Marantz 2225 Voltage Adjustment Issue

[Wirehead_be]

I have a Amp and it has 40mV DC at the speakers out of the factory ....... Runs fine even with 40mV

Perfectly ok. Some might not even have dc offset adjustment. In that case, you need matched ltp's.

 

[llwhtt]

What were the correct test points?

Craig

 

[tomharrison1]

First adjust the power supply to 35V.

Then there's the Service Manual error:
You need to measure between J714 and J716; and J715 and J717. Both channels 20mV. (Manual incorrectly states 712/718; 713/719)

As Wirehead and you indicated. Typo in service manual.

 

[llwhtt]

It makes me wonder if it is a typo or just different versions of PCBs as many of the manuals have the same "typo". Anytime I work on a Marantz receiver I make sure the manual agrees with the PCB I'm working on. Many times when you connect your meter you end up with rail voltages instead of idle current voltages. Anyway you got it sorted and learned something.

Craig

 

[tomharrison1]

Quite right Craig. And so you know, the service manual I have is for the 2225L model, not the one I have which is just 2225. The L model has additional short wave radio band but I would assume main amp board is exactly the same in both. Maybe they are different...

 

[Wirehead_be]

A lot of Marantz service manuals have errors.. It's ridiculous.. Wrong values compared to the pcb, different testpoints, polarity reversed.. Always check the boards. As for bias, it's sometimes handy to measure directly across the emitter resistors. That's the best way of calculating / calibrating it.