So I am dealing with a bad relay on a Parasound HCA-806 amplifier. It's a 6 channel amp, I've got 5 going and working. The 6th one is the bugger. So I know a bit about amps and the relays. I tried to force the sixth one to engage, sandpaper, electric contact solution, whipped out a nail file, etc, (it wants to remain unopened) but it won't engage at all. Tried forcing it, still nothing. Bottom line is it will take 3 hours just to remove this thing. Can a relay be bad all on its own and even if forced to work (i.e. Prongs pressed together and it still does not work) Is it worth it to try to remove and replace the relay or could it be possibly something else? I've checked every fuse twice, they all look good inside.
If the relay coil has no voltage across it (or an incorrect low voltage) then the contacts will not close.
If the contacts themselves are suspect, then that is confirmed in seconds with a meter/scope check of the signals/voltages into and out of the relay.
If you manually close the contacts and the unit still does not function as you expect then you really need to look elsewhere.
If the contacts themselves are suspect, then that is confirmed in seconds with a meter/scope check of the signals/voltages into and out of the relay.
If you manually close the contacts and the unit still does not function as you expect then you really need to look elsewhere.
Thanks for the response. I don't have a meter or scope unfortunately. The relay contacts are open so I just assumed it has to be the relay. But manually closing it, the channel still doesn't come on, which surprised me. I eyeballed all the fuses in the amp, they all look ok. What might cause other part in the amp may cause a relay to not engage? Would it be a total waste of time to put in a new relay? I have one. Just didn't want to waste hours putting it in if it wasn't going to make a difference.
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you'll likely need access to the underside of the pcb where the relays are mounted. What brand and type of relay is it ? can you post any photos ?
If you look up the datasheet of the relay, it will show you the pin-out, from which you can choose where to probe. Your meter will allow you to do what Mooly suggests.
If you look up the datasheet of the relay, it will show you the pin-out, from which you can choose where to probe. Your meter will allow you to do what Mooly suggests.
My god man, have some self confidence! You can DO IT! I replaced all output relays in two HCA-806A amps that I used to own. Both amps had several relays with contacts that would often decide not to conduct. Very annoying! Taking the amp apart is not difficult, you just need to keep track of parts (e.g. all the darn screws). If you lay the amp on a large table it makes it easier. The replacement relays are from Omron. I forget the exact part number but they are a common type and cost about $5 each. If you can do some basic assembly and soldering work, you can do the replacement. Maybe three hours start to finish for all of 'em. Really! After that the amp will operate like new again, well at least the relays...
P.S. I think you can phone Parasound and get some tech help over the phone. You can ship the amp to them for a repair ($$$) or they can ship you the OEM relays if you want to do it yourself. I chose the latter, then once I knew the part I bought the same relays directly and did the other amp myself. Easy peasey and saved a bundle.
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Here is a close up pic I found of the output board on one side of the amp. These are directly mounted to the heatsinks, on of which is to the rear in the pic. The four heatsinks, if I remember correctly, are actually the sides of the chassis with two on each side connected with a small connector bar or bars. Once you take off the cover and unscrew a number of screws, the heatsink will come off the rest of the chassis and you can just lay it down next to it and then you get pretty good access to the PCB. I think you don't even have to disconnect any wiring to do this. You then unsolder the old relay with a sucker-bulb unsoldering tool, clean the thru hole of soldermask or other residue, and then solder in the new one.
You can see two of the relays in the pic. They have a clear cover and you can see the copper of the solenoid winding.
You can see two of the relays in the pic. They have a clear cover and you can see the copper of the solenoid winding.
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Here is another pic I found of an HCA-806 with the heatsink "laid down" on the table like I explained above. You get to the relay pins (to unsolder them) on the back side of the PCB (in this view). In the middle of the heatsink (just to the left of the white thing mounted to it) you can barely make out one of those connector bars I mentioned.
Thanks Charlie! I have 6 new relays and was going to do all 6 at once eventually. Before going through all that work though I wanted to see if I could coax the one faulty one into working. But no. It's dead. Do you find it odd that even manually forcing it to close does not engage the channel? The protection light is lit for the channel as well on front. I have a solder sucker and I have replaced a relay in a different amp a decade ago so I know I can do it, but wanted to see first if I could coax the thing to work first. Taking the easy way out. I hauled this thing from the USA (where it worked fine) to Australia and the problem arose a few weeks after I had it hooked up here. I googled and saw all the relay issues there are and went ahead and bought 6 new relays. Seems they will all go bad over time anyhow.
Hi Joel,
If the relay isn't closing, there is a reason for it. The protection circuit won't allow the load (speaker) to be connected if there is a problem with that channel. If you used anything abrasive on the relay contacts - you destroyed it. The connection is made with a thin, plated contact surface. As long as it wasn't pitted, it can be cleaned. You killed it.
From the sounds of things, you should take your amp to the manufacturer or a good audio technician. You don't have the experience or the equipment to do this work. Sorry for saying this, but you know in your heart this is true.
In time you can get the experience, working on DIY projects and buying equipment that you can trust. I'll disagree with the statement that you only need a cheap meter. Nothing could be further from the truth. You don't need a real expensive one either, but please consider something from Fluke or Keysight. The same can be said for a soldering station. You can get good ones for $100 + or -. Buy one with digital display made by Quick, Solomon or Hakko. Any of these will serve you well. Buy a bunch of "screwdriver" tips as the conical one some come with is next to useless.
-Chris
If the relay isn't closing, there is a reason for it. The protection circuit won't allow the load (speaker) to be connected if there is a problem with that channel. If you used anything abrasive on the relay contacts - you destroyed it. The connection is made with a thin, plated contact surface. As long as it wasn't pitted, it can be cleaned. You killed it.
From the sounds of things, you should take your amp to the manufacturer or a good audio technician. You don't have the experience or the equipment to do this work. Sorry for saying this, but you know in your heart this is true.
In time you can get the experience, working on DIY projects and buying equipment that you can trust. I'll disagree with the statement that you only need a cheap meter. Nothing could be further from the truth. You don't need a real expensive one either, but please consider something from Fluke or Keysight. The same can be said for a soldering station. You can get good ones for $100 + or -. Buy one with digital display made by Quick, Solomon or Hakko. Any of these will serve you well. Buy a bunch of "screwdriver" tips as the conical one some come with is next to useless.
-Chris
All good points. The protection light was on all on its own before I started so I figured I couldn't screw it up anymore then it already was, lol! Amplifier service in rural Australia isn't going to be an easy option I'm afraid, which is why I bought the relays to do myself here:
I do have a brand new soldering station I brought here for the job and also a new soldering de sucker with 2 extra tips. At this point I think I'm just missing a kick in the **** to get on it properly. It looks so scary lol!!
I do have a brand new soldering station I brought here for the job and also a new soldering de sucker with 2 extra tips. At this point I think I'm just missing a kick in the **** to get on it properly. It looks so scary lol!!
http://s36.photobucket.com/user/Joel_Kozlowski/story
Don't think my pics ever worked from my previous post so here is a different link.
Don't think my pics ever worked from my previous post so here is a different link.
I'm afraid I agree with Anatech on this... now that you mentioned the protection light also being on casts a whole new dimension to this. There is a lot more than just a duff relay to this.
There will probably be a fault on one of the channels power output stages. An experienced tech would be able to determine the basic reason such as high DC offset or a failed and shorted output transistor etc.
Replacing the relay is a waste of time at this stage I'm afraid.
There will probably be a fault on one of the channels power output stages. An experienced tech would be able to determine the basic reason such as high DC offset or a failed and shorted output transistor etc.
Replacing the relay is a waste of time at this stage I'm afraid.
No, no. At least I know that much! The amp worked great for about 2 weeks until I lost the one channel. I found a repair specialist of all things high end that I will be going to next week. I'm also going to get it switched to 240v so I can dispense of the mega step up transformer I needed to get the thing going. Which who knows, may have caused the fault. The bad news is the repair shop is 5 hours away but at least I will be able to get it to them in person as I happen to be driving right by. Gonna need it shipped back though!
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