Thanks Roly, I'm sure it's just a matter of time.

Just to confirm, in your humble opinion,  this problem is most probably mechanical rather than faulty components ?

BTW thanks for the link to the Lamington amp, it could be a great winter project after this bugger.

Two weeks later.

Guess what ? Yes you probably know what I'm going to say.  The same static has started again  :trouble

I'm assuming I should start with the same fault finding process again ?

All very strange as the amp was "whisper" quiet after the initial fix. I should imagine that as this is
an old amp this sort of thing comes with the territory. Nothing new to you guys that have dealt with these
things for decades.

Yes DrG, Enzo did give me a good answer with a nice slab of food for thought. I suppose I've come to this forum thinking I could just Part A to Part B problems but now I realise I've got to bite the bullet and start asking myself what is actually going on in a circuit.

I really hadn't thought about what was going on with the physics of for example a transformer or a diode too much. Enzo has made me realise I have some catching up to do.

I think I need a copy of Electronics For Dummies to bone up on and conceptualise a simple amp circuit  :dbtu:

Just found this idea which is basically what Enzo is suggesting.

http://www.ifixit.com/Guide/Constructing+a+Capacitor+Discharge+Tool/2177/1

Thanks Enzo, I did a search on the forum but nothing came up.

Sounds like I need to make myself something like a 10 watt resistor with some shortish leads with alligator clips.

Seems like you pro's just know what *not* to touch just like the electricians that have fixed things for me without flicking the power off. They seem to like to work without a net.

Can I use a lamp limiter to discharge capacitors ? I was thinking that if the L/L was connected to the amps power cable and then completed the circuit that the all capacitors could be discharged.

If not what is the correct / best practice way to go about surviving around them ?

Thanks Roly, yep I put a spring washer under the tagstrip. The amp sounds the best it ever has.  <3)

Maybe I should get myself an old Goldtone and start another project  8|

Well fellas, with your great amount of help the Peavey PA-100 ia now working !!  :dbtu:

The final push to the summit was made last night and tested with a newly constructed lamp limiter [ thanks JM ]. When the lamp glowed a dull red all those present [ myself and the dog ] gave three cheers and toasted the members of SSGAF. See photo of lamp limiter with 25W bulb.

Wiring as per diagram supplied by Roly was a success. I've attached a photo  [I've been using my Canon 7.1 mega pixel camera set on macro & flash disabled ] which shows the rewiring for 240V as :

Please excuse another one of my wiring descriptions.

From mains switch ~ to fuse 1.5amp ~ to  thermal cutout
: Active Brown / switch / Brown / 1.5amp fuse / black [top LH just out shot]/ thermal [ switch ] / black /  blue with yellow stripe RH tab strip .

From LH to RH on Tab Strip
Tab 1 : Neutral Blue + Black from transformer + Red to "pilot light".

Tab 2 : Blue + Black from transformer + Red to "pilot light".

Tab 3 : Earth Green & yellow

Tab 4 : Blue with yellow stripe + black [ from 1.5 amp fuse ]

Third photo shows insulated red wires from transformer

Fourth photo is of the step down transformer that found it's way into the circuit. Sort of like some alien sleeper waiting all these years to be removed only to take over another unsuspecting piece of electronics.

Now let's see over the next while how amp  will perform.

JM: thanks for the good information.

As for filament bulbs, I think they've all but disappeared from the Australian market. We've been told that the tungsten and fluro replacements are more energy efficient and with the cost of electricity, Australians have accepted that premise.

I have completed the rewiring for 240V and removed the .022uF caps.  I've also removed the large convertor transistor from the cabinet. I had to rig up a block and tackle to get it out  :cheesy:

Roly, thanks for the revised wiring diagram. I'm going to carry out the rewiring and then make a Limiting Lamp.

Re: the Lamp Limiter I read where JM feels the simplest circuit is the best but I'm having trouble sourcing a bulb. Also seeing this amp is 45W is a 75W bulb suitable ?

I can't get my hands an incandescent light bulb, only thing on the shelves at the Burringbar general store are tungsten globes are these I assuming this would work. But being a neophyte { a what ? :lmao: } I could be wrong.

As a teetotaler I won't be opening a bottle of champagne if this works, but maybe a bottle of the finest mineral water  :dbtu:

Thanks JM

Yes I had a gut feeling that the way I have the 1.5amp fuse & thermal fuse wired is unsafe  :duh   One reason why I wasn't going to plug the amp in.     How should they be wired ?

The ominous sounding "death cap" is the second of two that were in the old "stepdown" wiring. I did remove one. The schematic shows two, #26 & #27. So am I right in saying just one should be in the "240V" circuit. If so where should it be in terms of between what combination of colour code wires ?

Had no intention of plugging it in until I got some feedback  :tu:

I know I have *no* idea about electronics and not the first clue about how to draw a proper circuit.

BTW Please excuse the quality of the drawing. Can do better but just dashed this one off.

Ok guys once again I *really* appreciate your eagle eyes on my amp.

Just to make it clear in the bottom of the cabinet that this amp is housed in a *huge* transformer that I've always believed was there for two things.

1] As I was told by the guy that I bought it from in the early eighties, when I asked why it was so heavy, that he put it in there so it would run on *Australian* power because *American* power is different. :duh

2] To herniate the discs in my lower back. These days I need the help of another person to get it into the wagon.

Work carried out today....... see attached photos. Please criticize this wiring.

a) Brown mains wire to switch blue / yellow stripe to other side.

b) Remove blue .022uf cap #26 ............ Of course this photo is during the stage when I was removing the stepdown transistor wiring. It was connected between the earth and black wire.

c) Following Roly's instructions on how to diffuse this thing is the 3rd photo  :lmao:
Mains earth is connected to the chassis.

Mains blue is connected to black from transformer.

Black/Yellow Stripe and Blue from transformer are connected.

I 'm not sure if the fuses are wired correctly to the circuit.

The two red wires with blue masking tape connect to the pilot light. I did this as they were like that in the stepdown configuration wiring.

Please be hyper critical on this one.

Tab strip with new wiring configuration to be riveted to chassis.

Quote from: J M Fahey on April 10, 2013, 04:36:51 AM
If that's the original Peavey power transformer, which it seems to be, it can be rewired for straight 240V primary, with no need for an external stepdown. :cheesy:

I wonder why Peavey used the step down transformer if they could have just rewired the power transformer to suit 240V ?

Sorry, but I'm so far behind the 8 ball on terms like "240V primary" that I don't understand what you mean. I'm really at a monkey see monkey do level    I wonder if you'd be able to give me a basic run down on what I would have to do rewire it ?

Quote from: Enzo on April 10, 2013, 02:52:28 AM
What is the power supply voltage in this?  50V? 70V?   Is the existing transformer a single secondary winding?  Like two red wires and that is all?

Rather than buying a smaller step down, why not find a 240v transformer that puts out the same as the existing one, and install it into the amp.  That way there would be no extra transformer.  A 50v transformer rectified and filtered makes about 70v.

Gee Enzo now you're asking me hard questions 

The attached pic I think shows the transformer in question. It has three red wires attached to the board.

If that transformer is changed won't I have to re-wire the back of the metal cabinet to take the step down transformer out of the circuit ?