25-08-2015, 04:27 PM
(This post was last modified: 25-08-2015, 04:29 PM by Nowhere-Man.)
I've been having problems today with soldering on this set. The problem lies in the fact the designers chose to mount the main capacitors and resistors on a small ladder. Each side of the ladder has small holes and then rungs. The idea is to actually thread in leads via the holes, twist and then solder so all the connections are ultra safe. That's all well and good at the time of manufacture but - 60 years later on it's a big problem.
There are two ways to approach the ladder layout. One option is to take the ladder off so you have full access. The snag with that is it will involve snipping at least 10 tangled and barely visible leads. Some of these go to valve pins or chassis lugs. Should you in any way get mixed up as to what goes where, tracing the circuit will be a nightmare. Lots of wires have been crossed tied together and some may disappear into holes and emerge with others, knotted up. Plus the original caps are so dirty, you can only read the ratings after cleaning with chemicals.
Second option is to leave the ladder where it is and attempt to solder regardless. That is the way I've tried to do it. I had no success at all with my usual soldering method as the further end of the ladder has a small surface area and is designed to solder and thread leads through the small perforations drilled out. I finally have found a system that offers some hope. I got some stiff, insulated wire and used lots of solder to fix one end of it to the furthermost end of the ladder where the original capacitor was. Then draw the wire forwards and loop a couple of turns around the near end of the ladder to take up any stress in the joints and provide a firm base. Next, solder the capacitor one end to the knotted wire and the other end direct to it's lug. It's not as good as the original layout but I found after a few attempts I ended up with a pretty strong joint.
Normally you'd just solder one lead to one valve pin and another lead to wherever it may go and you can see it all in context with the circuit. In this case, it's much more awkward.
I'll need a 5000 K volume pot a bit later on.
Definitely much harder than the GEC I was working on. Hopefully now I worked out a viable approach it may be easier tomorrow.
There are two ways to approach the ladder layout. One option is to take the ladder off so you have full access. The snag with that is it will involve snipping at least 10 tangled and barely visible leads. Some of these go to valve pins or chassis lugs. Should you in any way get mixed up as to what goes where, tracing the circuit will be a nightmare. Lots of wires have been crossed tied together and some may disappear into holes and emerge with others, knotted up. Plus the original caps are so dirty, you can only read the ratings after cleaning with chemicals.
Second option is to leave the ladder where it is and attempt to solder regardless. That is the way I've tried to do it. I had no success at all with my usual soldering method as the further end of the ladder has a small surface area and is designed to solder and thread leads through the small perforations drilled out. I finally have found a system that offers some hope. I got some stiff, insulated wire and used lots of solder to fix one end of it to the furthermost end of the ladder where the original capacitor was. Then draw the wire forwards and loop a couple of turns around the near end of the ladder to take up any stress in the joints and provide a firm base. Next, solder the capacitor one end to the knotted wire and the other end direct to it's lug. It's not as good as the original layout but I found after a few attempts I ended up with a pretty strong joint.
Normally you'd just solder one lead to one valve pin and another lead to wherever it may go and you can see it all in context with the circuit. In this case, it's much more awkward.
I'll need a 5000 K volume pot a bit later on.
Definitely much harder than the GEC I was working on. Hopefully now I worked out a viable approach it may be easier tomorrow.
