Underlying Distortion Issue.

[J M Fahey]

Well, standard solution to weak/poor/underrated connectors is to remove them for good and replace them with real sodered wires to the same pads.
AFAIK Bugeras suffered mainly from overheating/melting filament feed pads, but replacing *all* is cheap insurance.
Good project for a rainy Saturday afternoon

[Enzo]

They were not the first company to find out that the Molex was not up to the task of heater current. It is a five wire connector, you can solder just the two heater wires direct and leave the others, but why? It is just three more wires, solder them. With the two now soldered, having the connector doesn;t allow you to separate the boards anymore anyway.

[Muskratt]

Well, standard solution to weak/poor/underrated connectors is to remove them for good and replace them with real sodered wires to the same pads.
AFAIK Bugeras suffered mainly from overheating/melting filament feed pads, but replacing *all* is cheap insurance.
Good project for a rainy Saturday afternoon

Yes I checked mine after I bought it and mine is all Factory soldered. I was glad about that being one less thing to concern with. On the Filament Feed pads are you referring to the heat sinks that i see other having to replace? And if so what should I replace them with..

[Muskratt]

They were not the first company to find out that the Molex was not up to the task of heater current. It is a five wire connector, you can solder just the two heater wires direct and leave the others, but why? It is just three more wires, solder them. With the two now soldered, having the connector doesn't allow you to separate the boards anymore anyway.

When i replaced that one capacitor I was able to disconnect the other wires and just put a non-conductive mat under it and flipped the board over on to it. Removed ad re-soldered the new one.

Despite the board being hard wired I still look for any signs when I go in for any reason.

[J M Fahey]

Sorry, don't know what heatsinks you refer to.

But anyway in general problem with connectors is that contact resistance totally depends on contact surface and contact pressure.

For modern ones contact surface isn't as large to begin with, for example in .156" "high current" connectors, they have a nice square post, which *begs* to be gripped on all 4 sides ... yet there's only a small curved leaf contact touching just one side ... and that for way less than 1 mm.



AMP or Molex have a patented "better grip" one called the trifurcon , which is still the same as the lower picture one, with two *very* small "wings" on both sides, nothing to write home about.
Extra contact surface is minuscule.

If at least they fully gripped 3 sides !!!!

Another problem is that they use thermoplastics which melt under heat , let springy contacts lose pressure, and then it spirals down.

Compare that modern technology with old obsolete one used in, say, 6L6/EL34 tubes:
thick tube pins make full contact all around with a split tube, (lots of contact surface), and are encased in thermosetting bakelite, mica-filled bakelite or straight ceramic.

Not even the slightest comparison is possible.

That's why plug-in tubes hardly have filament contact problems and modern connectors fail often.

They should make a special, square tube female connector which gripped the square post all around, along most of its length.

[Enzo]

The problem isn't the pins, the problem is expectations. I have seen these burn up in other industries too. Mostly the problem is a 5A rating makes the designer decide to run 5A through it. If your circuit dissipates 1 watt in a resistor, do you install a 1w resistor there? These connectors work fine within their limits, the trouble is over-specing them.


If you look at the "nose" sticking out of the pin, only the tip of that makes contact, a pretty small surface. Those small wings in the trifurcon effectively almost triple the contact area. I carry the trifurcons in my kit, and they have turned failure prone equipment into reliable gear many times.

[Muskratt]

The things with the Heatsinks I was referring to others have had issues with them as well. Seems after they send them back they put a better part/s in it and beef up the heatsink.
Apparently the amps also had this inherent problem on some units.