Hi,
I had a mishap with my 3 channel B22. The problem is with the ground channel. After hooking up probes to R9 and powering on, I saw a couple of sparks by the probe and powered down. Looking at the board I nipped/scrapped the board coating and probably shorted the left side of R9 to the ground plane. I should be more careful
I checked the diodes, it looks like CR7 is toast (nothing visible but fails the diode check on my multi-meter. Q25 measures differently to the other boards, I've been measuring between the base-emitter base-collector using the diode check on my multimeter. Q23 seems a little inconsistent measuring between the gate/drain/source when comparing to the other boards.
The other pnp/npn transistors seem OK, they pass the diode check when measuring between base-emitter, base collector.
Does anyone have any advice checking MOSFETS and JFETS?
The resistances between the gates/drain/sources are consistent with the other two boards. Other diodes on the ground channel board check out.
I've been listening with basic two channels, so I have two working boards to use as reference. Sounds great with just two channels by the way!
Before I order new parts I wanted to check if there are better ways of determining if the MOSFETS/JFETS are OK preferably in circuit. I've not powered up the ground channel since the mishap.
If the board will take too much re-work it might be worth starting over.
Thank in advance for any help anyone can provide.
James