DR #32 - Parasound HCA-800II Repair

hi everyone welcome to duality repair this is the Paris sound AHCA 802 high current power amplifier this is another unit sent in by a viewer and of course it's got a problem so let me show you so the relay does not engage and the status LED stays in standby red so let's open it up ok and we're inside let's take a quick walk around before we get started on the bottom left here we have the power switch followed by the speaker selection board next we have the toroidal transformer and the two bolt caps these are huge these are Elna 15,000 micro farad at 71 volts I sure hope we don't have to replace those that would be very expensive in the center we have the power supply slash protection board on the bottom here we have the level selection board and on the right we have the amplifier section so since we have a protection issue I want to first start by looking for DC on the output I can't actually look at the speaker terminals because the relay is not engaging so I'm gonna start by looking at the amplifier board itself alright I'm going to first check for DC on the right output which is this red wire here and then I'll check on the left output which is the white wire so I'll turn it on you can see we don't have anything on the right output let's take a look at the left output no we don't have a DC problem change of plans through a bit of troubleshooting I was able to determine that if I leave the unit on for just a little while maybe 30 to 45 seconds the relay does eventually engage I think this delay is due to one or several failed capacitors are just not charging up as fast as they should you'll notice as well that the status LED does start off red but it does eventually change from red to orange and orange to green I think this is also due to a failed or failing capacitors I hooked up some audio and it sounds decent through both channels so let me do that now we'll turn it on and here the relay engage it struggles for a while there and that was much faster than the original this took only I don't know three or four seconds that's probably because the unit's been on for a while as I've been testing it and it's just warm I'm sure that if I let it get cold it would take just as long as it did originally so let me put some audio on and can see what it sounds like [Music] so it sounds pretty good actually both channels sound pretty level I don't hear much of any distortion from either Channel right now and you can't see again the status LED is red if I were leave it on for maybe another minute or so you would see a change to orange and then eventually to green so I think this unit could definitely benefit from a recap that was on my list to do anyway as these are all original and they're all 85 C rated I'm going to start by pulling this relay off this is another Guardian relay this is the same relay or very very similar to the relay that I had to remove and clean in the Carver unit that I did recently so we'll pull that off we'll clean the contacts and also recap the power supply section just this power supply board here and I believe just doing that will get rid of the delay and the status LED changing colors as well as the delay in the relay engaging so let's start with that all right here's another Guardian relay for you this is a 12 volt coil five amps and it's in really good shape we'll take the spring off so we can take a look at the variable contacts but I'm sure they need to be cleaned up just a little bit for cleaning what I do is I use computer paper soaked in contact cleaner and that does the trick pretty well so let's get started with that [Music] [Music] [Music] [Music] [Music] [Music] [Music] the relay has been cleaned and reinstalled and the power supply section has been recap let's see if that made any difference and yes it looks like it did the relay engaged almost immediately and at the same time the status LED immediately went to operation green so I think the caps and the dirty relay contacts were probably the major issues with this unit let's see how it sounds [Music] sounds really good so just like the HCA 500 pretty much was just needed a little work in the power supply section course I'm not quite done with this I'm also gonna recap the amplifier section before I call it complete so I'll get started on that now actually before we do that let's take a look at the ESR of the five caps that I replaced just to see if we can find a smoking gun with one of those okay so the four on the Left checked out okay some of them are a little high but nothing too concerning but the one under measurement right now c00 7 which is a 33 micro farad at 10 volt cap is failing miserably so this should be something like 2 to 3 ohms of ESR and obviously we're looking at greater than 30 ohms ESR this cap is directly in line with the power supply section and the coil of the relay so it makes sense that this failing cab was causing our issue so now let's get started with recapping the amplifier section [Music] [Music] all right we're completely recap so this one is done it wasn't the most exciting video so I appreciate you watching but we did get some meaningful service in that prolong the life of this unit we'll see you next time you