Keithley 2410 Sourcemeter

[plesa]

Purchased on eBay for 350 USD as not working for parts. It has almost same specification like 2400, only the output voltage capability is higher ( 1100V).
Full specification can be found
http://www.keithley.nl/products/dcac/voltagesource/highvoltage/?mn=2410

Unit has fan, so there was lot of dust in it, but nothing obviously burned.But it power up only on output is pernament voltage.
Which can indicate blown output stage mosfet like on electrometer.
VFD is quite dim but working. So mayby anothe 7001 will be harvested for display.


First I needs to clean it and repair can begin:)

Service manual is available without full schematic
http://www.tek.com/keithley-source-measure-units/smu-2400-series-sourcemeter-manual/model-2400-sourcemeter-service-manu

[plesa]

During tear down I broke main switch So  used donor 7001 for switch and noticed that 2400/2410 use similar power supply, 14.6/6V  versus 12V/5V, dimensions are identical.
Now the unit is clean, there was lot of black dust collected by high voltage like in CRT. It is pity that there is fan and electrostatic field collect it.
Calibration data is not possible to backup by one command :CAL:PROT:DATA?, there is separate set of commands for source/sense and it reads only the active range.
Unit has been calibrated 3 times and unit calibration just expired ( last week ).

[HighVoltage]

I have the 2420-C and solved a problem with the partial schematics available in the service manual.
All it needed was the replacement of a couple MOSFET's
These are really great Source Meters, worth a lot of money, when they are working.

[TiN]

You can use my cal python from 2400 thread to read cal data and just modify accordingly for kV range.
But since you have access to calibrated 3458, it's not a big deal to recal again once box is fixed. 

Looking forward for teardown and pics..

[plesa]

You can use my cal python from 2400 thread to read cal data and just modify accordingly for kV range.

That is a good tip!! I§m planning to use it for calibration, the change will be minor.

I have the 2420-C and solved a problem with the partial schematics available in the service manual.
All it needed was the replacement of a couple MOSFET's
These are really great Source Meters, worth a lot of money, when they are working.

I hope so, just desoldered them for inspection. Negative rail has 1375V versus positive 1245V and on negative rail first three mosfets were quite hot, so I expect problem there.
Found one resistor on rear side overheated but still OK for troubleshooting.

2410 use:
6x MTP2P50E
4x MTP3N100E
1x TIP101
1x TIP106

[plesa]

One MTP3N100 seems to be dead. Rest seems to be OK and works. On VFD is visible during VFD burn in test text "High Voltage!". It comes from rack or test fixture. This explain no scratches and other defects from daily use.
I just tried to increase the brightness by running VFD burn in for while. We will see if it helps.

[plesa]

Running VFD burn in for few days does not have any positive impact. During removing heatsink two screws stuck in it because they were inserted and tightened in angle
Damaged N-MOSFET is Q514 only and when swaped with Q500 SMU is working on low voltage ranges correctly.
I tried to find replacement of MTB3N100E because it is obsolete and found Vishay IRFBG30 and IXYS IXTP3N100P.
Front panel color is restored by hydrogen peroxide.

[plesa]

Transistor Q514/Q500 replaced by IRFBE30 and unit seems to be working to +/- 940V, but not beyond. Current source also seems to be OK.
Any ideas what to check? Voltage on both HV rails is >1200V. Based on behavioral it does not seems to be related to output stage MOSFET misbalance.

[klaus11]

 

[HighVoltage]

may be a calibration will help?

[plesa]

may be a calibration will help?

Unfortunately calibration does not help. It end up with "Error 505  :CAL:PROT:SOUR command generates an invalid
source offset calibration constant." Maybe it is time to replace all output stage transistors.
Maximal output voltage is +/- 945V.

[Le_Bassiste]

hm, couldn't resist to dig this up again. any progress on the repair?  would be great to see some teardown pictures to compare w/ 237...
also, IRFBE30 has no DC rating in the SOA diagram, so i'm curious how it does behave in your unit.  IXTP3N120 for example is DC rated to 0.1A at 1200V, but then again, you pay ixys prices