[time-nuts] Fluke monitor

ernieperes at aol.com ernieperes at aol.com
Thu May 6 15:04:26 UTC 2010

Hi Art,
Thanks for the info, but until now I had no time to chk the circuit....
But now here is the finding..... The monitor board has the 7805 SMD version and I was feeding from +12Volt and after a while
the SMD voltage regulator overheated and started to drop the voltage.... and it was the reason to receive/display garbled msg.....the display is built into the same box as the gpsdo..... the temp of the gpsdo was around 45 Celsius, so inside the box 
the temp also was elevated so no wonder why the SMD voltage reg overheated.....

Now     used a serial 75 Ohm resistor to drop the +12 voltage down and.... no more overheating..... and ever since it is working
 fine......The display draws about 50mA.
Thanks to everybody to pointing out the possible problem and also found additional info about the volt reg IC on Fluke home page.
Rgds Ernie.

-----Original Message-----
From: Arthur Dent <golgarfrincham at yahoo.com>
To: time-nuts at febo.com
Sent: Wed, May 5, 2010 7:13 pm
Subject: [time-nuts] Fluke monitor

"I mean when I remove the power from the monitor and let it cool down the 
fter about 1Hrs it starting to work again normal, the later on displaying 
arbled msg...... like something is overheating??????"
luke.L has sold 2 versions of the monitor. one works on 5VDC while the 
ther has a 78M05 regulator and requires approximately 9 to 12 volts to 
perate. It would help to know which of these you have and what you are 
sing for a power supply. If you bought your display about 5 months ago 
hen it is probably one designed for +5V. The display this unit uses is a 
Y-2002A-803. The pinout for the display connector can be found at: 
heck for the +5 on the correct pin of the display. if you have the correct 
oltage the problem could well be a parts failure on either the display or the
aughter board. 

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