Hello all,
First, let me start by saying I'm somewhat of a newbie in electronics. I can replace parts, soldering is no problem, but I've never taken any electronics classes.
The whole story starts when the I noticed that the power switch on my Hafler DH500 does not light, so I decided to open it up and look around. I dusted things off, cleaned the fuse blocks and other connectors with deoxit, made sure all connections were tight, and closed it up.
Right afterwards, I hear a AC hum on the speakers, unless I disconnect my cable TV from my Mitsubishi TV (which is connected to my Yahama pre via hdmi, which is connected to my Hafler). The amp sounds great, better than before, except for the hum, but only when it finds a ground via the CATV.
Neither the mitsubishi TV, yamaha receiver, nor Hafler have a ground on the AC plug, so I'm thinking the Hafler is finding a ground through the CATV. The cable company came out and put an AC current filter on their line and verified their ground is good. Moving the speakers to the Yam, no hum, so I'm sure it's the Hafler. Any ideas on this?
So, at this point I've started a list of changes to improve the unit, and at the same time try to fix the issue.
Check every connection with a DVM to find a bad or cold solder joint
Install an IEC connector to be able to easily swap power cords
Remove the power switch completely, to reduce number of connectors and points of failure, (+ the unit is on all the time anyways) (??)
Replace the RCA connectors with new ones
Replace the input wiring from the RCAs with shielded Cardas
Replace most of the wiring, since some are frayed plus somewhat thin (??)
Replace the ground bus between the large caps with a thicker copper strap
Remove the output fuses completely (??)
Replace the remaining 4 fuse blocks on the audio path with inline (to get them off the floor)
Misc questions:
What brand / type of audio wire is a good fit for this amp? I've read of undesirable results with some expensive wires. I'm thinking a little thicker can't hurt either, maybe 16 or 14ga.
Where can I find good inline fuse blocks (off the floor) to replace the stock audio fuses, and the copper strap?
I've read replacing the electrolitics is a sure bet with this amp. Exactly, what does that mean? Is there a parts list I can work from to upgrade the sound?
Any info / thoughts are appreciated.
Cheers, Alex
First, let me start by saying I'm somewhat of a newbie in electronics. I can replace parts, soldering is no problem, but I've never taken any electronics classes.
The whole story starts when the I noticed that the power switch on my Hafler DH500 does not light, so I decided to open it up and look around. I dusted things off, cleaned the fuse blocks and other connectors with deoxit, made sure all connections were tight, and closed it up.
Right afterwards, I hear a AC hum on the speakers, unless I disconnect my cable TV from my Mitsubishi TV (which is connected to my Yahama pre via hdmi, which is connected to my Hafler). The amp sounds great, better than before, except for the hum, but only when it finds a ground via the CATV.
Neither the mitsubishi TV, yamaha receiver, nor Hafler have a ground on the AC plug, so I'm thinking the Hafler is finding a ground through the CATV. The cable company came out and put an AC current filter on their line and verified their ground is good. Moving the speakers to the Yam, no hum, so I'm sure it's the Hafler. Any ideas on this?
So, at this point I've started a list of changes to improve the unit, and at the same time try to fix the issue.
Check every connection with a DVM to find a bad or cold solder joint
Install an IEC connector to be able to easily swap power cords
Remove the power switch completely, to reduce number of connectors and points of failure, (+ the unit is on all the time anyways) (??)
Replace the RCA connectors with new ones
Replace the input wiring from the RCAs with shielded Cardas
Replace most of the wiring, since some are frayed plus somewhat thin (??)
Replace the ground bus between the large caps with a thicker copper strap
Remove the output fuses completely (??)
Replace the remaining 4 fuse blocks on the audio path with inline (to get them off the floor)
Misc questions:
What brand / type of audio wire is a good fit for this amp? I've read of undesirable results with some expensive wires. I'm thinking a little thicker can't hurt either, maybe 16 or 14ga.
Where can I find good inline fuse blocks (off the floor) to replace the stock audio fuses, and the copper strap?
I've read replacing the electrolitics is a sure bet with this amp. Exactly, what does that mean? Is there a parts list I can work from to upgrade the sound?
Any info / thoughts are appreciated.
Cheers, Alex
