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Dead Marantz 2270

hotgas

hotgas

Super Member
Banned
My recently acquired 2270 is a dead meat. No sound from speakers or headphone. Could it be a relay because I don't hear the normal click? Need quick diagnostic recommendations before I decide to send it to my tech. BTW it has all jumpers on.
 
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Check for the DC offset, if good then replace the caps on the relay board.

X
 
The unit turns on and tuner strength is strong. However, there is no sound from both channels and phone.
 
Don...

Wish I could be more specific, but if you don't hear the output relay engaging, then either the protection circuitry has issues that won't let the relay engage, or the circuitry is doing its job, and protecting the speakers from excessive DC.

The trick is to find which is true. :yes:
 
Could be bad Cap's in the relay circuit but my guess is that the output transistors have been gone (at least 1 or pherhaps all?!)

Check those To3's and then tell us what the result is.
 
If the outputs are gone (which about always means shorted), it will eat fuses. If the fuses are good, then it's either offset or protection circuitry problems.
 
EchoWars said:
If the outputs are gone (which about always means shorted), it will eat fuses. If the fuses are good, then it's either offset or protection circuitry problems.
Click to expand...


Thats not allway's the case (eat fuses).
I had one difficult piece of power amplifier (Marantz 250)
Allmost everything was gone and i replaced all of the transistors and a lot of resistors , allso outputs,drivers and pre drivers and it still blew fuses !!

Bad DC-offset can occure when the 10 ohm safety resistors are gone and more offcourse

i had about 7 V offset when my SM 7 was broken and it still turned on !!!

I spent last christmas with a soldering iron :banana:
 
I checked the DC offsets and they look excellent. :scratch2:

Channel A : L: 0.13; R: 0.25
Channel B : L: 0.13 R: 0.24 mv

Does it sound too good to be true? I set the meter at mV and followed exactly what EW said in his DC offset thread. If that is the case then the cap on the relay brd is bad?
 
If the relay is not engaging, and you're measuring at the speaker terminals, you aren't measuring much...(terminals are not connected to anything till the relay engages). :)
 
You might get lucky and fix it that way, and you might not. My money would be on the latter.

Randomly replacing parts until you happen to stumble upon the root cause is a poor method of repair...slow, ineffective, and costly. What is needed is an understanding of the way the circuit works, and then an analysis of why it is behaving in the manner that it is...Is the protection simply doing its job by refusing to engage the relay, or is the protection circuitry itself at fault?

This is not an earthshaking problem and can be solved pretty easily, but a planned approach and troubleshooting method is mandatory. And a manual...
 
hotgas said:
It sounds like I need to replace all the caps (9 or 10 total) :worried:
Click to expand...
Make sure you check the protection relay itself
before going too far. Marantz had trouble with them
to the point they had to put out a service bulletin
concerning it. This applies too units with serial no. 50260 or earlier
If you have to replace the caps you
shouldnt be looking at too awful much parts wise.
 
I've had about 8 2270's come across my bench with relay problems. 1 had shorted output transistors, on had a transistor bad on the relay board. The rest were the caps on the relay board. C807 and R816 form a time constant circuit that delays the relay 5 seconds after power on. I usally at the very least have to replace C806 and C810 to get a good snap in the relay. Small caps are so cheap I usually just replace the rest of the caps on the board while I'm in there with a soldering iron.

You can find a scat at www.dummyload.com.

X
 
Punker X said:
I've had about 8 2270's come across my bench with relay problems. 1 had shorted output transistors, on had a transistor bad on the relay board. The rest were the caps on the relay board. C807 and R816 form a time constant circuit that delays the relay 5 seconds after power on. I usally at the very least have to replace C806 and C810 to get a good snap in the relay. Small caps are so cheap I usually just replace the rest of the caps on the board while I'm in there with a soldering iron.

You can find a scat at www.dummyload.com.

X
Click to expand...


I ussualy work the same way when i'm at it.
Cap's arent expensive and not very reliable after 25/30 years.
Just replace all cap's on the relay board and check the remaining components on the board.

Once you are finished you can allso replace all cap's on the power modules!!

Not to track the fault but to make the power module's reliable again.
(just in case.....)
 
EW's approach is most accurate as well as efficient if I had his knowledge and experience. I always believe in a systematic approach but for an old mechanical guy like me to acquire such electronics knowledge and maybe test equipments is probably a long shot :sigh:

I think I'll try to to the random approach like Punker and Mr Marantz suggested by replacing the C807/C816 and see what's going on. If it still doesn't work I'll replace the C806/810. Then see if the transistors on the relay is bad. Last is to send it to my tech :cry:

I like Punker's aproach as this has a probability of > 70% sucsess. :yes:
 
Here are what I did last night. Clean the pots and then replace the caps one by one. Now the relay brd has all brand-new caps BUT the relay still doesn't click.

Here is the pic. I label the pins as follow:

1 2
3(blue) 4(yellow)
5(gray) 6(orange)
7 8

Voltage between 1 and 2 is 47.2V while between 3 and 4 is 35.6 VDC. There is no voltage betwen 5 and 6. My question is :" is the relay bad or the protection relay circuitry bad?"

My concern is that this is a 24V relay why applying voltage is so high!
 
Last edited:
hotgas said:
Here are what I did last night. Clean the pots and then replace the caps one by one. Now the relay brd has all brand-new caps BUT the relay still doesn't click.

My concern is that this is a 24V relay why applying voltage is so high!
Click to expand...

This could be a case of the circuit needing to have
a load before it shows the proper voltage. The first
thing to do would be desolder one of the terminals
for the coil. They are small but you should be able
to trace the wires from the coil to the corresponding
terminals. Then check to see if you have continuity
across the coil. If you don't the coil is open and the relay
needs to be replaced.
Also check transistors 805 ,806 and 807. Check resistor R815
its a 560 ohm 1w. “if its shorted it will cause the voltage to shoot
up” Then check Dual diode H811 its in series with R815.
Also check diode H812 its conected parallel with the relay coil.

Hope this helps
 
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