Fluke 732A schematic re-drawn?
The schematic for the A5 Reference and Oven Controller Board has to be one
of the worst schematics I've seen in a while, breaking pretty much all the
rules on making a schematic understandable. I suspect this was done
deliberately.
Has anyone ever re-drafted this (to include the A4 pass transistor
components) to make sense of it?
May your volt always be stable
Dave
David:
I will be guessing that you are discussing the lack of Q14 that is
chassis mounted on some versions of A4, driven by Q13.
I have sent you by PM a pdf of a 732A manual that I probably got from
FLUKE.
If you look at the schematic for A4 this one has the chassis mounted Q14
shown and listed in the parts list for A4.
The interesting thing here is that a manual I sent you is P/N
645051 dated May 1983, while another manual P/N 788414 dated
May 1986 does NOT show Q14.
So for some reason known only to the people at FLUKE Q14 must have been
dropped by May 1986. Go figure.
I don't have any other manuals except those two P/Ns. The best I can
figure out at this time is that Q14 was dropped between A4 Rev A and A4 Rev
D. According to the parts list in the May 1986 manual Q13 is a 2N3906. The
Ic maximum is 200 ma. I know that the overall current draw from the
batteries when no AC power applied is about 250ma, but I don't know how much
of that is for the heaters.
Bill
----- Original Message -----
From: "David C. Partridge" david.partridge@perdrix.co.uk
To: "'Discussion of precise voltage measurement'" volt-nuts@febo.com
Sent: Friday, January 19, 2018 4:16 AM
Subject: [volt-nuts] Fluke 732A schematic re-drawn?
The schematic for the A5 Reference and Oven Controller Board has to be one
of the worst schematics I've seen in a while, breaking pretty much all the
rules on making a schematic understandable. I suspect this was done
deliberately.
Has anyone ever re-drafted this (to include the A4 pass transistor
components) to make sense of it?
May your volt always be stable
Dave
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and follow the instructions there.
Bill,
The reason why Q14 was dropped was that there was an additional pcb added
to the reference. The A8 preheater did not exist on the older models. It
appears the heating was changed to a split design where the heaters were
divided into two groups.
The control line still goes out P2-1 but connects to A8.
One of my 732A has this board and the reference also has the higher value
thermistor reading between 4k-5k ohms.
Todd
On Sat, Jan 20, 2018 at 2:06 PM, Bill Gold wpgold3637@att.net wrote:
David:
I will be guessing that you are discussing the lack of Q14 that is
chassis mounted on some versions of A4, driven by Q13.
I have sent you by PM a pdf of a 732A manual that I probably got from
FLUKE.
If you look at the schematic for A4 this one has the chassis mounted Q14
shown and listed in the parts list for A4.
The interesting thing here is that a manual I sent you is P/N
645051 dated May 1983, while another manual P/N 788414 dated
May 1986 does NOT show Q14.
So for some reason known only to the people at FLUKE Q14 must have been
dropped by May 1986. Go figure.
I don't have any other manuals except those two P/Ns. The best I can
figure out at this time is that Q14 was dropped between A4 Rev A and A4 Rev
D. According to the parts list in the May 1986 manual Q13 is a 2N3906.
The
Ic maximum is 200 ma. I know that the overall current draw from the
batteries when no AC power applied is about 250ma, but I don't know how
much
of that is for the heaters.
Bill
----- Original Message -----
From: "David C. Partridge" david.partridge@perdrix.co.uk
To: "'Discussion of precise voltage measurement'" volt-nuts@febo.com
Sent: Friday, January 19, 2018 4:16 AM
Subject: [volt-nuts] Fluke 732A schematic re-drawn?
The schematic for the A5 Reference and Oven Controller Board has to be
one
of the worst schematics I've seen in a while, breaking pretty much all
the
rules on making a schematic understandable. I suspect this was done
deliberately.
Has anyone ever re-drafted this (to include the A4 pass transistor
components) to make sense of it?
May your volt always be stable
Dave
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and follow the instructions there.
All is now explained. I just never considered all of this before, nor has
it ever come up. This should help David understand what is happening in his
732A. His is a later model obviously. I will have to examine all of my
instruments next time the opportunity presents itself.
Thanks,
Bill
----- Original Message -----
From: "Todd Micallef" tmicallef@gmail.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Saturday, January 20, 2018 11:33 AM
Subject: Re: [volt-nuts] Fluke 732A schematic re-drawn?
Bill,
The reason why Q14 was dropped was that there was an additional pcb added
to the reference. The A8 preheater did not exist on the older models. It
appears the heating was changed to a split design where the heaters were
divided into two groups.
The control line still goes out P2-1 but connects to A8.
One of my 732A has this board and the reference also has the higher value
thermistor reading between 4k-5k ohms.
Todd
On Sat, Jan 20, 2018 at 2:06 PM, Bill Gold wpgold3637@att.net wrote:
David:
I will be guessing that you are discussing the lack of Q14 that is
chassis mounted on some versions of A4, driven by Q13.
I have sent you by PM a pdf of a 732A manual that I probably got
from
FLUKE.
If you look at the schematic for A4 this one has the chassis mounted Q14
shown and listed in the parts list for A4.
The interesting thing here is that a manual I sent you is P/N
645051 dated May 1983, while another manual P/N 788414 dated
May 1986 does NOT show Q14.
So for some reason known only to the people at FLUKE Q14 must have been
dropped by May 1986. Go figure.
I don't have any other manuals except those two P/Ns. The best I
can
figure out at this time is that Q14 was dropped between A4 Rev A and A4
Rev
D. According to the parts list in the May 1986 manual Q13 is a 2N3906.
The
Ic maximum is 200 ma. I know that the overall current draw from the
batteries when no AC power applied is about 250ma, but I don't know how
much
of that is for the heaters.
Bill
----- Original Message -----
From: "David C. Partridge" david.partridge@perdrix.co.uk
To: "'Discussion of precise voltage measurement'" volt-nuts@febo.com
Sent: Friday, January 19, 2018 4:16 AM
Subject: [volt-nuts] Fluke 732A schematic re-drawn?
The schematic for the A5 Reference and Oven Controller Board has to be
one
of the worst schematics I've seen in a while, breaking pretty much all
the
rules on making a schematic understandable. I suspect this was done
deliberately.
Has anyone ever re-drafted this (to include the A4 pass transistor
components) to make sense of it?
May your volt always be stable
Dave
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To unsubscribe, go to
and follow the instructions there.
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Actually I wasn't speculating on the absence of Q14, though the manual you emailed me explained why that happened (A8 board added).
I was more concerned about the way the A5 reference schematic was drawn makes it harder to understand.
Thanks
Dave
-----Original Message-----
From: volt-nuts [mailto:volt-nuts-bounces@febo.com] On Behalf Of Bill Gold
Sent: 20 January 2018 19:06
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A schematic re-drawn?
David:
I will be guessing that you are discussing the lack of Q14 that is chassis mounted on some versions of A4, driven by Q13.
I have sent you by PM a pdf of a 732A manual that I probably got from FLUKE.
If you look at the schematic for A4 this one has the chassis mounted Q14 shown and listed in the parts list for A4.
The interesting thing here is that a manual I sent you is P/N
645051 dated May 1983, while another manual P/N 788414 dated May 1986 does NOT show Q14.
So for some reason known only to the people at FLUKE Q14 must have been dropped by May 1986. Go figure.
I don't have any other manuals except those two P/Ns. The best I can figure out at this time is that Q14 was dropped between A4 Rev A and A4 Rev D. According to the parts list in the May 1986 manual Q13 is a 2N3906. The Ic maximum is 200 ma. I know that the overall current draw from the batteries when no AC power applied is about 250ma, but I don't know how much of that is for the heaters.
Bill
----- Original Message -----
From: "David C. Partridge" david.partridge@perdrix.co.uk
To: "'Discussion of precise voltage measurement'" volt-nuts@febo.com
Sent: Friday, January 19, 2018 4:16 AM
Subject: [volt-nuts] Fluke 732A schematic re-drawn?
The schematic for the A5 Reference and Oven Controller Board has to be one
of the worst schematics I've seen in a while, breaking pretty much all the
rules on making a schematic understandable. I suspect this was done
deliberately.
Has anyone ever re-drafted this (to include the A4 pass transistor
components) to make sense of it?
May your volt always be stable
Dave
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To unsubscribe, go to
and follow the instructions there.
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and follow the instructions there.