Mesa Boogie amps have more bells and whistles than a Shriner Circus parade and this is one of their most complex designs - the Dual Rectifier Roadster. This amp came to me with a supposed bad output transformer, but after repairing that I found other problems, namely NO output or very, very LOW output. In this video, we'll diagnose the problem through the dense morass of schematic and PCB and find out why so many technicians loathe working on Mesa amps.<br /><br />SPOILER ALERT: The fault ends up being with the switching matrix. The amp had entered a state known to Mesa engineers as "permanent mute" or "permamute". To fix this issue requires replacing one or more of the JFET transistors in the switching matrix. Not something you want to do with a bad soldering iron tip! This video includes an overview and discussion of this ingenious mute switching circuit for which Mesa holds a patent.<br />------------------------------------------------<br />*WAYS YOU CAN SUPPORT THIS CHANNEL:*<br />♠Stand in the Middle of the Street Naked Screaming "LONG LIVE THE GUITOLOGIST"!<br />OR<br />♠Send an unwanted piece of gear or send a small tip via Paypal: [email protected]<br />Thanks for your support!<br /><br />♠STUFF I USE<br />-5A Variac: <a href="http://amzn.to/2FNWthU" target="_blank" rel="nofollow">http://amzn.to/2FNWthU</a><br />-Jameco Isolation Transformer: <a href="https://amzn.to/2PRv1Fa" target="_blank" rel="nofollow">https://amzn.to/2PRv1Fa</a><br />-Fluke 87: <a href="http://amzn.to/2DwHjvr" target="_blank" rel="nofollow">http://amzn.to/2DwHjvr</a><br />-Yotec 936 Soldering Station: <a href="http://bit.ly/2JqB1Vw" target="_blank" rel="nofollow">http://bit.ly/2JqB1Vw</a><br />-Sealody SSA51 soldering station: <a href="http://amzn.to/2DJTS7P" target="_blank" rel="nofollow">http://amzn.to/2DJTS7P</a><br />-Black and Decker Heat Gun: <a href="http://amzn.to/2DWpDhr" target="_blank" rel="nofollow">http://amzn.to/2DWpDhr</a><br />-Geekcreit® LCR-T4 Mega328 Transistor Tester <a href="http://bit.ly/2J9uLSA" target="_blank" rel="nofollow">http://bit.ly/2J9uLSA</a><br />-HT02 Handheld Infrared Thermal Camera <a href="http://bit.ly/2LXfLoD" target="_blank" rel="nofollow">http://bit.ly/2LXfLoD</a><br />-Solderless Breadboard: <a href="http://bit.ly/2stkVAq" target="_blank" rel="nofollow">http://bit.ly/2stkVAq</a><br />-Breadboard Jumper Wires: <a href="http://bit.ly/2JowaEh" target="_blank" rel="nofollow">http://bit.ly/2JowaEh</a><br />-Geekcreit® XR2206 Function Signal Generator DIY Kit <a href="http://bit.ly/2LYBvkb" target="_blank" rel="nofollow">http://bit.ly/2LYBvkb</a><br />-Contact Cleaner: <a href="http://amzn.to/2FVitro" target="_blank" rel="nofollow">http://amzn.to/2FVitro</a><br />-Deoxit Fader Cleaner: <a href="https://amzn.to/2LPwtsE" target="_blank" rel="nofollow">https://amzn.to/2LPwtsE</a><br />♠RECORDING<br />-JVC Everio Camcorder <a href="https://amzn.to/2RLIleU" target="_blank" rel="nofollow">https://amzn.to/2RLIleU</a><br />-Andonstar USB Microscope: <a href="https://bit.ly/2q8QIWz" target="_blank" rel="nofollow">https://bit.ly/2q8QIWz</a><br />-Articulated Boom Arm with Cam Mount: <a href="https://amzn.to/2Hlo2AX" target="_blank" rel="nofollow">https://amzn.to/2Hlo2AX</a><br />-Shure Beta 87A <a href="https://amzn.to/2rNPnoW" target="_blank" rel="nofollow">https://amzn.to/2rNPnoW</a><br />-EV 635A Omnidirectional Dynamic Mic <a href="https://amzn.to/2pR8HQT" target="_blank" rel="nofollow">https://amzn.to/2pR8HQT</a><br />♠BOOKS<br />-RCA TUBE MANUAL <a href="http://amzn.to/2GOBVqS" target="_blank" rel="nofollow">http://amzn.to/2GOBVqS</a><br />-DESIGN AND CONSTRUCTION OF TUBE AMPLIFIERS: <a href="http://amzn.to/2HSNMne" target="_blank" rel="nofollow">http://amzn.to/2HSNMne</a><br />-Designing Tube Preamps for Guitar and Bass: <a href="http://amzn.to/2DK5tmt" target="_blank" rel="nofollow">http://amzn.to/2DK5tmt</a><br />♠2006 FENDER AMERICAN STD TELECASTER PICKUPS<br />-TV Jones Magnatron Neck: <a href="https://amzn.to/2q1zQjD" target="_blank" rel="nofollow">https://amzn.to/2q1zQjD</a><br />-Seymour Duncan Vintage Stacked Bridge: <a href="https://amzn.to/2GyZjrK" target="_blank" rel="nofollow">https://amzn.to/2GyZjrK</a><br />...<br /><a href="https://www.youtube.com/watch?v=4kNMtOmT76U" target="_blank" rel="nofollow">https://www.youtube.com/watch?v=4kNMtOmT76U</a>