Dynaco A-420 output trans

Robert Fries

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Dec 5, 1996, 3:00:00 AM12/5/96

to

A buddy of mine has one of these in an old Fender Bassman. He'll probably
replace it with a Fender part. The transformer appears to be in good
condition, the amp sounds fine.

Anybody have any info on the A-420? Specs, impedance, power rating, stuff
like that? How much would one of these sell for these days?

Thanks,
RF
*****************
Robert Fries
415-988-9475
rfr...@netcom.com
*****************

Michael S. LaFevre

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Dec 5, 1996, 3:00:00 AM12/5/96

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Robert Fries wrote:
>
> Anybody have any info on the A-420? Specs, impedance, power rating, stuff
> like that? How much would one of these sell for these days?
>

The A420 has a primary impedance of 6600 ohms CT and secondary
impedances of 8 & 16 ohms. It is rated at 30 watts max power. The 420
is the same exact size as the more widely known A470 (from St 70 amp)
and has the same mounting footprint.

We just built these (from the orig factory blueprints) about two weeks
ago. We sell these and the A470 Classics in the Japanese market. The
retail price for the A420 is $149 each.

Hope I've been helpful,

Mike

Robert Fries

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Dec 5, 1996, 3:00:00 AM12/5/96

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Michael,

Thanks for the excellent information. Do you perhaps know the color-code
of this transformer's wires? specifically, the secondary leads?

Thanks,
Robert

>Mike

*****************

Michael S. LaFevre

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Dec 5, 1996, 3:00:00 AM12/5/96

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Robert Fries wrote:
>
> Michael,
>
> Thanks for the excellent information. Do you perhaps know the color-code
> of this transformer's wires? specifically, the secondary leads?
>

The secondary has three wires. The yellow is for 16 ohms. The orange
is 8 ohms. and the black is ground.

On the primary there is five wires. Easiest is the red...this is B+.
The solid blue and solid green goes to one tube (tube A) the blue is
plate and green is screen. Then there are two wires left a green/white
striped and a blue/white striped again the blue/white goes to a plate
and it's sibling the green/white goes to the screen.

Mike

Rick Francis

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Dec 6, 1996, 3:00:00 AM12/6/96

to Robert Fries

Robert, I believe that's the output transformer that was used in the
original Dynakit ST-70 amp. To buy a new one now costs about $100 from
Sound Values in Columbus Ohio. Used price seems to go to $50. In any
case, if it's for sale, I have a friend with a perfectly good ST-70
except for one faulty OPT, and I'd get it for him. Let me know.

Rick Francis (we have the same initials...)

Robert Fries wrote:
>
> A buddy of mine has one of these in an old Fender Bassman. He'll probably
> replace it with a Fender part. The transformer appears to be in good
> condition, the amp sounds fine.
>

> Anybody have any info on the A-420? Specs, impedance, power rating, stuff
> like that? How much would one of these sell for these days?
>

> Thanks,
> RF

> *****************
> Robert Fries
> 415-988-9475
> rfr...@netcom.com
> *****************

--
================================================================
RICK FRANCIS rfr...@uoft03.utoledo.edu
http://www.research.uh-west1.utoledo.edu/RFrancis.html
The University of Toledo V:(419) 537-6193 F:(419) 537-7893
================================================================

Michael S. LaFevre

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Dec 6, 1996, 3:00:00 AM12/6/96

to

Rick Francis wrote:
>
> Robert, I believe that's the output transformer that was used in the
> original Dynakit ST-70 amp.
>

The A420 was not the transformer used on the ST70. The ST70 used the
A470...same footprint and overall size as the A420. The A470 has a 4300
ohm primary as opposed to a 6600 ohm primary.

Mike