What does this mean of the amplifier?

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Thread Starter

Skylar Coy

Joined Apr 29, 2017
133
This amp was built in the 70's and I need to replace the output transformer. Here is a schematic of the Amp. My issue is that I dont think the transformer is hooked up correctly now! Red is 16 ohm, Grey is 8 ohm, black is 4 ohm, brn is common. 8 ohm doesnt seem to be hooked up to anything. Just confused. Tell me what is wrong or if its just fine.

Amp pics: https://ibb.co/kU6NBQ
https://ibb.co/iP6NBQ
https://ibb.co/iKhJkk

Schematic: https://ibb.co/fWFXBQ

But right near the output transformer there are these symbols. -^- or that but the arrow is facing down. what are they?
 

recklessrog

Joined May 23, 2013
985
They are the symbols for the contacts on the speaker output jack sockets, when you plug in an extension speaker, they switch the correct windings in for impedance matching.
 

ian field

Joined Oct 27, 2012
6,536
but isnt there like 3 or 2 contacts. which is wihich
Most speakers only have 2 contacts - I've only ever seen 3 contacts on early transistor sets. The voice coil was center tapped to eliminate the final push-pull transformer.

Your transformer has taps for the grids - this is commonly referred to as; "ultra linear" - check that point when identifying a replacement.
 

Thread Starter

Skylar Coy

Joined Apr 29, 2017
133
Most speakers only have 2 contacts - I've only ever seen 3 contacts on early transistor sets. The voice coil was center tapped to eliminate the final push-pull transformer.

Your transformer has taps for the grids - this is commonly referred to as; "ultra linear" - check that point when identifying a replacement.
okay. my question. why is 8 ohm not connected and why is com on the output jack
 

ScottWang

Joined Aug 23, 2012
7,397
About t
so how does relate to the output transformer and how does that help with output jacks
What I said was the input power transformer for the filament of tubes, the output transformer arrange like these:
1. 16 Ω speaker is independent.
2. 4Ω and 8Ω used the plug to choose which speaker that you want to use, when the plug of 4Ω speaker is plug in then the 8Ω wire connection will be cutoff, even you plug the 8Ω speaker in, but it still won't works, 8Ω speaker only can be works when the plug of 4Ω speaker doesn't plug in.
 

ScottWang

Joined Aug 23, 2012
7,397
thats so weird.
Actually that is quite normal, you felt that because you don't know how the plug works, when the plug of 4Ω speaker plug in then the plug will push the -v- away, and the -v- is connected to the output of 8Ω, so the wire connection of 8Ω will be cutoff.
 

Thread Starter

Skylar Coy

Joined Apr 29, 2017
133
Actually that is quite normal, you felt that because you don't know how the plug works, when the plug of 4Ω speaker plug in then the plug will push the -v- away, and the -v- is connected to the output of 8Ω, so the wire connection of 8Ω will be cutoff.
it only has two jacks though 8 and 16
 

ScottWang

Joined Aug 23, 2012
7,397
it only has two jacks though 8 and 16
The two jacks are 4Ω and 8Ω, maybe 16Ω didn't connect.

The theory as the earphone of mp3, mp4, cellphone, the internal speaker like 8Ω and the earphone like 4Ω, so when the earphone(4Ω) plug in and then the internal speaker(8Ω) will be disable the output function.
 

Thread Starter

Skylar Coy

Joined Apr 29, 2017
133
The two jacks are 4Ω and 8Ω, maybe 16Ω didn't connect.

The theory as the earphone of mp3, mp4, cellphone, the internal speaker like 8Ω and the earphone like 4Ω, so when the earphone(4Ω) plug in and then the internal speaker(8Ω) will be disable the output function.
hmm. I want to have 16 and 8 ohms. how can i accomplish that
 

Thread Starter

Skylar Coy

Joined Apr 29, 2017
133
Find out the 16Ω wire from the output transformer and cutoff the 4Ω wire from the jack and connect the 16Ω wire to it.
It's very odd that the chassis is labeled 8 and 16 but it is 4 and 8 I still don't quite understand. The red whire is 16 ohm and it goes to a whole other connection thing
 

ScottWang

Joined Aug 23, 2012
7,397
It's very odd that the chassis is labeled 8 and 16 but it is 4 and 8 I still don't quite understand. The red whire is 16 ohm and it goes to a whole other connection thing
I can't find the wire of 16Ω from the pictures, and where did you find the 8Ω and 16Ω on the chassis?

but it is 4 and 8 I still don't quite understand.
What you don't understand, I already explained that on the post #12, #14, are they not enough for you?
 

Thread Starter

Skylar Coy

Joined Apr 29, 2017
133
I can't find the wire of 16Ω from the pictures, and where did you find the 8Ω and 16Ω on the chassis?


What you don't understand, I already explained that on the post #12, #14, are they not enough for you?



red is 16 ohm grey is 8. I found it labeled right by the ouput jacks. I just want to have 8 and 16 ohm jacks. Just was clarifying. So all i have to do is replace the 4 ohm wire with the 16 ohm wire, putting the four ohm where the 16 ohm is and the 16 where the 4 is
 

ScottWang

Joined Aug 23, 2012
7,397
In the circuit the 16Ω was labeled as F.B.II, so it should be connecting to somewhere, if you can draw the wiring of 16Ω then it will be more clear.
 
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