Need a help

[MarkBolton]

I have a 1970s fender reverb tank and I was going to replace the electrolytic caps and would like some advice.

There are two large black and yellow mallory capacitors that i believe are electrolytic. 400uf 35v. I can't find an exact replacement but could i use one that is 40v or even 75v?

The other smaller one is a 25uf 50/60v

I see options for vishay/sprague for these - is that a good brand to use?

Thanks!

[Jon Snell]

Vishay are fine and reputable.
400uF is not a common value, 470uF 35volts is a prefered value.
The values follow the E6 range; 1, 1.5, 2.2, 3.3, 4.7, 6.8 and multiples thereof.
Other values are available; 25uF as an example.

In the UK a good source is RS Components. US would be Mouser etc.

[Chuck H]

FWIW the "reverb tank" would refer to the actual metal tank or "pan" with the springs in it. I think we're talking about a stand alone reverb unit?

Given the choice you should go with the higher voltage rating. Especially considering that wall voltages today are likely higher than when the unit was made.

Electrolytic caps have a plus (positive) end and a minus (negative) end. Be sure to observe correct polarity.

[vintagekiki]

#1

I have a 1970s ...

Be a little precise.
Some pdf?

[Helmholtz]

I'm wondering where a Fender tube reverb unit would use 400µ/35V caps. Do they look original?

Is this the schematic for your unit? (If you can't read schematics, go by number and type of tubes.)
http://ampwares.com/wp-content/uploa...everb-Unit.pdf


Are you sure you're not mixing up capacitance and voltage rating, meaning the caps are actually 35µ/400V?
Maybe a picture?

[nevetslab]

Or, perhaps the earlier Reverb Unit 6G15:

reverb_6g15_schem.pdf

[Helmholtz]

Or, perhaps the earlier Reverb Unit 6G15:

[ATTACH]n936563[/ATTACH]

That's what I looked at first, but 2 big 400µ/35V caps wouldn't make more sense in here either.
And the OP said the unit is from the 70s.

Need pictures of unit and caps.

[eschertron]

Could the OP's caps actually be 400uF/35v and had been put there by a dyslexic previous owner? Photos, please.

[nevetslab]

Of course I just reached in and pulled that older document in and loaded it before reading all of the posts, seeing that too didn't make any sense. Yup....photos needed. There were larger values used in the Vibro-King amp...my service manual for that has three versions in the schematics, though none with the values stated.

[Chuck H]

I'm thinking it's a solid state reverb.

[Helmholtz]

Like this? https://schematicheaven.net/fenderam...erb_fr1000.pdf

In fact has 2 x 400µ caps.

[g1]

OP never responded to the other post he started either.

[J M Fahey]

That!!
When I read "400uF" together with "35V" I instantly thought "70´s electronics".
Way back then electrolytic technology was *crude*, to say it politely, and thet jammed "as much as they could" inside a certain case size, whatever the final capacitance results.

Tons of today weird values such as 35uF, 2900uF, etc. , just check late 60s early 70s Kustom, Peavey, Ampeg SS circuits or similar era Teisco, etc.

And 400uF is ludicrously low, I would use *at least* 1000uF ones, if not 2200uF ; modern caps are MUCH more compact and will easily fit there.
Think OLD Fender amps with ludicrously low caps such as 8uF ,same thing back in then40´s.

This SS Reverb is same era as the "infamous" SS Fender such as "SS Showman" or those New Age names such as Zodiac or Libra, today (justly) forgotten.

VOX did something similar with the SS AC30 but at least those sound good, although quite different to the Tube version.
Excellent *clean* sound.