CurtPalme.com Home Theater Forum

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

Mac,

I have a SR5006 here that has a distorted right channel. I took the amp out (it scarily looks rather identical to the VSX-50 amp, but is different), and the front right channel must have blown at some point and gotten repaired.

The problem I'm having is finding the bad part, there's an open component somewhere in the circuit and I can't locate it. Without the schematic I don't know where the hell it is.

Any ideas? Razz

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Huh. I don't have that manual. Stops at SR 5005. Must be just new enough I don't have it yet. Checked some of my search places and nothing there either. Oh well.

So, tell me, how do you know the problem is in the amp section?

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

Well, the FR channel has new outputs and emitter resistors, and there is a problem in it somewhere, I am reading open across 2 pins on a transistor where I should be reading 0.780 (as all other channels read on those 2 pins on that transistor)

And the FR channel is distorted, so that's what has led me to believe its the FR channel on the amp board. Otherwise the entire receiver, and all other channels work as they should.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Have you pulled that transistor and verified good or bad?

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

Yep I pulled the one im testing on and its fine, the outputs are as well, and the complimentary transistor to the A1024 is good as well.

There are 2 surface mount transistors on the back of the channel but I don't want to remove them and risk damaging them if they are good. In circuit they look fine, but when I test between them, I notice the same problem between the 2 xsistors on the bottom as I do on the 2 pins on the A1024

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Whats the location id of the transistor your getting the funny reading on?

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

Its Q414, the middle pin and the one outer pin that doesn't have a circle going around it are the ones I'm getting the off reading

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

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

Here's a pic I took of the distorting FR channel, as well as partial of the SBL channel, the pic shows each channels A1024 and describes what they do on the multimeter in diode scale,

Positive lead is on the middle pin, negative lead is on the left pin. To be honest mac I get confused somewhat still with transistors, don't ask why, but I've never quite understood them Wink

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

The emitter is on the right, base is on the left

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

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

How odd, I read it to you as the datasheet described... oh well Razz

Anyway, I already had the 2560 out of circuit, along with a good 2560, both of them are identical readings. I don't get the .780 on the good channel with the 2560 out of circuit I don't get the .780 reading on the KTA1024 anymore though. The same still goes for the bad channel.

On a good note though, I have also tested the same 2 leads on the KTA1024s using resistance. Now that the good 2560 is out of circuit, the resistance reading is 200K, just like the channel with the questionable 2560 was with it in circuit (also reads the same out of circuit)

On another good 2560 that is IN circuit, it reads 131K ohm. So is it possible that while the 2560 is reading ok on diode scale it is leaking since I am getting the same resistance reading on it as I would out of circuit?

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Rather than get into a big conversation on testing those parts, just swap them between channels and see if the readings/problem follows.

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

From the datasheet. The upper picture is the front face of the transistor. Follow the red line. Pin 3 is what?

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

The base

By the way it was the 2560 mac, I put a good one in and it took care of the issue

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

So this one is done? Now I'm bored. What else you got? Laughing

**Curt Palme** · Posted: Mon Jul 08, 2013 9:42 pm Post subject:

I have one.. soon.. and you'll both be jealous! D

Pioneer SX1980. 1 owner. He offered to sell it to me, hadn't had it out of storage in years. He fired it up, it worked fine for a bit.. then the audio died. He was asking a reasonable (retail) price for it, but I passed. I bit as soon as it died. Very Happy

I don't think I'll need help fixing it. Very Happy

No, I'm not selling it, it goes into MY 2 channel system that I'm building up..

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

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

Damn you curt, damn you, I've owned 3 of the SX-1980s, one was literally new in condition, and I REALLY regret selling it, the other 2 weren't as nice, but man, WHAT A RECEIVER!!!

You win the YOU SUCK award for that one Razz

And yes mac, we are done with this one pretty much, I had to order some 2560s and 1647s because I robbed them from a denon, and I ordered some KSA992s as well (plenty of those fail in denons Very Happy

)

Sorry that was so easy mac, lol. I'll see what else I can find, I think soon we're going to be working on some that have HDMI issues though Razz

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

I got one for ya mac, its a Yamaha RX-V671 that's stuck in standby, I'll start a new thread