Marantz 2230B Power amp adjustment

audiojung

Active Member
I'm trying to adjust power amp but my voltage is way high. J718-J712 needs to be 20mV but it can't go lower than 600mV. When R733 is in middle, it is 1.2V. It is same in both channels.
 
Last edited:
The number makes sense in the thread. I adjusted and I'm just copying it here too.

Connect J714(+) and J716(-) and adjust R733 for 20mV.
Connect J723(+) and J722(-) and adjust R711 for 0mV.
Repeat.
Connect J715(+) and J717(-) and adjust R734 for 20mV.
Connect J724(+) and J722(-) and adjust R712 for 0mV.
Repeat.
 
Since I got this receiver, the sound is improved without too much work. It was very noisy and dull like not well tuned radio although I'm listening mp3. After cleaning volume and balance controls, it makes much clean and sharp sound. It still makes a little noise sometimes but not that often. Probably I need to clean balance control again. It was really sticky before cleaning. I'm happy with this when the sound is very sharp. 95% there.
 
I listened each channel and R channel is a little noisy. Instead of using balance switch, I connected one channel at a time but R channel is noisy and volume is a little lower.
 
Last edited:
One place I missed was a selector. After cleaning the selector, it sounds better. The cause of noisy sound was all contact issue. I see why DeoxIT is so loved. I'm not sure whether I need to lube the selector since I cleaned it. Now it sounds good !
 
I measured two capacitors in each amp. They are 3.3/25V and 47/16V in schematic.
C701/C705 - 4.7(7.8ohm)/46(0.97ohm)
C702/C706 - 4.7(8.3ohm)/46(1.1ohm)

Both C701 and C702 are out of its range and ESR is too high. I checked this while the capacitors are on board so I'm not sure whether its correct. Both C705 and C706 are close to max ESR. I don't know why only one channel sounds bad.
 
After taking out C702 from the board, I measured again but it is 3.26uF and 5.7~7.5ohm. This doesn't seem bad. The brand of this capacitor is ELNA and it is different with other capacitors. I wonder if the previous owner replaced these and it did not fix this.
 
I miss read the model, my post was directed at the 2230, not the 2230B.
Sorry for the confusion!

Tom
 
That's fine. The rule still stay same. I did not know that I should tune it when there is no output. I tuned it while paying. As soon as I put new capacitors, I will play with bias. Thanks for the instructions.
 
Fixed the clipping issue and weak channel. It was the capacitor issue. It was 5~6 ESR but new one ( nichicon gold ) is 2 ESR. I replaced both C701 and C702. Sound is very sharp. I like it.

System1 does not work for some reason. when system1 is on, aux input comes out whatever I do. Even volume control does not do anything. System1 button is sticky so I guess it shorts the input to ground.
 
Strange sound output was caused by 3.5mm jack to RCA cable. After switching to bluetooth, it is clean. There must be a light short in the cable. Everything works fine now. The sticky button is fine after deoxing. Everything is fine now so I can polish.
 
For some reasons, I can't adjust bias on one channel. Others are fine but I can't produce 20mV. Although I adjust R733, the voltage changes between 2mV ~ -2mV only.
* Connect J714(+) and J716(-) and adjust R733 for 20mV.
 
Back
Top Bottom