Sony xm-7547

[mnhiphop101]

On the 4 jumpers from left to right I have
Jw608: -3.88vdc
Jw607: -15vdc
Jw606: 15vdc
Jw605: 0vdc

All the solder joints looked fine

 

[Perry Babin]

Check the DC voltage on the points indicated A and B. Check all 4 diodes connected to those points.

When the amp is in operation, you should have ±45v there.

This is the full SM if you want it.

http://www.bcae1.com/temp/sony - XM-7547_Car Power Amplifier SM.pdf

 

[mnhiphop101]

I do have +/- 45v on a and b

 

[Perry Babin]

Find the break between the diodes and the jumpers.

 

[mnhiphop101]

maybe I'm on the wrong jumpers because the 4 jumpers I am measuring seem to be correct.
Jw608 is measuring 3.3 and is labeled fan control
Jw606/7 are +/- 15v
Jw605 is labeled ground


All measurements are good.

 

[Perry Babin]

Now you need to check further down the line.

Check the ±15 at the op-amps.

Check the ±45 at the jumpers JW638 and JW639.

Push on the board to flex it slightly while checking the voltage.

 

[mnhiphop101]

I have +/- .8v on all op amps

I believe they are supposed to be +/- 28v which they are

 

[Perry Babin]

What's the resistance from 638/639 to the ±45v rectifiers on the low-voltage supply?

The op-amps obviously can't work from 0.8v. Find the break.

 

[mnhiphop101]

0 to point a
130kohms to point b

 

[mnhiphop101]

Also I'm sure u know this already but u are correct, jw638 and 639 should be +/- 45v

 

[Perry Babin]

I don't see any components that would fail and break the circuit so you're going to have to trace the circuit and find the break. Mark it with a sharpie as you go if it's hard to follow.

 

[mnhiphop101]

Ok thanks for your help

 

[HolgiD]

Has there been a solution to the mentioned problem? I am chasing an issue with my 7547 as well (some kind of distorted sound, mainly noticeable through a midrange speaker) and thought to start a thread myself.... Thanks.