ENGL Powerball 645-9

[Jon Snell]

Is anyone working on one of these or can take a photo of the mains transformer wiring onto the board?
I have one on the bench that needs sorting out; wires in the wrong place etc.
Noghtmare to get right!
Thanks for any assistance.

[x-pro]

https://www.youtube.com/watch?app=desktop&v=BRZu3F7mG98
2.15 min.

[Jon Snell]

https://www.youtube.com/watch?app=desktop&v=BRZu3F7mG98
2.15 min.

Thanks for that but the amp displayed s a different version, very close but a different transformer.
Thanks for the post.
This is the beast in question;

[Pedro Vecino]

I don't know what a Powerball 645-9 is. I only know the two versions (I and II). While the first version has a single common gain control for the clean channel and the second channel (crunch), the second version has independent gain controls for those two channels.
I looked through my photos and found these two (both correspond to Powerball I). The connection points on the board and the distribution of adjacent solder points appear to be identical to what your photo shows.
Although the transformers are from different brands and have some wires with different colors, I think they should be identical in specifications.

[Jon Snell]

I don't know what a Powerball 645-9 is. I only know the two versions (I and II). While the first version has a single common gain control for the clean channel and the second channel (crunch), the second version has independent gain controls for those two channels.
I looked through my photos and found these two (both correspond to Powerball I). The connection points on the board and the distribution of adjacent solder points appear to be identical to what your photo shows.
Although the transformers are from different brands and have some wires with different colors, I think they should be identical in specifications.

Thank you for the photo, it will cut down my time reverse engineering it.
The PSU has 10 x 33v zener diodes instead of 3 x 150volt diodes. They have burned up due to being fitted on the pcb surface with no ventilation.
Looks the same as the Mk2, just as you say slightly different colours of the windings.
Thanks again.
The power supply looks like the 640;

[Jon Snell]

I reverse engineered it and all working now.
I have also added the mods that Engl recommend to increase the life and reliability of the amplifier.
The main issue was the burnt regulator section on the main board.
Removing the damaged components, removing the fibre glass that was burnt, sealing the board on the top side with Conformal Coating, fitting new diodes and the extra diode then cover with a light cover of Conformal Coating.
Replace the suspect bridge diodes and fit a 1.5A W07 bridge in its place with a heat sink, clean up the board and we have a fully working amplifer again.


Drawing and photos for anyone who may encounter a similar issue;