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Hafler DH-200 rectifier diode

HomerJSimpson

HomerJSimpson

Addicted Member
I picked up a Hafler DH-200. It had a blown main fuse, I put in a new one and saw a bright flash. I knew from experience, to check the rectifier diode, and sure enough, it was shorted. I have the manual for it, but it doesn't list the values for it.

What would be a good replacement? It does say 8001 AC on one side of thr bridge diode. KBPC25-02 on the other side.
 
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Mouser:

853-MB252W-BP is a 200 volt 25 amp rectifier bridge from MCC priced at $4.40.

583-MP252 has the same specs from Rectron priced at $2.77.

Make sure that the load, as seen by the diodes, is not shorted as well -- esp. the output transistors and/or main supply capacitors.

Fred
 
Thanx Fred, I checked the outputs, and found one channel is shorted:sigh:

Caps did not test shorted.

Now I need to find replacement outputs...2sk134 and 2sj49
 
I'f I ever lost a set of the output devices, I'd be in contact with Musical Concepts. He builds replacement driver boards for the Haflers but also uses them in his own power amps. John has been really helpful to me over the last 10 years.

BTW, I'll put in a plug for his driver boards. As I write this, I'm running a DH200 with them and they're quite an improvement over the original boards.

Homer, glad you able to find some replacement, too!

Cheers,

David
 
Those fets have been obsolete for years. Beware of fakes. Radio shack probably has a bridge for less than the cost of freight to order it. Any 25 amp bridge with greater than 200V will work. Check the 100mf caps on the driver. When they open the amp will oscillate which could be why it failed.
 
Dh 200

Hey:
I would use a 600 volt bridge rectifier just to be on the safe side.
I try to go over 3 times the RMS voltage of the secondary for safety.
Hope this helps
Ed
 
Crap

I replaced the bridge diode and the outputs , pluged it in with a 2.5a fast blow fuse, and it blew. It does call for a 5a slow blow fuse.

After the fuse blew I checked the diose and outputs, they test good.

What gives?

Could it be the switch?
 
Well I desoldered the top jumper wire to the AC (I think this is to light the power switch) and put in a 5a fast blow fuse. The fuse did not blow.

Did the jumper do the trick, or was it the difference in the fuses??
 
HomerJSimpson said:
I replaced the bridge diode and the outputs , pluged it in with a 2.5a fast blow fuse, and it blew. It does call for a 5a slow blow fuse.

After the fuse blew I checked the diose and outputs, they test good.

What gives?

Could it be the switch?
Click to expand...
If it calls for a 5A slo-blo then the 2.5A is way to small to handle the in-rush surge.
 
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