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</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple><div class=WordSection1><p class=MsoPlainText><span lang=EN-CA>Jean,<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Here is the link for the good schematic and PCB layout:<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><a href="https://www.audioservicemanuals.com/p/peavey/peavey-kb/1335254-peavey-kb-100-12-89-schematic">https://www.audioservicemanuals.com/p/peavey/peavey-kb/1335254-peavey-kb-100-12-89-schematic</a><o:p></o:p></span></p><p class=MsoPlainText><b><i><span lang=EN-CA>There are KB100 schematics showing on Google which actually are<br>KBA100 schematics so not the one you need..<o:p></o:p></span></i></b></p><p class=MsoPlainText><b><i><span lang=EN-CA><o:p> </o:p></span></i></b></p><p class=MsoPlainText><span lang=EN-CA>I've been working on music instruments for many years..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Here is a list of what you could do:<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Since it's powering up that means there are no shorts caused by shorted power transistors (Q101, Q105).<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Many times this ‘no sound problem’ on both the output speaker and headphone jack<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Is caused by jacks connected between the preamp section<br>and the power amp section.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>These jacks have normally <u>closed contacts</u> that carry<br>the signal through them when there are no plug connected in them.<br>These contacts get dirty when these jacks are not used<br>and cut the signal completely from reaching the final output stage..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>In the case of the KB100 there are 2 jacks to check for:<o:p></o:p></span></p><p class=MsoPlainText><b><span lang=EN-CA>Front Pre-EQ patch jack<o:p></o:p></span></b></p><p class=MsoPlainText><b><span lang=EN-CA>Rear PWR AMP IN jack<o:p></o:p></span></b></p><p class=MsoPlainText><span lang=EN-CA>You can first feed the PWR AMP IN jack with some audio source<br>and check if there is sound at the speaker. If so the internal contact is dirty and<br>need to be cleaned.<br>Do the same test on the EQ patch jack at the front.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>JP<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><b><span lang=FR style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>De :</span></b><span lang=FR style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Synth-diy [mailto:synth-diy-bounces@synth-diy.org] <b>De la part de</b> Jean Bender via Synth-diy<br><b>Envoyé :</b> 3 avril 2021 14:52<br><b>À :</b> SDIY List<br><b>Objet :</b> [sdiy] Need help about how to service an amp<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>Hi list !<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>A friend gave me a Peavey KB100, not working, i mean it's powering up but no sound, even in the headphone output.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Well, i realise in don't know from where to start when you have to service an amp. Is there a specific way to work once you have check all the basics (fuses, power supply, and visual check up around caps and chips) ?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Do i need, for example to simulate the speaker impedance if i disconnect it from the board for troubleshooting the circuit ?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>So this thread is more to have tips, readings about this kind of thing, since i don't feel really comfortable working on it from scratch knowledge !<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks per advance<o:p></o:p></p></div><div><p class=MsoNormal>J.<o:p></o:p></p></div><p class=MsoNormal>-- <o:p></o:p></p><div><div><div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><a href="https://hearthis.at/jean-bender/" target="_blank">Jean Bender</a><br><br><a href="http://h.a.k.free.fr/" target="_blank">Hak Lofi Record</a><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal style='margin-bottom:12.0pt'><br><br><o:p></o:p></p></div></div></div></div></div></div></div></body></html>