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Old 20th November 2007, 01:24 AM   #1
elshout is offline elshout  United States
diyAudio Member
Join Date: Jul 2006
Default Hafler DH500 help

I just purchased two Hafler DH-500 amplifiers. One is working and the other is not. I am a long-time audio buff but new to electronics.

All of the fuses are good. Here is what I have noticed. When I power up the working amp, the fan comes on, then a few seconds later I hear a click (sounds like it comes from near the power supply). On the non-working amplifier, the fan comes on, but I never hear a click.

Can anyone help? still4given, are you still out there?

I think it may be the 48 volt relay. Can someone give me very specific directions for checking this. I have a volt meter. Again, remember to be basic as I am new to electronics.

It it does turn out to be the 48 volt relay, does anyone know where to get this item. I saw one on ebay being sold by soundvalves. I missed the auction but emailed soundvalves. No response. It looks as though soundvalves is not very good at responding according to some of the post I have seen on this forum.

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Old 20th November 2007, 11:37 AM   #2
d3imlay is offline d3imlay  United States
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Join Date: Sep 2004
Location: Ohio
the relay doesn't pull in because there is most likely DC on the output. If fuses aren't blown you likely have a driver board problem. If fuses are blown you have a bigger problem because the fets are long ago obsolete. Get a meter and check for DC going into the relay.
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