[volt-nuts] Fluke 732A Questions

J. L. Trantham jltran at att.net
Sun Dec 29 19:51:01 EST 2013


Very good information.

Sounds like we are getting close to the correct P/N for the mating plug for
the socket.

My 732A has only a single transistor mounted to the frame from the A4
Regulator Assembly, in the position of Q4, and the resistance is 4230 ohms
after the unit is 'warmed up' and stable.

I recently bought a manual as well but it did not have any 'update sheets'.
I would love to have a copy of your 'update sheets'.

I did a 'clean up' of the update sheets on Didier's site and can send them
to anyone that wants one.

I printed the .PDF from the Fluke site and added the 'cleaned up' version of
the update sheets and it makes a very nice manual.  I would love to add the
other sheets to this.

I also have a 735C that is very similar to the 732A but lot's of mechanical
differences.  It has two transistors on the Regulator Assembly, presumably
A4 and Q4 and Q14.  I do not have a manual for the 735C. 

It's thermistor value is in the mid 3K range.  It, too, is very stable and
has many similarities to the 732A but has recently developed a 'new
problem'.  The 'NO CAL' LED comes on after a few days for no apparent
reason.  I need to open it up again and take a look at that circuit to see
what the problem is.

On the 732A, the 'IN CAL' LED is continuously lighted when there has been no
power interruption.  On the 735C, the 'NO CAL' LED illuminates when power is
restored after a power failure.  

I replaced the NiCd battery pack and all seems to be well but the 'NO CAL'
LED comes on after having been reset (by inserting a copper wire in the
'adjust' opening).  I wonder if my 'reset' process is the problem.  On the
732A, you connect to the negative terminal then touch the 'pad' inside the
'RESET' opening.  There is no such 'RESET' opening on the 735C.  Just
placing the wire (that I use to adjust the 10 V adjustment) inside the
adjustment opening and aiming to the side would reset the LED.

Happy to help with the scanning of the manual and update sheets if needed.

Thanks again for the info.


-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of T. Micallef
Sent: Sunday, December 29, 2013 6:05 PM
To: volt-nuts at febo.com
Subject: Re: [volt-nuts] Fluke 732A Questions


I have the external battery pack (732A-7003) that I picked up a while ago.
It is indeed the D01 connector. It is printed clearly on the outside edge
along with the three letters that look like ARB.

The company's website states they are now owned by Smiths Connectors and the
connector is part of Hypertac. No list of distributors was found on the

I found a seller Astrex Electronics, but they do not have a price listed for
the female version, just the male. I searched for D01P306FSTAH. This is the
female plug with solder cups.

To date, I have reconditioned three 732A's and they have been operating fine
with little issues, except when I lost power for an extended time and two
batteries in one of the packs died. All four were replaced and they have
been working fine.

The two older 732A's have thermistor values in the 3k-4k range. The newer
unit (based on the newer heater rev) is around 4.25K.

All three had their potentiometers changed on the regulator and
pre-regulator boards. The datecodes on all appeared to be from 1985. The
parts list must have been updated as some of the pots did not have the same
value as the ones installed. I cannot remember which ones were different. I
did not see a mention in the change/errata.

Also, I had to remove the reference ovens to repair broken 10V
potentiometers, as someone had broken one (free spinning) and another unit
appeared to have a noisy wiper so it was replaced as well. The 1V and 1.018V
pots were not changed. The third 10V pot was replaced because I had success
with the other two and it was much easier the third time around. The jumpers
on the all the A7 boards were adjusted.

I highly recommend checking the inline fuse to the heater if you suspect it
is not working. You can find it tucked inside behind the oven. It should be
covered in heat shrink. 

Lastly, there was a rev done that does not appear in the downloadable users
manual on Didier's website.  It appears the heaters were separated into two
groups of two instead of one group of four. Some of the parts were mounted
under the oven assembly on the A8 Preheater PCA. If you look at the A4 board
from the top, you will see either one or two transistors mounted to the
frame (Q4,Q14). If you see only one (Q4), chances are you have the newer

I bought the manual recently and just noticed these revs were in my book.
I will try and scan the extra info and upload them.


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