One channel on dh220 has 43 vdc at speaker binding posts

z-adamson

Addicted Member
All was well, then I noticed one channel was cold and had a blown output fuse. Replaced the fuse and noticed speaker hum.

Pulled the amp, measured dc voltage at the binding posts and got 43 volts dc.

Luckily, the speaker is fine.

What could have caused this?
 
You already did it! You measured 43VDC at the speaker output (binding post), right?
Uhh, I don't think we are on the same page.

I get 43vdc at the speaker binding posts. I should have just a few mvdc.

Savatage1973 said that an output transistor likely failed.

I asked how to confirm that the problem is at the output transistor.

Do you follow?
 
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Odd.

Now I get 250mvdc and the variable resistor allows me to lower it to dang close to zero.

A few hours ago it was 43 volts dc and the variable resistor did nothing.

But, the variable resistors are turned very far to get desirable readings.

See the pic...
 

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The DH-220 uses MOSFETs I don't think the std transistor test works on them but you can search the web for the way. I think it worked for me when I did that.
 
You already did it! You measured 43VDC at the speaker output (binding post), right?
No he hasn't..There are two possibilities.. 1. shorted Lateral MOSFET 2. Something upstream holding the MOSFET at rail.
 
OP Check the integrity of the power supply wiring going to the driver boards.
 
2SK134
2SK135001.png
 
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