Marshall Superbass with mystery short in power supply. Exorcist required.

[HaroldBrooks]

I am not sure where is the best place to post the solution to a Problem. Right back under the original post? Or right after the last post?

I think I would have gone nuts if it wasn't for you guys coming up with your brilliant suggestions. In the end it was G1 who alerted me to a possible short at the junction of the 2 x100uF totem caps, and Helmholtz who said I didn't need to use totem resistors because of the CT of the HT windings performing that role. Enzo also had me double checking my wiring with the parallel-series-parallel configuration of the caps....

And there it was! I did it. I created this problem, or at the very best I copied the problem created by the Tech before me when replacing the filter caps (the amp came in with this problem). I had mindlessly connected the yellow CT wire to the + of the top totem capacitor instead of its negative (ie I should have connected it to the centre of the totem). My regret was writing down the connections during the process instead of taking photos with my camera.

Along the way, I learned some very very clever problem solving procedures, including "how to check if the switch shorting to the chassis", the "build an external bridge with no caps", "don't trust a component just because you put in a new one".

Even though you guys are on the other side of this planet, it felt like I had a dozen eyes looking over my shoulder and giving me ideas. Wow. That's an amazing feeling when you work on your own every day. THANK YOU all.

Hear Hear !

A smart man is one who knows when when to ask for help, and has the courage to ask questions, and the tenacity to finsh the job, and you did all that.

I still find myself hesitating to ask for help every now and then, and then I think of the hours I wasted in the past aimlessly poking around, just because my ego or fear is getting in the way !

The smartest people on the planet have the most unanswered questions, to ask others.

It was also you that stuck to the issue until it was resolved. Never underestimate your own role in the solution !

[g1]

Ah... Then yes. Thank you. Not sure how I missed that FROM THE FIRST POST!

It happens to all of us. My post was mostly to assure you that we weren't ignoring your excellent response.

I am not sure where is the best place to post the solution to a Problem. Right back under the original post? Or right after the last post?

Not sure how you view the forum, most of us see it in 'linear mode', so in order of date. So even if you put it under the original post, most of us would not see it that way, we would just see it as the newest post. I'd suggest you use the 'linear' setting, people using other settings sometimes miss some responses. The button up near the top right of the page labelled 'display' is where you adjust the setting.

It was also you that stuck to the issue until it was resolved. Never underestimate your own role in the solution !

Amen to that. Nothing worse than reading through a long thread to find there is no conclusion because someone junked the item or couldn't be bothered to post the resolution.

[christarak]

But I can only enjoy it because I know that the solution is only as far as this forum If I actually thought I was completely on my own I'd be overwhelmed and frustrated. So I know how you feel.

Thanks Chuck. It is quite humbling that someone of your experience gets stuck enough to refer to this almighty Brains Trust.

[christarak]

Yeah, I suspected a CT wiring error. Connecting the CT to either B+ or ground would cause the same symptoms by partially shorting the HT winding.
This will make 2 of the diodes get very hot (and eventually fail) and cause a strong increase of PT primary current.

Glad you fixed it.

Were it not for your clue to the CT, Helmoltz I would still be staring at the problem. And you're exactly right...my FLIR thermal image showed those 2 diodes getting way hot at 50VAC mains input. Thank you Sir

[christarak]

Hear Hear !

A smart man is one who knows when when to ask for help, and has the courage to ask questions, and the tenacity to finsh the job, and you did all that.

I still find myself hesitating to ask for help every now and then, and then I think of the hours I wasted in the past aimlessly poking around, just because my ego or fear is getting in the way !

The smartest people on the planet have the most unanswered questions, to ask others.

It was also you that stuck to the issue until it was resolved. Never underestimate your own role in the solution !

Thank you for your insightful words. I found that turning 60 meant I had no ego to bruise, nor do I care what people think about the way I dress. My partner said "why did you buy that red Fez?". "Why, to wear out when we are having breakfast, my dear". And I did. She was embarrased (not yet 60)...but I wasn't

[christarak]

Amen to that. Nothing worse than reading through a long thread to find there is no conclusion because someone junked the item or couldn't be bothered to post the resolution.

Amen to your Amen, G1. I have followed so many threads where the originator doesn't have the courtesy to say "I quit" or "here's what I found, and we can now add to our knowledge base".
Thanks again, G1. Next time you're in Sydney, I'll owe you a craft beer or two...or three.

[Chuck H]

Thank you for your insightful words. I found that turning 60 meant I had no ego to bruise,..

I'm only starting to experience that at 51. It feels pretty good. In fact I feel like I'm becoming a better version of myself. Not that I ever thought poorly of myself but now I regard my own personal judgment above that of others. Along with this comes an understanding of, and an ability to make concessions for those around me that goes deeper more easily than when I regarded their judgment. It's interesting, fun and liberating actually. And since I'm in the middle of the process I'm still paying attention enough to notice that others don't seem to think any less of me for it An ego is a heavy thing to carry around. But how could I have made my younger self, or any younger people in my life now understand that? The million dollar question. We're all just people and we all know it. Let your freak flag fly.