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[TenTec] Corsair Repair Saga - Long

To: <tentec@contesting.com>
Subject: [TenTec] Corsair Repair Saga - Long
From: kh7m@hsa-kauai.net (Jim Reid)
Date: Fri, 1 Sep 2000 20:45:51 -1000
Hi to all Ten Tec fans,

For those who might be interested,  a used rig purchase
saga:

Back in mid-July,  I bought a Model 561,  Corsair II,  mint
condition,  alleged.

Rig arrived toward the end of the month -- non-operating!

Symptoms:

It did not play;  neither rcv nor xmit.  All I heard was the 
internal noise of the Corsair,  nothing from the antenna
jack is being heard.  I used a coax switch to go between
the Corsair and my FT-1000 and 544 Triton;  so the Corsair 
hears nothing, 1000/544,  lots of signals, same frequency.

Opened the unit,  and pushed on all the little plug
on connectors,  and the crystal cans.  Nothing seemed to
be out of place or loose.

Still:

1.  Very high receiver noise level,  much higher than the
band noise on any band.  So high,  you cannot hear
noise introduced when the antenna is connected or
removed!  Usually the rcvr noise is 20 or 30 dB below
the band noise on 20 meters.  I cannot hear the band
noise increase when I connect the antenna.

2.  Very weak signals when any can be heard at all.  I
have the Ten Tec Triton 544 right beside the Corsair,
with a coax switch to go between rigs with the antenna.
An S9,  SSB signal as heard on the Trition,  is very
difficult to hear/copy on the Corsair,  and the Corsair
S meter does NOT move!  So the rcvd signal is low,  and
the noise introduced by the Corsair is very high.
This condition holds whether using the Corsair VFO
or the External 263 VFO is used for the rcv mode.

3.  When following the Transmit instruction in the Corsair
manual for set up,  there is no output.  That is,  the manual
specifies that one should first set the ALC control fully
clockwise; next,  rotate the mode switch to the LOCK
position (which keys on the rig to transmit);  next,
rotate the DRIVE control until the ALC light just glows.

The result of doing this is:  no indication of output nor
SWR,  nor collector current shown on the meter;  that
is,  nothing is happening or transmitted! No ALC glow.

I suspected that the IF/AF board #80984 per the manual
might be where the recv problem might be occurring;
that is,  loose connectors or something.  So I looked
that one over especially carefully for a loose plug
or something -- could see nothing obvious wrong.

Going over the Corsair II block diagram in the manual,  I
identified two boards through which both transmit and
receive signals pass.  They are:

1.  Crystal filter board # 81252

2.  RF Mixer board # 80987

Opened the rig up,  and wiggled and removed/replaced
the slip on connectors on both those boards hoping to 
a connection that might have been bad.

Made no difference in the rig performance.....

So,  on August 1,  called TT service,  and described
all to Paul Clinton, the apparent Corsair "specialist".
Described the symptoms and all I had done to try
to find what might have gone wrong in the shipping
of the rig out here.  Fellow from whom I bought the
unit says all was operating FB when he unplugged,
packed up and shipped the 561 and the remote VFO
out to me.

Paul Clinton said the best thing to do was to return to them
for check out and fix.  I described all the symptoms again,
and what I had tried to do to find the fault.  He says all
has been done that could without them using test gear.  He
believes that one of the two boards I had already
suspected has somehow gone bad;  he ventured the
guess that it was more likely the Crystal Filter board,
the vertical one,  not the CW filters.  The vertical one
does have both xmit and rcv signals passing through,
so he agreed that was the likely trouble area,  but he
said you never know for sure,  nor what to do to effect
a repair of this sort of fault.

So the rig  was shipped,  and the post card back from TT
acknowledged receiving it on August 3rd.

Today,  September 1st,  the Corsair returned,  working
FB!  Has been on 10,  20 and 40 meters,  QSO's on all
including tonight,  VK0MM down on Macquarie Island
for a new one on 20 CW for me! (hoo haw...).

Paul Clinton included a very complete list of what was
done to rejuvenate the rig:

Quite a list of things done.  Seem to have been a few bad
parts replaced,  not sure exactly which one's caused the
non-op conditions I was experiencing.  Here is a copy,
direct from TT's invoice of what they did:

1. Replaced Q3 on PBT board (note:  nowhere near what I thought
might be the problem).

2. Replaced 3 bad diodes at the mode switch(??)

3. Replaced Band switch knob (old one looked fine to me,  hi)

4. Replaced L3,  was open,  on RF mixer board (this might
have been the part which caused the rig to be non-op,
not sure,  and TT didn't specifically say and I have no
idea from looking at the circuit in the manual exactly
what L3 does;  however,  this is one of the two boards
which I had earlier identified as having both xmit and
rcv signals pass through,  see back above)

5. Replaced components on LPF and SWR boards(have no
idea which ones,  nor why? no explanation is given for
any of the work)

6. Replaced speaker and bracket(!!? I had never tried
the internal speaker,  had only used headphones and
the speaker in the PS unit)

7. Rebuilt the PTO assembly(I had specifically requested
this rebuild,  as long as it was going in to the factory
for service,  why not)

8. Complete realignment of all stages

Material cost,  $29.33 (no itemized list)

Labor,  $175.00

Seem to be "bargain"  prices for all that listed and done
by Paul!

Paul Clinton included a complete list of all operating functions
which he tested after the repairs were completed.  He 
indicates the date of his tests was 22nd August; that's
a week ago last Tuesday.

So,  the complete saga for any who have read this far,  hi.
Which of all of the stuff above would you believe might
have gone amiss during shipping?  The boxes Fed Ex
delivered here back in July looked pretty good.  They
were "soft" cardboard,  and only slightly pushed in on the
tops -- obviously from other stuff sitting atop them.  But
the Corsair and VFO inside appeared untouched as they
were deep within bubble wrap and that surrounded by
piles of plastic "peanuts".

The obvious loose connectors and boards problem did
not seem to have been the problem,  but just flat out
N/G component:  replaced a transistor and an open coil,
most probably  non-operating causing fixes TT performed.
All the other stuff......guess Paul just wanted to fix it up
to be "as new",  hi.  And that is fine with me.

Just wonder if the rig really could have failed in the described
ways from the non-op condition when I rcvd it as described
above?  The seller continues to say the rig was FB at
his QTH when last used,  had had no problem with PBT,
SWR read out,  mode switch,  etc;  all was well,  and of course
was operating fine......just failed from the handling and
shipping.

Anyway,  appears to be very FB now after being shipped
back out here in a brand new TT box,  hi.

73,  Jim,  KH7M




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