Restoring NS-690s

DahaiTX

Active Member
Greetings all,

New to the Hi-Fi world, I just picked up a pair of NS-690s Friday evening for $165 knowingly they have some problems but I'd like to fix them up and restoring them back to their glory. Here I'd like to share my experience and hoping to learn more about these speakers along the way.

Friday 03/15/2019
I picked up this pair of NS-690s from a lady who seems to know very little about them.
The good: these speakers were not opened before, everything is original.
The bad:
1. One bad mid range - voice coil is pushed in, and the back of the driver seems to be leaking some kind of oil when I pulled it out of the cabinet. Good thing is that it didn't get on the inside of the cabinet.
2. Both woofers are frozen - I've pulled one out and was able to confirm that it is caused by shifted magnet, additionally I do see some rust in the back of the woofer. All seem to be repairable according to the video on YouTube. Here is a link to it, be warned it is in Japanese, but it is detailed enough for you to follow for the most part. (I don't speak Japanese BTW)
3. Missing Grills - haven't been able to locate any used NS-690 grills on eBay yet.

Sunday 03/17/2019
1. One bad mid range - I bought a replacement JA-0701A off of eBay from Canada for about $100 shipping included. One of the screws got stripped when I attempted to pull out the mid range driver, so I also had to get another one off of eBay as well.
2. Both woofers are frozen - Been researching around but haven't been able to find anything on Ebay. Someone locally did reach out to me and mentioned he has a pair, but I have not heard back when I replied to his message. I wonder if I can use JA-3060 (from NS-690 2nd gen) or even JA-3058A (NS-1000) to replace these? I was also told someone here can repair them, I will reach out and see if I can afford it. (These woofers are pretty heavy to ship) I'm attempted to fix them myself, but I do not have any tool to align them perfectly, so I don't think I will risk it.
3. Missing Grills - not even bothered at this point, did find a pair of grills for NS-670 on eBay but I don't think they would fit since the dimensions are different between NS-670 and NS-690.
4. New Capacitors - I wonder if I should go ahead and replace the caps at this point. Could anyone tell me what kind I would need? Better yet, provide me with some suggestions? Please tell me the full model number and where I can find them.
5. Getting a better amp - someone had also suggested that I should get a much better amp than what I currently have (Onkyo TX-8511) to push these speakers. For example, Yamaha CR-1040 or Sansui 881, but I cannot seem to find any that is available, any other suggestions?

IMG_8571.jpg IMG_8572.jpg

My current setup, excuse the turntable being on top of the amp, I had to move it for the NS-690 =)
IMG_8569.jpg
 
1. One bad mid range - voice coil is pushed in, and the back of the driver seems to be leaking some kind of oil when I pulled it out of the cabinet.
Sure its just not dried glue..Photo please..
 
5. Getting a better amp - someone had also suggested that I should get a much better amp than what I currently have (Onkyo TX-8511) to push these speakers. For example, Yamaha CR-1040 or Sansui 881, but I cannot seem to find any that is available, any other suggestions?
M-4,M-45 Power amplifier with a C-4 or C-45 Control amplifier.
 
Just wipe it off. There is nothing within the driver that is suppose to be liquid. Unless something got spilled on it.
 
Just wipe it off. There is nothing within the driver that is suppose to be liquid. Unless something got spilled on it.
Well, it's getting replaced with the one I just purchased on eBay today. It's one less thing to worry.

I am now looking into the woofers. Does anyone know who Gordon W is on here? I was told he offers repair services for these woofers, not sure how to find him.
 
Update:

1. One bad mid range - One from eBay is coming via Canada Post, will arrive Mar. 25th. ($87.72)
2. Both woofers are frozen - I got in touch with someone local that offered a pair of JA-3060 (from the 2nd gen NS-690) for $175, I think I will use these frozen ones and build my own tool for fixing the shifted magnets..going to be fun.
3. Missing Grills - Still cannot locate any.
4. New Capacitors - Haven't looked into this.
5. Getting a better amp - Yamaha CR-2020, CR-2040, M4/C4, M45/C45...I have no idea but looking at these it seems around $800 is what I should expect to spend here?
 
Yamaha separates.. The only way to fly ...Of course I might be a little biased.:biggrin:

I do find the separated pre amp control and the amp very sexy. It's pretty tough to make a choice without actually hearing the difference though..
 
Update:

1. One bad mid range - One from eBay is coming via Canada Post, will arrive Mar. 25th. ($87.72)
2. Both woofers are frozen - I got in touch with someone local that offered a pair of JA-3060 (from the 2nd gen NS-690) for $175, I think I will use these frozen ones and build my own tool for fixing the shifted magnets..going to be fun.
3. Missing Grills - Still cannot locate any.
4. New Capacitors - Haven't looked into this.
5. Getting a better amp - Yamaha CR-2020, CR-2040, M4/C4, M45/C45...I have no idea but looking at these it seems around $800 is what I should expect to spend here?
Try reaching out to @baco99 regarding the crossovers...I think you'll find him to be helpful in cap values, types, and brands...
 
That was my first set in 1981-82. Bought them new at a BX in Germany. Those and a set of NS-1000's.

I cant believe these stuff came out back in the 70s, they still look relatively modern today!
I also came across someone local selling a M-80 for $700, is it really worth that much considering you can get newer gears for that much? Again I've never hear any of these in real life so I cannot be sure.
 
It still will need to be looked at. Regardless if it works or not. No doubt it has glue damage to some degree and possible cracked solder connections.
 
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I think they are a real fine sounding amplifier. The M-80 and M-85 are identical electronically. Both output the same amount of power. In excess of 290 wpc.;)
The only difference is whats printed on the front & rear panel.
 
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I think they are a real fine sounding amplifier. The M-80 and M-85 are identical electronically. Put out the same amount of power. In excess of 290 wpc.;)
The only difference is whats printed on the front and rear panel.

Man~! I came across many other choices as I scan through the local ads:

Yamaha A-S501 for $260

and

Yamaha M-50 Power Amplifier
Yamaha C-50 Pre-Amplifier
Yamaha T-520 AM FM Tuner
For $700 obo

life is too hard make any decision right now...
 
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