Mojotone electrolytics in a Musicman RD-50

[BobW]

I changed out the stock electrolytics, 60uF/350V (2 each), and a 2uF/350V, to Mojotone caps at 100uF/350V, and 20uf/350V. The original caps are not noisy, and the B+, Screen and pre plates are higher than with the Mojos. I would have anticipated better performance with 100ufs. The size of the mojos are at least 2/3's the size of the original Mallorys. the mojo also provie no other data than the capacitance and voltage ratings. I plan to buy quality caps this time, probablt the Sprague Atoms, or the TVAs.

Has anyone else had this problem with the Mojos? the are considerably smaller and suspect they may not have the same ESR and ripple current ratings compared to the Spragues, Mallorys or other quality caps.

[BobW]

I forgot to mention,

1. I usually buy only Sprague or Nichicon Filter caps.

2. I had the same issue swapping out old electrolytics for mojo electrolytics, (same uF and V ratings), in a Twin Reverb.

[Leo_Gnardo]

Knock yourself out spending on those big Spray-goos if you like, but have a look at this old thread before spending your grocery money:

http://ampgarage.com/forum/viewtopic.ph ... sc&start=0

Yes even the mighty Sprague, now Vishay, has taken to stuffing those big blue cylinders with - stuffing - oh - and a mini capacitor. And they'll take your money for that. Didn't just start this year either, it's been going on for a while.

FWIW I get excellent caps from Ruby/Magic Parts. I'm sure there are other sources for reliable well built caps. Don't be surprised if they ARE physically smaller than the old cans. Good caps have shrunk too, as well as those cynically stuffed into big cans and marketed to the guitar amp crowd at nosebleed prices by Vishay/Sprague, and yet others that are made from who knows what, who knows where.

[NickC]

I also like Nichicon caps, but have had good results with F&T and Ruby caps as well. I like the smaller size of modern caps. Easier to cram into congested spaces.

[ToneMerc]

The size of the mojos are at least 2/3's the size of the original Mallorys. the mojo also provie no other data than the capacitance and voltage ratings............ the are considerably smaller and suspect they may not have the same ESR and ripple current ratings compared to the Spragues, Mallorys or other quality caps.

As far as HV axial caps, I tend not to drift far from F&T and Mallory/Vishay caps. Also, I believe the TAD brand is rebranded F&T's.

The Mojo caps are the Richey brand.

See the MDI series

http://www.richey.com.tw/products.php

TM

[Firestorm]

Almost everyone is using etched plates, which can be smaller. Physical size of the package is for esthetics. How big a voltage difference did you measure? And how much was DC versus ripple?

[Randall]

I'll chime in if only to say I like F&T caps. If it's gonna be an off shore manufacturer, I think German engineering isn't a bad place to be.

[JazzGuitarGimp]

I'll chime in if only to say I like F&T caps. If it's gonna be an off shore manufacturer, I think German engineering isn't a bad place to be.

I whole heartedly agree. I like F&T's as well, and for the same reason.

[David Root]

I've been using Nichicon from Mouser, F&T from Parts Connexion, and MIEC from justradios.com, a lesser known Canadian supplier. Had no problems with any of them. Also a Richey Gold 40+40uF can cap in my #102.

Just radios also has 600V axial electrolytics up to 100uF, also MIEC, at very reasonable prices. Very handy for space saving plate caps!

[ToneMerc]

I also like the RIFA PEG124 series, I used to special order them from Allied.

TM

[BobW]

How big a voltage difference did you measure? And how much was DC versus ripple?

Firestorm,

I measured approx. an additional 10 volts of ripple higher w/ the mojotones compared to the original Mallorys at the B+, under approximately a 75% output load (~17 Vrms, w/8 Ohm load). The unloaded B+ was approximately the same in both caps. That indicates to me these mojotones (maybe not all mojotones), are either bad or have a low ripple current rating.

I temporarily placed some Nichicon radials in, and the probelm went away. No more mojotones for me, the spraygoos are on order. lol

[BobW]

Thanks for all the replies.

No more mojotones for me. I'll stick with the Vishays and Nichicons.

Anything that works well in the design of military switchmode power supply is good enough for a guitar amp.

As Dogears has said many times, ymmv