elnaldo
Lunatic Member
I wouldnt worry about that by now. I'd jump the switch soldering a wire and take it out of the equation . You can't trust that switch. And, as mentioned, check if you have 120V right at the transformer.
elnaldo
Lunatic Member
PLEASE KEEP IN MIND THAT THE MAIN 120 V IS VERY DANGEROUS. Please double your precautions or stop here and take it to a tech or to somebody who can help you in person.
jpreza
Active Member
Thanks! I think I’m done. Not sure where in this picture I’d check for 120V?
Attachments
jpreza
Active Member
Or here?
Attachments
see if this thread will help: https://audiokarma.org/forums/index.php?threads/pioneer-sx-550-issues.923943/
google: Pioneer SX-550 audiokarma site:audiokarma.org
Pioneer SX-550 no power audiokarma site:audiokarma.org
google: Pioneer SX-550 audiokarma site:audiokarma.org
Pioneer SX-550 no power audiokarma site:audiokarma.org
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jpreza
Active Member
Thanks! I appreciate your help.
cademan
Lunatic Member
Don't part it out if the power transformer isn't bad. Just because you are a noob doesn't mean it is not repairable.
You really shouldn't be messing with it if you don't know some simple electronic terms like primary and secondary. Here is an explanation:
The transformer winding connected to the voltage source is the “primary.” The transformer winding connected to the load is the “secondary.” The voltage that can be induced in the secondary winding from the primary magnetic field is a function of the number of secondary conductor loops (turns) cut by the primary electromagnetic field.
The primary takes in the mains 120 volts from the wall. 240 volts if you are in Europe. The secondary puts out the voltages needed for the entire stereo to work like 6 volts, 8 volts, 12 volts, 32 volts, etc. Here is a simple schematic representation of a transformer:
Let's see a pic of your unit including the rear panel. According to the schematic, there are 6 fuses, 1 either behind the transformer (probably the one you found and tested) and 5 more (probably underneath the chassis). I see in post #5 that you checked the fuses.
Unfortunately the schematic doesn't show wire colors for the transformer but it does show numbers where they go into the circuit board. All the circuit boards should have numbers and letters printed on the top side. Numbers 1 & 3 are the 120 volts primary input. Numbers 4 - 11 are the secondary output voltages.
With your volt meter, Pins 1 & 3 should have 120 volts on them. Pins 4 - 11 should also have lower voltages on them. If nothing on any pins 4 - 11 then this says to me that the power transformer is shot. If this is indeed the case then you need a new transformer and if this is not anywhere near your reach, then go ahead and part it out.
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jpreza
Active Member
Don't part it out if the power transformer isn't bad. Just because you are a noob doesn't mean it is not repairable.
You really shouldn't be messing with it if you don't know some simple electronic terms like primary and secondary. Here is an explanation:
The transformer winding connected to the voltage source is the “primary.” The transformer winding connected to the load is the “secondary.” The voltage that can be induced in the secondary winding from the primary magnetic field is a function of the number of secondary conductor loops (turns) cut by the primary electromagnetic field.
The primary takes in the mains 120 volts from the wall. 240 volts if you are in Europe. The secondary puts out the voltages needed for the entire stereo to work like 6 volts, 8 volts, 12 volts, 32 volts, etc. Here is a simple schematic representation of a transformer:
Let's see a pic of your unit including the rear panel. According to the schematic, there are 6 fuses, 1 either behind the transformer (probably the one you found and tested) and 5 more (probably underneath the chassis). I see in post #5 that you checked the fuses.
Unfortunately the schematic doesn't show wire colors for the transformer but it does show numbers where they go into the circuit board. All the circuit boards should have numbers and letters printed on the top side. Numbers 1 & 3 are the 120 volts primary input. Numbers 4 - 11 are the secondary output voltages.
With your volt meter, Pins 1 & 3 should have 120 volts on them. Pins 4 - 11 should also have lower voltages on them. If nothing on any pins 4 - 11 then this says to me that the power transformer is shot. If this is indeed the case then you need a new transformer and if this is not anywhere near your reach, then go ahead and part it out.
Thanks again for your help. I stayed up way past my bedtime.
I double checked pins 1 and 3 = 0V AC or DC
pins 4-11 = 0V AC or DC
Sadly the only sign of any power is only at the power switch when you set it to ON where I get 120V AC at the switched outlet. So I have said my peace with this receiver - too much trouble for a newbie like me, so I'm moving on.
I've learned that there are times you have to quit while ahead, and this is one of those times, for my own sanity.
To fight a battle another day....JP
elnaldo
Lunatic Member
If an old amplifier is in mint condition, I wouldn't part it out. Electronics are usually repairable, but not the cabinet and faceplates. I'll keep it and repair it in the future, or sell the whole unit as non working. Power transforners can be fixed by a tech or transformer factory (rewinding the primary or sec. As needed).
ecluser
Super Member
The fuse that is before the power transformer, on the power line, is located under a removable cover at the back of the receiver. That is FU6 on the schematic. Did you check that fuse? All the other fuses that are visible on the printed circuit board are located on the secondary side of the transformer.
ecluser
Super Member
I think you didn't reassemble the power switch correctly. With the receiver disconnected from the wall outlet, connect your Ohm meter directly at the power switch terminals and see if you have zero Ohm in any position but in the OFF position. You did it the long way. When I restaure the power switch I don't remove the face plate. I remove the first fuse holder just behind the power switch and the power switch can be removed from the back.
cademan
Lunatic Member
Here is an easy problem........the power switch looks to be bad whether or not you reassembled it correctly.
If you are not getting any 120 volts at pins 1 & 3, this is where the wall power comes into the transformer after the switch. You're going to regret it if you part it out and found out that it was just the switch.
You could easily attach a wall plug directly to the wires going to pins 1 & 3 and see if it powers up but if you do this, make sure that the transformer wires are disconnected from pins 1 & 3 and attached solely to the wall plug.
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jpreza
Active Member
Hi ecluser - yes I did check and replace FU6 as well. Continuity was good.
Thanks everyone for your help! As I said before, it was way beyond my expertise. I get around with my DMM and I've been pretty good in the past when replacing lights, transistors, and caps.
This power issue really stumped me because I originally thought it was probably going to be something simple like a fuse.
I wanted a nice vintage receiver in the garage but it was not meant to be. I ended up taking back to Goodwill and got my money back. Hopefully the next owner can figure it out.
Best to all! JP
Thanks everyone for your help! As I said before, it was way beyond my expertise. I get around with my DMM and I've been pretty good in the past when replacing lights, transistors, and caps.
This power issue really stumped me because I originally thought it was probably going to be something simple like a fuse.
I wanted a nice vintage receiver in the garage but it was not meant to be. I ended up taking back to Goodwill and got my money back. Hopefully the next owner can figure it out.
Best to all! JP
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