HOW TO REPAIR AND BIAS A MARSHALL 4203

REPAIR AND BIAS OF A MARSHALL 4203
Join me as we look at getting this Marshall amp going. It arrived in my workshop with no sound, and left sounding way better than I expected it to sound. Why my prejudgement? This amp is a hybrid with solid state preamp and tube power amp stages. As a great man once said “Judge not a hybrid amp lest ye be judged as a cork-sniffing wanker".

Some video markers:
5:35 Grab a small taste of the Bondi Cigars, Australia’s premier blues band
7:30 See the correct way to replace PCB mounted capacitors and other precautionary tasks to do while the PCB is out.
12:00 The OCD way to service potentiometers and tube sockets
19:50 How to check plate current and transconductance of power tubes using the MaxiMatcher
21:30 How to set bias by measuring the current through the output transformer
28:00 Eliminating Cross-Over Distortion using oscilloscope to fine-tune the Bias on the Marshall
30:00 How to set bias when there is no bias pot
34:00 Testing 1-2-3. The Soundcheck of the Marshall 4203 using Les Paul with Sliders pickups.