SX-62 Recap

[W1GFH]

I curse you, Hallicrafters. You used cheap wax caps, and you wedged them in inaccessible places. Didn't you realize they would have to be serviced someday? What were you thinking?


I wonder if anyone has a trick to get at caps hiding deep within layers of shielding, components, and complex bandswitches.

I am recapping an SX-62, and there are only 3 caps that have me beat. The only way to get at them would be (a) take the bandswitch apart in order to remove the steel partitions (almost as easy as brain surgery), or (b) some kinda very long-nose pliers with side-cutters at the tip, and an absurdly long, pencil-thin soldering iron.

[ka0pad]

Can you clip one end and leave the cap in there? It's been a while since I recapped mine but I seem to remember the tough ones had one end at ground, clip the signal end at the cap, slip the replacement cap lead over the old lead and solder, ground the other end someplace else close by. Great radio, what a monster.

[W1GFH]

Yes, one end of the problem caps is at ground. Although I hate the idea of leaving those wax bastards in there, I will think about your suggestion - it has a lot of merit.

[K6JEK]

Yes, one end of the problem caps is at ground. Although I hate the idea of leaving those wax bastards in there, I will think about your suggestion - it has a lot of merit.

Don't forget them resistors, pardner.  When I recapped my SX-62 a few years ago I found almost all of the resistors way high.  A couple of other things I remember.  After the fact, I was advised to leave the braided lead caps alone.  Somebody explained (and I forgot) why Halli needed these special super low impedance leads.  Well I chopped mine out but maybe it's not too late for you.  Also when you get around to re-aligning you'll find several wax-sealed slugs.  The folks I talked to said to their amazement after they carefully melted the wax (big debate on the safest way to do this) they discovered the darn things were still dead on -- didn't need any alignment.  So their advice, which I followed, was unless you're really convinced you need to tweak them, leave them alone.

You know why it's called the SX-62?  My theory is that there are 62 steps in the alignment procedure.

Jon

[W1GFH]

Thanks Jon, I really shouldn't curse Halli, cuz from the looks of the component layout under the chassis they were trying their best to save space and make these rigs fit a convenient "desktop" size.

[w3jn]

Because the front end works from 500kc-110MC, the braided caps have muich lower lead inductance than regular waxies.  This is so the cap actually does some bypassing at VHF regions.

And no, I don't have a magic method for that front end.  I used a looong needle nose and just bent the caps back and forth till the one end broke, then soldered onto the broken wire.

And BE SURE you replace the caps associated with the tone switch.  If one shorts the output tranny goes "poof".  I'd check both sections of the output tranny primary to make sure they're good.  Out of 6 or 8 SX-42s/SX-62s I've done I think I've only seen one or two good output trannies.

73 John

[ka0pad]

I've used solder wick  to reproduce those low-L leads, as long as solder doesnt wick down the length and turn it into a thick wire, what you want is all that surface area from all those little wires. Take care relocating the grounding points on those buggers too.

[W1GFH]

JN, my output tranny is good. Those old tone switch caps did their job.

Thanks to your (and others) hints and kinks I have gotten EVERY wax cap out of the SX-62 now -- except for TWO of the little buggers that are wedged in like sardines at the bottom of a sardine tin. They are the .05's going cathode-to-ground on V1 and V2 (the 6AG5's - 1st and 2nd RF amp) and yes, they have braided leads. Screw this braided lead crap. I will just make my new poly cap's leads as short as possible. But none of my cutters can get "down in there" to pin 2 of the tube bases to cut the signal side lead of the cap. Twisting with needle nose pliers worked in other locations, but this one is too tight, delicate ceramic padders would be twisted too. I've been staring at these two caps for hours, trying to visualize a way to get at them without taking the bandswitch apart. Hmmm, I see the row of padders on L-brackets look removeable - but wait - no - they are also soldered at multiple points right into the bandswitch.
AaaIIIIYYYIIIIIIaaaaaaaaaaaaaaAAAAAGH.

[w3jn]

I wouldn't bother with 'em if they're cathode bypass caps.  Solder another one in parallel if you must, but they won't short due to the low voltage on 'em, and who cares if they leak, they're in parallel with a 180 ohm resistor or something.  Screw it, call it good enough 

[W1GFH]

Followed your advice, left those two caps in. Here's the finished SX-62....as imagined in a 1950's fallout shelter, waiting for nuclear war.