Dead Dx7II

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hearteh
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Dead Dx7II

Post by hearteh » Sun Dec 06, 2015 5:45 pm

Im a noob at this. I have a dead dx7II and I get no readings measuring dc voltage for the -12v,+12v and 5v pins. I also checked the fuse and its fine. What should I check when the psu seem completely dead? Is there any easy way to check the switch?

db0451
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Re: Dead Dx7II

Post by db0451 » Wed Dec 09, 2015 12:11 pm

This should've gone in "Help", not this unrelated section. I flagged it for moving, but no one seems to have noticed. Maybe you want to try flagging it again.
What should I check when the psu seem completely dead?
Inputs/outputs of rectifiers, voltage regulatorss, transformers, other things involved in transforming the input AC.
I get no readings measuring dc voltage for the -12v,+12v and 5v pins.
Which pins? On the output of the vregs? Or the inputs to some particular chips later on the PCB?
Is there any easy way to check the switch?
Seems simple... When the switch is on, does the input AC reach its output side?

Needless to say, please be very careful when dealing with high voltages - if you are in any doubt whatsoever, get a trained professional to do this - which I am not. And naturally, I can't be liable for any accidents, etc.

JFunc
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Gear: Juno 106, Juno-6, JP-4, A-Juno-2, DX21, CZ-101, 01/Wfd, SY85, X3, XV3080, M1, M3R, D110, MPC1k, S950, Prophecy, Plugiator, TR-8, MFB-522, Volcas

Re: Dead Dx7II

Post by JFunc » Fri Feb 19, 2016 2:00 pm

Hey there!

As db0451 has said - if you're not sure about tinkering - DON'T do anything - and always make sure the AC plug has been removed from the wall socket...

There's a T1.25A fuse on the left of the power regulator board (it should be labeled) that could have popped. These fuses mostly look like little glass tubes. If you remove the fuse and use a digital multimeter set to continuity (the one that makes a beep when the probes are touched together), hold the probes at each end of the fuse. If it beeps it's good. If not, it's bad...

If bad - then replace with a similar fuse - if good then there's a more in-depth fault. One that should be tackled by a competent service tech, i'm afraid.

Best,

Andy.

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