Marshall JVM Bias Drift PCB Surgery

A brief video demonstrating how to perform a Marshall JVM 410 PCB modification to deal with unstable bias and PCB conductivity causing blown tubes and high tension fuses.
As with many modern PCB-based multi-channel Marshalls, this JVM 410 was blowing the high tension B+ fuse. As recommended by Dr. Tube (drtube.com/en/...) the power tube grid leads (pin 5) were isolated from the PCB to ensure (-)DC voltage reaches the tubes without any possible leakage from the other tube socket leads.
Hack to safely bias this amp using a Molex 3-pin connector is shown, that Molex connector is: www.ebay.com/i...
Additionally, a filter choke was added (see the link below on how to install). The filter choke helps smooth out the B+ which feeds the preamp tubes and helps reduce a lot of the noise from the OD channels.
Also if you like my channel and this video on amps, I suggest subscribing to the following awesome channels:
-Uncle Doug: / @uncledoug
Uncle Doug has tons of other videos, probably the best teacher on TH-cam regarding amps
-The Guitologist: / @theguitologist
Brad runs an all-around great channel, loves to work on wonky stuff as well
-D-lab: / @d-labelectronics
Terry is likely the best electronics technician working to repair tube amps on YT
Related links:
-Safety! Rob's word on capacitor charge: robrobinette.c...
Rob's site is likely the most comprehensive resource regarding classic Fender amps, and now amps work.
-Brad the Guitologist working on a similar Marshall: • Mother of All Marshall...
-JVM Choke Install: • How to add a choke to ...
-Why install a choke: • PI filter, Resistor Ch...
-drill bits: www.amazon.com...
-Marshall Bias Drift info www.lynx.net/~j...
-Uncle Doug on Biasing: easiest way to really understand how biasing works
• Biasing Single-Ended A...
• Biasing Double-Ended A...
• Biasing Double-Ended A...