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Electronics => Repair => Topic started by: AirScooter on April 30, 2021, 01:12:54 pm

Title: Negative output in my oscilloscope
Post by: AirScooter on April 30, 2021, 01:12:54 pm

I use a LeCroy 9400 oscilloscope. It has 4 separate power supplies. + and - 5volts and + and - 15volts.
The power supplies that output -5volts and -15volts have quit.
I assume the output of these voltages is related electronically. Could someone explain to me how the two power sources are related and what I might try to get them going again,
Thank You,
AirScooter

Title: Re: Negative output in my oscilloscope
Post by: ledtester on April 30, 2021, 02:45:42 pm

You can find schematics and an upside-down service manual on archive.org - search for "lecroy 9400":

https://archive.org/search.php?query=lecroy%209400

I'd first look at the service manual -- it is very complete in describing how the scope works.

Maybe start on page 185 for details on the power supplies.

Another resource to investigate is the Lecroy Owners group on groups.io (formally a Yahoo mailing list).

Title: Re: Negative output in my oscilloscope
Post by: AirScooter on April 30, 2021, 09:50:04 pm

Thank you for your helpful reply.
AirScooter

Title: Re: Negative output in my oscilloscope
Post by: james_s on April 30, 2021, 11:18:08 pm

Is this the one that has essentially the same power supply as the Tek TDS400 series? The one with the 4 separate magnetic amplifier regulator channels and the vertical daughter board on the output end that has a the regulator control circuitry?