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REPLACING CAPACITORS ON MARANTZ 140 POWER AMP

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Bogdan1986

New Member
Hello guys, i would really appreciate any advice regarding my attempt to replace the big capacitor on Marantz 140 with 2 x 10 000uF/63V instead 13 000uF that comes from the factory.Since that dual 13 000uf isn't available i have 2 new audiograde caps Matushita 10 000uF gold audiograde.Will the amp sound good since will have 3000uF lower capacitance?
Regards Raul.
 
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Yes, several of us have wired the two new caps wrong. Not taking the time to look at the side of the old can.:confused: I got it right the first time on my second 140. :thumbsup: very fun amps to work on. Everything is modular. Some screws and most everything unplugs.
 
elnaldo said:
I think you'll be fine with 10000uF. They are 20% tolerance. and you can always add a 3300 uF in parallel.

But, MAKE sure about the right way to connect them. I've seen recently a "dual" cap that was wired as 2 caps in series inside one can. (http://i.ebayimg.com/images/g/buYAAOxyXp5SSzUJ/s-l400.jpg )

If you are in doubt, post a pict here.
Click to expand...
Thankyou very much for your reply sir.What i have are 2 normal caps, and im planning to wire the caps this way : http://audiokarma.org/forums/index.php?threads/marantz-3200-140-restore-and-recap.678255/ just scroll a bit down please. What do you think about that ? One more thing sir: i would like to adjsut the dc offset but im not sure which resistor i have to adjust in order to do that.I have the manual but honestly i don't understand the way it says in the manual. Do you have any idea how can i adjsut the dc offset?
Greetings Raul
 
Lavane said:
Yes, several of us have wired the two new caps wrong. Not taking the time to look at the side of the old can.:confused: I got it right the first time on my second 140. :thumbsup: very fun amps to work on. Everything is modular. Some screws and most everything unplugs.
Click to expand...
Could you please post a picture of how you've done it? What about the dc offset, which resistor do i have to adjust on each channel?
Thank you for your support.
 
Bogdan1986 said:
Thankyou very much for your reply sir.What i have are 2 normal caps, and im planning to wire the caps this way : http://audiokarma.org/forums/index.php?threads/marantz-3200-140-restore-and-recap.678255/ just scroll a bit down please. What do you think about that ? One more thing sir: i would like to adjsut the dc offset but im not sure which resistor i have to adjust in order to do that.I have the manual but honestly i don't understand the way it says in the manual. Do you have any idea how can i adjsut the dc offset?
Greetings Raul
Click to expand...

This is the way to connect a split power supply. I say this because some people could think that the negative end should be always connected to ground, but you see it's not like that, negative end must be connected to the lower voltage. In this case, -50V is lower than 0V. Anyway, I think that somebody who ignores this shouldn't be poking inside an amplifier.

MAKE SURE THE CAPACITORS ARE DISCHARGED BEFORE TOUCHING THEM, JUST MEASURE DC VOLTAGE ACROSS ITS TERMINALS. IF YOU HAVE SOME VOLTAGE, CONNECT A RESISTOR (LET'S SAY 100/500 OHM 5 WATT, OR HIGHER OHM, LESS WATTS) UNTIL IT DISCHARGES. DISCHARGE BOTH OF THEM. SOME CIRCUITS INCLUDE A BLEEDING RESISTOR THAT WILL DISCHARGE THE CAPACITOR.

PS.jpg


Can you post the procedure for DC offset adjustement? It's usually to measure DC at the speakers terminals, and adjust a trimpot to set it to Zero.
 
You can download the 140 repair manual from the AK data base or hifiengine.com just register its free.
 
elnaldo said:
This is the way to connect a split power supply. I say this because some people could think that the negative end should be always connected to ground, but you see it's not like that, negative end must be connected to the lower voltage. In this case, -50V is lower than 0V. Anyway, I think that somebody who ignores this shouldn't be poking inside an amplifier.

MAKE SURE THE CAPACITORS ARE DISCHARGED BEFORE TOUCHING THEM, JUST MEASURE DC VOLTAGE ACROSS ITS TERMINALS. IF YOU HAVE SOME VOLTAGE, CONNECT A RESISTOR (LET'S SAY 100/500 OHM 5 WATT, OR HIGHER OHM, LESS WATTS) UNTIL IT DISCHARGES. DISCHARGE BOTH OF THEM. SOME CIRCUITS INCLUDE A BLEEDING RESISTOR THAT WILL DISCHARGE THE CAPACITOR.

PS.jpg


Can you post the procedure for DC offset adjustement? It's usually to measure DC at the speakers terminals, and adjust a trimpot to set it to Zero.
Click to expand...
Thank you very much sir.I will put the caps in the amplifier connect the wires and before powering on, i will post pictures here in order to get confirmation that everything is good connected.Regarding the adjustment dc offset, which particulary trimpot is related for the left channel ,what about the right channel? i know im asking a lot of questions, but this i just don't want to burn anything in this amp.i have the manual for this model,by the way,
Greetings,Raul
 
Hi - Dunno why old amps have 13000uf smoothing caps, the 10000 uf cap will work fine.
Did a costing experiment the other day 3x4700uf in parallel is more expensive than 10000uf and not much better, 3300uf, 4 in parallel are cheaper and gives the same result. In My Honest Opinion over 10000uf and you are nearing the too many uFarads for the price region. Over 10000 uf and you have diminishing returns....... Very few amps will suck a 10000uf cap dry for a transient .....
 
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