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Marantz 2220B Not starting up

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pieterv1

New Member
Hi AK friends! Hope you're well. This is my first post here.
A friend brought in his Marantz 2220B which isn't switching to "active" mode anymore. I immediately suspected a bad speaker relay, but first checked voltages here & there + followed the adjustment procedures.

Voltage of the PSU board is correct at 35V. Voltages coming in at the power amp board are 31V (J725) & -31V (J721)

At step 12 (power amplifier) is where things get odd. I was able to check the bias which was more or less alright between both sides. (it took me a while to find out the test points in the service manual were incorrectly named)
The 0mV DC test points however were exactly 0v & the trimmers didn't seem to have any effect.. Is this a direct indication of a faulty relay? Mine has the hazy, translucent version.
 
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There are errors in the service manual for the 2220B. Clicky here for the Marantz Service Manual error thread. This one befuddled me too my first time around.

2220B Idle current adjust:
SM says measure J712 - 718 for one channel, 713 to 719 for the other. WRONG! Do this instead: Measure bias at J714 to 716 and adjust R733 for 20mVDC on that channel. Then measure J715 to 717 and adjust R734 for 20mV on the other channel.
 
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pieterv1 said:
Hi AK friends! Hope you're well. This is my first post here.
A friend brought in his Marantz 2220B which isn't switching to "active" mode anymore. I immediately suspected a bad speaker relay, but first checked voltages here & there + followed the adjustment procedures.

Voltage of the PSU board is correct at 35V. Voltages coming in at the power amp board are 31V (J725) & -31V (J721)

At step 12 (power amplifier) is where things get odd. I was able to check the bias which was more or less alright between both sides. (it took me a while to find out the test points in the service manual were incorrectly named)
The 0mV DC test points however were exactly 0v & the trimmers didn't seem to have any effect.. Is this a direct indication of a faulty relay? Mine has the hazy, translucent version.
Click to expand...
If it's not coming out of protection, it has nothing to do with the relay. These relays don't fail. Something is wrong in the amp section.
 
If it's not coming out of protection you can't measure the offset voltage at the speaker terminals, you have to do it before the relay. A good place is on the driver board where the 2 white ceramic emitter resistors connect together, or at the air core coil. Tape the tip of your meter probe so only the very tip is exposed to help prevent shorting things when you slip.
 
BeerLegs said:
There are errors in the service manual for the 2220B. Clicky here for the Marantz Service Manual error thread. This one befuddled me too my first time around.
...
Click to expand...

Thank you, yes, I already stumbled upon this :) so bias is already at 20mV

dr*audio said:
If it's not coming out of protection you can't measure the offset voltage at the speaker terminals, you have to do it before the relay...
Click to expand...

Thanks! Exactly what I wanted to try. Will give it a go tonight. And if the DC balance is way off, could that be causing the relay not to switch? Or does it work with a very basic timer circuit instead of voltage detection?
 
pieterv1 said:
Thank you, yes, I already stumbled upon this :) so bias is already at 20mV



Thanks! Exactly what I wanted to try. Will give it a go tonight. And if the DC balance is way off, could that be causing the relay not to switch? Or does it work with a very basic timer circuit instead of voltage detection?
Click to expand...
Yes, the protection circuit has a timer but also senses DC voltage on the output.
 
Oops, actually that was very obvious... & probably where it got its name from in the first place :rflmao:

I'll try to probe the DC offset first, somewhere before the relay. If I can get it right around 0mV, should I suspect a faulty relay?

It's not that it only has dirty contacts.. There's no click at all
 
Happy to say that after a full re-cap of power board, amp, eq and RIAA eq + installing the NOS Omron LC2-N relay, the amp is singing happily again!
 
That 2220B relay with the translucent cover is a common fault.

I have found that an LC2 "N" relay they used on some Luxman's will work if you can find one, and try to keep one here.
 
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