Marantz PM7003 help with schematics???

[nad]

Hello folks,

The time has come to delve into my PM7003 amp, amplification is new to me so I was wondering if any of you kind guys out there would help me out a bit?

All I'm after is swapping a few caps around for now and getting familiar with the schematics.

One of the images below shows the main board schematic, this seems very complicated to me so I've highlighted the sections in orange with A?, B?, C? and so on, hopefully someone can can tell me what they are?

My first hunt is the feedback caps, a noddy question but are there feedback caps for both the pre and power or just one section?

Once I've found the feedback caps my intention is to swap them out for 'better' caps, I'm guessing they will be around 47uf? so if this makes sense I was planning on 'upping' the capacitance to increase the bass? Does that make sense?

Anyhow, here's the schematics......

http://imageshack.us/photo/my-images...003schem2.jpg/

http://imageshack.us/photo/my-images...owerstage.jpg/

I have some 22,000uf 63v Kendeil K01's to go in place of the 15,000uf 63v Elnas so while the board was out (a bitch of a job) I thought it would be a good time to look at the feedback caps.


Thanks,
Ant

[big jim]

if the amp is working ok leave it alone its a good amplifier

[nad]

Originally Posted by big jim

if the amp is working ok leave it alone its a good amplifier

You know what.... I think temptation had the better of me this time.

Without a doubt you're right in what you say, I'll leave this one alone.


Cheers
Ant

[Stormrider]

It is a good amplifier, leave it be.

What you're calling the preamp in the main schematic is the input and VAS stages for the power amp itself.

[aparatusonitus]

Section F is an input buffer for direct CD input.
Section C is an input buffer for all the rest line inputs.
Section D in an output buffer for recorders line out.
Section A is a preamplifier.
Section B is an voltage regulator + amplifier protection.
Section marked as "pre amp?" is a part of power amp (input stage + driver stage),
Power amp output stage bias control, output transistors and part of protection are shown on the yours 2nd link.

Do yourself a big a favor and live the amp alone.

[nad]

Originally Posted by Stormrider

It is a good amplifier, leave it be.

I will do just that.

Originally Posted by Stormrider

What you're calling the preamp in the main schematic is the input and VAS stages for the power amp itself.

Thanks for your info.

Ant

[nad]

Originally Posted by aparatusonitus

Section F is an input buffer for direct CD input.
Section C is an input buffer for all the rest line inputs.
Section D in an output buffer for recorders line out.
Section A is a preamplifier.
Section B is an voltage regulator + amplifier protection.
Section marked as "pre amp?" is a part of power amp (input stage + driver stage),
Power amp output stage bias control, output transistors and part of protection are shown on the yours 2nd link.

Excellent, thank you.

Originally Posted by aparatusonitus

Do yourself a big a favor and leave the amp alone.

I'm not going to touch it, after a re-think I'd probably end up screwing it up.

Thanks,
Ant