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Pioneer VSX-514K Amp error then shuts down

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  • Pioneer
Last response: in Audio
November 10, 2016 4:59:10 PM

So grateful to have found this site and the knowledgeable and helpful members here. I have fixed one amp so far with your help. This one is going to be a bit more challenging. Here we have a very nice Pioneer that was working just fine and then all of a sudden one day when it was powered up it gave the AMP ERR on the display and then went into shutdown mode and wouldn't power back up. I tried to reset the error but got the same results which means it wasn't a fluke. Nothing obvious when I look at the board from the top side - no bulging caps or burnt diodes that are visible, but there is a lot to look at and I'm aware that defective components aren't always visible to the naked eye. I haven't gone any further yet (no disassembly) and have been studying the schematic in order to familiarize myself a bit before I start digging. Any tips or suggestions are certainly appreciated! Thanks in advance ..

More about : pioneer vsx 514k amp error shuts

November 11, 2016 9:46:31 AM

To make sure the problem is internal to the Pioneer disconnect the speaker wires from it and then turn it on. If there is a short in one of the wires or a bad speaker then the Pioneer should come on without the problem. Disconnect the inputs next and try is again. If the problem persists I don't think the unit will be worth your investing any money to repair. Used ones go for about $50.
The learning curve is pretty steep to fix and you would need some test gear too.
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November 11, 2016 1:14:08 PM

If it shows amp error even with all speaker wires unconnected, the amp is short. This happens a lot with these VSX, they aren't exactly solid. I suggest you use an ohmmeter, and check each individual output transistor.
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November 11, 2016 3:05:36 PM

This unit was pulled and replaced by a friend of mine when it failed so there are no speakers attached when the error occurs. I assume I should check the transistors while the unit is powered down? It won't stay on for more than 5 seconds after the error is reset before it goes into shutdown mode and won't power back up until the error is again reset. I've checked most of the resistors and got 'good' readings from all but the one that goes from the secondary to the main for the power supply (I think?). That may be a different animal though, as I checked the one that performs the same function on my SX-205 and didn't get a reading on that one either. The resistor I speak of is R51 toward the center of the bottom of this schematic. https://www.manualslib.com/manual/792810/Pioneer-Vsx-D5... I'm guessing that it has to be powered to be checked?
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November 11, 2016 3:31:16 PM

Yes, always unplug the amp for checking transistor shorts and resistances/fused. R51 is a 2.2Megaohm resistor. It's a very high resistance, and you won't be able to measure it without the meter being in MΩ.

What you are looking for is voltage on the PAC10A or PAC11 (IC601/IC602) ICs. If there's a DC voltage when you plug it before it switches off, the amp is short. Measure this on the large white resistors, right next to the amp.

Do this with an analog voltmeter:
Set your meter to volts DC. (50V or more)
Plug the negative terminal of the meter to a ground plane. The casing is good usually.
Then connect the positive terminal to R615. (.22 5W white usually)
Connect the amp to the AC 120V. Power it on.

If there's DC volts, that amp is bad. If not, test R616 restarting from the unplugged amp. If it has DC, then your IC601 is short.

If not, test R638, R665, R666 using the same method. If one has DC, IC602 needs to be replaced.
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November 12, 2016 6:01:21 AM

Thanks again Natsukage. I will get busy checking those today or tomorrow. I think that R666 might have the devil in it! ;-)
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November 12, 2016 8:55:40 AM

Haha. xD It's not the resistors the issue, but the IC...xD Those IC "PAC"s are prone to failure.
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November 12, 2016 11:10:53 AM

I've read that those PAC's are prone to fail .. just tryin' to keep things light with my last reply. :-) I've checked every one of the resistors you named and there's one that's giving a reading of -65 - R638. I have a question. Since only R638 failed and not R665 or R666, is it possible that one of the surrounding Zener diodes is allowing a backflow of current when it shouldn't be? I see D677 and D678 in the block just below and to the left of R638. I've heard that sometimes those fail as well. Is there a way to check them to confirm that they are working properly? Here's the link for that schematic page to simplify things for you. https://www.manualslib.com/manual/792810/Pioneer-Vsx-D5... I certainly do appreciate your expert knowledge! I'm learning a lot!!
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Best solution

November 12, 2016 12:36:43 PM

If R638 has DC, then the most probably explanation is that your IC602 (PAC11) is short.

You can first unplug everything, and test Q631 and Q632 (driver transistors) by removing them and checking if they are short using an ohmmeter. Even then, you shouldn't have DC on R638... The only other way to get a DC would be for every other transistor and diode around it to be short (Q633, D632). If all those (Q631,632, 633) are okay, and you have DC on R638, you need to replace IC602 (PAC11).

These amps are self-contained, and usually shouldn't have DC whatsover...
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November 12, 2016 2:31:24 PM

Understood, but I have seen Zener diodes that have still functioned, but failed to restrict the passage of current from the opposite direction (i.e. a power surge) that will also trigger an error. My next question is: is IC602 / PAC011A even available to purchase new? I don't want to bother with all of this if I can't even secure the part I need. I checked Pioneer's parts site but came up empty.
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November 12, 2016 2:43:52 PM

The answer is that those PAC have been hard to find new even 10 years ago....

You can find them on ebay or amazon:
Amazon
ebay.com

They are relatively cheap...but some chinese ones are not new, they're refurbs..... It's worth trying a 7$ IC though. It's 30$+ if from the US.

I personally recommend Utsource. Never once had trouble with them over the years.

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November 13, 2016 6:09:06 AM

I'm sounding like a broken record, but thank you again Natsukage. There's no way to check those Zener diodes in circuit without removing them, is there? I'd hate to order parts that I don't need and then end up not having the part I do need so I want to make sure to be certain I've got the right culprit.
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November 13, 2016 10:42:49 AM

You can test them in circuit, just test with an ohmmeter. Unplugged from the wall socket of course. If they test short in circuit, you can always just cut off carefully one side of the wires and test again. Just cut off in the middle of the wire, so if they're good, you can solder it back together. For example, cut at the black line:
Spoiler


Test for conductivity, it should be only one side, like a normal diode. You can always replace them alongside the IC though if you're not sure? They're 16V zener diodes.
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November 13, 2016 8:10:08 PM

They both tested good. Using the diode test setting on my meter 8.0 in only one direction each. You called it - that chip is bad. Now the fun begins of the tear down. Are those power leads crimped to the posts coming out of the board? How do you go about removing them? Do I have to cut them? And what about those ribbon cables .. tips or tricks for removing and re-inserting them? The only other question I have at this point is what is that white grease on the backside of that chip between the chip and the plate of that heat dissipater? White lead? Dielectric grease? I assume I'm going to need to goop up the new one before I install it. This job would have been a LOT easier if Pioneer had made it with a peek-a-boo plate so you could remove the bottom to work on it. Thank you again for your continued guidance!
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November 13, 2016 8:27:33 PM

Hmm? You need to remove the whole board main board, and unsolder the leads underneath. There's no wire to cut or remove usually in this amp?

Following this https://www.manualslib.com/manual/792810/Pioneer-Vsx-D5...
Remove every screw on the board, heatsink and rear of the amp, then carefully twist the whole board upside down or sideways, with all the wires connected. (remove all plastic tie wraps for easier manipulation) You then need to unsolder all the pins of the IC underneath using either a desoldering pump, or drywick. Once unsoldered, remove the screws on the ic, and remove the IC from the board, pulling upwards. (in relation to the board)

That white grease is called thermal paste. It is necessary for heat transfer. You need to keep as much possible, or if it's all gone, replace it with new thermal paste.

And yeah, I miss the old days where amps has a removable plate underneath....xD
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November 15, 2016 2:24:02 PM

Thanks a million Natsukage. I have ordered the part and will gather the necessary implements to do the job. It will be a couple of weeks before the part arrives and I don't want to take the board out until I have everything I need in front of me so I can do the job and reassemble without losing parts or forgetting where they go. If I get stuck I'll post .. and I'll be certain to post when the job is complete. You're the best! :-)
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November 15, 2016 2:29:04 PM

You're welcome, and nah, I'm not the best. >_< I barely compare to the main repairman in our business....and I've been doing repair work for more than a decade now...^^;

If you ever want to be sure not to miss anything, take some pictures. ^^ Better safe than sorry when dismantling these amps.
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November 15, 2016 8:45:36 PM

Just know that you're the best to someone that appreciates you! Yes, pictures for sure before I begin disassembly. Thank you!!
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November 28, 2016 3:22:34 PM

:-)
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November 29, 2016 8:25:38 PM

Natsukage said:
You're welcome, and nah, I'm not the best. >_< I barely compare to the main repairman in our business....and I've been doing repair work for more than a decade now...^^;

If you ever want to be sure not to miss anything, take some pictures. ^^ Better safe than sorry when dismantling these amps.


I got that module today and got right to it. Took me a couple of hours, but having the right tools helped immensely. Glad I picked up the de-soldering iron with the vacuum on it. With having to de-solder 26 pins, it could have gotten extremely ugly! I had my fears about soldering the new module in since the posts are so close together and there are so many of them, but it went amazingly well. The biggest challenge for me was lining up those pins on the new module to get them to seat into the board before I could reattach the module to the heatsink and begin soldering. I had to remove the module a couple of times before I got it to seat properly, but after that it was smooth sailing! I've just plugged the receiver in and I didn't get an error message.. so that's one hurdle. Now I just have to hook it up to some speakers to make sure it's working properly and hopefully I'll be done! Thank you again for all of your help and knowledge NATSUKAGE! You really saved me a ton of money and kept this old receiver from heading off into the electronics recycling pile or perhaps even a landfill! THANK YOU THANK YOU THANK YOU!
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November 30, 2016 6:27:13 PM

^__^ Glad I could be of help. These are nice amps, and I hope it'll last you for years to come~ Have fun listening!
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December 13, 2016 6:09:58 PM

Natsukage said:
^__^ Glad I could be of help. These are nice amps, and I hope it'll last you for years to come~ Have fun listening!


Thank you! I hope so as well. I bought the best thermal paste I could find and I hope it helps to make this new module last longer than the original one. Thanks again and Happy Holidays to you and yours!
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