Wiring on old 50's Valco amp

[Eyesoftheworld]

Good day,

I have an old 50's Valco and I have a few wiring questions. It has a field speaker and I am unsure how to wire it. I was told to wire it like a choke but I am honestly unsure how to do it.

Was wondering if anyone had an idea of wiring the field speaker in? 2 wires only.


I have schematic but having trouble adding it.

[SEL49]

Wire it exactly as the schematic shows.

[Eyesoftheworld]

Got that idea - I’m just asking where the 2 wires go from the field coil.  Does one go to the B+ on the big cap?  Not sure where the other goes.

[SEL49]

Does this drawing help?

[Eyesoftheworld]

I believe that makes it more clear!  I appreciate it.  I will get back to you asap.

[Eyesoftheworld]

Ok - here is what I have done:  Taken the brown and blue wire from the OT primary and attached them to pins 3 on the 6V6s.  Ive taken the red middle wire from the OT and put it on a tab on the capacitor.

I have taken the brown and red wires from the field coil and wired the brown to one tab of the capacitor and the red to another tab of the capacitor.

Please advise if I have done something wrong.

Thanks!

[SEL49]

Can you read and understand a schematic? Post a hi-rez pic of your work inside the chassis and field coil speaker. Post a drawing that shows your wiring between the caps, FC, and OT. Don't forget that the output tube screens (pin 4) have to connect to the same cap as the OT red wire and FC wire.

[Eyesoftheworld]

I thought I did - Ive built a 5f1 and a 5e3 before.

Here is a drawing and a pic of the cap.

[shooter]

I have an old 50's Valco and I have a few wiring questions.

Taken the brown and blue wire from the OT primary and attached them to pins 3 on the 6V6s.

was is un-wired when you got it?

[Eyesoftheworld]

Yes - wires had been removed.  Likely someone was trying to change speaker maybe and gave up. 

[SEL49]

What you drew will not work. FOLLOW THE SCHEMATIC!

[AlNewman]

According to the schematic you provided, wire one side of the field coil to the center tap of the OT, and wire the other side of the field coil to pin 8 of your rectifier.

[bmccowan]

This may help you understand the reasons for wiring it the way the schematic illustrates and Al describes. Always good to understand what is going on before heating the soldering iron. https://www.youtube.com/watch?v=mspkAX1GNF0
Be aware that the field coil puts high voltage at the speaker - so extra caution is advised.

[Eyesoftheworld]

Ok - last kick at the can before I dump this thing.

Look right yet?

[SEL49]

Look right yet?

No. That's wrong.

This is not difficult to do. Post a hi-rez pic showing the guts of your chassis and we may have a better idea of what to tell you other than just follow the schematic.

[Eyesoftheworld]

Ok - thanks.  Here is a good pic.  I know the caps are done for.  Just trying to wire it all properly first.

[bmccowan]

This is not difficult to do.

That's right. It's not difficult to do if you learn how it works. Then it is just logical. And it's not a lengthy study.

[tubeswell]

field speaker and I am unsure how to wire it. I was told to wire it like a choke but I am honestly unsure how to do it.

The field coil is wired in series between the rectifier tube’s cathode and the center tap of the output transformer.

Was wondering if anyone had an idea of wiring the field speaker in? 2 wires only.

Won’t work. The field coil speaker is designed to work with a field coil. The impedance will be all wrong if you leave out the field coil.
If you want to run a normal speaker, run a normal speaker.

[SEL49]

See attached pic to correctly connect your field coil and OT.

Where is the rest of the amp? There has to be a 27K resistor connected between cap lugs B and C. Where is it? We need more pics that show where that blue wire on cap C goes. Also need a pic showing the other tubes.

And we also need to know exactly what you are doing. Are you simply reconnecting the original FC speaker and OT? Are you replacing the OT? Tell us.

[Eyesoftheworld]

Ok - here is the entire chassis, full view and left and right view.  This amp was bought as you see it, except all the wires from the field coil and the speaker were disconnected.  I haven't removed or added anything.

[SEL49]

Where's the speaker? The field coil and the OT would have been mounted on the original speaker. What are your intentions?

[Eyesoftheworld]

Sorry, didnt add speaker pic.  Intention is to get it speaker wired properly and see if I can get sound. 

[SEL49]

Intention is to get it speaker wired properly and see if I can get sound.

You should be able to do that with the last pic I posted.

[Eyesoftheworld]

Great!  Will let you know.