[Peter Loeser]

I am having an issue with my Parasound HCA-1205A. It powers on and plays fine, but after warming up for a few minutes the current overload protection comes on for channel one. This happens even if the amp it sitting idle with no inputs or speakers connected. The protection LED will flicker on and off a few times, then stay on. The other channels still play ok while channel one is in protection mode.

Internally, each channel has its own amp module, and they all share an I/O board along the back of the case. I switched a few of the modules around and from what I can tell, the channel one module and the I/O board at the rear are not causing the problem. At this point I have disassembled as much of the amp as I'm comfortable doing, and based on a couple of basic troubleshooting tactics, I believe the problem lies in the protection circuit (separate board between the main power input and the transformer, with some type of feedback from the individual amp modules). Visually this board looks ok. I did notice at least one component (a relay if I remember right) appears to have been removed and/or replaced based on the solder points looking different than the others on the same board.

Anyone have experience with the Parasound HCA amplifiers, or any insight as to what could be causing the protection to be activated on just one channel under these conditions? I'm comfortable replacing components on the circuit boards, but my ability to troubleshoot at the component level is limited. I have checked a couple of other forums for answers, but other owners seem to be experiencing this problem while playing at high volumes, rather than just sitting idle - i.e. the protection circuit is doing what it's supposed to do. I can remove the cover and post some photos of the internals if that helps.

 

[Peter Loeser]

Update: I decided to do some listening this evening, and there is more than one problem with the 1205A. After about 15-20 minutes of use, channel two dies. It does not appear to be going into protection mode like channel one, but the output diminishes to nothing. At this point I am still interested in trying to fix it if I can find some proper guidance, but losing hope

:gah:

 

[lcaillo]

The first thing that I would do is look for bad solder connections and obvious signs of stressed parts. A visual look and some gentle poking with a non conductive stick can often identtify a problem.

 

[Wardsweb]

The first thing that I would do is look for bad solder connections and obvious signs of stressed parts. A visual look and some gentle poking with a non conductive stick can often identtify a problem.

Pay particular attention to the power supply section. Specifically the regulator transistor(s). If they unsolder themselves or have a cold solder joint, they won't supply the voltage needed to drive the circuit or activate a relay. Also look for capacitors that are swollen, fat or leaking. They would need to be replaced.

 

[Peter Loeser]

Thanks guys, I'll poke around some more tonight and see what I can find. The fact that it seems to be temperature related makes me think it could be a bad solder joint.

 

[Sevenfeet]

I have the same problem with my Parasound HCA-2200 2 channel amp. During the winter I don't have a problem with the unit but during the summer, it's hard to keep the temperature of the room down in my home theater room) and the second channel (right) sometimes goes to overload. I do need to figure out a way to get better cooling to it but I never considered it would be a bad solder joint. I may have to investigate that.

 

[Peter Loeser]

Ok, I poked around a bit more and took a few photos. Here is the board that connects to the AC mains and (I think) handles the current overload protection.

Image 1 - Top:

Image 2 - Bottom (the suspicious looking solder joints belong to the little transformer):

Image 3 - The only cap that looks a little off is the one near the bottom right with some sort of crusty film on top. It isn't bulging though.

Image 4 - Below those couple caps is a dark brown substance. I am under the impression this is some kind of adhesive, and I see it in quite a few locations thought the amp. I could be wrong.

Besides this, there is the transformer and the 5 amp modules. Nothing else sticks out to me at this point. If nothing can be determined visually, I'll probably end up taking it to a service tech. I'm in Houston, and the closest one listed by Parasound is in Austin. Guess I'll need to find a excuse to make the drive. I don't feel like shipping this big thing.

 

[Sevenfeet]

Yeah, it's really hard to make a determination with electrical engineering without proper tools and training (unless it's obvious like a blown cap). Since you have a Parasound service center in your state, I'd take advantage of it. It's possible they may have some experience with this behavior which would make the service time a lot shorter and less expensive.

 

[Anthony]

Your original description sounded like a blown output stage on that channel. But your pictures definitely show a bad cap, so maybe it is "simulating" a short (very low impedance) and kicking in the protection circuitry. That is odd, though. Caps shouldn't look like that -- any bulging or leakage means they are at best out of spec and at worst dead (open or short).

 

[Peter Loeser]

Your original description sounded like a blown output stage on that channel. But your pictures definitely show a bad cap, so maybe it is "simulating" a short (very low impedance) and kicking in the protection circuitry. That is odd, though. Caps shouldn't look like that -- any bulging or leakage means they are at best out of spec and at worst dead (open or short).

The one circled in red below?

 

[Anthony]

Yeah, that's the one I was looking at.

Had some fried caps in a power supply (easy to spot). A while ago when I did some IT work we had Dell motherboards that had bulging caps near the memory. Occasionally crashed the computer for no reason -- real bear to isolate and figure out.

Once the magic goo leaves the caps they are poorly behaved.

 

[Sevenfeet]

Yeah, that's the one I was looking at.

Had some fried caps in a power supply (easy to spot). A while ago when I did some IT work we had Dell motherboards that had bulging caps near the memory. Occasionally crashed the computer for no reason -- real bear to isolate and figure out.

Once the magic goo leaves the caps they are poorly behaved.

Good call. Nice to have someone here who knows what they are talking about. I may have to take my Parasound out of the rack one of these days and inspect it.

About five years ago my Mitsubishi 65" rear projection monster TV stopped working after only 4 years of service. One of the other home theater forums had a Mitsu section and one of the best Mitsu techs around had noticed that Mitsu had been putting cheap caps in the main processor board for the TV. And usually after 3-4 years, the caps would all give out. So he put together a multi-page HOW-TO guide on dissembling the back of the TV, getting the board out, ordering the replacement caps (with better ones) and then how to solder them in yourself since it was unlikely most people could get the TV to a service center and repair guys who actually do this kind of TV work are a vanishing breed.

Sure enough after being extremely careful about monkeying around the back of my set, I got the board out, got the old caps off, attached and soldered the new ones on, replaced the board, powered the TV on and PRAYED.

Sure enough it fired right up and has been great ever since. I hope that's the last time I need to do something like that to protect an expensive investment like that. Now if I can just convince my wife it's time to retire the set after nine years with a proper plasma or LED-LCD...

 

[Peter Loeser]

Thanks Anthony! I will try replacing the suspect cap and see what happens. Would be great to find a solution that simple. Let's hope...

 

[Peter Loeser]

Well, I have been too busy (or maybe lazy, who knows) to track down a replacement cap and continue with my troubleshooting. That combined with the fact that the amp has multiple problems, convinced me to just bite the bullet and send it out west to Parasound's service dept, since they seem to have a great reputation. Aaaaand it's turning into much less of a bargain... maybe no bargain at all. Tony didn't give me many details over the phone, but I'm looking at at least $150 for the repair, then shipping back home. I didn't expect it to be cheap, but honestly didn't think it would be quite that much. :doh:

 

[Anthony]

My 4 Ohm Magnepans blew two output stages of my Marantz receiver years ago and the damage came to $300 or so for the repair. It was local, though, so no shipping.

The $150 isn't too bad, but the shipping is.

Being in Houston, do they not have a local repair facility? I know those are becoming rarer, but being in a big city, that would help your odds.

 

[Peter Loeser]

There is a Parasound tech in Austin. I contacted them via email and got the feeling they didn't want my business. Just didn't get a great vibe from the guy who responded to my messages. :dontknow: I figured it wouldn't be cheap to ship regardless of distance, so I opted to send it to the source.

I went back and forth about the whole thing, and at a certain point I committed to keeping it, for better or worse. I do like the sound.

 

[Sevenfeet]

Well, I have been too busy (or maybe lazy, who knows) to track down a replacement cap and continue with my troubleshooting. That combined with the fact that the amp has multiple problems, convinced me to just bite the bullet and send it out west to Parasound's service dept, since they seem to have a great reputation. Aaaaand it's turning into much less of a bargain... maybe no bargain at all. Tony didn't give me many details over the phone, but I'm looking at at least $150 for the repair, then shipping back home. I didn't expect it to be cheap, but honestly didn't think it would be quite that much. :doh:

$150 for an authorized repair is actually pretty good, especially for an old unit. Their hourly work charge is going to be $90-$110 easy, then there are parts, bench testing, etc. And yes, shipping is horrible for anything heavy, like an amp.

At some point with every thing, you have to weigh whether it's worth fixing versus going out and getting a new amp. In many ways, this is why my next amp purchase will likely be Emotiva. Not only are they good, but they are local to me, which means all I have to do is pick up or drop off at their doorstep, and even talk directly to the service tech if I wanted.

 

[Peter Loeser]

Yeah, like I said, I wrestled over whether to keep it, but fixing this one will cost me less now than buying a whole new amp, even if the total cost of this one ends up being more than it should have. I really like the Paradigm/Parasound combo, so I want to hang onto this one for now.

I am also starting to think buying new electronics is a better idea than used. I'm all for tinkering and fixing my own stuff, but there is definitely something to be said for having things that just turn on and work like they're supposed to...

 

[Peter Loeser]

Just got a call from Tony at Parasound. The repairs are done and he says all channels are working properly. They replaced the transistors and capacitors on the protection board, which lines up with my suspicions about where the problems were coming from. Total for the repair was $175 including new feet (which were $20). Shipping back to TX is going to hurt :gulp: but at least I'll have a working (and great sounding) amp. I could have done some trial and error component replacements and possibly solved the problem (and saved a bunch of shipping costs) but there is some peace of mind that comes with knowing it has gone through bench testing and looks ok.

 

[ALMFamily]

Good to hear Peter - just think, it will be just like getting an early Xmas present! :bigsmile: