...So I’ve got to find the screw now which is on the inside of the tube shield and reinstall it in case it falls out somewhere and shorts something. That possibly means removing the tube ![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
Ah well I wanted a project. Nice to be back in the trenches!
Mmmhmmm... have you tried *gulp* shaking it out...? ![Scared :scared:](https://www.eevblog.com/forum/Smileys/default/scared.gif)
mnem
Hold onto your butts...
Can't tell you how many times I dropped a screw into the bowels of a 400 series and I had to resort to shaking, turning, and lots of cursing until it finally dropped onto the bench. ![Phew :phew:](https://www.eevblog.com/forum/Smileys/default/phew.gif)
The transistors for the Type 547 showed up but too late in the day. Tomorrow's activity.
Marconi will do the dropping for you!
Years ago, at work, we had a sideband analyser which, at odd intervals, would blow a HT (around 400v) fuse.
This device was of a "clever" construction, being made up of three hinged units that, when mounted on a rack, folded in like a roadmap, making it very compact design for a tube design.
To chase faults, you obviously folded it out, & every time this was done, & the fuse replaced it was"no fault found".
Eventually, we hung an AVO meter on the 10 amps range in place of the fuse, folded it up & turned it on.
Luck was with us, the fault appeared, the needle swung well up the scale, & we could see a wirewound resistor glowing red.
Investigating, we found the resistor mounted across two terminals of a tag strip, with about a 2BA nut sitting just under one terminal.
With the unit unfolded, there was just enough clearance that it didn't short on the terminal, but folding it up distorted things just enough to either almost do so, or to do so immediately, depending on luck.
Even if you were lucky & "jagged" the non- shorted condition, over time, the assembly could distort enough that it would give you a random short circuit!
The nut was removed, nor without difficulty, using a pair of long nosed pliers, & all was well.