An angled desoldering tool for cleaning tube socket terminals

Removing components and solder from tube socket tabs is not difficult. But it's a tedious business. If you're removing a lot of components you'll be glad for anything that speeds the process up. Here's a standard solder sucker or solder pump:








It's a common tool used to suck molten solder away from a solder joint. It's spring loaded inside. After it's cocked, pushing the black button releases the internal plunger and causes a vacuum effect at the tip to suck solder away into the body of the pump. It works well in plenty of situations but frequently the flat tip doesn't quite fit the bill. I keep a collection of desoldering tools suited for specific jobs (here's another one I modified for use for PC board mounted pots). On this one I've cut away part of the tip for use at tricky angles. Here's the stock tip and the angled one:











The angled tip is hugely helpful for getting a good seal against the old solder joint on a tube socket terminal. Here it is pressed against one side of the solder joint with the soldering iron heating the joint from the other side:







Note the angle of the tip. In tight quarters it's impossible to get a straight tip to sit this snugly against the tube socket tab. With a nice tight seal against the joint the terminal comes clean with just one activation of the pump:







This may seem trivial, but when you have enough joints to do it saves serious amounts of time. There are around 50 joints for me to desolder and clean on this Ampex 601 rebuild. Futzing around with awkward positioning of the desoldering pump makes for a poor seal and it can easily take a half dozen shots to clean the joint out well in a cramped chassis. If you fiddle with each joint for 2 or 3 minutes you could be spending a couple hours just sucking the solder out. Getting the remaining wires and component leads off of the terminals without damaging them can still be fiddly. But having the old solder removed quickly speeds the process up immensely and gets you on to the interesting parts of the work.

Desoldering Tool for PC Board Mounted Pots

This picture's from an Ampeg B25B that came in for intermittent/scratchy performance and one broken channel. The channel 2 bass pot wouldn't turn at all. When I opened it up I found this dead bug and a bunch of what looks like it might have at one time been a clutch of eggs or something sprayed around the outside of the pot. Inside the pot there was another bug ground up and mixed with the pot lubricant which through some foul miracle turned into a sort of cement that held the pot stationary.







But that's not what this post is about.

The pot had to come out to be opened and cleaned. Taking resistors and axial caps off a board isn't so tough because they flex enough for you to heat the solder connection at one end of the component and gently pull that side out while the solder is still liquid. Then you just repeat for the other end.

Stiff components can be a pain though - especially ones held to the board at more than two points.

For this kind of job I frequently use this slightly modified desoldering iron. This style is just a regular iron with a suction tube attached to a hollow angled tip. You squeeze the red suction bulb and press the end of the iron against the joint. When the old joint becomes liquid you release the bulb and the solder is ostensibly sucked away.







The original tip has a fairly small opening so the only option for desoldering larger leads was to press the tip to one side of a joint, clear it and the do the other side. The seal against the board wasn't very tight this way. This meant that the suction wasn't great either so it usually would take a few passes to get enough solder off to free a joint.

To make the iron more useful for amp work I pulled the tip off and drilled it out from the back to 3/32 of an inch. Now the tip fits right over the ends of most components leads - even the fairly large ones on these Ampeg pots. With the lead fed up inside the tip the the whole joint is heated very evenly. Once the solder melts the opening of the iron can be pushed flush with the board. The tighter seal makes suction good enough to pull the solder off the joint, off the lead and out of the mounting hole in one fell swoop.







The desoldering tip goes right over the protruding lead. As soon as the old solder liquifies, release the bulb and the old joint is almost completely removed.

Part of the trick to having it work well is to tin the hole over with solder before using it. Tinning is just melting new solder onto the hot iron to form a molten solder coat over the tip. This protects the tip from corrosion and aids in the heat transfer. The old joints heat much more quickly this way. Most take only about 2 seconds. This is great becuse the shorter time and more even heat means less chance of damaging the board.

Here I'm melting a bit of fresh solder into the tip:







It's important to squeeze the suction bulb in before you start and then hold it there while you do the tinning - otherwise you'll just blow the solder out when squeeze the bulb before cleaning the joint. You can see below that the hole is completely filled with molten solder.







I find it's not necessary to re-tin the tip for every joint. I just do it when it starts taking a bit longer for the old solder joint to melt.

I ended up removing all the pots for good measure. Here are the joints from the treble pot. You can see the backplate for one of the disassembled rocker switches floating above suspended by it's leads.




These joints came clean with just one pass from the iron. The old pot pops right out without having to heat the joint again.




The mounting holes are generally clear enough that they don't have to be touched up at all before the pot goes back in - makes the whole business go a lot quicker.

Fender Champion 600 - Discharging the Filter Caps Pt 1

Here's the procedure for discharging the filter caps in a Fender Champion 600.



The video is pretty small so I'll put up another post with pictures so the detail is a bit clearer.

I'll cover the construction of the probe in a later post.

THE UBIQUITOUS DISCLAIMER: AKAVALVE ASSUMES NO RESPONSIBILITY FOR THE SAFETY OF ANYONE IMPLEMENTING THESE INSTRUCTIONS. IF YOU ARE NOT FAMILIAR WITH SAFE PRACTICE IN HIGH VOLTAGE CIRCUITS, DO NOT ATTEMPT THIS YOURSELF.

Discharging Filter Caps - The Basics Pt 2

Here's hows how a discharge probe is used to bleed voltage off of a capacitor. This cap is completely removed from the circuit for illustrational purposes, but the procedure is the same when a cap is installed in an amplifier. The meter is tough to read here but I hope it's good enough to get the general idea.



The resistor at the clip end of the probe is a 56K 3 Watt one covered in two layers of shrink tubing for safety. The resistor will limit the current from a 450 Volt supply to under 10 ma but it is still a very good idea not touch the alligator clip end of the probe while connecting the other end to the B+. I'll cover the probe construction in a later post.

THE UBIQUITOUS DISCLAIMER: AKAVALVE ASSUMES NO RESPONSIBILITY FOR THE SAFETY OF ANYONE IMPLEMENTING THESE INSTRUCTIONS. IF YOU ARE NOT FAMILIAR WITH SAFE PRACTICE IN HIGH VOLTAGE CIRCUITS, DO NOT ATTEMPT THIS YOURSELF.

Discharging Filter Caps - The Basics Pt 1

Here are the basic reasons and methods for discharging filter caps. The meter is a little tough to read here but I think it's clear enough to get the basic idea. This is just for illustrational purposes, it's NOT the the method I recommend. I'll cover that in part 2.

THE UBIQUITOUS DISCLAIMER: AKAVALVE ASSUMES NO RESPONSIBILITY FOR THE SAFETY OF ANYONE IMPLEMENTING THESE INSTRUCTIONS. IF YOU ARE NOT FAMILIAR WITH SAFE PRACTICE IN HIGH VOLTAGE CIRCUITS, DO NOT ATTEMPT THIS YOURSELF.

Spring Clip Tube Removal Tool

Tight spring clips do a good job of keeping your power tubes in place. They can be a pain when you're trying to get the tubes out though - especially when the amp is still is it's cab and you're trying to wrestle two hands around a hefty output transformer. Here's a tool I came up with to make the job a bit easier.