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Cgs synth

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Message

Re: CGS82 Negative Slew

2013-10-07 by Stephen Richards

Removed the chips , put them back in one by one starting with the LM3900's , then the CA3046's.

Now it's working !!??

Whatever gremlin was in the works seems to have been evicted.

Maybe cheap IC sockets ? I couldn't get 14pin machined sockets in time for this build. I dunno ; but thanks , Ken.

From: "sasami@..." <sasami@...>
To: cgs_synth@yahoogroups.com
Sent: Monday, October 7, 2013 1:48 PM
Subject: Re: Re: [cgs_synth] RE: CGS82 Negative Slew

Find out what voltage is on the "6V" line - it's probably less than 6V.
Start isolating bits of the circuit to find out what is causing the massive
current drain - power rail will return to 6V when the affected circuit is
disconnected. Try pulling out the chips to start with. I assume they are in
sockets.
Replace the BC547, but expect the next one to behave in exactly the same way
until the fault is found.

Ken

>Hi Ken
>
>When the PCB is powered up , if i put my finger on the BC547 in the the 6V
section. It is cool to the touch for a few seconds then becomes very hot
very quickly.
>
>I have changed out all of the electrolytics and there is no change , i have
looked over and over and can't find a short.
>
>Now that the electros in the power filtering are changed , should i put
another BC547 in ?
>
>I'm racking my brain but can't find a solution.
>
>
>________________________________
> From: "sasami@..." <sasami@...>
>To: cgs_synth@yahoogroups.com
>Sent: Saturday, October 5, 2013 12:13 PM
>Subject: RE: Re: [cgs_synth] RE: CGS82 Negative Slew
>
>
>
>Â
>The links are all part of the 0V power rail. with any of them missing,
nothing was working properly.
>
>
>
>---In cgs_synth@yahoogroups.com, <cgs_synth@yahoogroups.com> wrote:
>
>
>Thanks Ken
>
>I've been looking for a short , will keep looking.
>
>Any clue on why it works without that link installed ? Could that be the
key to tracking down this problem ?
>
>
>________________________________
> From: "sasami@..." <sasami@...>
>To: cgs_synth@yahoogroups.com
>Sent: Saturday, October 5, 2013 9:21 AM
>Subject: [cgs_synth] RE: CGS82 Negative Slew
>
>
>
>Â
>First, find where the short circuit is! The transistor should not get hot.
>
>Ken
>
>
>
>---In cgs_synth@yahoogroups.com, <cgs_synth@yahoogroups.com> wrote:
>
>
>Hi Ken and All
>
>I finished building the CGS82 Negative Slew. Had i 'working' , as far as i
can understand it so far , but the bottom section LED was not working.
>
>While i was trying to troubleshoot that problem , i noticed i had omitted
the link that's between the RATE pads on the PCB and the 22K trimmer.
>
>When i put that link in , every thing seems to have stopped working and the
BC547 in the 6V section directly above the 6.8K resistor is getting very hot
under power.
>
>Should i replace the BC547 , not too sure how to proceed.
>
>
>
>
>
>
><head>
>
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>
><div style="color:#000; background-color:#fff; font-family:tahoma, new
york, times, serif;font-size:10pt"><div style="margin-top: 0px;
margin-right: 0px; margin-bottom: 0px; margin-left: 0px; color: rgb(0, 0,
0); font-size: 13px; font-family: tahoma, 'new york', times, serif;
background-color: transparent; font-style: normal; "><span>Hi
Ken</span></div><div style="margin-top: 0px; margin-right: 0px;
margin-bottom: 0px; margin-left: 0px; color: rgb(0, 0, 0); font-size: 13px;
font-family: tahoma, 'new york', times, serif; background-color:
transparent; font-style: normal; "><span><br></span></div><div
style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left:
0px; color: rgb(0, 0, 0); font-size: 13px; font-family: tahoma, 'new york',
times, serif; background-color: transparent; font-style: normal;
"><span>When the PCB is powered up , if i put my finger on the BC547 in the
the 6V section. It is cool to the touch for a few
> seconds then becomes very hot very quickly.</span></div><div
style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left:
0px; color: rgb(0, 0, 0); font-size: 13px; font-family: tahoma, 'new york',
times, serif; background-color: transparent; font-style: normal;
"><span><br></span></div><div><span>I have changed out all of the
electrolytics and there is no change , i have looked over and over and can't
find a short.</span></div><div style="color: rgb(0, 0, 0); font-size: 13px;
font-family: tahoma, 'new york', times, serif; background-color:
transparent; font-style: normal; "><span><br></span></div><div style="color:
rgb(0, 0, 0); font-size: 13px; font-family: tahoma, 'new york', times,
serif; background-color: transparent; font-style: normal; "><span>Now that
the electros in the power filtering are changed , should i put another BC547
in ?</span></div><div style="color: rgb(0, 0, 0); font-size: 13px;
font-family: tahoma, 'new york',
> times, serif; background-color: transparent; font-style: normal;
"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 13px;
font-family: tahoma, 'new york', times, serif; background-color:
transparent; font-style: normal; "><span>I'm racking my brain but can't find
a solution.</span></div><div style="color: rgb(0, 0, 0); font-size: 13px;
font-family: tahoma, 'new york', times, serif; background-color:
transparent; font-style: normal; "><br></div> <div style="font-size: 10pt;
font-family: tahoma, 'new york', times, serif; "> <div style="font-size:
12pt; font-family: 'times new roman', 'new york', times, serif; "> <div
dir="ltr"> <hr size="1"> <font size="2" face="Arial"> <b><span
style="font-weight:bold;">From:</span></b> "sasami@..."
<sasami@...><br> <b><span style="font-weight:
bold;">To:</span></b> cgs_synth@yahoogroups.com <br> <b><span
style="font-weight: bold;">Sent:</span></b> Saturday, October 5, 2013
> 12:13 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> RE:
Re: [cgs_synth] RE: CGS82 Negative Slew<br> </font> </div> <div
class="y_msg_container"><br><div id="yiv7783768150"><div>
><span > </span>
>
>
><div id="yiv7783768150ygrp-mlmsg" style="">
> <div id="yiv7783768150ygrp-msg" style="">
>
>
> <div id="yiv7783768150ygrp-text">
>
>
> <div>The links are all part of the 0V power rail. with any of them
missing, nothing was working properly. <br clear="none"></div> <div
class="yiv7783768150yqt6770454614" id="yiv7783768150yqt52476"><div
class="yiv7783768150ygroups-quoted"><br clear="none"><br clear="none">---In
cgs_synth@yahoogroups.com, <cgs_synth@yahoogroups.com> wrote:<br
clear="none"><br clear="none"><div
id="yiv7783768150ygrps-yiv-920038537"><div style="color: rgb(0, 0, 0);
background-color: rgb(255, 255, 255); font-size: 10pt; font-family: tahoma,
'new york', times, serif; "><div><span>Thanks Ken</span></div><div
style="color: rgb(0, 0, 0); font-size: 13px; background-color: transparent;
font-style: normal; font-family: tahoma, 'new york', times, serif;
"><span><br clear="none"></span></div><div style="color: rgb(0, 0, 0);
font-size: 13px; background-color: transparent; font-style: normal;
font-family: tahoma, 'new york', times, serif; "><span>I've been looking for a
> short , will keep looking.</span></div><div style="color: rgb(0, 0, 0);
font-size: 13px; background-color: transparent; font-style: normal;
font-family: tahoma, 'new york', times, serif; "><span><br
clear="none"></span></div><div style="color: rgb(0, 0, 0); font-size: 13px;
background-color: transparent; font-style: normal; font-family: tahoma, 'new
york', times, serif; "><span>Any clue on why it works without that link
installed ? Could that be the key to tracking down
> this problem ?</span></div><div><br clear="none"></div> <div
style="font-size: 10pt; font-family: tahoma, 'new york', times, serif; ">
<div style="font-size: 12pt; font-family: 'times new roman', 'new york',
times, serif; "> <div dir="ltr"> <hr size="1"> <font size="2" face="Arial">
<b><span style="font-weight:bold;">From:</span></b> "sasami@..."
<sasami@...><br clear="none"> <b><span
style="font-weight:bold;">To:</span></b> cgs_synth@yahoogroups.com <br
clear="none"> <b><span style="font-weight:bold;">Sent:</span></b> Saturday,
October 5, 2013 9:21 AM<br clear="none"> <b><span
style="font-weight:bold;">Subject:</span></b> [cgs_synth] RE: CGS82 Negative
Slew<br clear="none"> </font> </div> <div
class="yiv7783768150ygrps-yiv-920038537y_msg_container"><br
clear="none"><div id="yiv7783768150ygrps-yiv-920038537yiv0802677040"><div>
><span> </span>
>
>
><div id="yiv7783768150ygrps-yiv-920038537yiv0802677040ygrp-mlmsg">
> <div id="yiv7783768150ygrps-yiv-920038537yiv0802677040ygrp-msg">
>
>
> <div id="yiv7783768150ygrps-yiv-920038537yiv0802677040ygrp-text">
>
>
> <div>First, find where the short circuit is! The transistor
should not get hot.</div><div><br clear="none"></div><div style="color:
rgb(0, 0, 0); font-size: 13px; background-color: transparent; font-style:
normal; font-family: arial, helvetica, clean, sans-serif; ">Ken<br
clear="none"></div> <div
class="yiv7783768150ygrps-yiv-920038537yiv0802677040yqt4146213120"
id="yiv7783768150ygrps-yiv-920038537yiv0802677040yqt98838"><div
class="yiv7783768150ygrps-yiv-920038537yiv0802677040ygroups-quoted"><br
clear="none"><br clear="none">---In cgs_synth@yahoogroups.com,
<cgs_synth@yahoogroups.com> wrote:<br clear="none"><br
clear="none"><div
id="yiv7783768150ygrps-yiv-920038537yiv0802677040ygrps-yiv-1760770583"><div
style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); font-size:
10pt; font-family: tahoma, 'new york', times, serif; "><div>Hi Ken and
All</div><div><br clear="none"></div><div style="color: rgb(0, 0, 0);
font-size: 13px;
> background-color: transparent; font-style: normal; font-family: tahoma,
'new york', times, serif; ">I finished building the CGS82
> Negative Slew. Had i 'working' , as far as i can understand it so far ,
but the bottom section LED was not working.</div><div style="color: rgb(0,
0, 0); font-size: 13px; background-color: transparent; font-style: normal;
font-family: tahoma, 'new york', times, serif; "><br clear="none"></div><div
style="color: rgb(0, 0, 0); font-size: 13px; background-color: transparent;
font-style: normal; font-family: tahoma, 'new york', times, serif; ">While i
was trying to troubleshoot that problem , i noticed i had omitted the link
that's between the RATE pads on the PCB and the 22K trimmer.</div><div
style="color: rgb(0, 0, 0); font-size: 13px; background-color: transparent;
font-style: normal; font-family: tahoma, 'new york', times, serif; "><br
clear="none"></div><div style="color: rgb(0, 0, 0); font-size: 13px;
background-color: transparent; font-style: normal; font-family: tahoma, 'new
york', times, serif; ">When i put that link in , every thing seems to have
> stopped working and the BC547 in the 6V section directly above the 6.8K
resistor is getting very hot under power.</div><div style="color: rgb(0, 0,
0); font-size: 13px; background-color: transparent; font-style: normal;
font-family: tahoma, 'new york', times, serif; "><br clear="none"></div><div
style="color: rgb(0, 0, 0); font-size: 13px; background-color: transparent;
font-style: normal; font-family: tahoma, 'new york', times, serif; ">Should
i replace the BC547 , not too sure how to proceed.</div></div></div></div></div>
>
> </div>
>
>
>
> <div class="yiv7783768150ygrps-yiv-920038537yiv0802677040yqt4146213120"
id="yiv7783768150ygrps-yiv-920038537yiv0802677040yqt92610"><div
style="color:#fff;height:0;"></div></div>
>
>
></div><div
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id="yiv7783768150ygrps-yiv-920038537yiv0802677040yqt42900"></div></div><br
clear="none"><br clear="none"></div> </div> </div>
</div></div></div></div></div></div>
>
> </div>
>
>
>
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__________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>



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