[QuadList] Rebuilding RCA TR-600s

Tue Sep 8 14:53:52 CDT 2009

Steve:

We did replace those caps (there wasn’t a big oil can type
but there were
several large caps in the power supply).

We are contemplating using an external frame synch in conjunction w/ the
internal TBC.  Any thoughts about this?

Or even using an external TBC
not sure if this would work though.  I did
notice one thing
before the TBC adjustments (alignments), the video actually
looked better in Demod
but we got it looking better now in TBC mode (which
you would expect)
as of right now, the picture looks better in TBC mode than
it does on the output
yesterday, before the machine went downhill, we had it
looking the best on video output.

More to come tomorrow.

John

From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of Steve Greene
Sent: Tuesday, September 08, 2009 3:48 PM
To: quadlist at quadvideotapegroup.com
Subject: Re: [QuadList] Rebuilding RCA TR-600s

I think we went over this a couple of months ago.  My experience was that
replacing that huge "oil can" capacitor to the power supply made a huge
difference to how stable the machine was.  That said, I'm not wild about the
TR-600's native TBC.  Probably fine with a nice studio tape, but it could be
hell outputting an already dicey recording to something like Digi Beta which
expects a clean signal.  We had mostly off-air recordings and the on-board
proc amp and TBC couldn't cleanup the jitter on the leading edge of sync.

Thanks for the update.  Let me know if you need documentation.

Steve Greene
Audiovisual Archivist
Nixon Presidential Library and Museum
(301) 837-1772

>>> jwalko at scenesavers.com 9/8/2009 3:24:48 PM >>>

Trevor:

These are equipped with the editor (although not sure if it is the AE600).

My big fear about these machines is stability.  Once we get them set up, are
they a continual nightmare to keep adjusted properly, or do they hold
settings pretty well?

I share your trepidation about the TR-600s.however it was a choice of
getting them working or leaving them to degrade.I just couldn't see doing
that.

John

From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of Trevor Brown
Sent: Tuesday, September 08, 2009 3:06 PM
To: 'Quad List'
Subject: Re: [QuadList] Rebuilding RCA TR-600s

John Walko

Interesting project like the rest of the list I wait for the second
installment

We do need to know if the machine is locked to external sync

Chris Hill is full of good advice

The issue with the color bars changing color in the regen mode tells me that
the machine is not gen-locking to the incoming black burst in that mode. 

 A way to tell this is to trigger your scope from the outside house burst
and look at the output of the machine.  If the two signals are moving, then
you are not locked

A quicker way is to put external sync on the picture monitor and select it

You will see then if it is locked and it will help you tell if the if the H
phase is working (Horizontal phase is not working at this point (knob turns,
but it doesn't do anything).

Love RCA machines hate the TR600 they were a problem from new, particularly
if equipped with the AE600 editor

Trevor

From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of John Walko
Sent: 08 September 2009 16:47
To: 'Quad List'
Cc: 'Jim Bird'
Subject: [QuadList] Rebuilding RCA TR-600s

Dear Quadlist:

Oh what fun it has been.

It has been awhile since I've updated anyone here about our rebuilding the
RCA TR-600 machines we have.  It is taking a while because we can not devote
full time to this project.  But it is interesting and I am learning a lot
about the operation of these machines.

These systems started out in pretty rough condition.  I swear when we
cleaned them, we got pounds of dust, dirt, tape trimmings and other junk out
of the machine (ok.maybe pounds is exaggerating a bit.but it was a lot).  

We are almost at the point of having one of the machines up and running
(yesterday was quite frustrating.more in a moment).  We picked what we felt
was the better of the two whole machines (we have a third for parts).  This
one had lower hours compared to the other machine and it would at least
power up (including the head wheel and capstan) and would pull tape.  We
were not able (at first) to get any true video signal, as it just wasn't
locking up.  After pulling all the boards, cleaning all the contacts and
reseating everything, we were at least able to see video, although color
wasn't locking (in other words, even color videos played in B&W).  We
checked power supplies and looked for any obvious things (broken wires,
burned caps/resistors/boards, etc).  After a thorough cleaning, we started
fine tuning the machine.

Last week, we started going through the alignment procedure.  Wow.what a lot
of adjustments.  A lot different than today's machines.  I'm only acting as
the assistant here (ok.really a go-fer.but what the heck.I'm learning).  Our
engineer has a better idea of what is going on with the machines, so some of
my explanations may seem a bit light, technically.

First step was alignment and EQ.  We got this looking pretty good.  What we
found is that many of the adjustments were close, but a couple were off by
quite a bit.  After going through the alignment, we made the TBC
adjustments.color is looking better at this point, but still getting banding
and drop outs in the video.  Horizontal phase is not working at this point
(knob turns, but it doesn't do anything).

After TBC adjustments, we went through the drop out compensator and got it
adjusted properly.  At this point, the video is looking really good.actually
surprisingly so.  Everything seems to be working properly.  Horizontal phase
is now working.

Now keep in mind that the whole time we are doing this, we are doing so with
the back off the machine, because we are looking at adjustments on the front
of the machine (cards in the nest) and looking at wiring on the back of the
machine to make sure everything is connected as it should be.  At this point
(yesterday about lunch time), we are feeling pretty good.  Good enough to
button up the back to make sure the cooling works on the machines as it is
designed to.  So, we put everything back together (all the panels and
guards) and roll the machine back into its place.  

Once this is done, we want to just try one last test.  I load up a tape,
which turns out to be B&W.  It looks pretty good (no burst, because it is
B&W), but it still looks good.  So we decide to put up the color tape we
were working with and it looks like absolute garbage.what the heck???  The
output video looked really bad when playing a color tape.lots of
banding.video taking a long time to lock up (we had it locking up in about 1
second.now it was back to several seconds.probably 5-10 seconds), horizontal
phase is no longer working, etc.  This is the same exact tape we saw play
great ½ hour ago.

Here is the situation.  We were not able to see output video by using the
top switcher (we always were able to see demod and TBC.but not output).  We
ended up changing that switch (which is just a manual switch).  In order to
see output video, we physically had to route the cables to the TV
monitor.but we wanted to be able to switch the video so everything could be
done from in front of the machine.  I can't believe this had anything to do
with the output video going from good to bad.since this is only a manual
switch.but who knows.  Talk about frustrating.here we are, seeing really
good looking video, thinking we are ready to go, only to have a setback like
this.

So here is our present situation.  We worked on it a little more yesterday.
We found that some of the boards in the "C" row might not have been seated
completely.  We got it to the point where we are able to get video to lock
up, but there is still a significant delay with the video output (the video
is shifted to the right side of the TV monitor screen and we can't seem to
adjust this at this point).  Our next step will be to go through the TBC
adjustment (alignment) again.

But at least we got to see the machine make really nice pictures for a
little while (so we know it can).

There are a couple of things that are strange.when looking at demod and TBC
video on an oscilloscope, we see one synch and one burst signal.but when
looking at video output, we see two.and one is in the wrong place (I can't
remember if we had the system in regen or house mode when seeing this.I
think maybe in regen).  Note that we are feeding a black burst signal into
the machine from an external generator.  This seems to be a timing issue,
but I would be interested in hearing input from others on the Quad list if
they've experienced anything like this in the past.  Alignment may solve
this problem.but if anyone has any thoughts or ideas, I'd appreciate them. 

Another, possible related issue is that if we feed bars to the machine and
it is in regen mode, the video signal drifts (as seen on both the TV monitor
and waveform) and the video is in B&W.  If we switch to house mode, this
clears up immediately (color bars are now in color and rock steady.note
color bars are from a synch/color bar generator.not an outside tape source).
The color bar generator is genlocked to the black burst generator feeding
the machine.  Terminations are correct (we checked).  Strange.

Another is the tension on the reels.we are playing a ½ hour tape and it
seems as if the mass of the reel is too much for the system to overcome (we
have to continually adjust the tension to compensate for this).  I have
spare reel motors, but don't want to get into replacing these unless we
absolutely have to.  We have not put a spring scale on the reel motors
yet.that will be our next step.  Along with the tension problem, we have a
buzzing (intermittent) that appears to be from one of the solenoids on one
of the reel motors (supply reel).  This comes and goes.not sure if it is
related to the tension problem or not.

Once we get the first system working, on to the second system.  We're close
on the first system.we'll keep you posted on progress.

A couple of things learned.

1.       A magnifying glass would be a great help when locating test points.
Fortunately, we have a second set of boards we can look at to help with
this.

2.       A short tweaker is a must (you just can't get at some of the
adjustments with a long one).

3.       When 2" video looks good, it looks really good, but it can go bad
in a hurry.

4.       I have a new-found respect for the engineers who kept these things
running.

5.       A second extender card can make your life a lot easier.

6.       A short chair is a necessity.knee pads would be nice (ok.just
kidding)

7.       Supply reels and take up reels of different sizes cause problems.

8.       Thank goodness for manuals.even if they aren't that well written.
You couldn't do this without them.  More pictures would be nice (of the
oscilloscope, demonstrating what the signal is supposed to look like.just
for confirmation). 

Thanks;

John Walko

Media Archive Manager

Scene Savers

www.scenesavers.com

800-978-3445

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