<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="">Indeed, I had a solar inverter blow up and short it's output, clearly a semiconductor failure, as my DVM didn't measure any significant conductivity between either leg and ground, but turning the power on immediately tripped the 60A 240V main breaker for that building.<div class=""><br class=""></div><div class="">Went back and forth with the vendor, finally opened up the AC power connection point:</div><div class=""><br class=""></div><div class=""><img apple-inline="yes" id="E4C9BABA-D812-40E1-968B-EBC7C5F8875E" src="cid:0204FC02-A365-4529-8520-70545AB5C39A" class=""></div><div class=""><br class=""></div><div class="">See the red wire third from the right? Yes, that red wire:</div><div class=""><br class=""></div><div class=""><img apple-inline="yes" id="0434DAD6-8556-4C0F-978D-8C4F7B1EAAD5" src="cid:38F758F8-A476-4947-B7D4-2DAA39CBCA87" class=""></div><div class=""><br class=""></div><div class="">Turned out the screws got loose over time, and the insulation got carbonized by the heat till it shorted out. Swapped the wire, tightened the screws, and it's fine. Also put a sticker on the box to remind me to (re)tighten the screws yearly.</div><div class=""><br class=""></div><div class="">When is a short not a short?</div><div class=""><br class=""></div><div class="">73, Willie N1JBJ</div><div class=""><div class=""><div><br class=""></div></div><div><blockquote type="cite" class=""><div class="">On Aug 22, 2022, at 9:50 AM, Geoffrey Feldman <<a href="mailto:geoffreyf@comcast.net" class="">geoffreyf@comcast.net</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta charset="UTF-8" class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 18px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class="">It would be interesting to know what “The fuse” really is and what purpose it is there to serve. Semiconductor junctions can change when stressed.<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class="">This brings up something which I feel is really important in electronics. Terms such as “Resistor”, “Capacitor”, “Transistor”, “Diode” , “Inductor” are really ideals of what the thing really is. Capacitors have inductance. Inductors have capacitance. Transistors and diodes have capacitance. Resistors have inductive properties. Conductors together on a board have all of the above. We need the ideals to simplify our thinking but we need to know – there is more to it than that. By the way, not all fuses are alike and none of the above die a natural death.<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class="">A favorite experiment is that LED’s actually can produce current when exposed to light. This actually is important in developing LED lighting because light reflecting back into the LED can increase current and reduce efficiency. The other fun thing is that LED’s are sensitive to light in a near but not exact wave length to what they produce. A fun Arduino type project is to pulse an LED just a the margin of producing light. This builds a charge in the junction. The Arduino can measure this charge. The charge dissipates quicker if the LED is exposed to light near the wave length it emits. So where are the ideals now?<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class="">This type of clip and measure process is one that I have used myself. Though, It can produce a poor customer response when the thing is “Fixed”. A more patient approach of observing whether voltages make sense on a schematic is another option.<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class="">W1GCF<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class="">Geoff<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div class=""><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(181, 196, 223); padding: 3pt 0in 0in;" class=""><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><b class=""><span style="font-size: 10pt; font-family: Tahoma, sans-serif;" class="">From:</span></b><span style="font-size: 10pt; font-family: Tahoma, sans-serif;" class=""><span class="Apple-converted-space"> </span>bars [<a href="mailto:bars-bounces@w1hh.org" style="color: purple; text-decoration: underline;" class="">mailto:bars-bounces@w1hh.org</a>]<span class="Apple-converted-space"> </span><b class="">On Behalf Of<span class="Apple-converted-space"> </span></b>Tim KC1RET<br class=""><b class="">Sent:</b><span class="Apple-converted-space"> </span>Monday, August 22, 2022 9:35 AM<br class=""><b class="">To:</b><span class="Apple-converted-space"> </span>BARS Reflector<br class=""><b class="">Subject:</b><span class="Apple-converted-space"> </span>[bars] When is a fuse not a fuse?<o:p class=""></o:p></span></div></div></div><div style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><o:p class=""> </o:p></div><p class="MsoNormal" style="margin: 0in 0in 12pt; font-size: 12pt; font-family: "Times New Roman", serif;">The saga of my 'dead' TS-2000 continues.<br class=""><br class="">So after hours of deciphering schematics and finally performing a radio autopsy on my kitchen counter I was struck with this conundrum... How could the supply voltage read 13.8v at the connector, but only 5.2 where the wire connected to the main board?<br class=""><br class="">At first I suspected the filter caps. They are soldered directly to the back of the connector inside the radio, dead-bug style. I cut they leads, one-by-one and they were all good & no change to the voltage reading. In a fit of desperation, I checked continuity between the board and the back of the PS; + was good, GND, not-so-much. Huh?? It was measuring 2.5k ohm! I disconnected the PS lead from the radio, 2.5k between the PS lead connector and PS terminal. Ah HA! (he says - well, I really said something else quite a bit more expressive but I'll leave the specifics to your imagination) I pulled the inline fuse out - Yup, it read not open, not short, but 2.5k. I replace the fuse and the rig fired right up!<br class=""><br class="">So, when is a fuse not a fuse? When it is a resistor!<br class=""><br class="">That is a new experience for me -- I'm def. NOT going to forget it.<br class=""><br class="">73,<br class=""><br class="">T.<br class=""></p></div></div></blockquote></div><br class=""></div></body></html>