CurtPalme.com Home Theater Forum

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

mac, this is a bit off the wall from the Yamaha I have yet to get back around to, its a Pioneer VSX-821 and the issue it originally had was a distorted right channel, I later found that the amplifier PCB itself had been badly burnt up. Looked to be from a shorted output on the front right channel...

Anyway, while repairing the amplifier, I noticed that a VSX-521 amp is literally identical in specs, performance, design and fit. I went ahead and pulled the good amp from the 521 and threw it in the 821, well everything LOOKS like it works, all relays click on that should, functions all work, but I get no sound at all from any channels on the speaker outputs.

Now I thought maybe it was the FM tuner so I tried a different input, no dice. Well I had to disable the damn demo mode on it since it was driving me nuts, and while I was in there I went to the speaker setting to adjust the channel level, and as you probably know the sound that the amp puts out while adjusting the channels should be there, but the setup sound for adjusting the MCACC or channel levels isn't heard either.

So, basically, no matter what, there is NO sound. The amplifier is just fine, checked it over, its not running hot, in fact, its not getting any signal it seems since its running rather cool, almost luke warm.

So I call upon your wise words of wisdom again mac, in hopes you'll lead me to the right path Razz

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

I think I already know the answer to this but let me look up a few things so I can be more specific.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Did you change anything else other then the AMP assy? How many boards in that assy?

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

Just the amp assy, and there is only one large board on the amp assy

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Did the 521 amp work before you pulled it out?

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

Yes it did mac, nothing wrong with it.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Well if before the swap the 821 all channels worked except for a distorted 1 and the 521 also worked fine before the swap and after the swap there are no channel outputs......... then you f*ck*** something up.

The 821 and 521 amps are identical...... and I mean, "IDENTICAL" including each and every part. Even the complete board replacement part number is the same.

So swap them back and see which one doesn't work now.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

Mac, I should have detailed that the receiver stopped putting audio out with the original 821 amplifier. It was cutting in and out on its own so I lifted the front of the receiver and let it drop onto the counter top, the audio then ceased to function.

I figured it was the 821s original amplifier since the main bus foils were burnt through like paper. Obviously that isn't it since as you said the 2 boards are identical.

I'm sure I f*ck*** something up due to the "drop" test, I'm almost willing to bet its something on the bottom of the motherboard of the receiver, since the amp mainly connects to that.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Ah ha...... leaving out pertinent information..... shame on you.... Laughing

Did you want to troubleshoot then? I do have some time today.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

Yeah if you're willing we can do some work on it. I don't have anything else on the table for the time being so why not Very Happy

And yeaaaa I know, but who likes to admit such details Razz

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

First thing, on that amp board is find connector CP403. DMM on DC and receiver turned on. Pin 8 for ground lead. Positive lead Pin 5 for - rail and Pin 2 for + rail. Let me know what you get.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

Well... I apologize about the delay mac, but curts site was down or something, I couldn't access it to reply with my findings so I gave up and went to calibrating a TV Razz

Anyway, the readings were +56.25v and -56.25v with pin 8 as ground. Sorry it took so long! Embarassed

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Ok, 2 question.

1) Are you sure the speaker output relays are closing. I know you said they were I'm just double checking.

2) Did you ever put together that signal tracer I told you about?

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

Yes to #1, and no to #2 Embarassed

I know I know, I'm bad Razz

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Ok. Lets check something else first and if it checks ok then you may have to put it together.

Locate the audio board. Should be the one with the audio inputs. It should have an ic400 on it. There should be a connector CP402, probably where it connects to another board. You need to check for 2 voltages there.

Use pin 5,8 or 10 for ground. DMM on DC. Turned on, pin 4 should have +6.8v and Pin 6 should have -6.8v. Let me know.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

Mac,

I thought just for the heck of it because it DID have audio output before the "drop test" that I would pull all the connections and reseat them....

... it actually worked! Neutral

I never get that lucky! I did another "drop test" which is only the front of the unit being lifted 3" from the counter, and it didn't cut out so it must have been a loose connection.....

Makes me feel somewhat dumb Laughing

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

It's no fun when they are to easy..... Laughing

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

You're telling me, lol. Don't worry I have a few here that I'm sure will work both of us over Wink