Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: SleepLess on February 08, 2014, 07:31:27 am

Title: Vibrochamp AC switch wiring
Post by: SleepLess on February 08, 2014, 07:31:27 am

Hi there.
I know... I have built amps ten times longer and harder to build. But hell, I'm stuck with a simple AA764 blackface Vibrochamp replica... The amp is finished but it's not working, the indicator lamp isn't even coming on. Of course I suspect a bad power wiring. So here's what I've done. The PT is a Classictone 40-18027 and wired for 240V (I'm in the EU).

The power cord:
- Neutral to bright switch (AC switch) through the two lower lugs.
- Live wire to end of fuse holder
- Green to ground

PT:
- 240V to Bright switch through the two upper lugs (brown/white wire)
- Black com wire to side of the fuse holder

Pics:
(http://imagizer.imageshack.us/v2/800x600q90/547/82zo.jpg)

(http://imagizer.imageshack.us/v2/800x600q90/542/b8bi.jpg)

(http://imagizer.imageshack.us/v2/800x600q90/33/5kyp.jpg)

Thanks a lot for this stupid debug!

Title: Re: Vibrochamp AC switch wiring
Post by: sluckey on February 08, 2014, 08:03:21 am

You have 6 lugs on that switch. Put the neutral wire on the two middle lugs.

Title: Re: Vibrochamp AC switch wiring
Post by: SleepLess on February 08, 2014, 08:13:16 am

Quote from: sluckey on February 08, 2014, 08:03:21 am

You have 6 lugs on that switch. Put the neutral wire on the two middle lugs.

Thank God you are here Sluckey... I don't really understand why what I did was wrong but now the light comes on! I'm off to the tests now. Thanks a lot Sluckey!  :worthy1:

Title: Re: Vibrochamp AC switch wiring
Post by: sluckey on February 08, 2014, 08:27:56 am

The switch is a DPDT. The lugs in the middle are the wiper or common contacts. In one position they make contact with the upper lugs. In the other position they make contact with the lower lugs. But the upper lugs will never make contact with the lower lugs and that's how you had it wired. Very easy to check with your ohm meter.

Title: Re: Vibrochamp AC switch wiring
Post by: eleventeen on February 08, 2014, 09:58:11 am

Sluckey has it exactly right. Done.

Title: Re: Vibrochamp AC switch wiring
Post by: SleepLess on February 08, 2014, 10:10:32 am

The amp works! I had made another mistake but managed to solve it. Great sound and the tremolo is really nice on this one! This amp is really good on 10 with a Les Paul!
Cheers!

Title: Re: Vibrochamp AC switch wiring
Post by: PRR on February 09, 2014, 08:51:29 pm

> I don't really understand why what I did was wrong

If still uncertain....

Imagine the switch as a Knife Switch (as seen in Frankenstein).

You wired it as shown below.

There is no position of the handle which will connect the two red lines.

Steve said to grab end-and-center lugs. You see that then the handle connects one way, not the other way, and your monster is alive or dead at your pleasure.

If you don't care to use a knife-switch, or bust-open a switch to see what is inside, use your ohm-meter.

Title: Re: Vibrochamp AC switch wiring
Post by: SleepLess on February 10, 2014, 03:34:43 am

Quote from: PRR on February 09, 2014, 08:51:29 pm

> I don't really understand why what I did was wrong

If still uncertain....

Imagine the switch as a Knife Switch (as seen in Frankenstein).

You wired it as shown below.

There is no position of the handle which will connect the two red lines.

Steve said to grab end-and-center lugs. You see that then the handle connects one way, not the other way, and your monster is alive or dead at your pleasure.

If you don't care to use a knife-switch, or bust-open a switch to see what is inside, use your ohm-meter.

Excellent! Thanks for this clear explanation!  :worthy1: