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Pioneer SX-1010 Tuner Problem

So I bought a Pioneer SX-1010 off ebay for $78 recently and everything looks to be in good shape except the tuning section. For some unknown reason, the tuner doesn't do anything! When you move the needle across the dial face, neither of the tuning meters move and the output to the speakers is dead silent.

Switch over to aux, phono, etc, and there is no problem. DC offset was measured at 1.2mv right and 7.6mv left. Any ideas where to start?
 
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Power supply.

Thge 1010s have heat problems with the power supply which kills capacitors and makes for bad solder joints.Its on the underside of the unit.A service manual would really help.Look fo 13v on pin 8 and pin 9 of the power supply board.Most likely pin 8s voltage will be missing.
 
Download the service manual from the database. ( I got the hi-res one)

Yes, the 13 v is just on pin 8, (pin 9 is -13 for the protection circuit) and one (Q7) of the two (2s)d313's on the heatsink is the regulator. First check Fu3 & Fu4 as they feed that circuit exclusively, but they BOTH need to be blown to shut it down.

Q7 is midway between the two rows of off board connections (middle of the board) along one edge on the heatsink. The other d313 that you are NOT interested in is closer to the off board wires. If there is no voltage at pin 8, read the three voltages (base, collector, emitter looking left to right, upright) on Q7. There's a drawing of the (2s)d313 on the pdf manual's page 48.

as rstsgsas says, they get HOT and crack their solder joints.... plus you may see heat discoloration on the board where they are mounted. Not having enough ventilation around the receiver aggravates the situation, with the power supply regulator mounted on the UNDERSIDE of the receiver, trapping and pooling the heat.
 
Ok, how do I check them? I have a multimeter, but the only thing I know how to do with it is check dc offset. Also, I can handle a soldering iron decently (not artfully). I'm a fast learner though if somebody wants to hold my hand through this, I would greatly apprecciate it.

I actually bought this receiver as a gift for my dad. I have an SX-1250 and absolutely love it.
 
I suspect you've not been around this forum a lot to see what a markthefixer fixing session is (or can be) like.........

Ground (a metal chassis ground) the black lead of the multimeter, use the red lead to probe the voltages, first on pin 8 of the lower power supply board, then on the three pins of the transistor I talked about. If the meter isn't autoranging, go to the 200v DC scale.

First, Inspect the bottom of the board for bad or cracked solder joints around that transistor, Or just clean the old solder off of them and resolder them. Then re-check the tuner function and read the voltage on pin 8. If you don't find 13v on pin 8 then read the three voltages on the transistor.

.
 
I suspect you've not been around this forum a lot to see what a markthefixer fixing session is (or can be) like.........

Ground the black lead of the multimeter, use the red lead to probe the voltages, first on pin 8 of the lower power supply board, then on the three pins of the transistor I talked about. If the meter isn't autoranging, go to the 200v DC scale.

Inspect the bottom of the board for bad or cracked solder joints around that transistor between finding NOT 13v on pin 8 and reading the voltages on the transistor. Or just clean the old solder off of them and resolder them. Then re-check the tuner function and the voltage on pin 8.

.

Even stupider question, grounding the black lead, does that mean I should just touch metal with it or is there a better/safer way?
 
Somewhere near the main capacitors, there will be a riveted lug where there are wires soldered to it. That's the main ground. For the purposes of a high impedance voltage reading, just touching the metal chassis ground is good enough. A wire SECURELY clipped to the metal nearby is optimal.
 
Ok, solder joints all look ok, no voltage measured at pin 8. The voltages measured at Q7 are left to right, 0, 23.38, 232.9. Now what?
 
Ok, solder joints all look ok, no voltage measured at pin 8. The voltages measured at Q7 are left to right, 0, 23.38, 232.9. Now what?

What is the model of your meter, or does it do autoranging? That 232.9 reading makes me suspect a shorted electrolytic capacitor (C19) OR a shorted 14 volt zener diode (D10) because I am interpreting it as 232 millivolts or 0.232 volt where it should be 14 volts.

I think the best thing is to get a replacement cap (25 cents?) and replacement diode (5 cents , cheap insurance) and just put them in.

One other test first, with the power off, and the unit cold for a while for all the capacitors to discharge, you need to set the meter to ohms and take a reading from pin 14 on the board where the wires go off of it, and the "right" transistor pin (the one with the "232" reading) and look for about 10,000 (or 10k ) ohms, to be sure R19 is doing it's job supplying a small amount of voltage that D10 or C19 is short circuiting away....

I will post parts numbers from mouser dot com for the cap and diode, and maybe the transistor (just in case... it's cheaper than another shipping charge) and during the checkout procedure you will be able to specify first class mail shipping and pay about 2 bucks instead of 6 or 8 for shipping. The parts themselves should be under a buck.

BUT>>>>>>>>>>>

IF you are feeling adventureous, you COULD just go to Radio Shack and get (IF they have it) part # 272-1029 a $1.29 220uF 35v capacitor and replace C19, and see if replacing it works.. (I give it a 75% chance) but they DON'T have a 14v zener diode, just a 12v (that's part # 276-563 at $1.29 for a pack of 2) that MIGHT get it running until the correct one is obtained....
 
Also I set it to ohms (the omega symbol, right?) and checked both of those points, pin 14 and the right transistor pin, and I get nothing..:scratch2:

The meter just shows 0.F, whatever that means?:headscrat
 
I downloaded the owners manual for your meter, and 0.f means over range.

That is a normal display when making a reading of a resistance greater than the meter is set to read. To get a zero on the display, touch the probes together....

Your meter is supposed to be auto ranging, and BE in auto-ranging when turned on, with a manual ranging over-ride, but the manual ranging over-ride limits the meter's usefulness and complicates taking the reading.

When doing manual resistance range selection when you see 0.f you should hit "select" to step to the next higher range. If the probes are NOT touching the resistance should be infinite.

BUT if it is in auto ranging a 0.f means that either you didn't make a good connection to bare metal at both the test points at the same time OR the resistor has become defective and open-circuited. Unlikely, but stranger things have happened.... AND HAVE HAPPENED, HERE, with HomerJSimpson.....

Thus I am NOT sure if the reading of 0.f in this case represents a defective 10,000 ohm R19, or rather just a meter stuck in the lowest range of 400 ohms, for which 10,000 is way too much. If I were making the reading and it read 0.f , it WOULD be the proof of the problem.

You need to take two other readings, from the points of the original readings to the leads of the possibly defective component, to verify an unbroken circuit through the resistor, meaning the break in the circuit (IF it exists) is INSIDE the resistor.

The problem is that the manual doesn't show a drawing of the parts locations on the board, and there are THREE 10,000 ohm resistors on it (color code = BROWN BLACK ORANGE) so I can't just tell you to look for the colors.

One thing we can try is for you to read all three components with the brown black orange color bands at their component leads. TWO of the three ARE correct as the receiver does come out of protect. The other two may not read exactly 10,000 ohms because they are installed in circuits that will affect the readings, but there WILL be readings, and any in-circuit effects will cause lower readings than 10,000 ohms.

Edit: here's a bit quicker way than the stuff below: set the meter for ohms, and touch one lead to the "right" lead of the transistor where you got the 0.232v reading on, then probe BOTH ends of the THREE resistors with the brown black orange color bands, one of these six readings SHOULD be almost ZERO ohms.... THAT'S R19!! Read from R19's other side to pin 14, and you should see TEN ohms. That means the PC patterns are ok. IF all three resistors read around 10,000 ohms we had a cockpit problem, not a bad resistor.


The other thing is for you to follow the conductors back from the points where you made the original readings to where they actually connect with the correct 10,000 ohm resistor, the correct path goes from pin 14, through a TEN ohm resistor (brown black black) from which there are TWO 10,000 ohm resistors connected at that point.

(I wish I could just POINT on a picture.... sigh)

The suspect (R19) 10,000 ohm resisitor will have it's other side connected to the "right" lead of the transistor where you got the 0.232v reading.

Thus from pin 14 where you took the original reading, to one component lead of R19 (when it is found) should read about ten ohms,
and the other component lead of R19 to the "right" lead of the transistor where you got the 0.232v reading should read zero ohms (well.... say less than two ohms).
The readings BETWEEN the TWO leads of R19 should be 10,000 ohms...

thus we have travelled in a circle, but we have proven the meter's operation and that the foil traces and solder joints that form that circuit in the power supply are uninterrupted...

(I'll say it for you, whew........... whatta mouthful!!)
 
I'll do all of that when I get home from work tonight. Gosh, I don't know how you know what you know about this, but it's pretty impressive.

Also, the meter is reading 0.F before I touch the lead to the test point and during, so maybe the meter is working correctly as you said that when the positive isn't touching anything the reading would be "infinite" and obviously greater than the meters range. Nonetheless, I will follow all of the above steps when I get home.

Another thing, the word "auto" does appear in the corner of the meter window, so I imagine that means auto-ranging?
 
Another thing, the word "auto" does appear in the corner of the meter window, so I imagine that means auto-ranging?

Yes, it means the meter is in auto ranging mode.

If the resistor R19 isn't conducting, Radio Shack part # 271-1335 @ $0.99 is a pack of 5 10,000 ohm 1/4 watt resistors.

Is the radio shack nearby, or is it a long trip?
 
WAIT A MINUTE! As I am testing these resistors, am I supposed to be leaving the black end grounded and just using the red probe to check each side of the resistor, one at a time?
 
The resistance test is usually NOT ground referenced, instead made BETWEEN two mobile probes. Like the first time :

One other test first, with the power off, and the unit cold for a while for all the capacitors to discharge, you need to set the meter to ohms and take a reading from pin 14 on the board where the wires go off of it, and the "right" transistor pin (the one with the "232" reading) and look for about 10,000 (or 10k ) ohms, to be sure R19 is doing it's job supplying a small amount of voltage that D10 or C19 is short circuiting away....

A lot of the resistance tests should be done (when possible) to the actual component leads, that little detail helps spot broken traces or bad solder connections.
 
The resistance test is usually NOT ground referenced, instead made BETWEEN two mobile probes. Like the first time :



A lot of the resistance tests should be done (when possible) to the actual component leads, that little detail helps spot broken traces or bad solder connections.

Ok, now that I got you here, let me recheck those real quick.
 
Okay, with one probe on pin 14 and one probe on the right side pin of Q7..Drum roll please.......NOTHING. WTF?

Trying to test the two resistors with the color banding you described, one probe on on pin, the other probe on the other pin...NOTHING. But, the meter appears to be trying to pick something up. Again, WTF?
 
The power IS and HAS BEEN off??


One other test first, with the power off, and the unit cold for a while for all the capacitors to discharge, you need to set the meter to ohms and take a reading from pin 14 on the board where the wires go off of it, and the "right" transistor pin (the one with the "232" reading) and look for about 10,000 (or 10k ) ohms, to be sure R19 is doing it's job supplying a small amount of voltage that D10 or C19 is short circuiting away....
 
Try reading the three brown-black-orange resistors at their leads as a check of the meter. At least TWO are good.
 
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