90's Sony TA-3600 BI-AMP Very Low Volume

[athlonus]

Hello,

This is my first post here, I have some experience in electronics repair (DSLR Cameras) but not much in the audio and amp field.

I have a nice MHC-3600 system stored for some years, in decent shape, not used much.

The other day when I wanted to use it again, it worked and sounded fine with all functions (except the bad cassette belts) around an hour or so. I did not put the volume all the way up to test, just somewhere near the middle and it got really high as expected.

On the next day, when I tried, there was no sound at all. I could hear the normal relay clicks when turned the unit on and off. All functions seem to work like before but no sound...

- When I turn the volume knob all the way up, I can hear the radio, CD play and etc. very faintly.

- EQ screen does not move the bars as if the sound input is not present.

- Same results with the headphones plugged in; very very low volume.

As you know Sony used to make really good systems like this in the past which still sounds amazing, that's why I'd like to get this back to life.

Would anyone have an idea on this issue? Thanks.

[jiroy]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

As a first step , Try cleaning the volume control and related audio switches , including the equalizer with Sonax or any similar cleaner .

remove the plastic covers from controllers and locate a small hole where you can spray inside .

[Andrew F. Ali]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

Look carefully at the Power Supply and Amplifier circuit boards. There is an electrolytic cap between 3300-4700uF has lost its value. Check the Power Supply board first. Pull the caps off the board and test them.

[athlonus]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

I do not think cleaning is applicable, the volume knob is excellent, other controls are all digital thanks though.

@Andrew F. Ali

I will check them, are you familiar with this system? Thanks.

[jiroy]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

TA-3600 is one model (manufactured since 70's probably) and MHC 3600 another , so i had to deal with it either ways ...
Nontheless , the best approach is 26 years . 26 years can do a lot to metals and caps too ..
good luck.

[Andrew F. Ali]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

No I am not familiar with this model but had a similar symptom showing on another SONY stereo and found the e-caps faulty in the power supply and poer amp sections.

[Longbow]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

Look carefully at the Power Supply and Amplifier circuit boards. There is an electrolytic cap between 3300-4700uF has lost its value. Check the Power Supply board first. Pull the caps off the board and test them.

You apparently are familiar with this model. Thanks for sharing your experience.

Using the critical path method: the problem description is: "No sound at all." That does not point to weak power supply filter caps. In fact, it is normal for large value caps to lose some of their microfarads over time and still function well.

As for pulling power supply capacitors and checking their values...that drudgery is obviated by the ESR meter. Function switches, pre-out main-in jumpers are likely culprits given that the unit has been stored, and that the audio is present when the volume is turned up.

Althonus, let's have a couple of snaps of this unit!

[budm]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

Good pictures of the back of the unit, and closed up of the front panel of each units.
Service manual:


See PDF page 124.
CN412, see if you do have record out signals or not, or if you do have IN-L, IN-R.
Since both channels are low, it has to be something in common to both channels, MUTE is not activated, right?

[sean0118]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

Have you checked all the fuses for continuity?

[athlonus]

Re: 90's Sony TA-3600 BI-AMP Very Low Volume

I will post the pictures shortly when I have some time.

Is there a mute function, for the amplifier which could be enabled other than the normal user interface? I see no muting is engaged anywhere on the display and controls.