philips CD473 volume control

[kst]

Hi there,

Just got hold of a Philips CD473, with CDM4 and TDA1541A.


Very surprise to find a volume control to the output signal with remote.
Understand that TDA1541 don't come with attenuation (right ?).

Can someone help to explain how the volume control done in CD473 ?

I would like to bypass it if it was done externally.

thank you very much

[TDA1540]

I would like to bypass it

No problem, the volume control is an add-on to the analogue section.

[hacknet]

i`ve seen this in other cdm4-era cd players, ie the 634. the variable volume isn`t too bad.

[kst]

Hi,

Nice to hear that it can be bypass. The vol control board seems complicated at first......
I will find some time to by pass it.

I have been wondering how the vol control is done here.

Looking at the signal flow, immediately after the op-amp filter after DAC, both L/R signal passed thru a MC14051BCP (A digital control analog mutiplexer ??). My guess is that the siganl is divided into 8 part (from small to large) using resistors network, then feed into the multiplexer. Digital volume control then is done by selecting the desired level (3-pin contorl from the spec of MC14051BCP = 8 states).

Any comments ?

I've seen a Philips CD880 that also used TDA1541A S1, but there are 2 sets of output available. 1 set with variable level (vol control) 1 set fixed level at 2 Vrms. Looking at the signal flow, the variable output part passed thru a small board that are very complicated at 1 glance. I think it works the same way as CD473.

Originally, when I get this set, I am only interested in the DAC. Thinking of making a NOS dac (after reading many reports). However after listen to it, I am really surprise to find that it sounds great. Considering the age of the set (>10yrs), the CDM still works well and the sound has certain character that I don't find in my CD67SE or CD6000OSE. So after changing some E-caps and the op-amp, I think it would perform better if the vol control is bypassed ??

[d to the g]

Did you ever get this player sorted? I've been looking high (and low) for the service manual so as to remove all the unnecessary things... like volume control.

[kst]

Hi,

Didn't manage to find the service manual or schematics....
Just referenece to many Philips CD player that used TDA1541A (I have few Philips CD player service manuals that use TDA1541A) .
The schematics are almost the same (I suppose.... 7220B (or A)-->TDA1541A.. the difference will be on 14 coupling caps, some player used po-cap, 473 used SMD cap)

So I removed the volume board, find the singal on the connector and connect it to the output (Anyway it is already buffered, also put in a socket for the buffer)....
BTW, on the board itself, there are some empty space that has some provision routing....
Trace the layout, put 2-3 jumpers/wires you will be able to route the signal all the way to the provision output connector or to find a better place to solder the output signal.

Rgds,
Mark

[hollowman]

Originally Posted by kst

Didn't manage to find the service manual or schematics....

Check you email.
Did you ever find a sol'n to the DC issue when you removed the volume ckt?

BTW: My CDB473 is a Magnavox (build date: August 1987). It has CDM2 and no fixed-level output.