Multi tank stereo spring reverb

[Tubetec]

Crafty folk the Austrians alright ,
the whole coil assembly on the bx looks like a very delicately balanced piece of kit alright .
Could the fault be a breakdown of the insulation on the coils themselves at the point there suspended ?
seems a bit unlikely that the goldie thing would degrade .if it is the gold thingy ,maybe you could detatch the wires from that leg insulate it ,and use it as a support for a piece of strong copper wire then re-attach your signal wires to it.
Saw this on ebay the other day ,looks like its been snapped up already though
http://www.ebay.ie/itm/AKG-BX-2-vintage-spring-reverb-tube-From-the-BX-5-BX-10-and-BX-20-family-/201896079100?hash=item2f01f1aefc:gi4AAOSwopRYb5rl
looked like a decent price too ,they must be a rare part to find these days

 

[zamproject]

Could the fault be a breakdown of the insulation on the coils themselves at the point there suspended ?

No it's not the suspension point to gold can, one coil is ok and the other too (200ohm) but I measure let say 2k to ground at one end and 2k2 at other hand meaning isolation problem is at one end only as I measure coil + "leak" to ground at other end.

f it is the gold thingy ,maybe you could detatch the wires from that leg insulate it ,and use it as a support for a piece of strong copper wire then re-attach your signal wires to it.

That's my goal, but not try yet... the coil wire are close to invisible...and the magnet huge force make any work with metallic tool at this place absolutely hazardous. I have to find a way to approach the soldering iron without having it catched, I assure you it's a pain or impossible to retain a tool in the centimetre range at this place of the system. And if in the uncontrolled move you pick a tin  wire or the coil/top spring you definitely broke the system  :-\
I'm thinking of removing the magnet, but seem not an easy task either

Best
Zam

 

[Tubetec]

Yes your right ,I hadnt factored in the magnets,and the potential for damage.
Only soldering iron I can think of without a magnetic tip is the heat gun type, thats just got tinned copper bar ,might be possible to put in a longer copper wire in place of the regular tip ,the other thing about a solder gun is it produces a strong AC magnetic field itself so theres a possabillity of demagnetiseation .
Maybe a small gas hot air  iron might be worth a try ,with this you wouldnt have to physically contact the workpiece, you could clamp the iron and the reverb securely apart.
Ive had to reconect guitar pickup coil wireing on a few ocassions ,very delicate job and easy duff it up beyond repair too ,
time to break out the lab coat , magnifying spectacles and the zircon encrusted tweezers!

 

[abbey road d enfer]

Yes your right ,I hadnt factored in the magnets,and the potential for damage.
Only soldering iron I can think of without a magnetic tip is the heat gun type,

Old-fashioned soldering irons, that you can still find in some hardware stores, have a copper end; the only problem is they tend to corrode and you have to reshape them from time to time.

  the other thing about a solder gun is it produces a strong AC magnetic field itself so theres a possabillity of demagnetiseation .

The magnetic field there is way much lower than the coercive field needed to demag the magnets; that's a non-issue.

Maybe a small gas hot air  iron might be worth a try ,with this you wouldnt have to physically contact the workpiece, you could clamp the iron and the reverb securely apart.

I wouldn't do that; the problem with hot air guns is it heats everything around and about, so you may end up frying the coils. In addition, the wind force is sufficient to tear up the fragile anchors.

 

[Tubetec]

I fixed up an old accutronics  tank by adding  a coil at the output end(600ohm), a bit like the Akg .Both springs attach to it .
The drive end is a standard two spring setup with an 8ohm coil .
I just need to find a way to mount my magnets so they dont come crashing together, and I'm ready to try it out.
No reason two of these coils couldnt be glued together at 90 degrees to replicate the Bx-25 drive/output coil setup .
See pic of armature wiring detail below .

 

[Gene Pink]

See pic of armature wiring detail below .

I like the "twisted pair with spiral shield".  ;D

A hard drive magnet has a field shape that might work if positioned just right, poles are marked red and green in the attached jpeg, and easy enough to mount using existing holes.

Perhaps long screws through the magnet carrier with compression springs around the screws and behind the carrier, and adjust like a guitar pickup.

Gene

 

[Tubetec]

Hi Gene,
Thanks for the suggestion.
I found a few cylndrical ndyms of enormous strenght, the thing is the power of the magnets is so strong that the little aluminium tray wont sit near the old steel trunking  without becoming locked to it . I think I'll try a piece of timber with a slot in the middle  for the transducer and two holes drilled in from either side ,once I put the magnets in their own strenght should hold them in place .
Instead of trying to connect the actual coil wires which would be very delicate and bound to break off  ,I wrapped the black and green wires around the coil ,then taped them with copper foil tape ,I then soldered a few pieces of silk wrapped magnet wire to make the pigtails . The other thing is both springs are now part of the magnetic circuit due to the copper support wire looping through the coil , I dont know what effect this might have until I get a chance to test it ,it may short circuit my signal voltage ,or could make it an effective radio frequency reciever. I'll post again once I've had a chance to test .