# Valco National



## Fuzzy dagger (Jun 3, 2016)

Bit of a flier here, a buddy gifted me this amp and it won’t light up.





































The model number is 1220, and research says it’s also a ‘59 Dwight, a Supro 6400 and a Valco 51. I’m assuming the speaker isn’t stock and it’s had a 3 prong added. The jewel lense is missing and it came with an owners manual this is really cool.
When I plug it in; nothing. The fuse is intact and the tubes are well seated and don’t light up.
I have a good amp guy but I want to see if I can fix it myself. I’m well aware the there may be voltage in the caps and not to poke around, but are there simple things that I can check or tutorials that can help? What is the typical ohm rating on this speaker ( mine has a transformer, I assume to step it down?!?). Any help/suggestions are appreciated.


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## Always12AM (Sep 2, 2018)

I’m not an expert, but my only advice is to not fry those tubes. If they are all original RCA’s it would be a same shame to lose them over a minor mistake.

Don’t touch the brown circle inside of the amp unless you want to lose a nipple.

I’d start my re soldering the black and the white leads coming from the power chord. Do not disconnect the green wire that is also coming from that chord unless you want to lose another nipple and be a nipple-less guy with a broken amp.

Replace the rectifier tube?

This is a very cool amp well worth taking to a tech as well.


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## Latole (Aug 11, 2020)

Can you ear a little hum or noise at maximum volume ?
Noise ; some voltage are there. check tubes first
No noise ; no voltage from the power supply. Fis power supply issue

There are lethal voltage on tubes amp. If you don't know electronic, see a good amp tech




How much ohms ; read resistance on the speaker, disconnect transformer wires besfore


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## Latole (Aug 11, 2020)

This might be the schematic


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## Alan Small (Dec 30, 2019)

A fuse can look fine and still be blown...meter to test or just swap it out.
Amp certainly needs a regular service which includes clean pins and sockets, clean and tighten pots to assure good grounding


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## fernieite (Oct 30, 2006)

That looks like the original speaker. 550-3 valco code is on the magnet.👍


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## Latole (Aug 11, 2020)

Alan Small said:


> A fuse can look fine and still be blown...meter to test or just swap it out.
> Amp certainly needs a regular service which includes clean pins and sockets, clean and tighten pots to assure good grounding



100% right

Check fuse caefully and check if it is the right one. A too powerfull fuse may destroy power transformer


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## Fuzzy dagger (Jun 3, 2016)

Thanks, good start!


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## Paul Running (Apr 12, 2020)

Latole said:


> This might be the schematic
> 
> View attachment 389356


The output tubes are not 6V6s, as shown in this schematic.


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## Paul Running (Apr 12, 2020)

Always12AM said:


> I’m not an expert, but my only advice is to not fry those tubes. If they are all original RCA’s it would be a same shame to lose them over a minor mistake.


I agree, if those are original 6973s...it would be a shame.


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## Paul Running (Apr 12, 2020)

Fuzzy dagger said:


> The fuse is intact


Check it with your ohm meter...it may look intact however, the continuity check will verify it's condition.


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## Paul Running (Apr 12, 2020)

Is there a power transformer on that model?
Edit: I should say where is the power transformer?


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## Sneaky (Feb 14, 2006)

fernieite said:


> That looks like the original speaker. 550-3 valco code is on the magnet.👍


Yup. Old field coil speaker.


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## Latole (Aug 11, 2020)

Paul Running said:


> The output tubes are not 6V6s, as shown in this schematic.



You are right, for a amp tech or anybody who know amps ,it doesn't make any difference


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## Sneaky (Feb 14, 2006)

Paul Running said:


> Is there a power transformer on that model?
> Edit: I should say where is the power transformer?


I don’t think these had power transformers. They didn’t call them widowmakers for nothing.


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## Latole (Aug 11, 2020)

Sneaky said:


> I don’t think these had power transformers. They didn’t call them widowmakers for nothing.



Give link where you saw that ,

Where on the amp can we see it is model 1220 ?

1220 with Google; not same amp as OP show


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## Paul Running (Apr 12, 2020)

Sneaky said:


> Yup. Old field coil speaker.


There is no field-coil on that speaker.


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## Paul Running (Apr 12, 2020)

Here's a schematic for the Valco 6400 which as you mentioned is the National 1220 equivalent:


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## Sneaky (Feb 14, 2006)

Latole said:


> Give link where you saw that ,
> 
> Where on the amp can we see it is model 1220 ?
> 
> ...


Here is some info on transformerless amps, not specifically the National shown here.






Widowmakers


Widowmaker Guitar Amplifiers



robrobinette.com


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## Sneaky (Feb 14, 2006)

Paul Running said:


> There is no field-coil on that speaker.


Hmm, maybe you are right. I have a 40’s Bronson amp that is identical to the 1220 posted above. It does have a field coil speaker.


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## Paul Running (Apr 12, 2020)

Latole said:


> Where on the amp can we see it is model 1220 ?


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## Paul Running (Apr 12, 2020)

Anyway, nice little amp you have there. Those 6973s will last a long time in that circuit...they are not pushed hard; similar to the 7189A, the 6973 is capable of 24W with a pair in push-pull configuration.


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## Paul Running (Apr 12, 2020)

Sneaky said:


> I have a 40’s Bronson amp


6V6?


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## Johnny6String (Aug 27, 2018)

Paul Running said:


> There is no field-coil on that speaker.


Hi Paul;
I’m a total Amp newb here (I mean I play them but don’t know a whole lot about the insides. But what is that attached to the basket of the speaker of it’s not a field coil?

Just trying to learn.

Thanks


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## Paul Running (Apr 12, 2020)

Johnny6String said:


> what is that attached to the basket of the speaker


That is called an audio output transformer...it matches the impedance from the output of the tubes to the speaker. For maximum power transfer the impedance of the source (the output tubes), should match the impedance of the load, the speaker so, a high-voltage/low current device is driving a low-voltage/high current load.


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## nonreverb (Sep 19, 2006)

It has to have a power transformer!! It has 6973's. Without a power transformer, you could not supply the filaments. If you look carefully at the pic of the chassis, you can just see the power transformer.


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## nonreverb (Sep 19, 2006)

Check:
1.AC cable continuity
2.fuse continuity
3.power switch.
4.wiring to the power transformer

Since you're getting nothing, there's always the possibility that the transformer itself is toast. First you must ascertain that you have full 120VAC voltage to the transformer primary wires before the next move.


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## RBlakeney (Mar 12, 2017)

nonreverb said:


> It has to have a power transformer!! It has 6973's. Without a power transformer, you could not supply the filaments. If you look carefully at the pic of the chassis, you can just see the power transformer.


the heavier blue/green wires by the rec tube?


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## nonreverb (Sep 19, 2006)

RBlakeney said:


> the heavier blue/green wires by the rec tube?


Yup....you don't even have to look at the wiring though, just the tubes themselves will tell you everything you need to know.


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## nonreverb (Sep 19, 2006)

Another quick info point. 6973 is NOT compatible with 7189/EL84. The pinout is different....looks identical but is not.


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## Sneaky (Feb 14, 2006)

Paul Running said:


> 6V6?


Yes.


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## Latole (Aug 11, 2020)

Sneaky said:


> Here is some info on transformerless amps, not specifically the National shown here.
> 
> 
> 
> ...


I know about transformerless amps, widows makers. I mod some.
I just say there are no proof the amp wich is the subject here is one as you say


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## Sneaky (Feb 14, 2006)

Latole said:


> I know about transformerless amps, widows makers. I mod some.
> I just say there are no proof the amp wich is the subject here is one as you say


I stand corrected as noted by non reverb. I still don’t see it.


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## RBlakeney (Mar 12, 2017)

Sneaky said:


> I stand corrected as noted by non reverb. I still don’t see it.


I didn’t see the PT either, I just saw those wires, between the light, rectifier fuse area and they resembled wires from a PT from my extremely limited experience.


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## nonreverb (Sep 19, 2006)

RBlakeney said:


> I didn’t see the PT either, I just saw those wires, between the light, rectifier fuse area and they resembled wires from a PT from my extremely limited experience.


Blow up the pic a bit and look just behind the 5Y3 rectifier. You can see it just over the edge of the chassis.


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## RBlakeney (Mar 12, 2017)

nonreverb said:


> Blow up the pic a bit and look just behind the 5Y3 rectifier. You can see it just over the edge of the chassis.


Can we change your name to eagleeye?


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## nonreverb (Sep 19, 2006)

RBlakeney said:


> Can we change your name to eagleeye?


...or perhaps too much unjustifiable free time on my hands?


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## Fuzzy dagger (Jun 3, 2016)

I will get my multi meter from my shop and test those things.


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## Johnny6String (Aug 27, 2018)

Paul Running said:


> That is called an audio output transformer...it matches the impedance from the output of the tubes to the speaker. For maximum power transfer the impedance of the source (the output tubes), should match the impedance of the load, the speaker so, a high-voltage/low current device is driving a low-voltage/high current load.


Thanks for taking the time to reply Paul. 

Would that be variable or would it still need to be matched to the particular application of tubes and speaker combination?


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## Paul Running (Apr 12, 2020)

Some audio output transformers have multiple secondary taps. This effectively varies the impedance ratio, depending on what tap you connect the load, in this case a speaker. The speaker impedance will vary dynamically, if you view a response graph for a speaker, you will see the variance in impedance vs frequency of the signal.
The operation of a transformer mainly functions through the principal of reflected energy...that's why you should always load the secondary of the transformer...infinite impedance cannot be reflected back to the primary...8Ω can be reflected back. The output tubes will last much much longer when loaded.
It can become quite complicated, if you wish to get into the nitty-gritty.
There are several accurate articles on the subject of reflected energy on the net.


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## WCGill (Mar 27, 2009)

Valco 6400. The schematic I have has the 550-3 speaker code, does have a PT. I also have hand written voltage notes on the page, not sure if I worked on it or just snooped around. The only 6973 tubes I ever ordered and replaced were in a jukebox.


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## nonreverb (Sep 19, 2006)

WCGill said:


> Valco 6400. The schematic I have has the 550-3 speaker code, does have a PT. I also have hand written voltage notes on the page, not sure if I worked on it or just snooped around. The only 6973 tubes I ever ordered and replaced were in a jukebox.


They were also used extensively in various Leslie speaker products. I have a pile of pulls that I've collected over the years.


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## Paul Running (Apr 12, 2020)

WCGill said:


> The only 6973 tubes I ever ordered and replaced were in a jukebox.


A favourite for the jukeboxes...it was initially designed for high-fidelity applications.


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## Fuzzy dagger (Jun 3, 2016)

It turns out it was just a broken solder from the power cord. I soldered it up and it’s working!


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