Magnavox 699A power switch connections

New to tubes, and this is the first of two projects (other is a full restoration of a Telefunken Opus Royal tube radio/phonogram...down the road a ways, as yet). Project 1 is to get a Magnavox AMP 169 AA mono turntable amp working. The design of this is one where the amp power connection is switched on from the turntable. There is a 3-wire push connector (I have no Magnavox turntable), with a red, yellow and black wire - presumably two of these need to be jumped to make the amp turn on? Which ones do I jump together? Naturally, I will fit a switch to the amp eventually. I am including pics of the amp (when removed), after cleaning, and detailed shot of wiring at the TT connector/romex plug.

Any advice would be appreciated. As yet, I have no idea if this amp even works. I have the speakers that came with the console.

Magnavox AMP 169 AA

OscarEmmy said:

New to tubes, and this is the first of two projects (other is a full restoration of a Telefunken Opus Royal tube radio/phonogram...down the road a ways, as yet). Project 1 is to get a Magnavox AMP 169 AA mono turntable amp working. The design of this is one where the amp power connection is switched on from the turntable. There is a 3-wire push connector (I have no Magnavox turntable), with a red, yellow and black wire - presumably two of these need to be jumped to make the amp turn on? Which ones do I jump together? Naturally, I will fit a switch to the amp eventually. I am including pics of the amp (when removed), after cleaning, and detailed shot of wiring at the TT connector/romex plug.

Any advice would be appreciated. As yet, I have no idea if this amp even works. I have the speakers that came with the console.

Click to expand...

I quoted the incorrect amp number (duh)...s/b AMP 169 AA

the schematic of this amp is on the magnavox friends yahoo group. sign up it free. it looks to me like pins 1 and 5 of that plug if shorted should get you power. check to see if where it goes thru the chassis that the black wire of the power transformer is connected to the plug. You can see how its wired on the schematic. Look in "files" and "magnavox amp schematics" for the 169aa in the yahoo group.
hope this helps.

According to your 2nd, 3rd & 6th pictures, you had better not plug that thing in until you put the 5Y3 tube where it's supposed to go, socket closest to the black power transformer, or you are gonna have a smoke show!

cademan said:

According to your 2nd, 3rd & 6th pictures, you had better not plug that thing in until you put the 5Y3 tube where it's supposed to go, socket closest to the black power transformer, or you are gonna have a smoke show!

Click to expand...

You're right...the schematic shows


6ANB

6V6GT 6V6GT

5Y3GT

Thanks for the heads up!!!

Oldhifiguy has it right about the power switch but just in case you still don't know how to power it up, let's see a shot of the underside. You will need to connect a power cord to the two black wires coming off of the big black power transformer.

Once you succeed with this, then simply connect a switch between one of the black wires.

Pretty basic amplifier! Speaker connection is the green & black wires, input is the RCA jack next to the 6AN8 tube.

cademan said:

Oldhifiguy has it right about the power switch but just in case you still don't know how to power it up, let's see a shot of the underside. You will need to connect a power cord to the two black wires coming off of the big black power transformer.

Once you succeed with this, then simply connect a switch between one of the black wires.

Pretty basic amplifier! Speaker connection is the green & black wires, input is the RCA jack next to the 6AN8 tube.

Click to expand...

Here are a couple of shots of underneath.

Update...It's working! The black and yellow wires are the ones to jump to test it.

I have soldered a phono plug to the pre-amp's phono input cable, allowing me to connect a cassette tape player (one channel only of course). It produces sound that is at times very clean...there is a noticeable 'cap failing' kind of sound distortion (it's not from the pre-amp, I don't think. I cleaned the bass, treble and volume pre-amp pots with contact cleaner). The bass control was initially working but then cut out, so perhaps a full recap will restore sound. All of the tubes light up, though, which is a great result . For a little amp, even with no enclosure for the 4 speakers (1 x 15 inch, 2 x 4 inch and 1 x 8 inch), it has not bad volume. When not distorting it really does sound sweet! Definitely worth fixing up to use as a 78 rpm mono amp (the stereo amp for my main 33.3 turntable will be a different project, using the Telefunken console tube amp).

I may get into tubes instead of vintage solid state, at this rate!

Good for you! Try it & see how you like the sound of the cassette deck connected straight into the input jack, by by-passing the preamp tone controls! You will of course need to control the overall volume level as it will be at full output unless the tape player has its own volume control!