Other than being dirty, it appears to be all there, so let's see what we have:
Typical dusty, dirty chassis - looks like a layer of nicotine residue, but no rust or mouse damage, and all the tubes are there. We're off to a good start!
This is interesting. At the top of the chassis, it looks like someone hacked-in a 40uF electrolytic and 500 ohm wirewound, probably because the multi-section filter cap wasn't doing it's job. Sigh. Kids.
That was an easy fix, though, and what's cool is that there aren't many tubular paper caps to deal with - National used ceramics for bypassing, and those don't usually fail.
Normally, I like to remove and restuff chassis-mounted electrolytics, but I really don't feel like this rig is worth the effort. I might change my mind tomorrow, but for now, I've disconnected the can and installed new caps on a terminal strip.
Now for the fun part! After changing the filters and inspecting for any other obvious problems - time to power it up! I don't have any pics of this process (not much to see, really) - I use a variac connected to an isolation transformer, and bring it up slowly, watching for any signs of trouble. This old National fired right up - no magic smoke was released! Yippee!
At this point, I gave it a quick evaluation, starting a "punch list" of things still needing attention:
- Band 1 (AM BC) is dead.
- Strange AVC "pumping" and background noise - mixer?
- Dirty controls/switches.
- Main tuning and Bandspread caps stiff - need clean/lube.
- Rudimentary cosmetics / degrunge.
- Screw terminals for antenna disconnected/rerouted to added SO-239 - need to be restored (why do people do this?)
Nothing looks too bad. On the good side:
- It receives: Envelope and product detectors are both working.
- ANL works.
- BFO works.
- Crystal filter/selectivity switch works.
- Dial calibration is reasonably close.
- Only a handful of tubular paper caps and one LV electrolytic (AF cathode bypass) to replace.
- Nothings smoking!
So, barring anything unforeseen, should be able to whack this one out in a few nights. Wish me luck!!!
73 - Steve