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Old 01-05-2022, 08:39 PM   #61
thetonywarren
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Physically the cap looks fine, doesnt look bulging or otherwise broken anywhere, although I know that just because it looks fine physically that doesnt mean that it's a good component....It does test low....but the reference to a wet bottom I dont know what he means by that, it wasnt actually wet, maybe it did look that way in the picture?
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Old 01-05-2022, 09:06 PM   #62
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

your picture appears to show a slight "oil like sheen" on the far side of the left pin... I think that is what is in question. Maybe flux from desoldering??? or leakage from the cap.
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Old 01-05-2022, 09:37 PM   #63
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Think of that cap as a battery, a dead battery that draws current but won't hold a charge. The 5v line is trying to charge it through the 100Ω resistor and the cap is drawing so much current it is killing the 5 volt supply. It likely leaked and dried up years ago.
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Old 01-06-2022, 08:24 AM   #64
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Quote:
Originally Posted by thetonywarren View Post
What do you actually mean when you say the cap is "wet" on the bottom, Im not familiar with that term.....

Thanks for the help!
your post #48, second picture. Look at the black rubber where the legs stick out. It looks wet to me as if it had leaked electrolyte.
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Old 01-06-2022, 08:34 AM   #65
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Ahh, good eye, I took another look at the cap, and I think you're right! makes better sense to me now, It does look like it could have leaked electrolyte......

Thanks for your patience with my ignorance......
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Old 01-13-2022, 12:15 PM   #66
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

So I was able to replace the suspect cap, and started re-assembly....now I have a different problem.....

As I started to re-assemble, in between mounting boards and re-installing screws, I would pause, plug the unit in, press the power button and make sure things were still working... which they did for a bit, I would press the power button, I would hear the relay click and the receiver would turn on...

I got to a point where I had to step away from it for a few minutes, and I left the unit powered on....then I heard a strange sound, turned around and I saw a small puff of smoke, but couldnt tell where on the board it came from.....

Now the unit, when plugged in, seems to turn on and looks like it's on by the screen, but for a sneaking reason, I feel like the actual amplifier portion is not turning on and something went awry.......

Can we start to troubleshoot that now?? Any help is appreciated and I can give any readings necessary to keep the process moving........
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Old 01-13-2022, 06:59 PM   #67
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

:-( looks like you have to go back to checking voltages at the various board connectors to see what is and what isn't as before you had the "shut down situation" but now you appear to have operational "stability" (ie. unit stays on). Hopefully, in your checks, you will notice where "puff the magic dragon" got out. :-)
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Old 01-14-2022, 06:28 AM   #68
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

That can happen. On an older amp that didn't run for a long time, I make sure I watch it like a hawk the first few minutes. Once it survives 5 mins, it will be fine. Just you were the lucky wiener this time. LOL
Anyway... look at the bright side: The amplifier has two channels, Left and Right being identical. All you have to do is to find the faulty component and compare it to the other channel. Check the big output drivers and the pre drivers. If smoke left a part, you should be able to see it.
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Old 01-17-2022, 09:47 AM   #69
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Can you be a bit more specific and take a look at the circuit diagram, just to point me in the right direction as to where to start to look?

Any help is appreciated....

Thanks so much.....
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Old 01-17-2022, 11:53 AM   #70
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

so you don't hear the protection relay "click" when you turn it on?
For starters, you need to figure out which channel is giving you the problem the left or the right? You have to compare the left and right channel to each other with a DMM. One is going to have voltage on the output.
The protection circuit sees power on one of the outputs, so the relay will not engage in order to save the speakers.
Not sure why, but I am always troubleshooting amps in "reverse". So measure the big output stage transistors, then the driver stage, pre driver etc. Anyway... I just wanted to throw this quickly in there... don't have time to read the schematic right now... got to go back to work.
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Old 01-17-2022, 12:07 PM   #71
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Ok, I'll see what I can do.....

I appreciate the help, will update with my findings......

If you get a chance to take a look at the schematic that would be awesome....whenever you would have time of course......

Thanks for walking me through this.....
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Old 01-17-2022, 12:21 PM   #72
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

basically look up the power amp section and go from Q1-4 backwards. Q1 and Q3 is one channel and Q2 and Q4 is the other channel. One of them channels has DC on the output. Once you find the channel that has the DC, follow it back through the individual amplifying stages... Page 9/31 on the service manual.
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Old 01-17-2022, 02:02 PM   #73
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

So I tested out the 4 main transistors and all 4 are shorted out...... I removed them from circuit just to check all of them, and they are all indeed shorted out.

Then I plugged it in and pressed the power button, the relay/circuit protection clicks in....

but im also assuming I'll have to follow the circuit further back to see if other transistors in the driver stage and pre driver stage, or other components are fried.....
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Old 01-17-2022, 04:16 PM   #74
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

The relay doesn’t matter now with the finals out. All 4 of them finals shorted? That is not usual. Usually it’s just one channel, but not both. However… check the other stages for shorted transistors.
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Old 01-18-2022, 01:44 PM   #75
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Ok, so I am tracing the circuit back and the next transistors for each channel, from what I can gather are Q509-Q512, I took those out of circuit and tested them, two of which are PNP, and the other two are NPN, I tested them and believe they test good....not shorted, and are showing with my DMM to be passing current correctly......do I stop there or should I keep tracing back to Q505-Q508, and then Q501-Q504? There's also Q515 and Q516 too......Thoughts?

On a different note, the 4 main transistors are from my research obsolete, can anyone help me with selecting suitable replacements? Typically i've been ordering from Digi-Key.....

Pictures are attached for review......
Attached Images
File Type: jpg 2022-01-18_13-41-55.jpg (191.3 KB, 7 views)
File Type: jpg PXL_20220118_182226960.jpg (712.9 KB, 6 views)
File Type: jpg PXL_20220118_193859712.jpg (500.2 KB, 8 views)
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Old 01-18-2022, 03:18 PM   #76
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

While you are in there, I’d check them all… after all you want to make one order if possible keeping shipping costs down. Also check the resistors, if they are going bad, to 99.999% they go higher in value or open. At the same time, check for bad caps on the supplies…
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Old 01-18-2022, 10:32 PM   #77
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

2SC3281 -> MJW3281AG (On Semiconductor)
2SA1302 -> MJW1302AG (On Semiconductor)

These should be more or less exact replacements.

Last edited by eccerr0r; 01-18-2022 at 10:34 PM..
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Old 01-19-2022, 07:45 AM   #78
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Amazing, thanks for the help with that....

Also is it ok to test the transistors in circuit, vs out of circuit, I just want to be as thorough as possible with my troubleshooting, but dont want to take each one out if not needed.....

Thanks!
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Old 01-19-2022, 11:36 AM   #79
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

if the transistor is shorted, it will show up in circuit.
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Old 01-24-2022, 11:13 AM   #80
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Default Re: Pioneer VSX-3300 Receiver Wont Power On

Looks like some of the resistors burned up, Im guessing that's where I let the magic smoke out.......In looking at the documentation, Im not seeing specifications for the required wattage, I think I read there that they should be 5%, but im not sure on wattage and how much that actually would matter.........any input?
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