We've hit a landmark! 1 week in man-hours, but in reality, with illness and waiting for parts to come in, it's actually been over a month!
So lets get down to business and recap that radio! :)
The first thing that has to go (seems as good a place as any) is that monster 20mfd capacitor that someone used to replace the original .25mfd capacitor. Somehow I don't think 1,000 times larger falls within the nominal 5% to 10% tolerance.
As you can see there is already an orange drop in there put in place by a previous owner.
From there we simply work our way though the paper caps.
Desoldering
Personally I don't like to solder new leads to old ones. Even though it's more work, I prefer to desolder the old component and completely remove it, clean the hole on the solder tab and solder the components up right.
Desoldering though, takes quite a bit of heat to get the old solder flowing plus your trying to overcome heat dissipation through the solder tab, the old passive or (God forbid) the Chassis in the case of chassis ground connections.
If I cannot get the old solder flowing again with my 40 watt iron, I bring in the big guns! Specifically an Archer 100 watt soldering gun!
Once I get the old solder flowing I reach for the 35 watt desoldering iron to "slurp" the old solder up.
You can, if necessary, then use a Solder Braid (or Solder Wick) to finish cleaning the tab. Just be careful not to solder the braid to the tab. LOL! (been there done that).
Using a Heat Sink
If there is more than one component soldered to the same tab and you plan to re-use those components (such as Resistors or Mica capacitors) I personally prefer to protect those components from the excess heat generated during desoldering... especially when using the 100 watt soldering gun!
To do this I simply use a Radio Shack heat sink made to protect transistors and diodes while soldering.
Some may say this is un-necessarily cautious, but I personally don't believe it is.
WARNING!!
Heat sinks protect the nearby components by ABSORBING THE HEAT IT'S-SELF!!
A HEAT SINK WILL BE VERY HOT TO THE TOUCH FOLLOWING ANY SOLDERING OR DESOLDERING ACTIVITY!!
BE VERY CAREFUL NOT TO TOUCH THE HEAT SINK UNTIL IT HAS HAD A CHANCE TO COOL DOWN!!
(trust me on this one! If you do it once, even accidentally, I can just about guarantee you'll never do it again.)
Once I finished installing the new orange drops, I realized that I was 3 capacitors short!! It turns out that the store didn't have the values I needed listed for these three (a .017 and two 16mfd) and I had intended to order them from Just Radios but completely forgot about them! So I've placed the order (and while I was at it I picked up the caps for my GE models 203 and 205M) and now we wait for UPS. :)
I did find one run of wire that was corroding and replaced it. I also found a place where a wire coming from the transformer was tucked behind a long screw. This had lead to wear through the insulation leaving a bare "metal on metal" short to ground!
A bit of heat shrink tubing covering the bare areas on the wire were all it took to get it serviceable again.
It's quite odd. As I get ever closer to the day when I can plug it into the dim bulb tester, I'm getting quite apprehensive! I am looking forward to finally getting it running again, but at the same time I'm a bit nervous too. :D
No comments:
Post a Comment