What is this?

[MKG]

I won this lovely rust bucket and a variety of rusty tubes in an auction for AK.
Now I need to figure out what it’s purpose is, as well as manufacturer and model number, and find a schematic.
There’s only one transformer so with my limited knowledge I’m thinking preamp?
Under the rust I can see “AUX” and underneath that what looks like “AKER”, and given the age I’m assuming it’s not a reference to Audiokarma, so it probably says speaker.
Nudes to come.

 

[MKG]

It’s really hard to make out through the rust, but after a bit of scrubbing it looks like it says “Wurlitzer amplifier model 7020, 115 volts, indecipherable, 160 watts”? To the left next to the fuse it says 2 amp, to the right pointing to two tube sockets it looks like it says 6L6.

 

[MKG]

Guts.
And random tubes that came with it.

 

[mrwood200]

looks like “SPEAKER”
and a mono juke amp?

 

[Lavane]

It does looks like a mono amp

 

[MKG]

Okay. Consensus so far is amp not preamp.
It does have another transformer underneath the chassis, so mono amp makes sense to me. Any leads on a schematic?

 

[century tek]

This is an organ amplifier.

It is not 160 watts speaker output but 160 watts of power draw from the wall. Using two 6L6 output tubes, this probably puts out somewhere between 20-25 watts output.

The transformer underneath is the speaker transformer. This amp might need a little more research as its possible that it uses a field coil speaker. I own a Wurlitzer 7062 and 7030 and the 7062 uses a field coil speaker and the newer 7030 can drive any permanent magnet speaker.

You would be able to tell if it uses a field coil speaker by connecting any regular permanent magnet speaker to the screw terminals with the white letter "G".

If it plays it just uses regular permanent magnet speakers. If there is no sound and no B+ to the tubes then it uses a field coil speaker which also acts as a choke coil in the power supply.

This might be too complicated for you?

 

[larryderouin]

Blew it up and adjusted pic to read out. Model 7020. 115V 60Hz 160W Manufactured by Rudolph Wurlizer Co. Tonowanda, Ny.

 

[MKG]

This might be too complicated for you?

It’s probably fair to make that a statement instead of a question.
That said, I’m a quick learner and quite determined when I put my mind to something, so this will eventually be functional. May not be pretty (I’ve never cared much form and I kinda like the rust).

 

[mrwood200]

I like your commitment! I have a couple of projects I am going to finish too!
Somebody already worked on this amp - you can see the new orange drop caps underneath. It may not take much to get some noise out of this amp.
Keep up with your research & make a plan. But be open to change.

its possible that it uses a field coil speaker

I saw a reference to field coil as well. This, plus the condition, might have me moving on to the next project.

 

[MKG]

I’m not opposed to purchasing a field coil speaker in need of a refoam, but I think I need to read up on them first. I’m assuming I can’t just hook up any field coil speaker to it? Guessing the coil needs to present the correct resistance to the amp?
The little bit of reading that I’ve done it says I can potentially use an inductor to make it drive fixed magnet speakers, no idea how to find out what value it may need.

 

[RWood]

Here is a 7020 amplifier and the speaker that came with it.

No foam on these - paper surrounds. They come up for sale from time to time. This one is a 1957 Jensen F12N.

Btw Wurlitzer made a solid state model 7020 also and that seems to be the service manual I have seen offered. I don’t have a schematic for this one but it is very similar to others made by them at around that time.

 

[century tek]

Oh boy, yeah, the 7020 looks like the field coil type. That speaker looks like mine from my 7062.

6000Ω choke coil or 2 or 3h choke coil should work to replace the field coil.

 

[MKG]

Thank you both, you guys are awesome!
I think I’ll go ahead and set it up for fixed magnet with a choke coil.

 

[century tek]

If you do use a permanent magnet speaker with that amp, be sure to:

1) Make sure you have a choke coil installed before turning it on.
2) Make sure the center tap from the power transformer is grounded to the chassis or it won't work.

Reason being is that the multi plug field coil connector has a jumper that connects the center tap to the chassis when the speaker is plugged in.