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Marantz 4270 Frankenstein!

P

Philox

New Member
Hey everyone! Hope you are doing great, got a set of 4270 amp modules with original pair of 50V /15000uF caps (marking great). As this is all I've got I would like to know if someone could give me a hand figuring out what should be done to get it working on 2x70W (don't want to use it as quadrophonic). I would firstly need to know:
#1: which transformer (voltage & aprox amps)
#2: apparently 5 wires go connected on a side of the board: J715 J723 J726 J722 J716 (I think J722 is -B, J723 GND, J726 B+, J715 & J716 no idea honestly :D )
#3: to use it in stereo mode (not quad),also each pair of audio input should be jumped? (J701 with J702).

Hope I got to express myself hahaha, merry Xmas to everyone! If you need me to explain anything please let me know. Thanks!!

Attaching photo of all I've got from this 4270

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AlUxI4Dr.jpg
 
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Welcome to AK.
I'm gonna be honest with you, it's gonna be a waste of time and money to do want you want to do.
Let those boards save another 4270 instead.
Plenty of amp kits out there that will offer much better performance and be easier to build. Check out Elliott Sound Products (no affl).
 
ivandezande said:
Welcome to AK.
I'm gonna be honest with you, it's gonna be a waste of time and money to do want you want to do.
Let those boards save another 4270 instead.
Plenty of amp kits out there that will offer much better performance and be easier to build. Check out Elliott Sound Products (no affl).
Click to expand...
Hey how are you? I would like to know those items before I give up, I've got the service manual (no ref voltages unluckly) so if I had to recreate any of the PCBs from the original amplifier I could do it ;)
 
You'll need to feed inverted audio to one of the two amps in bridge mode. There's a separate board in 4270's to do that. If you jump the audio straight into both amps, they will be in phase and while swinging lots of voltage, no sound will be produced.
 
rBuckner said:
You'll need to feed inverted audio to one of the two amps in bridge mode. There's a separate board in 4270's to do that. If you jump the audio straight into both amps, they will be in phase and while swinging lots of voltage, no sound will be produced.
Click to expand...
Thanks for your answer, specifically do You know the number of the board to give a look at?
 
You are going to need the PM01 BTL phase inverter board and a good understanding of how it and the power mode switch interact with the power amps and speaker outputs.
Careful study of the service manual and schematic should be enough to get the job done.

Let us know how it works out, what you are doing is pretty interesting!

Tom
 
catrafter said:
You are going to need the PM01 BTL phase inverter board and a good understanding of how it and the power mode switch interact with the power amps and speaker outputs.
Careful study of the service manual and schematic should be enough to get the job done.

Let us know how it works out, what you are doing is pretty interesting!

Tom
Click to expand...
Thanks! This Will be my January project, will be really soon with some updates, btw got any idea of transformer voltages? Merry Xmas!!
 
The PM01 probably wants +35V. The filters are rated at 50V so the + and - rails will be less than that.
If you have the old transformer, P800 (power supply board) and rectifiers (I think they are part of the P800) you could reuse them if they are OK.

Tom
 
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