Todd Micallef | 29 Sep 02:09 2014
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Fluke 732A pre-regulator revs

I wanted to pass on some information that may not have been previously
discussed.

I just finished working on a 732A with minor issues. I replaced the R10 and
R20 pots on the A3 board just like on my other 732A's along with the two
big caps C1 and C3. After performing the same battery charger procedure
that I used on the other three references, I could not get the charger to
go from CC mode to CV mode. I checked the output charge voltage and it
never reached the 31V necessary to change to CV. The manual I used was PN
645051.

I went through the board and found four carbon comp resistors out of
tolerance (R3,R6,R15-16), but they didn't seem to be causing my problem. I
changed them anyway and decided to use the procedure in the other 732A
manual PN788414.

The other procedure differs only by the setting of R20. Instead of setting
it to 33V, I set it to 28.2V.
I looked at the schematics and noted that Fluke made some subtle changes to
the design. R17 and R18 were changed to CR29 and CR30. The RT1 thermistor
was also removed. R19 was added through an errata/change. R16 changed from
10K to 100K.

The newer procedure worked fine and I could watch the charger voltage
increase to 31V and then drop to CV mode.

I looked through my other three references. One other had the newer design.
A second one was modified and RT1 was removed. There was an additional 15K
resistor in parallel with R19 near the card edge connector. I removed it
since this resistor does not exist in the newer design.
(Continue reading)

J May | 27 Sep 20:31 2014
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Solartron 7081 Calibration Key

Reading through the archives it appears that the calibration switch keys 
are not unique.

Can someone with a key tell me if the key blanks are a common size, and 
if they are would someone (preferably UK based) be prepared to send me a 
key so that I could get a copy made?

J May | 26 Sep 15:29 2014
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Solartron 7081 Calibration

I need to have a Solartron 7081 calibrated - can anyone recommend 
someplace in the UK (or the EU)?

Unfortunately Ametek no longer provide a calibration service for the meter.

starbook | 25 Sep 18:01 2014
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Fluke 845AB 1993 Modification Schematic

Need the schematic of the Fluke 845AB 1993 modification.
Thanks,
John
Kgoodhew | 25 Sep 06:33 2014
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fluke 5200a extender

Had a look at the pin outs on both the power amplifier and the power supply regulator boards and the maximum
potential difference between any two adjacent pins is 190 volts.
EG. +300 v to +190 v to 190v return to -190v to -300v on consecutive pins on the power amplifier board.
A similar situation exist on the power supply regulator board, at no stage is there a 300 volt difference
between any two adjacent pins, so this should drop the possible arcing problem considerably
Ken Goodhew.

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Mark Sims | 25 Sep 04:32 2014
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5200a extender

The tightest clearances are where an etch runs between two pin on the ribbon cable connector.  The connector
pin are spaced 0.10" apart.  The pads are .060" octagonal pads so edge-to-edge is a .04" gap.  A .016" trace
runs in that gap.  So there is a .012" clearance between the pad edge and trace.  Worse case would be 300V
bridging that gap,  but the Fluke edge connectors are set up so that (I think) the highest potential
difference is 190V (between the +/-190V lines and GND.   There is a possibility of +300V and a signal called
/LIMIT.  
The layout/pad sizes could be tweaked some and that .012" gap could be increased to maybe .020"   A board
layout that didn't run etches between pads is not practical and/or would require a board size that exceeds
that permitted by my CAD program (or requires a $1700+ upgrade).  So what's the safe arc-over distance for
300V on a G10 circuit board?
The ATTEN,  PWR AMPL,  and PWR SPLY boards all have the high voltages on them... and they aren't on the same pins...

 		 	   		  
Kgoodhew | 25 Sep 03:30 2014
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5200a extender

Hi Mark.
	I appreciate your concerns regarding the +- 300 volts and would be a bit worried too.
Where is the minimal spacing you mention, is it between the card edge connector pads or the tracks that
connect these pads to the ribbon cable?
From memory the only two boards that have the +- 300 volts on them are the power supply and power amplifier
boards, guess I will have to drag the manual out again and look at what is connected to the adjacent pins.
Where to now?
I have pushed my 5200a aside for the last month waiting to see what develops on the extender front, however I
would like to get it going soon but I have at least one problem with the attenuator board which is virtually
impossible to troubleshoot without some type of extender.
I have managed to get hold of two 34/86 pin card edge sockets but I need the double sided card edge connector to
go into the socket on the main chassis to be able to fabricate my own extender.
Ken Goodhew.

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Dallas Smith | 24 Sep 21:06 2014

845ab Led Mod Update

Well I finally got the 615nm Led's installed and the results seem so so. 
The zero drifted was significantly on the 1uV range. So I used two 
LT1634 1.25 Volt references with the current set by two 43k resistors 
from the ±15 volt supplies. The previous reference used came from the 
-0.4 volts at TP1 and +0.6 volts at TP8. Removed the 150k resistor at 
the positive end of the zero control and lifted the negative end from 
the circuit board the connected the ±1.25 ref to the zero pot. Much 
better stability, drifts by noise about  ±.1 to ±.2uv now on 1uv range. 
Is this normal now? Never used a new Fluke 845ab before. The white led's 
seemed to filter the noise better with its persistent, may go back. The 
zero seems stable with ±2 F change in room temperature now.
Mark Sims | 24 Sep 00:16 2014
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Fluke 5200a extender

That would be me...  I have the boards in and they probably work with all the cards,  but they scare me...  Three
of the 5200 boards have +/-300V and +/- 190V on some of the pins and I don't totally trust them to handle that
properly.  The ribbon cable is rated at 300V and the box headers are (supposedly) 1000V.   There is only
around .012" clearance between the etches and the header pins they run between.
The high voltage pins are surrounded by guard pins and 190V pins.  It should work and I have tested one by
applying 300VDC across both sides of the edge connector and didn't have any arcing issues,  but it still
makes me rather nervous... 		 	   		  
Mark Sims | 24 Sep 00:06 2014
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Does anyone have a 3458A CalRAM dump routine in C ?

I tried to send you a copy of my program,  but the email bounced...   		 	   		  
Kgoodhew | 23 Sep 23:55 2014
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Fluke 5200a extender

One of the members was getting some pcb's made to fabricate some extender
boards, has there been any developments yet?

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