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-   -   Quad SPST Analog Switch (http://www.diyaudio.com/forums/solid-state/133521-quad-spst-analog-switch.html)

RCruz 20th November 2008 07:46 PM

Quad SPST Analog Switch
 
2 Attachment(s)
Hi All

I have been modding my meridian 101b and found a DG308CJ on the output stage of this preamp.

It sits near the output opamp but I can not understand what it is for.

Also would like any opinion about the three 10uF16v caps in the pcb... decouplers ?

I can not find any output caps and this module has balanced output wiring. (Does this obviate the output caps ?)

Sorry for the poor quality pic:xeye:

Ricardo

RCruz 20th November 2008 07:51 PM

2 Attachment(s)
Another pic with the pcb in place... with the new LM4562.... big difference ;)

RCruz 21st November 2008 11:08 AM

Should I replave the 10uF16v el caps by some 33uF BG N ?

RCruz 23rd November 2008 07:52 PM

2 Attachment(s)
Quote:

Originally posted by RCruz
Should I replave the 10uF16v el caps by some 33uF BG N ?
I replaced the caps but there was no improvement on the sound.... Just noticed a bigger turn on time lag (now 2 secs). I believe the caps are used to turn the switch on during power on.

I can not imagine why this switch is after the opamp outputs.

As I am now using a LM4562, maybe I could short the DG308 2/3 and 6/7 pins.

Hope someone has any idea.

Regards

Ricardo

Jan Dupont 24th November 2008 04:21 PM

The DG308 is used as an output relay with delayed turn on to prevent "plops" in your speaker.

You can find the datasheet here;
http://pdf1.alldatasheet.com/datashe...XIM/DG308.html

RCruz 24th November 2008 07:58 PM

Quote:

Originally posted by ACD
The DG308 is used as an output relay with delayed turn on to prevent "plops" in your speaker.


By reading the datasheet, I understand that the Drain / Source resistance and capacitance may vary depending on input voltage.

I do not like this is my signal path....

how should I disable the switch ?

Short legs 2 3 14 15 and 6 7 10 11 ?

Can you sort what are the electrolityc caps for ?

I just replaced them for HiQ caps (what a waste) and the only difference was a longer turn on time lag.

I apreciate your input... :)

Regards

Ricardo

darian 24th November 2008 08:58 PM

Teh caps are there to set the turn on delay. Just shortcut this chip, from D to S, no need for desoldering I think.

RCruz 25th November 2008 12:07 PM

Thank you indeed !

I will short D and S legs and report latter.

Ricardo


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