sony st- jx430

[mmoore5553]

Okay all i had to take a break from the other reciever i was working on. My dad's tuner went out today and brought it over. It is sony jx430 tuner. I turn on power and hear one click that is it. The standby light is on. What is funny though I was measuring AC coming in and it only showed 80 . I thought that was odd as it was coming in from the plug on two posts and the transformer was also connected to the posts.

Yes I am new to receivers so i look forward to the fun. I am having a hard time finding a service manual on this one.

Should AC volts be that low ? I only seen a resistor on the power board and tried to do continuity on it and it showed a 1 so open. But i figured that probably was okay but pulling the board out to look.

[mmoore5553]

Re: sony st- jx430

Here is a picture of the layout.

[mmoore5553]

Re: sony st- jx430

Here is where i measured 80 volts. This was coming in the AC cord directly to the spot

[budm]

Re: sony st- jx430

So that is the AC power cord's end, so is your meter showing 120VAC right at the outlet?

[mmoore5553]

Re: sony st- jx430

Yeah the outlet is showing 120 ac but when it gets to the board it is 80. I know this was in good shape and was just moved and then dad plugged it in and dead. Not sure why.

[budm]

Re: sony st- jx430

Well, that does not make sense, unless I not seeing how the connection is on the two black leads. What resistance do you read from the end of the plug to the end of the two ends of the power cord. The one with WHITE stripe is the Neutral.
Wait a minute, the picture #1 of post 2 is not the same chassis as the rest of the pictures.
OK, I see it now, #1 picture is from other website.

[mmoore5553]

Re: sony st- jx430

Yes sorry i took the other pictures. I am showing .4 ohms resistance. I did take a look at the underside of board and there is a small resister that is by the cap and relay and it does not show continuity as i would think this would be a fuse sni9ce i do not see one in this one and it shows on the back of board as these are connected.

i tried to ohm it out in circuit and it shows a 1 which means open on my multimeter.

So maybe if i jump this it might get it out of standby ?

[mmoore5553]

Re: sony st- jx430

This one does have where you can plug in another ac cord in the back that is bridged off that same post.

[mmoore5553]

Re: sony st- jx430

The resistor from the bottom shows it going to the where i screw down the board so i assume a short to ground.

[budm]

Re: sony st- jx430

If you do read 0.4 Ohm resistance from the male plug end to the end of the cable, that will not make sense since it is just the power cord which you are reading the voltage at the end of it. The outlet in the back is turn on by the power switch, the outlet will be label with "SWITCHED OUTLET", the other one may be always on outlet. So check the Ac on those outlet to see what you are getting.
That resistor is just for bleeding resistor (very high value resistor that is connected between power line and the chassis. I need to see the picture.

[mmoore5553]

Re: sony st- jx430

Here is the back of the board. I checked continuity from the resistor and it shows 1 and no buzz. i then check the ground to the beginning of resistor and continuity. I assume the short to ground is what is bring down the voltage and kicking on standby ?

[mmoore5553]

Re: sony st- jx430

oh on those outlets i am getting 80 volts on the back outlets too.

[budm]

Re: sony st- jx430

That resistor may be around 10M Ohms, that is not the cause of 80VAC reading. There must be an error in your reading some where.
Can you take straight shot pictures of the TOP and the bottom side of the board.
I also trying to see how many wires are connected to the power switch.
I can see the Neutral wire (Black with White stripe) is connected to the White wire of the transformer primary, it is also connected to the blue wire which goes to the Neutral terminal of the AC outlet.
The Line (Black) is connected to the pots on the board but I cannot see where it goes on the bottom side of the board. But no matter what, that 80v reading on the end of the power cord is just is right.

[mmoore5553]

Re: sony st- jx430

oops i am sorry i am getting 3 volts on the back outlets. I just double checked. Oh so i was wrong on the resistor. I swear audio equipment is so much different then other things i have worked on.

[budm]

Re: sony st- jx430

3V with power switch is on?

[mmoore5553]

Re: sony st- jx430

yes 3 volts with power switch is on. But the standby light is light up. I have attached some more photo's. One is of a diode that when i did a reading in circuit it was showing 180 which usually i am use to seeing around 500 - 600 in circuit.

Thank you in advance for your help.

[budm]

Re: sony st- jx430

That Black box is the power relay that will supply the 120V (Line) to the rear panel switched outlet when the Tuner is powered on. The Diode is the the snubber Diode connected in parallel with the relay winding, that is why it show the conduction in both direction due to the 180 Ohms DC resistance of the relay coil. If the relay does not click on, then there will be no AC at the rear outlet.
There are two red wires which is the secondary side of the power transformer, what do you read on those two red wires? We still need to find out why you are getting 80VAC though.

[mmoore5553]

Re: sony st- jx430

Per each post I am reading 10 volts per leg.

[budm]

Re: sony st- jx430

You mean 10v at the two red wire's ends? That is kind of low. What do you read a the white and brown wire of the power transformer? 80VAC?

[mmoore5553]

Re: sony st- jx430

Yes that is correct. I am reading 80 - 88 volts on all legs. I did find a service manual but it states for jx430L - AEP model G-AEP model. I looked at the some the schematic and it is missing the resistor which this one has. So i am not sure if this is correct manual but it shows 19 volts at the red wire. Both posts individually have 10 volts and it says suppose to have 20. So I figure at least that is correct.

I might buy another manual that says it is just for st-jx430. Not sure though.