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Pioneer SX-650 Protection Issues

moodydan

moodydan

I love the punk rock.
I've got an SX-650 that was kicking into protection, so I followed several older threads that had common issues. My symptoms were that the receiver would come on as usual, get the click after 5-7 seconds, then the rushing sound I associate with bad transistors kick in and the receiver would kick into protection mode.

I have currently replaced three 100uf/35v caps (swollen) with 100uf/50v, as well as two Sanyo .22uf/10v with .22uf/50v on GWR-101, and the 1uf/25v caps on GWH-101 with 1uf/50v electrolytics. For transistors, I've done the following:
GWR-101
2SB507 > MJE15033
2SC945 > KSC945C (ECB)
2SC1649 > 2SC1845
2SC1384 > KSC2690A
2SA823 > KSA992
(3) 2SC1647 > KSC945 (EBC)

GWH-101
(2) 2SC1438 > KSC1845

With all that reported, the now the receiver will only come out of protection sometimes, but with no consistency. When it does come out, that some rushing sound is present, in both speakers, with the volume turned all the way down. It will kick in and out of protection like this. Is this a symptom of bad filter caps?

-Dan
 
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First things first:
Power Supply voltages?
Disconnect the speakers for now.
 
Also without a signal, measure directly at the amplifier output (before it hits the relay) for the presence of any DC voltage.
 
A series of observations, based upon my SX-650:

I'd noted with mine that it does run quite hot, despite the large open space inside. A good proportion of the electrolytics in mine were completely cooked and were marginal at best. It wouldn't kick into protection nor make a rushing noise, but it wasn't at its' best.

I just bit the bullet and redid the entire thing. The measurement suggested by Glen65 on mine is +20mv on one channel, +25mV on the other, for reference.

Both main filter caps on mine were bad but all they did was pop fuses.

--Phil
 
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zebulon1 said:
First things first:
Power Supply voltages?
Disconnect the speakers for now.
Click to expand...

Voltages on GWH-101 are the following:

1 +31.15
3 -31.88
5 +31.50
7 -31.29
12 -36.26
14 +32.28
23 -44.7
26 +44.4
28 -32.25
29 +32.30

While I was taking the measurements, I did not hear the relay click in.
 
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that appears to be the amp board voltages ..not the power supply ... you also missed out important pins 17 and 19 ...
 
petehall347 said:
that appears to be the amp board voltages ..not the power supply ... you also missed out important pins 17 and 19 ...
Click to expand...

I'll measure GWR-101 and post tomorrow. I'll also get 17 and 19 from GWH-101, but I do not see expected values on the schematic (I see they connect to F and B on GWR, but no values to compare).
 
From GWH-101:
Pin 17 fluctuating -21v to -28v
Pin 19 fluctuating -7v to -12v

GWR-101 (so far)
B -10 to -13
F -19.57
H -36.18
K +42.3
N -43.3
P +32.34 (schematic shows -50?)
30 +29.6
31 0V
35 13.36
R +32.24

Q7
E +13.37
B +13.90
C +32.24

Q8
E +32.30
B +32.30
C +40.12

I'm still working on the voltages at the transistors, but I thought I'd get this stuff up first as it seems P and 31 are red flags.
 
I'm not sure what pins on what board you are reading but pins "B" and "F" are the speaker outs and are way "WAY!" off. Should be near zero volts. Suspect modules but other voltages need to be checked. Like the modules pins them selves. The power supply voltages as well. Is the set railed?
 
P +32.34 (schematic shows -50?) suspect wrong pin read ...
if you look on schematic there are pin numbers as well as letters .
Q8
E +32.30
B +32.30
C +40.12

base emitter being same don't bode well for q8 ..measure it again ..maybe measured same pin twice ..
as zeb says pin voltages on power packs will help .

on another note i suspect if you pull r32 the relay will click in ... if you try this don't have a load connected at speaker terminals as dc will pass through ..
 
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I only saw the letters on the schematic, I'll go back and take a better look! I'll also measure the pins at the power packs (and make sure of Q8).

While I'm in there, I'll pull R32 and see what happens.

petehall347 said:
P +32.34 (schematic shows -50?) suspect wrong pin read ...
if you look on schematic there are pin numbers as well as letters .
Q8
E +32.30
B +32.30
C +40.12

base emitter being same don't bode well for q8 ..measure it again ..maybe measured same pin twice ..
as zeb says pin voltages on power packs will help .

on another note i suspect if you pull r32 the relay will click in ... if you try this don't have a load connected at speaker terminals as dc will pass through ..
Click to expand...
 
I see where the letters clearly correspond to numbers on the schematic, I just had it blown up so for on my computer screen I couldn't see that part of the page. Silly! Anyway, I measured the pins of the power packs, or tried to. In the cases of pins 3, 5, 6 and 7, I couldn't get a steady value (the values ranged greatly, and where there was supposed to be mV values there were V).

Left:
1 35.71V
2 -10V to -15V
3 not steady
4 not steady
5 -35.71V
6 -9V to -23V
7 -9V to -19V

Right:
1 35.71V
2 9V to 11V
3 not steady
4 not steady
5 -36.20V
6 -14V to -24V
7 not steady

Regarding Q8, now this is happening:
B 3.0V to 3.2V
C 51.7V
E 2.6V to 2.7V

Q7:
B .028V
C 52.4V
E .036V

If P is at R53, I'm getting -44.1V, which makes much more sense (I was measuring at the cathode of D12).

What a mess...
 
right channel looks like its blown .open bias diodes .....
left channel looks like positive missing pin 2 .check r22 3.9k .... r18 1.8k ...check 33v at pin 14 ..
 
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With R32 pulled, relay still did not kick in. If it tells anything, I have 3V at pin 30, no voltage at pins 31, 35.

At Pin 14, I have about 3.5V.

R22 3.84k, R18 1.81k.
 
pin 30 should be 30v .
31 should be 7.5v AC
35 should be 13v
check 48v at pin 26 ..
check AC voltages each side of fuse 3 and fuse 2
also -50v at pin 13
 
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I replaced both SP-40W's, my voltages at those pins are now:

Right
1 36.04 V
2 34.51V
3 25.80V
4 32.21V
5 -36.18V
6 -36-19V
7 34.21V

Left
1 35.98V
2 34.35V
3 26.18V
4 33.00V
5 -35.97V
6 -35.99V
7 34.18V

It's encouraging that they are consistent on both channels, however, pins 2, 3, 6, and 7 are way off. Thoughts?
 
I've had similar problems caused by the wire wraps and jumpers on the main amp board.


Barney
 
where did you get the SP-40W's from ?first thoughts both are dud ...
sanity check all amp board pin voltages including the grounds ..
also q4 q5 BCE voltages ..
 
you can pull both sp-40's, then connect pins 2 4 and 6 together.

This will eliminate the modules, yet allow the amplifier feedback circuit (the 2sa798 and 2sc1438) to dc balance itself and allow the protection to operate, then watch and wait for the protection to pop out. You CANNOT have ANY load on the outputs, no headphones or speakers.

If it is stable, and behaves, you know it's the modules.

When the protection misbehaves, then look at Q5, q6 2sc1649, the 0.22uf caps if still original, and then the rest of the protect circuit.
 
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markthefixer said:
you can pull both sp-40's, then connect pins 2 4 and 6 together.

This will eliminate the modules, yet allow the amplifier feedback circuit (the 2sa798 and 2sc1438) to dc balance itself and allow the protection to operate, then watch and wait for the protection to pop out. You CANNOT have ANY load on the outputs, no headphones or speakers.

If it is stable, and behaves, you know it's the modules.
Click to expand...

is this sort of in place of the modules internal diode string etc ?
 
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