Avalon 747 technical schematic

[salurdigat]

Hi. Anyone has the Avalon 747 schematic document? The valves section in not working
Sending it to the manufacturer from the country where I live and receiving it again would be very expensive due to the fees
Thanks in advice.

 

[gyraf]

We have never (yet) seen such a schematic in the wild. Your best chance is probably to ask the company.

 

[noizetoys]

Avalon's tech guy is a friend of mine. He said they never release their schematics to customers.

He recommended you email '[email protected]'.

Without knowing the specifics he just had a list of things to check:

• Bad Tube?
• Bad cap (check for puffy caps)?
• Bad rectifier that took out a supply voltage?
• Molex connector on the secondary side of the main transformer. Look to see if the red/black pins are discolored. If so, hard wire the connector and replace the last, large bridge rectifier

 

[pucho812]

Avalon's tech guy is a friend of mine. He said they never release their schematics to customers.

He recommended you email '[email protected]'.

Without knowing the specifics he just had a list of things to check:

• Bad Tube?
• Bad cap (check for puffy caps)?
• Bad rectifier that took out a supply voltage?
• Molex connector on the secondary side of the main transformer. Look to see if the red/black pins are discolored. If so, hard wire the connector and replace the last, large bridge rectifier

Audio rehab is their u.s. authorized service center, might be better to send it elsewhere. Especially if you are in Europe. As for schematics the units are pretty easy to work in without them, you just have to think like Avalon.

if the tube section is not working, there are very few things it could be. I have test notes I can get you. Assuming the tubes are ok the usual suspect is the psu. It’s rare that it is anything else. The good news is it shares a supply with the 737. I would bet a failed bridge rectifier, kbu6d on the 6.3v rail and a shorted c23 capacitor. I forget the value off hand. That is a common failure point. When replacing the bridge rectifier, make sure to cut it out so that you have individual pins to desolder, otherwise you risk pcb damage. This is because the kbu6d absorbed a ton of heat making it hard to remove as 1 piece.

 

[salurdigat]

Thanks to everyone for the help.
The valves are new ones.
I´lll write to Greg for support to repair here in Brazil if possible.

 

[Memo Solis]

Check +6V on power Supply usualy its working very very hot remplace it an be sure use new mica too.

 

[Memo Solis]

+6V regulator, TO-220 style

 

[pucho812]

Any update on this?

 

[Memo Solis]

Try to use ON Semi brand