Re: 4xx voltage selector block contact removal


tom jobe <tomjobe@...>
 

Some comments about removing the pins from the voltage selector / fuse block on some 4xx scopes such as a 465 or 475.
After experimenting with some homemade tools, it became very obvious that an ordinary 1/8" mechanics punch with a nice flat end on it would work every bit as well.
The pins you are trying to remove have a springy three legged thing in the middle of them that holds the pin into the socket, and any form of a 'push' will make then fall out of the back of the block.
In my experimenting I used a brass hammer, but will change to a soft hammer or a block of wood for a hammer next time to lessen the chances of damaging anything.
The pin I took in and out of the same hole several times show no hint of damage, so it's not a delicate situation.
If anyone wants some photos of this experiment, I will send them directly to you on request.//If you think these photos should be posted anywhere, I will send them to you and you can do it.
tom jobe...

On 10/7/2018 5:57 AM, tom jobe wrote:
Hi Jim,
I have carefully studied your written explanation of how the contacts are held in the voltage selector block, but I still do not have a clear idea what it all looks like.
Probably the best plan at this point would be to make a two piece removal tool like I think you have described and see if I have it right.
It makes sense that the pins are probably soldered onto the transformers leads before the pins are inserted into the backside of the block, so the tool should probably drive the pins back into the scope's interior the way the block is mounted on the back of the scope.
I will report back, and offer photos of whatever happens with this pin removal experiment.
tom jobe...


 >>>   George, Tom, and all,
    I cut the thing apart so I know what it looks like inside the socket bore and also the config of the socket. It is as George says it has a three tab annular ring in a groove about three fourths of the way up from the opening. The socket bore has a shoulder, (ridge) with square edges both sides that the ring snaps over, the ring is split so its springy. there is a fixed shoulder built into the socket at the wire crimp area to rest against the ridge to stop it from going out the other end of the block. The three tabs on the front side have a small rolled ridge tapered front and rear to allow it to slide over the ridge inside and then expand around the ridge to locate it in the block. tried the extractor over the socket after it is out and there is no way to use a tubular tool to extract it it will not slide over the tab ridge. I believe the tool used is a tube to center the socket and then it has a pin inside used to drive out the socket the tabs are designed to compress as it is forced out they have a longer taper on the back ridge side than the front insert side.
    The forcing pin should be double sized a smaller guide pin to fit inside the socket with a ridge at the larger dia to set against the socket and force it out almost lightly tapped on the push pin to snap it over the inside ridge some lube used maybe to assist?

    Jim O   <<<



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