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Marantz 2230 Voltage Adjustment

A

allan1832

Active Member
Hi all,

I just finished recapping my 2230 and making what adjustments I could. The idle current adjustment went fine, but I have an issue with the voltage adjustment. According to the service manual, I'm supposed to measure voltage at J08 (essentially the speaker terminals as far as I can tell) and adjust trimmer R810 to a reading of 35.6 volts. My reading was between 15 and 16 volts no matter how I adjusted the trimmer. The trimmer was the original, and didn't have that really touchy action that trimmers tend to have. So, I replaced the old trimmer with a new Bourns multi-turn trimmer in hopes of an easy fix (4.7K, Mouser part # 652-3339P-1-472LF, http://www.mouser.com/Search/Produc...virtualkey65210000virtualkey652-3339P-1-472LF). But no such luck. Again, no matter how I adjust the trimmer the voltage is no higher than 16 volts.

Where do I need to start testing things to find my problem?

I started working on vintage receivers in part to learn some electronics skills. I've recapped several receivers so far and have developed pretty decent soldering skills, and I'm getting better at reading schematics. So, I guess this is a good next step in the learning process. I've got another receiver with some more complex problems, so this should be a good step before I tackle the harder one. Any help would be greatly appreciated.

Allan
 
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Adjust R810 for +35VDC on J808. If you don't have a scope, set R760 for ≈+30VDC on J758 on both power amps. The 2230 has capacitively coupled outputs, so you will read a phantom voltage on the speaker terminals with no speakers attached.

Tom
 
catrafter said:
Adjust R810 for +35VDC on J808. If you don't have a scope, set R760 for ≈+30VDC on J758 on both power amps. The 2230 has capacitively coupled outputs, so you will read a phantom voltage on the speaker terminals with no speakers attached.

Tom
Click to expand...

Now that makes more sense! I knew about it being capacitively coupled. I researched that after the first time I measured at the terminals to check idle current and freaked out. However, I did think it strange to have the terminals be the measuring point, but didn't think about it being a misprint. I'll give this a try this evening and report back.

Allan
 
Tom,

Boy, adjustments go great when you're measuring at the right place. Everything worked fine, and being able to do the clipping adjustment without having an oscilloscope was a real plus.

On another note, the Bourns variable resistor was a real job compared to the old one-turn type. I think I'll start regularly replacing the trimmers.

Thanks guys.

Allan
 
catrafter said:
Adjust R810 for +35VDC on J808. If you don't have a scope, set R760 for ≈+30VDC on J758 on both power amps. The 2230 has capacitively coupled outputs, so you will read a phantom voltage on the speaker terminals with no speakers attached.

Tom
Click to expand...


Tom

Is there an easier way or another spot to measure r-774 to set idle current?

Just kind of awkward to get to.

Thanks.
 
Detailman said:
Tom

Is there an easier way or another spot to measure r-774 to set idle current?

Just kind of awkward to get to.

Thanks.
Click to expand...

Turn the receiver on it's side. Connect your meter, set to measure DC milli-Volts to J757 and J759 (3rd ones in from each end), volume all the way down. Adjust R765 for 10mV. The voltage is twice what the service manual says because we are measuring across both resistors instead of just one.

Tom
 
catrafter said:
Turn the receiver on it's side. Connect your meter, set to measure DC milli-Volts to J757 and J759 (3rd ones in from each end), volume all the way down. Adjust R765 for 10mV. The voltage is twice what the service manual says because we are measuring across both resistors instead of just one.

Tom
Click to expand...

Thank you for you're valuable help Tom

Appreciate you sharing:yes::yes:
:D:D
 
Sorry to revive an old thread, but I wanted some clarification on this one...

catrafter said:
If you don't have a scope, set R760 for ≈+30VDC on J758 on both power amps. The 2230 has capacitively coupled outputs, so you will read a phantom voltage on the speaker terminals with no speakers attached.

Tom
Click to expand...

Do you mean this measurement is to be made between J758 and ground?

I've already set voltage at J808, and set the idle current across R774 as well as R774 and R775, and was getting ready to set the clipping according to this advice, however I wanted to clarify before starting...
 
Tom or anyone:

RE: 2230 audio adjustments...

Clipping level adjustment

"If you don't have a scope, set R760 for ≈+30VDC on J758 on both power amps..."
Click to expand...

Q1: when I do this J758 setting, should the volume control be at min?

Q2: the manual says to apply a 1KHz audio signal, gradually increase it, etc., etc... does this alternate method negate the need for all of that?

Phono-amplifier adjustment

Q3: is it possible to also do this one without a scope somehow? (it also talks about applying a 1KHz audio signal etc.)
 
THANK YOU Tom -- fantastic info!!!

this will come in very handy once I finish my 2230 restoration... it's going to be great... fully recapped including Nichicon HEs (PSU), Pana FCs (general), Elna Silmic IIs (preamp + amps), Nichicon KG (cans), full LEDs, a few transistors, cleanup and resoldering anywhere it looks questionable
 
speaking of readings...

I've taken some "before" readings, and noticed that the Idle Current readings were quite low across J757-J759... I'm wondering as to what would cause this? (should be 10 VDC)

L = 5.9 VDC
R = 3.0 VDC

I expect that my full recap and subsequent adjustments will bring this into line, but I'm just curious in case there is something I should be looking out for while I've got her opened up for surgery

thx!
 
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