troubleshoot Pioneer SX-2900

[jts1957]

MARK HEAT SINK next to each with (Q1) "C" or (Q3) "A" and then remove Q1 & Q3.

All of the following you can check 'IN Circuit' or 'Out Of Circuit.' I'd start with resistors (Meter on appropriate ohm scale for expected value. Sometimes if you reverse your test leads you get two different readings, but one reading should be close to the expected value, if not pull one end or other end of that resistor from the board and check again.)
R561; R527; R529; R533; R535; R551; R553; R555 & R557

Next on Diode test: D521 & D523

Next on Diode test: Q521; Q523; Q541; Q551 & Q553

If you have doubts about any transistor, you can test as you did before with two legs floating.

If ALL test OK, obtain replacements for the two outputs that you just removed - install them, reassemble receiver, cross your fingers, toes, arms, legs, and eyes - plug in unit and hopefully you'll hear music or talk radio.
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[scar]

the cost of those two transistors is over $50[1][2]. i understand it's important to match the replacement transistors as exactly as possible, but are there cheaper alternatives elsewhere? it would be cool to have the receiver working again after all of this trouble but the $70 one on eBay is looking more attractive

1. http://parts.pioneerelectronics.com/part.asp?productNum=2SC3181N
2. http://parts.pioneerelectronics.com/part.asp?productNum=2SA1264N

[jts1957]

Try HERE

If you want to try to find even cheaper they are probably available. Just be sure of item's shipping location and legitimacy. There has always been problems with Chinese knockoffs.
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[scar]

thanks i also found these that look more exactly like the ones in the receiver, except the receiver transistors say "R OJ" and "R OL" on them and the ones in the auction both have "O OJ" on them. do you know what that is? just some production date/code or something?

[jts1957]

Or sumthin.

Either will work.
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[Guest]

R561: this is weird resistor with 3 legs? it says 0.33ΩKX2 but when i measure it the DMM says about 2.0 to 2.5 between each leg (on 200Ω setting)
R527 (rated 68±5%): 70.0
R529 (rated 2.2±5%): this one acted weird and kind of jumped all over the place to 7, 12, and 20 before finally resting at about 4.4 which is outside the tolerance
R533 (rated 680±5%): 688
R535 (rated 100±5%): 101.4
R551 (rated 100±5%): 100.7
R553 (rated 100±5%): 103.0
R555 (rated 100±5%): 101.5
R557 (rated 100±5%): 102.3

D521: not exactly sure how to measure, on the diagram one of the leads has a double-circle and the diode has a blue line on this end, does that mean put the negative probe there? when i did that i got a low (629) reading. when reversed i got a high reading.
D523: "

Q521: this one had 3 low and 3 high measurements
Q523: "
Q541: " but the high measurements were 1000-1500 and not "off the scale"
Q551: 4 high and 2 low measurements
Q553: "

guess i need to take R529, Q521, Q523, and Q541 out and re-measure? and R561?

[jts1957]

[scar]

so R561 should be 330 ohms between the middle leg and either of the two ends?

when i touch the probes together, the reading is about 1.9 ohms on 200 setting and 2-3 ohms on 2000 setting. if the probes are moving at all while touching then this value fluctuates wildly. anyway if i subtract that value from the measurements of R561, which i've measured all six ways, it equals about 0

and the diodes seem fine... i did a little research and the end with the line is where the negative probe goes and you should get a low reading, which i did, and then an OL reading when reversed, which i did.

[jts1957]

so R561 should be 330 ohms between the middle leg and either of the two ends?

so R561 should be .33 ohms between the middle leg and either of the two ends.
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[scar]