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Marantz 2270 Relay issue

saam

saam

Member
I recently got a 2270 recently from garage sale and it's relay was not engaging. Checked everything and amp modules seems to be working with under 10 mV DC offset on both the channels. But relay not engaging. Checked the voltage on the relay coil (see attached picture) an I'm getting 46.7 VDC on both the points (red lead on these points and black lead on the body/ground). I did the recap of the power supply board but no change on these voltage. Input Voltage to the Power supply board is as required i.e. 35 VDC. Any advice ?


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Is the 10mV measured at the speaker terminals? Or is that the idle current measured at J754 and J760? Both of those measurements must be somewhere near normal range on both amps (0 mV for DC Offset and 10mV for idle current). If either is way out of range in either amp, the relay won’t come out of protection.
 
saam said:
No not really. I'm getting - 4 VDC (minus) on the base and + 46.7 VDC on the collector.
Click to expand...
That means either the protection circuit isn't working, or you measured the speaker outputs wrong and it's acting correctly, I'm guessing the latter.
 
Steven Tate said:
Is the 10mV measured at the speaker terminals? Or is that the idle current measured at J754 and J760? Both of those measurements must be somewhere near normal range on both amps (0 mV for DC Offset and 10mV for idle current). If either is way out of range in either amp, the relay won’t come out of protection.
Click to expand...

No not on the speaker terminal. There want be any volts on speaker terminal since the relay is not engaging. I measured it on the blue and yellow wires on the above picture which is actually the outputs straight from the amp modules. I even connected speakers on these 2 wires and I get the sound so the amp modules works fine with under 10 mV DC offset on both the channels.
 
ivandezande said:
That means either the protection circuit isn't working, or you measured the speaker outputs wrong and it's acting correctly, I'm guessing the latter.
Click to expand...

I think its the protection circuit because if connect speaker before the project circuit it works fine and there is very very low DC offset (under 10 mV)
 
I have a working 2270 open on my bench right now. I checked DC voltage at the two terminals pointed to. The one close to the blue wire was about 18V and the one near the yellow was about 33V for what it’s worth.
 
ivandezande said:
That means either the protection circuit isn't working, or you measured the speaker outputs wrong and it's acting correctly, I'm guessing the latter.
Click to expand...

Sorry about the confusion ...

I did some more testing with fresh mind this morning and you are right. I was not measuring the speaker outputs right. I disconnected the output wire going from amp to protection circuit one at a time and right amp seems to be the problem. Disconnection this from the protection circuit engages the relay. I'm getting 46 VDC on the output speaker wire of the right amp module. So the right amp module seems to be the issue. Just fyi even with the right output speaker connected to the protection circuit the receiver passes the DBT i.e. the bulb dims when power ON.

46 volts DC on the speaker output = output transistors issue or something else ?
 
saam said:
Sorry about the confusion ...

I did some more testing with fresh mind this morning and you are right. I was not measuring the speaker outputs right. I disconnected the output wire going from amp to protection circuit one at a time and right amp seems to be the problem. Disconnection this from the protection circuit engages the relay. I'm getting 46 VDC on the output speaker wire of the right amp module. So the right amp module seems to be the issue. Just fyi even with the right output speaker connected to the protection circuit the receiver passes the DBT i.e. the bulb dims when power ON.

46 volts DC on the speaker output = output transistors issue or something else ?
Click to expand...
If the output transistors were the problem the DBT would be glowing.
Most likely your input transistor pair, I change these on all early Marantz units.
 
ivandezande said:
If the output transistors were the problem the DBT would be glowing.
Most likely your input transistor pair, I change these on all early Marantz units.
Click to expand...

Thanks. Inputs = H751/52 = Zetex ZTX795A right ? Replacement would be 2sa640 or KSA 992 ?
 
I replaced the 2 transistors and now I'm getting 500 mV DC offset (I was getting 46 VDC earlier). I'm unable to adjust the DC offset using R762. Rotating R762 does not affect the DC voltage. It stays at 500 mV. Just fyi I've DeOxy'ed the complete system including R762
 
Sounds like you have one good amp and one bad one. Time to troubleshoot the bad one. I just went through this on a 2270, and I am not much help. It was a lot of trial and error removing and testing parts. Turned out I had installed the wrong transistors in the diff pair. If you have recapped that board or replaced anything, check your work first - proper components, polarities, solder joints, etc. if all is good there, you might have to start testing transistors starting with the outputs and work back. I think the blue wire is the left amp, but check just to be sure.
 
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