<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Could I trouble some patient soul to cast their eyes over this circuit and explain what should happen?<div class="">The JP8 CPU reset circuit is in the grey box on the right half of the image.</div><div class=""><br class=""></div><div class=""><img apple-inline="yes" id="326C713F-FDFE-40BC-9279-054BCEC4273B" src="cid:3D7F897C-F0C4-4CBA-96A1-2F04E5028368" class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class=""><br class=""></div><div class="">My jupe has been taking its time booting these last few months, 5 or 10 minutes, and now sometimes is refusing to boot at all. (Occasionally it will boot as usual in a couple of seconds after going through the tune routine, so the fault appears to be intermittent). </div><div class="">Up on the bench, when failing to boot, I measure the reset pin 26 on the CPU as 1.4 v. When it boots successfully, that voltage takes a second to go from 1.4 up to 4.9 volts.</div><div class="">So I’m suspecting something in the reset circuit.</div></div><div class=""><br class=""></div><div class="">When working:</div><div class="">Transistor 1 measures</div><div class="">E = 00 v</div><div class="">C = 0.14 v</div><div class="">B = 0.59 v</div><div class="">Transistor 2 measures</div><div class="">E = 00v</div><div class="">C = 4.9 v</div><div class="">B = 0.14 v</div><div class=""><br class=""></div><div class="">When not working the only change is the collector of TR2 doesn’t come up above 1.4 v</div><div class=""><br class=""></div><div class="">cheers</div><div class="">Adam</div></body></html>