Westrex 3DII cutting head on ebay for a measly...

This is where record cutters raise questions about cutting, and trade wisdom and experiment results. We love Scully, Neumann, Presto, & Rek-O-Kut lathes and Wilcox-Gay Recordios (among others). We are excited by the various modern pro and semi-pro systems, too, in production and development. We use strange, extinct disc-based dictation machines. And other stuff, too.

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dietrich10
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Post: # 4848Unread post dietrich10
Fri May 01, 2009 9:17 am

helium mod is nice but double price. it is still a great cutter head
cutting lacquers-vms70 system

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Simon
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Post: # 4849Unread post Simon
Fri May 01, 2009 12:17 pm

I agree m8 - they must be appealing to all those bedroom DJs
Happy to learn something new.
Wanted: Stylus for Presto, Mono heads Grampian, Fairchild, Presto, Fairchild 740 lathes, Presto 8n, 8d 8dg lathes or parts or Presto or wot ever recording Amps, PM me what you have for sale.

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Aussie0zborn
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Post: # 4871Unread post Aussie0zborn
Tue May 05, 2009 10:39 am

Looks like this cam off a Scully lathe. I didn't know this had a helium cooling option - retro-ftted perhaps??? I had a 3D-II with Westrex valve amps but I sure dont remember any helium cooling options.

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Maistrow
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Post: # 4906Unread post Maistrow
Thu May 07, 2009 5:25 pm

I think perhaps this Westrex cutter head has been modified for use with helium to cool the drive coils. The later Westrex cutter head, the 3-D 2AH was sold to use with helium in cutting. Thus the letter H, for helium after the model number of the cutter head. I believe this is to be correct after reading this from my Westrex product brochures.

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audadvnc
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Post: # 18056Unread post audadvnc
Mon Feb 06, 2012 10:01 pm

I'm refurbishing a Scully lathe with Westrex 3DIIa. It has what appears to be a cooling line for compressed gas; I'm not going to set it up with helium, but may run it with compressed air.

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Aussie0zborn
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Post: # 18058Unread post Aussie0zborn
Tue Feb 07, 2012 4:22 am

@ Masitrow : Yes, I think you're right - thanks.

@ audadvnc : Im not sure you will get the same effect with compressed air. Maybe someone else here has tried it???

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audadvnc
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Post: # 18061Unread post audadvnc
Tue Feb 07, 2012 9:44 am

From what I've read here and elsewhere, the reason for helium is that it is a better heat conductor than air. Considering that the Westrex 3DII head with the 1700 amplifier was originally designed to run without any sort of forced gas cooling (and the gas line is an upgrade to an already successful design), my guess is that use with any gas (or none) would be fine. But we'll find out. How much is a coil replacement again? :roll:

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petermontg
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Post: # 18063Unread post petermontg
Tue Feb 07, 2012 10:09 am

audadvnc wrote:From what I've read here and elsewhere, the reason for helium is that it is a better heat conductor than air. Considering that the Westrex 3DII head with the 1700 amplifier was originally designed to run without any sort of forced gas cooling (and the gas line is an upgrade to an already successful design), my guess is that use with any gas (or none) would be fine. But we'll find out. How much is a coil replacement again? :roll:
could you not put a fuse in the link from rack to head to minimise blowing a coil. Am sure with both cooling and fuse your chance's of blowing a coil are very slim.
Peter Montgomery
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Stereo cutter head wanted. Send email or smoke signals.

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audadvnc
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Post: # 18068Unread post audadvnc
Tue Feb 07, 2012 8:02 pm

Perhaps you're right, but due to the feedback network in the 1700 electronics, an open circuit to the record head can cause other problems. Today, while doing machine setup, I smoked both the Westrex 1703 record coil power amps by inadvertently applying high amplitude sweep waveforms from my generator ( of course the manual warned us about how touchy the amps are, but did I listen?)

"What's that smell - and why is the ammeter reading negative current?" SNAP - Pooffffff..........ssssssssssssssssssssssssssss!

"Ooh, no, I didn't... Criminy."

Ah well, chalk up one to experience - at least the record head coils weren't damaged. I can fix electronic gear, if I can find the parts, but ...

Do you know how hard it is to find modern replacements for 1970's era transistors? I'm looking all over the Internet for MPSU04 driver transistors, and so far my only leads are to a couple NOS pieces here and there. I hadn't counted on parts shortages.
Last edited by audadvnc on Tue Feb 07, 2012 8:15 pm, edited 15 times in total.

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gold
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Post: # 18070Unread post gold
Tue Feb 07, 2012 9:05 pm

Air has oxygen in it. Lacquer is flammable...

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opcode66
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Post: # 18071Unread post opcode66
Tue Feb 07, 2012 10:11 pm

I think compressed air would have a good bit of moisture in it too. You would need a special compressor that removes moisture. Don't think I would want damp cutterhead.
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petermontg
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Post: # 18074Unread post petermontg
Wed Feb 08, 2012 6:50 am

audadvnc wrote:Perhaps you're right, but due to the feedback network in the 1700 electronics, an open circuit to the record head can cause other problems. Today, while doing machine setup, I smoked both the Westrex 1703 record coil power amps by inadvertently applying high amplitude sweep waveforms from my generator ( of course the manual warned us about how touchy the amps are, but did I listen?)

"What's that smell - and why is the ammeter reading negative current?" SNAP - Pooffffff..........ssssssssssssssssssssssssssss!

"Ooh, no, I didn't... Criminy."

Ah well, chalk up one to experience - at least the record head coils weren't damaged. I can fix electronic gear, if I can find the parts, but ...

Do you know how hard it is to find modern replacements for 1970's era transistors? I'm looking all over the Internet for MPSU04 driver transistors, and so far my only leads are to a couple NOS pieces here and there. I hadn't counted on parts shortages.
Fuse will leave your loop open/closed. It won't change you loop. If you just place it on one of the wire into the cutter head after all racks, will act as circuit breaker. Give Len/Dan a shout about Westrex gear and where to find what http://www.hrsrecords.com/
Peter Montgomery
+353(0)894926271
peter(at)petermontgomerymastering.com

Stereo cutter head wanted. Send email or smoke signals.

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Kiss the Groove
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Post: # 18079Unread post Kiss the Groove
Wed Feb 08, 2012 11:40 am

audadvnc,

The NTE replacement for the MPSU04 is their NTE190. Here's the data sheet. It reads identically to the MPSU04. $16.60 at Mouser.

I wasn't so lucky -- back in the 70's when my boss and I were calibrating a brand-new SC-2 at A&M records, I stupidly turned the test oscillator frequency decade switch the wrong way. A full-power 10 kHz screech filled the room for a few seconds before I figured out what I'd done. Too late. The varnish on both coils was bubbled, and they had to be rewound.

After that, I didn't try to do that stuff at the end of a 10-hour workday anymore.

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audadvnc
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Post: # 18087Unread post audadvnc
Wed Feb 08, 2012 8:39 pm

Peter and KTG, thanks for the leads. I did find the needed parts around the WWW, but will keep the NTE190 in mind if ever I blow up the Motorola parts I'm getting in. As you recommend, I will be fusing the drive coil leads, at least until I'm done getting the machine back up and aligned. A cooked $15 transistor is a minor annoyance - a blown cutter head is a big deal.

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