Adjusting B+ on Nanao MS9-29

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sergiopolog
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Adjusting B+ on Nanao MS9-29

Post by sergiopolog » May 8th, 2019, 9:20 pm

Hi forum!

I just recapped my Nanao MS9-29T from Egret 2 cabinet (it still had the factory capacitors marked from 1997 :-o ) and I think it was a good opportunity to check the B+ voltaje, so I attached a small wire to TP2 when recapping it in order to read B+ easily when it will be mounted into cab.

I check voltaje between that wire and ground from tube and it reads about 74,5Vc. Checking Nanao manual it says that is should be 76Vc +/- 0,2 so I'm wondering if I need to adjust it properly to that value or let it be as is now.

I also read about how to read it. Someones uses voltaje between C515 pins and others between Highvalue white resistor next to TP2 and ground.


PD: I checked another spare MS9 chassis I have and it reads 79VC :eh: Should I tweek it? I'm afraid of frying something....

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Re: Adjusting B+ on Nanao MS9-29

Post by grantspain » May 8th, 2019, 9:21 pm

74-76 is perfect
adjust the other chassis,79 is just a little too high

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Re: Adjusting B+ on Nanao MS9-29

Post by sergiopolog » May 8th, 2019, 9:25 pm

grantspain wrote:
May 8th, 2019, 9:21 MP
74-76 is perfect
adjust the other chassis,79 is just a little too high
Thanks grantspain for your quick reply!

Then I'll tweek my spare chassis but, am I doing it well? should I use the other methods to read B+?

Thanks in advance.

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Re: Adjusting B+ on Nanao MS9-29

Post by grantspain » May 8th, 2019, 9:27 pm

sounds ok to me, i normally go on the 100uf 250v cap in the psu but of course i am bench testing so its easy to access the solder side

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Re: Adjusting B+ on Nanao MS9-29

Post by sergiopolog » May 8th, 2019, 9:38 pm

Nice! thank you

Talking about B+, sometimes I read that it should be needed to be tweeked when using MS9 chassis with an MS8 yoke, but what's the truth behind those affirmations? I also read people that swapped MS8 and MS9 chassis successfully without touching B+ at all.

Thanks!

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Re: Adjusting B+ on Nanao MS9-29

Post by grantspain » May 8th, 2019, 10:43 pm

don't touch b+ when swapping between ms8-29 and ms9-29 tubes, its not required as the ms9 has so many adjustments it can handle the slight difference in the yoke

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