Marantz PM62 protection mode

[superjb]

Hello Guys,
I am trying to fix a Marantz PM62.
Speaker relays are not clicking, even headphone sound not working.
With a DBT B+ is 63v and B- 25v

What I've done:
- Change all electrolytics capacitors even filtering 8200uf
- test with another bridge rectifier
- test styroflex capacitors
- tested all transistors with a TC1 tester (only concern was Q707 and Q708 2sd1508 was 4500 hfe and 7000 hfe)
- tested resistors on circuit (compare channel right and left)
- test with replacement diode D702 zener 15v and DN03
- test another protection IC TA7317p
- reflowed a lot of soldering
-looking for ground issues
- replaced speakers relay
- measured transistors voltages

I'm still not understanding this rail voltage B- 25v ..


I'm stuck now with no idea, or changing the AN7062p but it looks my last desperate trial

Please help

 

[superjb]

Transistors measure:
QN02
B 0v
C 67.2v
E 0v

QN03
B 0v
C 67v
E 0v

QN04
B 66v
C 19.1v
E 66.5v

Q717
E 1.1v
C 67v
B 0v

Q718
E 1.1v
C 68.1v
B 0v

Q719
E -1.2v
C -25.2v
B 0v

Q720
E -1.1v
C -25.1v
B 0v

Q709
E 61.1v
C 67.8v
B 1.6v

Q710
E 1.1v
C 68v
B 1.6v

Q711
E -1.2v
C -25.2v
B -1.7v

Q712
E -1.1v
C -25.1v
-1.7v

Q703
E 67.4v
C 1.6v
B 66.8v

Q704
E 67.4v
C 1.6v
B 66.9v

Q705
E -24.6v
C -1.7v
B -23.9v

Q706
E -24.5v
C -1.1v
B -23.9v

Q707
E -1.7v
C 1.6v
B -0.5v

Q708
E -1.7v
C 1.6v
B -0.5v

 

[superjb]

the issue with B- -25v was due to a ground issue. Now i get -46.20v B- and 46.20 B+.
In fact screws behind the amp around the speakers connectors were necessary to get ground everywhere on the power amplifier board.

So this is ok.

I will look at the speaker relay not clicking now.

 

[mbz]

Q709
E 61.1v

Gotta be a typo, connects to Q717b, should be +1.2V

Q717
E 1.1v
C 67v
B 0v

Can you get pin voltages from the AN7062... wouldn't rush replacing parts until you get a handle of what's going on.

 

[superjb]

Gotta be a typo, connects to Q717b, should be +1.2V

Can you get pin voltages from the AN7062... wouldn't rush replacing parts until you get a handle of what's going on.

Yes sorry typo Q709 E is 1.1v.

yeah i took this one as well.

AN7062
1 0v 18 -8.8v
2 0v 17 0v
3 0v 16 0v
4 44.52v 15 44.48v
5 44.45v 14 44.43v
6 45.71v 13 45.68v
7 44.24v 12 44.24v
8 45.14v 11 45.16v
9 45.96v 10 -15.13v

In addition of what i was looking right now.
QN04

B 46.09v
C 0.65v instead of -0.7v
E 46.12v

 

[superjb]

Yes sorry typo Q709 E is 1.1v.

yeah i took this one as well.

AN7062
1 0v 18 -8.8v
2 0v 17 0v
3 0v 16 0v
4 44.52v 15 44.48v
5 44.45v 14 44.43v
6 45.71v 13 45.68v
7 44.24v 12 44.24v
8 45.14v 11 45.16v
9 45.96v 10 -15.13v

In addition of what i was looking right now.
QN04

B 46.09v
C 0.65v instead of -0.7v
E 46.12v

to be true
on pin 2, 3 16 and 17 i have -0.033v

 

[superjb]

On protection circuit TA7317p
i have :

1 0.65v (should be -0.70v )
2 0v (ok)
3 0v (ok)
4 0v (ok)
5 -0.78v (ok)
6 24v (should be 1.1v)
7 0.06v (should be 1.3v)
8 2.94v (ok)

 

[Goldie99]

The 24V on TA7313P pin 6 suggests the protection IC is not turning the relay on. The offsets on pins 2 & 3 look ok, so I'd probably have a look at pin 1 - where the missing -ve voltage ? RN13 (fusible) is probably worth checking, also DN03 next to it, and CN03 (could also be reverse biased if the -ve supply is missing ?).

 

[superjb]

You got it !! RN13 was 4mohm ...
I don't know why i did'nt get it.
Not looking nice not looking burnt but clearly dead !

Thanks a lot