Author Topic: HELP! Yamaha NS690 Frozen  (Read 408 times)

Offline skip

HELP! Yamaha NS690 Frozen
« on: July 10, 2018, 04:59:04 PM »
So my vintage 690's are frozen! I am deeply saddened by this as I love these speakers.

My old faithfuls have suffered what appears to be a common problem of shifted magnets. I've taken the one apart - no way of removing the magnet without destroying the cone. There is evidence of rust on the glued surfaces and the pole piece has broken loose and stuck to the ring magnet.

What to do? Is this assembly repairable? I'm thinking along the lines of making a jig to assist with alignment and re-gluing the magnets back together. Then I will need to purchase new cones and have the woofers re-built.

Any experts around here that can share some advice?

Is the juice worth the squeeze?

Mods, please re-post if this in the incorrect section.






Online Shonver

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 10,506
  • Total likes: 19
  • Criss-cross rhythms that explode with happiness
    • Elipse (under construction)
Re: HELP! Yamaha NS690 Frozen
« Reply #1 on: July 10, 2018, 07:42:50 PM »
It will require some careful mechanical jigging but, yes, that can be restored. They usually only magnetise those parts after assembly.
________________

DON'T PANIC
Capie

Offline XL1000

Re: HELP! Yamaha NS690 Frozen
« Reply #2 on: July 10, 2018, 07:47:40 PM »
Give Merle a call.
Music is a moral law. It gives soul to the universe, wings to the mind, flight to the imagination, and charm and gaiety to life and to everything. Plato

Offline skip

Re: HELP! Yamaha NS690 Frozen
« Reply #3 on: July 11, 2018, 05:01:55 PM »
Thanks for the replies.

I have poured a lot of time into finding replacement parts but this is proving somewhat difficult.

My only other alternative is to replace the drivers with something similar.

I have found T/S parameters for the (similar) JA-3060:

Thiele Small Parameter   
Fs (Hz)   19.6
Qms   4.91
Qes   0.29
Qts   0.27
Vas (Liter)   228
RMS (ohm)   2.6
Mms (kg)   105
SPL (dB)   89.59999999999999
Bl   15
Re (ohm)   4.4


1st prize would be to find something similar so I don't have to modify crossovers or the box. Where do I even start looking?

As a last resort I would have to find the closest match and fall on the expert knowledge of the forum members to assist with a new crossover design.

The latter 2 suggestions fall way beyond my knowledge.

Online Shonver

  • Trade Count: (+8)
  • AVForums Grandmaster
  • *****
  • Posts: 10,506
  • Total likes: 19
  • Criss-cross rhythms that explode with happiness
    • Elipse (under construction)
Re: HELP! Yamaha NS690 Frozen
« Reply #4 on: July 11, 2018, 05:21:53 PM »


I'm thinking along the lines of making a jig to assist with alignment and re-gluing the magnets back together.

Sounded like you had a plan. I would try to preserve the cone if possible. Once you glue the motor parts back together, send everything to Merle so she can replace like for like as far as possible.

Sent from my LG-H870 using Tapatalk

________________

DON'T PANIC
Capie

Offline HBAutomation

Re: HELP! Yamaha NS690 Frozen
« Reply #5 on: July 11, 2018, 07:24:43 PM »
I would contact Merle first.
Pretty sure she will be able to assist.
Her pricing is reasonable and she walks the talk!
When You Come to a Fork in the Road, Take It!            [Yogi Berra]

Offline skip

Re: HELP! Yamaha NS690 Frozen
« Reply #6 on: July 12, 2018, 12:13:27 PM »
May you send me Merle's contact information?

My biggest concern is that I cant even find re-cone kits for these drivers. I might be lucky and she can make a plan.

Offline HBAutomation

Re: HELP! Yamaha NS690 Frozen
« Reply #7 on: July 12, 2018, 04:19:48 PM »
Merle Doubell 
Mobile 074 647 2242  :thumbs:
When You Come to a Fork in the Road, Take It!            [Yogi Berra]