Aguilar DB750 PSU transformer damaged

[melmsmidth]

Hi everybody, I have a friend with a problem with his Aguilar DB750. As soon as he switches on the amp, it enters protection mode and obviosly there is no sound.

The unit right now is at a reliable repair shop here in Spain, and he’s been told that the problem is in the power supply toroid transformer and needs to be replaced. The problem is that this is a discontinued model and a custom transformer is used and Aguilar (now Korg) doesn’t have spares anymore so the technician who saw it says that we need to order a custom one from someone but we don't know the exact specs needed.

I tried to contact Aguilar but they sent me to the local dealer ("Please contact the Aguilar distributor in your country who will be better equipped to assist you.") The local dealer doesn't have any info or spares, of course, since it's a discontinued model.

So, we have the schematics (attached) but It's out of my knowledge to find the current and voltages required in all the windings. Can it be calculated based on the schematic? Specially the power and Valves sections. If we figure out the required scpecs we can order a custon wired transformer and try to repair it.

Any info or recommendation is greatly appreciated, as I said I don't have the amp with me right now so i can't run any tests or checks, but feel free to ask any questions or advices.

Thank you very much in advance!

 

[CJ]

Hard to believe that the pwr xfmr would trip the output circuit, a blown fuse yes .but not the output relay.

Get a meter on that xfmr while the secondary leads are disconnected.

 

[melmsmidth]

Thanks CJ. Yes, I think I need a little more information about the fault since you are right.
The truth is that some people have had problems with the input transformer shorting out in this amps... but I will tell my friend to bring it to me and see what I can do by myself, it's still on the repair shop so I can't take any measurements right now.

 

[pucho812]

A power transformers is low on the list of things to check based on the fault description.
I would be more inclined to check for faulty transistor in the output circuit

 

[CJ]

if one of the legs of the secondary were open and you lost a rail, that might trigger a fault,

 

[pucho812]

if one of the legs of the secondary were open and you lost a rail, that might trigger a fault,

possible but could easily be determined with a DMM

 

[melmsmidth]

I think I'll have the amp with me in a couple of weeks. As soon as I can confirm if the problem is the transformer I'll let you know, I should have started there
Thank you both!