Help me identifying the multiple leads coming off this pcb

[RussJ]

Very frustrating. I have a NOS Archer 1 watt / 4 transistor / push-pull audio amplifier and I can't find any info on it other than an add in an old electronics magazine that says the following: Can be used as an intercom, phono, tapr, or microphone amplifier. Color-coded leads. Freq. response +-1.15db 300 - 15,000 cps. In the picture you can see that it has8 leads total (2 on one end and 6 on the other. Judging by the voltages on the caps I think it must be a 9volt or 12volt system but I need some help id'ing which is the power input, source in, speaker out etc. This thing is driving me crazy because I can't find any schematic or instructions anywhere on the webs. So any help will be greatly appreciated. Thanks

 

[Jouellet]

you may want to retake the back picture, as we can't see much !

 

[RussJ]

Ok here's another shot. My camera is kinda crappy and sharp images are hit and miss, sorry. But this one looks better.

 

[Harald Kapp]

The cable to the left would be the audio input. The white wire being the signal, the shield (metal mesh) being ground.
Working onward from this the black wire (top in post #1, bottom in post #3) would be ground, too.
Red and Ornage are short circuited and seem to be going nowhere. Do these wires have any connection to other components I can't see? Do you have an Ommeter to check?

Brown and black (post #3, bottom) seem to be short-circuited, too (via the metal encapsulation of the transformer). I have no idea where Brown is supposed to be connected. You can probably leave it open.
White (right) is connected to the transformer, the second pin of the transformer is connected to ground. This suggests white is the output of the amplifier.
this leaves the top black wire (post #3) as the positive supply.

The design looks suspiciously like the one shown here.

 

[davenn]

The design looks suspiciously like the one shown here.

the one in the video does look similar, but has a far fewer component count, particularly the number of capacitors

 

[RussJ]

The cable to the left would be the audio input. The white wire being the signal, the shield (metal mesh) being ground.
Working onward from this the black wire (top in post #1, bottom in post #3) would be ground, too.
Red and Ornage are short circuited and seem to be going nowhere. Do these wires have any connection to other components I can't see? Do you have an Ommeter to check?

Brown and black (post #3, bottom) seem to be short-circuited, too (via the metal encapsulation of the transformer). I have no idea where Brown is supposed to be connected. You can probably leave it open.
White (right) is connected to the transformer, the second pin of the transformer is connected to ground. This suggests white is the output of the amplifier.
this leaves the top black wire (post #3) as the positive supply.

The design looks suspiciously like the one shown here.

I'll ohm it out in the AM. Thanks for the quick replies.

 

[AnalogKid]

The amp you have is from back when transistor circuits were patterned after tube circuits. There is an input amplifier stage (not on the google schematic), a driver for the interstage transformer (the small one), and a split push-pull class B output stage driving an output transformer (the large one) as shown in the google schematic. All transistors are PNP, and the + battery terminal is connected to the circuit ground.

Black next to red - battery negative terminal
Red next to black - battery positive terminal
Orange - battery power out to on/off switch
Brown - switched power - this is the power input that runs the amp
White - speaker output
Black next to white - signal ground for the speaker (connected to the input shield)

This two-transformer audio amp was the basis for jillions of transistor radios in the 50's, 60's, and 70's.

ak

 

[AnalogKid]

Here are three variations on the theme. The last one, "transistor-topics", is the closest to what you have, with PNP transistors and a "positive ground".

ak

 

[RussJ]

The amp you have is from back when transistor circuits were patterned after tube circuits. There is an input amplifier stage (not on the google schematic), a driver for the interstage transformer (the small one), and a split push-pull class B output stage driving an output transformer (the large one) as shown in the google schematic. All transistors are PNP, and the + battery terminal is connected to the circuit ground.

Black next to red - battery negative terminal
Red next to black - battery positive terminal
Orange - battery power out to on/off switch
Brown - switched power - this is the power input that runs the amp
White - speaker output
Black next to white - signal ground for the speaker (connected to the input shield)

This two-transformer audio amp was the basis for jillions of transistor radios in the 50's, 60's, and 70's.

ak

You, Sir, are a life saver. Can't thank you enough as this worked.

 

[AnalogKid]

A very long time ago I inherited an interesting collection of electronics from a mentor, and a versions of that amp were in it. I still have 1 or 2, waiting for the right project.

ak

 

[RussJ]

A very long time ago I inherited an interesting collection of electronics from a mentor, and a versions of that amp were in it. I still have 1 or 2, waiting for the right project.

ak

I was going to use this as a replacement in my Cerwin-Vega XD-3 computer speakers (the pcb is completely cooked) but that negates the stereo function so now I'm thinking about a micro guitar amp. Sounds like a worthwhile endeavor to me.