What do you prop your chassis up with?

[oguinn]

I'm experiencing some weirdness with my right channel (it popped loudly then went out, then came back when I swapped tubes - pretty sure I have a flaky connection on the 2A3 socket) so I need to have at it with a chopstick. So here's a dumb question - what are you all using to prop the chassis up when you're doing this sort of troubleshooting since the 2A3 glass is taller than the wood base?

More of a brainstorming session than a progress blocker at this point since I could probably just use some... bricks or something.

[Tom-s]

I just borrow the fattest books to be found here in the student dorm.
Law and medicine student's are helpful when it comes to finding fat books to hold the SII. 

All serious, use books. They are a solid foundation to work on.
I've worked on both mainline and S3X with the help of some Sobota's, Boron and Boulpaeps, and others.

[oguinn]

That’s what I’ve been using but turning the chassis upside down with all the stuff attached suuuuuucks. I’ll carry on!

[oguinn]

Stacked it on some books, spent 30 minutes wailing away at it with a chopstick, re-ran voltage checks. Nothing happened, works fine. I dunno.

[Paul Birkeland]

I would very carefully check the connection of the big white cathode resistors.  If you have a flaky solder joint on one of those and the bias resistor falls out of the circuit, weird stuff can happen!

[oguinn]

Are those the ones that sit on top of the trim pots or the ones that sit to the inside of the A and D tubes sockets against the plate?

I jammed around on both for a bit, but I can try again.

[Deke609]

 I assumed PB meant the 2K and 3K resistors alongside the 4 pin socket against the chassis (in parallel with the 220uF cap), but looking at the schematic it seems that the hum pot and 22R and 0.15R resistors also technically form part of the cathode resistor circuit - so maybe check all of the above?


cheers,


Derek

[oguinn]

Yeah I spent a pretty good amount of time prodding with no pops or clicks or anything. I’ll let it run for a while and see if it crops up again, but I wasn’t able to replicate.

[Paul Birkeland]

The 2K and 3K resistors.  If the other resistors between the hum pot and pins 1 and 4 on the 4 pin sockets becomes disconnected, you'll just drop a channel as the 2A3 cools off quickly.

[oguinn]

Maybe something will manifest itself again tomorrow. It was on and running for a solid 8 hours today when that channel dropped, so maybe it needs to get warm for the issue to present.

[oguinn]

I would very carefully check the connection of the big white cathode resistors.  If you have a flaky solder joint on one of those and the bias resistor falls out of the circuit, weird stuff can happen!

By the way, when you say “weird stuff” do you mean “weird noises” or “hundreds of dollars in new parts and tubes”, since that will color how cavalier I am with troubleshooting.

[Paul Birkeland]

Weird noises certainly, though I haven't ever experienced major damage from a loose connection there.  The major damage happens when you plug a tube in with the fat pins not in the larger holes in the socket.

[oguinn]

Got it, thanks.

[Tom-s]

So yesterday i spend my day building the SII (it sounds awesome! Wow) and had to think about this topic.
Here's the SII next to the oral surgery book i used for the needed elevation.

https://ep1.pinkbike.org/p5pb17470141/p5pb17470141.jpg

[oguinn]

Tom - your Stereomour looks really nice! Send me a couple close up pics and I'll post them to the gallery site.