Allen & Heath DB2 power supply (help)

Thread Starter

Paulcmusik

Joined Jan 15, 2022
12
Hi I wonder can some help, I have a Allen Heath DB2 mixer witch has never left my studio in 7yrs, I switched it on today, and i got a burning smell from it, and then mixer switched off by itself, I tried to switch it back on, it did and then i got pop noise, now the mixer wont switch on at all, I have opened the mixer, and i can see there is a component burn or blown "HS1 U4" (maybe a heat sync), it also has blown the fuse in the mixer and the wall plug. Any help would be appreciated
IMG_2485.jpg
 

Dodgydave

Joined Jun 22, 2012
10,303
That's a switchmode psu, looks like a chip U4 and probably a Mosfet transistor blown.
These are a nightmare to repair, and are prone to exploding.

Can you take closer pictures?
 

Thread Starter

Paulcmusik

Joined Jan 15, 2022
12
Yes it's the same.

Check the diodes and the transformer primary for shorts before you fit the new one.
Ok I checked the diodes and they seem to be ok ,AFF1609D-B0E3-498E-9628-CCA001811BAC.jpeg

Not sure about the transformer,
I think it’s the yellow component in the middle, I don’t really know how to check it 50AE4949-1C17-4BCF-8803-95FBEF38F7C6.jpeg

this is the reverse side of the board
0A04B88A-89D7-44A4-8A8B-23BC8A25C144.jpeg
 

Thread Starter

Paulcmusik

Joined Jan 15, 2022
12
It seems the off line switcher from online stores are all out of stock till July

EBay is the only place I can find, that’s selling them now

will this one be ok

https://EBay
 

Thread Starter

Paulcmusik

Joined Jan 15, 2022
12
Looks the same one should be ok, check the bridge rectifier as well as the diodes.
Hi, the off line Switcher came today in the post, and was a pain in the ass to replace, anyway I managed to replace it after a couple of hrs, to be honest my soldering/electronic skills would be amateurish, put the mixer back together, switched it on, we now have power.
Tomorrow I will use the mixer for several hours to see what happens.
Thank you so much
CAE6AAFE-45BB-472D-AD1C-01E0FCF9FC98.jpeg
 

Thread Starter

Paulcmusik

Joined Jan 15, 2022
12
Hi, the off line Switcher came today in the post, and was a pain in the ass to replace, anyway I managed to replace it after a couple of hrs, to be honest my soldering/electronic skills would be amateurish, put the mixer back together, switched it on, we now have power.
Tomorrow I will use the mixer for several hours to see what happens.
Thank you so much
View attachment 265182
An update, I used the mixer today and after 2hrs it switched of by itself again,

I tried to switch it back nothing so I let it sit for 20 mins and it came back on again.
I guess it’s something heating up which is causing it to power off
 

Dodgydave

Joined Jun 22, 2012
10,303
This is a typical circuit using this chip , yours looks like it's got 3v and 5V regulators on heatsinks, hard to tell from the picture,, but it has two outputs from the transformer. Does any output go down on it's own before it shuts down, what could be happening is it's going into current overload because the output is pulling too much current.


di66.jpg
 
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