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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Mar Sun 02, 2014 12:33 pm 
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azenithnut wrote:
...

Got the power supply.
So far the transformers check out just fine.

...

The chassis is completely unmolested! Just the way I wanted! :D

...

This takes things one step further. many many more to go.

-Steve




Great news Steve. Glad that you got the chassis. So, will you use the chassis that you just got for your restoration?

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Mar Sun 02, 2014 1:34 pm 
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Thanks Don, that is the plan! The other chassis is missing a few other parts, but its not as if they were going to be used anyway.

-Steve

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Mar Sun 02, 2014 8:11 pm 
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Location: Beaver Falls, PA. USA
Great news, Steve! You have to love the build quality of that old Hammond stuff; it looks as though they expected it to last 100 years.

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Mar Sun 02, 2014 8:43 pm 
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Hi Steve-I just found this thread. I can't believe it-163 tubes if I counted right. What a beast !!
Well done Sir. The Big Bull Mastiff has just entered the room. :-)

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Mar Mon 03, 2014 5:22 am 
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azenithnut wrote:
Thanks Don, that is the plan! The other chassis is missing a few other parts, but its not as if they were going to be used anyway.

-Steve


That sounds like a good plan. Unmolested and original so you know what you are starting with. That other chassis has obvious tampering and you don't know what has happened.

Good luck and great to see that you found the chassis. I am just glad that someone who had no real need for the chassis bid you up. Good to see a winner for once. Now, please stop sending that snow to the mid-Atlantic states!!!

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Mar Wed 05, 2014 3:20 am 
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Wow Steve, you really lucked out having Joe point you to that power supply on E-bay. Good luck.


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Mar Wed 05, 2014 4:59 am 
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Location: Long Beach, CA 90808
WOW! I am blown away by that shot of the bottom of the power supply!

Incredible attention to detail and workmanship is evident there!

Makes you wish that all electronics were put together so neat and tidy.

Aloha, Ken


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Wed 16, 2014 3:30 pm 
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Location: UK
Why am I getting a terrible feeling of deja vu!...

I went down a very similar path in 2009 with #346... including two massively burnt out HT transformers that I had to reverse engineer..

...however - I had to ship #346 (built 1938) from Seattle, WA to Bath, England in a crate weighing 680 pounds first...

My original restoration thread is on the Vintage Synth forum - search for Novachord.

It formed the basis of the world's first sampled Novachord.


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Thu 17, 2014 12:42 am 
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Location: Dayton Ohio
Well, I already have read much about your Novachord! As well as watched your YouTube videos.
I was thinking about yours when I discovered one of the power transformers was toast...
I suppose they are a weak link in the design?

Thank you for the comment! I do plan to work on mine. Now that the weather is improving and my feet don't go numb while in the garage, I will get back to my Novachord.
The winter here in Ohio was one of the nastiest and coldest on record... I had things setup to work on it through the winter, complete with an electric heater to keep the fine instrument at least 50 F, but even so, I could not stand to be out there for very long at a time.

There is more to come. Again, thank you for joining in!

-Steve

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Thu 17, 2014 9:26 am 
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azenithnut wrote:
Well, I already have read much about your Novachord! As well as watched your YouTube videos.
I was thinking about yours when I discovered one of the power transformers was toast...
I suppose they are a weak link in the design?

-Steve


Hi Steve... Good to see you've joined the model H gang.. no I wouldn't say the transformers are weak but rather the PSU is exceptionally complex (as complex as many tube radio restoration projects in their own right!) for one of its age and capable of delivering a lot more power than is actually required by the generator chassis. The main issue is that generator chassis is actually a remarkably low power design considering there are well over 100 tubes in it so there is a major contrast when an overload situation occurs. Each anode is typically only drawing 200uA - ie. way below even your average triode pre-amp. Naturally the heater supply is a brute but it's local to the generator chassis and they sensibly spread the power distribution over several heater circuits on separate smaller transformer windings (but, again, it's not fused!!)

When 346 is running, despite her 163 tubes, the 3 transformers and 4 chokes are only warm to the touch after over an hour of use.

The main issue is, and this is where running an unrestored instrument is very risky, that there is no fusing or current limiting whatsoever in the Novachord and very unfortunately there are two tar potted multi-caps acting as supply decouplers that have a very nasty habit of failing dead short. They are the two silver coloured boxes with square edges situated right next to the heater transformer in the preamp channel. It is the failure of one of these that destroyed the PSU on 346. The state it left the HT transformers in was unbelievable - I have never seen such badly damaged transformers - they were basically charcoal wrapped in laminated iron!

The PSU is very clever - it generates 7 rails, two of which feature active noise cancelling circuits which drastically reduce the requirement for smoothing caps. It was designed by a guy called Herbert Meinema and it was protected under a patent.

I had a company here in the UK help me reverse engineer the transformers and they made me superb replacements that accepted the original end bells and they slotted perfectly in place of the originals. The transformers are tricky because they have several tappings and many of them are biased by directly heated rectifiers so you have to be careful of the relative voltages between windings. In a way it was probably a good thing I had new transformers made as I'm not totally sure how happy the originals would have been running at 50Hz here in the UK. The transformer company did express some concern that there is perhaps not as much metal in the transformer as they'd have expected and I know it was a bit of a challenge getting so much wire into such a tight space.

Attachment:
NC346 PSU Chassis_lr.jpg
NC346 PSU Chassis_lr.jpg [ 137.35 KiB | Viewed 4297 times ]


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Sat 19, 2014 7:45 pm 
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Keep it up, very interesting!


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Sun 20, 2014 8:06 pm 
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Hi all. Sort of stumbled over this thread looking for other things. I just wanted you to know that i am in the works of restoring another novachord (1277) in sweden that i bought from US some time ago. Its not going very fast since other things tend to take up lots of time, but im progressing slowly. I have started some trheads in other forums (organforum) and in a swedish one for other ppl to see whats goin on. Seems like we all have different troubles..My biggest issue so far is the vibratoswitches that had rusted to a really bad state..but now seems fine after some hours of grinding ;).
Anyway..nice to see others goin the same path.
Cheers
Ola


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Mon 21, 2014 2:27 am 
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Location: Woodinville, WA USA
dunderola wrote:
I have started some trheads in other forums (organforum)
Can you provide a link to that forum discussion? Thanks!

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Mon 21, 2014 8:19 am 
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Sorry no can do. Links made my post look too spammy for a new user so i cannot help you there at the moment.


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Tue 22, 2014 11:30 pm 
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dunderola wrote:
Sorry no can do. Links made my post look too spammy for a new user so i cannot help you there at the moment.

:?: :shock:

Sorry, I just don't understand that statement! I guess I wonder why you bothered to post in our forum in the first place....

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Tue 22, 2014 11:32 pm 
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When someone becomes a new member on ARF, they have to wait a few days before they can post URLs and pictures.
This was implemented not long ago due to spam issues.

Don't blame me, I'm just the messenger. :wink:

-Steve

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Tue 22, 2014 11:39 pm 
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azenithnut wrote:
When someone becomes a new member on ARF, they have to wait a few days before they can post URLs and pictures.
This was implemented not long ago due to spam issues.

Don't blame me, I'm just the messenger. :wink:

-Steve


Then, I guess a more detailed explanation (by the OP) may have been more informative. I can certainly understand the banning of the spam...

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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Wed 23, 2014 8:07 pm 
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Well, hopefully Ola can post things here soon.

Welcome to the forum and thanks for commenting! Its good to meet other Novachord owners.
I know I have been slow to show any progress on mine. I hope to change that soon.

-Steve

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Consoles and floor models, the bigger, the better!


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Apr Wed 23, 2014 8:48 pm 
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azenithnut wrote:
Well, hopefully Ola can post things here soon.

Welcome to the forum and thanks for commenting! Its good to meet other Novachord owners.
I know I have been slow to show any progress on mine. I hope to change that soon.

-Steve

Well thanks alot! :) Slow progress is something im familiar with..theese things take a huge amount of time..been doin it from time to time for a year and a half now..theres so much other things to take care of too..


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 Post subject: Re: 1939 Hammond Novachord - Unrestored
PostPosted: Aug Mon 11, 2014 1:03 pm 
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There's a rough but complete Novachord on ebay if anyone's interested.

http://www.ebay.com/itm/291214526673?ss ... 183wt_1135

-Joe :-)


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