Hafler DH-220 Troubleshooting Help

illtrick

Member
2010-12-08 8:55 pm
I just opend up my Hafler 220 that I purchased from Hawthorne Audio in Seattle a few years back. I'm hoping to figure out what the heck is wrong with it. When it's hooked up to the rest of my system it will sound like it's powered up for about 0.5 Seconds then whirr a bit then die out. This is happening in both channels and does it with or without any input.

I've checked all fuses inside and out and they're all intact.

I measured the voltage coming out of the transformer, each side is reading 47.1 vAC. The I measured the voltage across the Right Channel Cap and it's 65.4 vDC, the left Channel is 63.7 vDC. My cheapo multimeter can't measure capacitance so I'm out of luck there.

There's a low hum comming from the transformer, but I don't think that's an issue because it's bearly audible.
I can't figure out if this thing is stock or modded, it has a couple of smaller caps (think they are anyway) paralleled across the main caps. Here's a picture:
[IMGHTTPDEAD]http://picasaweb.google.com/lh/photo/iKG3SzbolWL12KROfAdTBg?feat=directlink[/IMGHTTPDEAD]

What else should I be looking for? what else should I be metering?

Thanks for the help!
 
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illtrick

Member
2010-12-08 8:55 pm
I can't see it either. Even though I wrote it up and posted it. HA! Okay. Here it is again (to the best of my remembering) just to make sure.

I have a hafler 220 that is not working anymore. I'd turn it on and the speakers would whirr for a few seconds then die out. Both channels were doing the same thing so I figured it was a power supply issue. After taking the lid off I inspected all the fuses and found they were intact. Nothing looks or smells like it's burnt out either. I took a few measurements but would like some help troubleshooting a little further.

117 vAC at the power switch
47 vAC out on each side of the transformer
65.2 vDC across Right Channel cap
64.3 vDC across Left Channel Cap

My multimeter doesn't read capacitance so I can't measure that.

There's a low level hum comming from the transformer, but I think that's normal as it's bearly audible.

I think it might be a modded version of the 220 as the board say musical concepts on them and there are some extra smaller caps across the main ones. I'll try to get the photo to work.

haflercaps.jpg


Any more help or steps to take would be awesome!
 

illtrick

Member
2010-12-08 8:55 pm
They're the PA-1. I'm not sure i'm using the right schematic, it's just the one on the Hafler website. I sent an email off to Musical Concepts, hopefully they can help me find the right schematic.
The schematic I have gives the value of R-11 at 1,800 ohms. Measuring it leads me to believe it's much lower than that, but I'm discovering that my Craftsman multimeter is less than perfect and is making it really frustrating to take a measurement, so I'll keep trying there.
My only question is that if it isn't exclusive to a single channel shouldn't that mean the problem has to be before the boards?
Thanks for the help!