Hafler MOSFET Amp Needs Repair Need a Advice

LAB3

LAB3

AK Member
I purchased a NOS (sealed) Hafler P3000 MOSFET amp that had never been used still sealed from 1999 and it played great for a week and and now one side/channel gets really HOT and a loud HUM. I have fans and used it gently for several days when I first opened the box and I really have not pushed it hard with efficient vintage Klipsch Cornwall speakers.
I worried about non use for 15 years and a cap failing etc but I got a great deal on it as it was going to be my back up for my analog system. I think Musical Concepts is one shop that works on Hafler but they are really expensive, anyone here work on a MOSFET amp? http://www.hafler.com/techsupport/pdf/MAN1461C_P1500_P3000_man.pdf

Thanks
Louis
 
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Louis, I can't recommend a shop near your location. It's possible the main caps have failed due to setting on a shelf for so long. I bought a Soundcraftsmen A5002 amp a couple years ago that was noted to have a bad hum in both channels by the seller. The amp had been used very little in it's life. For electrolytic capacitors about the worst thing they can experience is no use or not being powered up.... (excluding putting them into a circuit with polarity reversed- that's probably worse I guess.... ; ))The visual inspection revealed nothing, but the main power supply capacitors were approaching 30 years of age. I put in new ones-- the larger caps are frequently computer type with screw terminals. Other than access, replacing the capacitors wasn't too difficult. The main thing is to obtain similar size physically and equivalent or better capacitance and voltage ratings. I never left the Soundcraftsmen powered up for very long, so I don't know if I had a heating problem with the amp or not before replacing the capacitors. I can't help you there. Sometimes a shorted device will drag down a power supply so much that the filter capacitors can't do their job filtering. At that point the hum can occur. I am a technician by vocation, so this sort of thing is not too much of a challenge for me. You may not have that sort of tech background, so a service shop is a good choice. Someone more local to you will probably come along shortly and make a good recommendation for you. Good luck.:thmbsp: Jim
 
GoRNR said:
Louis, I can't recommend a shop near your location. It's possible the main caps have failed due to setting on a shelf for so long. I bought a Soundcraftsmen A5002 amp a couple years ago that was noted to have a bad hum in both channels by the seller. The amp had been used very little in it's life. For electrolytic capacitors about the worst thing they can experience is no use or not being powered up.... (excluding putting them into a circuit with polarity reversed- that's probably worse I guess.... ; ))The visual inspection revealed nothing, but the main power supply capacitors were approaching 30 years of age. I put in new ones-- the larger caps are frequently computer type with screw terminals. Other than access, replacing the capacitors wasn't too difficult. The main thing is to obtain similar size physically and equivalent or better capacitance and voltage ratings. I never left the Soundcraftsmen powered up for very long, so I don't know if I had a heating problem with the amp or not before replacing the capacitors. I can't help you there. Sometimes a shorted device will drag down a power supply so much that the filter capacitors can't do their job filtering. At that point the hum can occur. I am a technician by vocation, so this sort of thing is not too much of a challenge for me. You may not have that sort of tech background, so a service shop is a good choice. Someone more local to you will probably come along shortly and make a good recommendation for you. Good luck.:thmbsp: Jim
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Thanks Jim for the reply. I am looking for someone local in the DFW area in Texas that has worked on MOSFET amps. Or someone that is good with Hafler amps as I don't mind shiping I have the factory box and packing.. I have emailed Musical Concepts and Avahifi as both of these shops work on some of the Hafler amps and pre/amps. Avahifi emailed me back they do not work on the P3000. Will see what M.C. reply is.
Louis
 
Have you popped the top and seen if any caps are bulging? The amp channels are actually modules that come out fairly easily. Each module has its own power supply. I don't recall there being a lot of caps in there.
 
FootFungus said:
Have you popped the top and seen if any caps are bulging? The amp channels are actually modules that come out fairly easily. Each module has its own power supply. I don't recall there being a lot of caps in there.
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No I have not touched it yet. I will look inside tomorrow, here is a link with a pic of the top removed. http://www.hafler.com/products/hafler_products_details.asp?productID=3273&viewId=3 I noticed you are in Big "D" have you serviced these haflers before?
Louis
 
Before you assume the worst check your sources and cables. If the amp isn't going into protection then maybe it isn't a problem in the amp itself. Disconnect the input cables and see if it still acts wonky. The hum makes me think it could be a ground or connector issue. I've never seen or heard a p3000 so I'm just brainstorming.
 
gonzothegreat said:
Before you assume the worst check your sources and cables. If the amp isn't going into protection then maybe it isn't a problem in the amp itself. Disconnect the input cables and see if it still acts wonky. The hum makes me think it could be a ground or connector issue. I've never seen or heard a p3000 so I'm just brainstorming.
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I did that first as I have two of these amps. So I unplugged the NOS P3000 I just purchased and plugged in my old P3000 and all is fine so I tried the new one again and the same thing but now both channels have a terrible Hum. Click on the links I posted and there is a pic of the amp with the top off and the other is has schematic.
 
louisjames said:
Have you called Hafler? Though part of Rockford / Fosgate they have their own tech support and a number of years back I had my P1500 amps that I use for my monitor system worked on and they did a great job. They might also be able to give you an idea of what to look for if you want to DIY it. I've actually called a couple of times last week to check on some things and got straight through to the tech so perhaps worth a try? Here's the # if you want to call 1-866-464-2353

:)
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No I have not ........Thanks good idea :thmbsp: I will call them in the morning.
Louis
 
LAB3 said:
Now both channels have a terrible Hum. Click on the links I posted and there is a pic of the amp with the top off and the other is has schematic.
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I clicked the pics and they are useless for troubleshooting. Shoot some full screen pictures of the power supply and both amp boards. A detail shot of any connectors would be useful as well.

My hunch is that the problem is some sort of connection failure and not a component fault. Without the amp in front of me I can only guess BUT given that both channels are now humming I'd look for a common grounding point aka star ground that is either not tight/badly crimped/dirty. A bad solder joint(s) is also a possible culprit. If the connectors on any circuit boards are removable then unplug them and plug them back in. Even just pushing on a connector can fix the problem. This morning I repaired a Toshiba multi DVD player by reseating all the fragile ribbon cables and other connectors.
 
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Transnova and Transana are two of the greatest acronynms in audio, in my opinion. More importantly the Hafler 9300 was the best power amp I have owned/heard. The problem with the P3000 is worth investigating.
 
llanger said:
Transnova and Transana are two of the greatest acronynms in audio, in my opinion. More importantly the Hafler 9300 was the best power amp I have owned/heard. The problem with the P3000 is worth investigating.
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I am retired now and this new/old 1999 P3000 amp will be repaired. I have never listened to the 9300 so I will take you word for it. I have owned these Klipsch speakers for over 35 years and I have used many different receivers and amps on them over the years and my Pop's McIntosh tubes :thmbsp: and this P3000 with this DH-110 pre/amp sounds really good for the money I have invested. I was looking at a Crown SL2/PL3/4 pre/amp and amp but they were too expensive for my budget right now. The good thing about my vintage (efficient) speakers is they do not require huge WPC amps to make them sing.
 
FootFungus said:
Are both channels getting hot now, or still just the 1?
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I have removed it from the rack and installed my other P3000 so I have not hooked it up again after I tried the other P3000 checking my grounds and connector cables. :scratch2: I did try it one more time before I remounted the good P3000 and then I got a hum from both speakers and turned it off before it could get warmed up. I did notice the signal lights came on but I had Not turned on the TT or R2R??
odd that the short light or the thermal light never came on at anytime when in use.... before or after the HUM hit it.

Two days before it started to act up I noticed the right side was warmer then the left as I have a fan mounted behind the amp. I read that this amp needs to be on for a hour before critical listening to hear it's best per the owners manual so I always touch the fins on both sides after 30 minutes or so to see if it is warmed up. This is how I noticed the right side was a Lot warmer then the left for a few days before the loud HUM hit me when I turned it on. Then both sides got the hum the next time I hooked it back up. It's unplugged and back in the box. I hooked up my other used P3000 and installed it back into the rack and all is fine. I have the amps mounted on top of the rail rack and the turner and then the pre/amp on the bottom of the rack as I read to keep them separated some. The fans are run from my USB ports on my PC so it's not the fans making the HUM.:scratch2:
 
louisjames said:
Have you called Hafler? Though part of Rockford / Fosgate they have their own tech support and a number of years back I had my P1500 amps that I use for my monitor system worked on and they did a great job. They might also be able to give you an idea of what to look for if you want to DIY it. I've actually called a couple of times last week to check on some things and got straight through to the tech so perhaps worth a try? Here's the # if you want to call 1-866-464-2353

:)
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Thanks :thmbsp: I called Rockford/Fosgate and they sent me to http://www.davidsonelectronics.com/ they use to be the Hafler East Coast Repair Center IIRC as I talked to Cory the Shop Cordniator and he quoted me a flatt rate of $275.00 to refurbish the P3000 to like new again. No matter what parts need to be replaced. Plus freight each way. I still want to the large caps checked to see if it is something less expensive that can be done local. I explained everything about the NOS amp that was never used for 14 years and said he would not "Guess" what was causing the hum in both channels.
 
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