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Marantz 140 Meter Adjustment

T

ToSch

New Member
Hello everyone,

I am Tobi from Germany and had to fix one bad channel of my Marantz 140. The capacitors have been replaced previously by the owner before. So I checked for cold solder joints but could not find any. Then I ordered replacements for all transistors of the amplifier board with the help of old threads in this forum. Thanks a lot for all the information in here!
Since it has been my first repair of electric circuits, I made some mistakes and had to use two solder bridges. Everything else seems to be fine.Thankfully, the Marantz is now playing on both channels together with the 3200 and I think, that it now sounds even better than before!
After adjusting the dc balance and the bias, which is now as described in the service manual, I have difficulties setting up the meters. As I read in old threads, I did the following:

1. I connected my iPhone with a signal generator app via cinch with the input of the Marantz. I set up the signal to 1kHz and very low volume.
2. I connected my DMM with the speaker output and selected AC voltage.
3. I powered the Marantz up.
4. I turned the volume of the signal up till seeing 9V on the DMM:
5. Setting RX03 and RX07 had no impact on the meter´s pointer. And this is where I am right now. The meters are working, when I play the music really loud, but I would like to adjust them. Any ideas, what I did wrong and should do in another way?

Thanks a lot and have a nice day!
Tobi
 
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You realize that there are RX03 and RX07 on the right side for the right channel and there are RX03 and RX07 on the left side for the left channel, correct?
There are push on connectors for the metering on both the power amp boards and the Meter amp boards, IIRC.

Tom

140 RX.jpg 140a.jpg
 
Hello Tom,

yes, I do have the problem of adjusting the resistors at both channels. The push on connectors are connected. Therefore, I think that maybe the input siganl or the points of my measurements for the 9 V RMS are wrong.
Do I need dummy loads?

Thanks a lot!
Tobi
 
Did you some how get the pin connectors backwards on both power amps?
I've not done it but I think it would cause metering problems and who knows what else.

Tom
 
Hi Tom and Jerry, :)

thanks for your answers! The problem was sitting in front of the DMM, it said 9 mV instead of 9 V. Now it is working, but another problem appeared. Sometimes on the left channel the peak indicator flashes and then the relay does not switch on. After reconnecting the peak board, everything works fine. Tomorrow I am going to check the peak board or what do you think?

Thanks and have a nice day!
Tobi
 
Yes, I changed the diodes H720 & H721 and now the problem has not appeared again. I connected the 140, 3200 and 104 and played them. Now it seems that I have to recap the 104 because when powering up the output is sometimes very high and made problems to the 140 and 3200. The 140 switched repeatedly on and of till I turned off the power. I hope it did not do any harm to the 140 and 3200, they are still playing really nice with other sources. I had a look to the 104 and capacitors on the power supply board are leaking. Is there no protection against high currents at the output of the 104 respectively the input of the 3200?

Thanks a lot and best regards,
Tobi
 
The 'leaking capacitors' might just be assembly glue. The output of the 104 should be muted until the power switch is actuated by a set of auxiliary contacts on the power switch.
I wonder if you could eliminate the issue by plugging the tuner power cord into the switched outlets on the 3200 Preamp and using the Power switch on the 3200 to turn the tuner on.

Tom
 
Hi Tom,

thanks a lot for your response. Sorry, that I haven´t been here for a while, I have been busy regarding the current situation. Yes, it could be assemly glue but if it is, it is not applied very accurate. When I power the 104 up, there is quite a high dc voltage of 0.5 Volts on the output of both channels, which then drops slowly to 0.001 Volts. It takes about 5 seconds. I cannot test your recommendation, since I do have the europe versions with other plugs. The one of the 104 does not fit into the switched outlets.
So is the high output of the 104 normal and I just have to power it up first before the preamp and the power amp? Or does a recap of the power board may help?

Thanks a lot and I hope everyone is doing fine,
Tobi
 
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