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<DIV>After Wayne's reply, I had a look at the VR-1000 manual. There was a
blower that supplied cooling air to the head channel electronics housing, but it
was totally separate from the headwheel cooling blower. The exhaust from
the headwheel blower simply exited into the bottom of the console cabinet.</DIV>
<DIV> </DIV>
<DIV>One other thing that I had not considered....on the Mark-3 head, there is a
shroud over the headwheel itself that is connected to one of the head blower
ports. Remembering that the head "blower" is actually pulling air from the
head assembly, this shroud acts as a vacuum cleaner for any tape fragments or
oxide that might be shed as the tape passes the heads. For this to be
effective, you would need a good bit of vacuum, and so perhaps that was more of
the reason behind the powerful system than the need to cool the
motor. </DIV>
<DIV> </DIV>
<DIV>Don </DIV>
<BLOCKQUOTE
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dir=ltr>
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=wayne.watson@sait.ca href="mailto:wayne.watson@sait.ca">Wayne
Watson</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=dwnorwood@embarqmail.com
href="mailto:dwnorwood@embarqmail.com">Don Norwood</A> ; <A
title=quadlist@quadvideotapegroup.com
href="mailto:quadlist@quadvideotapegroup.com">Quad List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, January 28, 2011 11:42
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> RE: [QuadList] Headwheel blower
questions</DIV>
<DIV><BR></DIV>
<DIV class=WordSection1>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt">The
recall is a bit foggy but in the VR-1000 there were tubes, (mounted upside
down as I recall) and the cooling was needed for them. If the blower quit the
tubes got so hot and the heat went up to the base causing them to melt right
out of their sockets. One head channel would be lost per tube and you would
find the tube in the bottom somewhere with the base still in the socket. So
perhaps that is why the VR-1000has much more air????<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt">Or
was there a separate blower for the headwheel???<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt"><o:p> </o:p></SPAN></P>
<DIV>
<P class=MsoNormal><I><SPAN
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Watson</SPAN></I><I><SPAN
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284 7079</SPAN></I><I><SPAN
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<DIV>
<DIV
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<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Tahoma','sans-serif'; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'Tahoma','sans-serif'; FONT-SIZE: 10pt">
quadlist-bounces@quadvideotapegroup.com
[mailto:quadlist-bounces@quadvideotapegroup.com] <B>On Behalf Of </B>Don
Norwood<BR><B>Sent:</B> Thursday, January 27, 2011 8:32 PM<BR><B>To:</B> Quad
List<BR><B>Subject:</B> [QuadList] Headwheel blower
questions<o:p></o:p></SPAN></P></DIV></DIV>
<P class=MsoNormal><o:p> </o:p></P>
<DIV>
<DIV>
<P class=MsoNormal>I recently dealt with a problem that led me to discover
something I had never thought much about before, the various schemes used to
provide cooling air for the video headwheel, and what the requirements were
for cooling the headwheel motor. It's something that had just always worked.
Aside from cleaning filters, I never thought much about it. Now I realize that
there was an evolution in this process, and it's caused me to wonder about
several things.<o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal>The original head blower on the VR-1000 was an incredibly
heavy-duty device. It was built like a vacuum cleaner inside of a very
thick-walled canister. The same assembly was used on the VR-1100. If you
measure the vacuum at the head-cooling ports on the transport plate, you'll
see that it pulls about 20” of water! <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal>By comparison, measuring the cooling port on a VR-1200
indicates only about 2” of water, and then, there's the AVR-2 with no head
blower. I haven't checked the AVR-1 or AVR-3, but I don't think they used any
cooling air either. Of course, the AVR series machines use different head
assemblies than their predecessors. RCA machines had fairly substantial
head blowers too, from the TRT-1 up through the TR-70. Don't know what was
done in the TR-600.<o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal>I have some Mark-3 heads which I never noticed running hot,
but then they were run on VR-1100's with the massive air flow. All newer
1100's were spec'd for the Mark-10 head, and there was obviously no cooling
problem with that combination! But the VR-2000 and 1200 still had
warning lights for the cooling air, even though the flow was much reduced.
<o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal>So, did the original headwheels really run hot and need the
cooling, or was this just “good engineering practice”? And a service question
too..... does anyone know the proper setup procedure for the airflow warning
switch in a 1200? I have the procedure for the 1000/1100, but can't find
anything for the 1200, and they are very different.<o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P
class=MsoNormal>Don<o:p></o:p></P></DIV></DIV></DIV></BLOCKQUOTE></BODY></HTML>