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 Forum index » DIY Hardware and Software » The Repair Shop
Repairing an SPX90 Reverb
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Snuffles



Joined: Dec 06, 2017
Posts: 8
Location: usa

PostPosted: Fri Aug 03, 2018 8:11 am    Post subject: Repairing an SPX90 Reverb Reply with quote  Mark this post and the followings unread

I am repairing a fried PSU on this Yamaha reverb and had a question about 1 capacitor. I have all the other parts to replace, but this 150uF 200V cap. I'd like to swap it out, but I do not have one on hand. I have pretty much all values around 150, but 150. Is there a rule of thumb for changing capacitance?

I read a repair blog where someone replaced the caps on this exact PSU. He used a 68uF 400V in that place. I have this value! It seems that this value is common as I confirmed it with other forum posts with people fixing the same PSU. I think this might be a value Yamaha changed to or from during manufacturing.
http://madtheory.com/site/repairing-a-yamaha-spx90ii/

Here is the service manual;
https://www.google.co.uk/url?sa=t&rc...,d.d2s&cad=rja

Any help or insight is appreciated.
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Snuffles



Joined: Dec 06, 2017
Posts: 8
Location: usa

PostPosted: Fri Aug 03, 2018 9:48 am    Post subject: Reply with quote  Mark this post and the followings unread

It seems this unit shipped with two different PSUs. One for w. Germany/ General and the other for US/CAN/Jap. This is why others use the 68uF cap. Bummer. I guess I'll throw it in my monthly mouser cart and shelve this for a few weeks from now.
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PHOBoS



Joined: Jan 14, 2010
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PostPosted: Fri Aug 03, 2018 1:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Getting the same value seems like a good choice to me. Judging by the schematic the value isn't too critical but I wouldn't go much
lower than the orginal one as this increases the ripple voltage which might cause some unwanted noise/hum. More importantly
make sure it is rated at the same or a higher voltage.

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