Atoll ST200 Amp Power Supply Problem

[habanerocat]

Hi, A friend's streamer wend down after a lightening storm. It's dead.
I'd like to get some pointers before I go at it as it's an expensive piece of kit.
I already posted this in the audio section but got no replies. So hopefully somebody with PSU knowledge can help me here.

I'm not familiar with the damage lightening can do so any pointers would be gratefully received.

I've had a look at this. Both the 5VDC and 3.3VDC are sitting on about 2VDC.
There's two 7805 regulators one has an output of 5VDC the other is very hot and has that 2VDC level on the output.

I'd like to cut the output leg of the 7805 next to see if it's being pulled low, but I can't get in at it. So I'd have to strip out the unit and remove it from the PCB.

My question is to ye experienced people, could the 7805 be blown or is it most likely being pulled low?
And if so, by what, given that this unit suffered from a lightening strike?

Thanks!

[eccerr0r]

more likely pulled low. 7805's rarely fail... do what you need to verify.

[sam_sam_sam]

I've had a look at this. Both the 5VDC and 3.3VDC are sitting on about 2VDC.
There's two 7805 regulators one has an output of 5VDC the other is very hot and has that 2VDC level on the output.

I'd like to cut the output leg of the 7805 next to see if it's being pulled low, but I can't get in at it. So I'd have to strip out the unit and remove it from the PCB.

I would carefully remove all of the parts that hold down the circuit board and remove the two 7805 regulators or whatever provides the 3 volt rail and test them out of the circuit if it has a capacitor on the input or output side of the regulator use them as well to test the voltage of each regulator if they produce the 5 volts that they are supposed to then you need to find out what has shorted out the power supply rails and remove them from the circuit board and see if you still have a short

I would be suspicious of any ohm reading less than 500 ohms as a short circuit

One note if you are not familiar with the pin outs of 7805 look at the data sheet for this information and make sure that you hook it up correctly for testing it out of the circuit

[habanerocat]

Thanks for the input lads.
In the meantime he has decided to send it back to the manufacturer.
Probably wise as that 5VDC line was going absolutely everywhere.