Waters 2487 Screen Has no Text

[bmoritz]

Hi All,

We have a waters 2487 dual abs detector for our 2695 HPLC and it started acting funny this morning. After powering on the unit the screen is blank. The screen is on, meaning the light is there and it has the familar green glow, but there is no Text displayed. I've yurned off the unit and disconnected the cables, reconnected, turned back on and still no text. When using Empower it puts the system in idle and states "system failure." Has anyone run into this problem before? Thanks for the help.

[uzman]

It looks like the CPU is not running on the main electronic board.
This may be because of a faulty power supply , which can not supply one or more essential voltages , or a CPU board failure.

[bmoritz]

It looks like the CPU is not running on the main electronic board.
This may be because of a faulty power supply , which can not supply one or more essential voltages , or a CPU board failure.

Uzman,

Thanks for the reply. Is there a way to check if this is the problem? Do I need to inspect the CPU board visually for signs of damage? Is there a way to check if the power supply is faulty? Thanks again for the help.

[uzman]

If you have a voltmeter , you may check the voltages on the electronic board , but you have to be carefull not to make a short circuit and worsen the situation. Also there may be live parts carrying high voltage on the board , but there must be warning signs for them.

I don't know the model you mentioned , but as a general approach ,first remove the cover , and locate the control electronic board, which is usually the largest one .

There may be check points on the board , stating the voltages of +5 , +12 , +15 , -12 , -15 etc and a GND ( ground ) .
Check the voltages carefully , black probe of voltmeter to GND and red probe of voltmeter to the check points , and read the voltages.

All of them must meet the stated values ( +/- 5% )

If you can not locate any check points , at least you may try to measure the voltages accross the TTL chips , which must be +5 volts.

TTL chips starts with a code 74 ( such as 74LS00 , 74122 , 74HCT74) .

For making the measurement easier , connect the black probe of voltmeter to the metal case of the equipment , and touch the red probe of voltmeter to the chip legs , one by one.

You should read +5 volts on one of the legs.

The problem may be originated from a tripped out fuse , so check also the fuses.
Remove the power cable from the equipment before checking fuses , in order to be on the safe side.
You may use the diode test function ( buzzer ) of your voltmeter to check the fuses , touch both ends of the fuse and you must hear a buzzing sound from the voltmeter , if the fuse is o.k.

Good luck !