Yup, John sorted it in no time at all. Although he hasn't told the complete story.

Firstly, though, amazing workshop. If anything can be tested, John has the equipment to test it. Loads of knobs, dials and analogue meters. Beautiful to behold. And drawers full of every component known to man. All neatly labelled and organised.

The full story went like this.

John and I got the amp into his workshop. He tipped it upside down, took the base plate off, strapped it to his oscilloscope, powered it up and began poking about like a man possesed.

"Hum", he said, "350 volts", he said, "oh dear" he said. Then, "that's not right" he said. Like a greyhound after a rabbit he whipped out his soldering iron (ooerr, missus) and his wire clippers. Clip, desolder, solder suck, he went. Then, like a dentist, he held up the offending part and proudly proclaimed "there's your problem".

He replaced his dentist impersonation with a magician impersonation. Turning theatrically through 360 degrees, opening and closing a drawer on the way, he produced an orange drop capacitor of the right value, fitted it before I had a chance to say "what are you doing", then refitted the base. Job done.

Excellent service, highly recommended.

We went in to see and listen to his Hi Fi. No need to go on at great length about it here, but two things. He has a really nice pair of 'speakers. They were clearly just for show, though. The amount of bass we could hear couldn't possibly have been coming from them, but he refused to tell me where the real 'speakers were.

Secondly, those glass shelves. Yowza, yowza, yowza. Want some!

Thanks John.

Guy

[John Caswell]

Hi all,
Thankyou for those kind comments Guy.
The speakers are ProAc Response D28s a 70th birthday prezzie from me to me.
Believe me there was much sucking of teeth B4 I committed Hari Kiri, but the wife and daughter reckon they are excellent, and i am well chuffed.
The shelves are 19mm float glass with polished and arrissed edges and then edge lit at the back with white LED strips, which of course gives a lovely green colour through the glass (very soothing).
I can highly recommend thick glass as shelving but it needs substantial support and deep pockets but does look superb.

John

[Richard]

Well done!
PIO, who'd 'ave 'em eh?
Just had a look and it really needs more than a 400V cap there as it may be higher at switch-on.