Peter Strickland

Oh, and if you do decide to open up the attenuator, send me a PM and I'll give important instructions to help you from damaging something...

Strick

sure,
# Note: The first two commands, shown below behind the hash symbols, only need to
# be executed once.
#
# Also, the entries shown assume your 'scope is set at GPIB Address 1 and your GPIB
# card is address 0. Alter the address values appropriately (second digit in the ibdev
# command) if you're using a different setup.
#
#ibfind gpib0
#ibdev 0 1 0 13 1 0
#
ibwrt "CH1:VOLTs 100E-03"
ibwrt "CH2:VOLTs 100E-03"
ibwrt "CH3:VOLTs 100E-03"
ibwrt "CH4:VOLTs 100E-03"
ibwrt "CH1:VOLTS 100E-02"
ibwrt "CH2:VOLTS 100E-02"
ibwrt "CH3:VOLTS 100E-02"
ibwrt "CH4:VOLTS 100E-02"
ibwrt "CH1:VOLTS 100E-01"
ibwrt "CH2:VOLTS 100E-01"
ibwrt "CH3:VOLTS 100E-01"
ibwrt "CH4:VOLTS 100E-01"
ibwrt "CH1:VOLTS 100E-02"
ibwrt "CH2:VOLTS 100E-02"
ibwrt "CH3:VOLTS 100E-02"
ibwrt "CH4:VOLTS 100E-02"

you save the above to a file (e.g. exer.txt) and then hook up a gpib and run run in a dos or dos window the ibic command: ibic <exer.txt  >con.  I usually cheat and run the ibdev command by itself and just invoke ibic < exer.txt > con without the ibfind and ibdev commands.  also, if you only want to exercise one or two channels, get rid of the others to make it faster to run.  When run several times, the gpib commend on my computer seems to get confused and will stop and give an error. just reboot and keep going.

the main thing you are doing is changing the voltage to exercise the relays from 100 to 200 mv and 1 to 2 volts. 

Good luck!   Strick

Mike,

somehow I missed the DSY (or display) memory error in your first post.  That would seem to indicate that one of the display ram chips has gone bad. Figuring out which memory chip is faulty might be a chore.  Let me think on this a little more...

However, your nvram error has gone away, indicating that your chip replacement worked.

The DAC problem that just popped up point to the three ICs U904, 905 and 906.  These convert the analog inputs such as position, trigger level and channel gain into digital signals and pass them on a common pipe to the various circuits. I've fixed a bunch of these circuits in TDS500 models, but I've never seen a TDS700 have problems here.  You might try checking these chips to see if you damaged one while messing with the board.

Sorry I can't be much more help..

Strick

Mike,
I just saw this.  Make sure the switch on the CPU board is to the rear.  That is, push the switch so it goes back.  If it's forward, the scope will go to the monitor.

Strick 

looks like it didn't take...

I've attached a picture of the chips on my TDS580C (same acq board).  However, they are on the back side of the board.  Virtually all the earlier series TDS ACQ boards only had resistors and smcs on the back side.  this one has chips on both sides...

:) Strick

Michael,
looks like the NVram on your ACQ board died.  Most folks are well aware of the Dallas NVram on the CPU board, but the "B" and later TDS500/600/700 series keep the calibration on two serial NVram on the ACQ board.

They are 24C02 chips and are still available.  If you replace them, the scope will know and ask to be calibrated.  You can probably get by with just SPC, or by doing the CVRCAL or voltage calibration if you have a sensitive voltage source and a gpib connection.  The HF/interleave calibration and triggers requires a leveled signal generator (which don't come cheap).

You can probably get a cal lab to do the calibration, but I'm not sure how much it would cost.  See the manual for the calibration equipment required.

Strick

Mike,

If you don't have the TEDS520  (not the 520B...) component service manual, then I strongly recommend you get it.  It will give very good instructions on troubleshooting - especially the power supply.  Although the power supply in the manual is the 300 watt supply, most of the circuits are the same as the 400 watt supply you probably have.

the only real changes are the addition of 10 more pins on the connector to the ACQ board to allow more power for a +5 volt line.  Between this manual and the TDS520B manual (downloaded from TEKwiki or KO4BB's web site), you can figure out all the circuitry for the various power supplies that were used.  The TDS520 manual can be ordered online from Artek Manuals and is delivered electronically in quick order.

Strick

Mike,
It could be that your problem may be with the power supply. You may be getting the 5 volts DC to run the CPU board, but you may not be getting all the voltages to the ACQ board.  The correct voltages are listed in the TDS520 component service manual under the power supply.  I once had a power supply I fixed that would power up the CPU board, but failed miserably once the ACQ board was attached.  What failed on the power supply that you had to fix?

BTW, when you say the dip switches are on power up with full diagnostic, do you mean that the dip switches are all off (closed)?  The manual indicates to set dip 3 open - this avoids the full power on self test.  That's fine to avoid the long self-test that TEK fixed with later C and D scopes.

Still, freezing after booting with the LED working normally is typical of a bad NVram image on loadup.  The flash is checksumed in the initial boot sequence and won't even load if the checksum is incorrect.  I sincerely doubt it's the flash.  However, I can assure you that an incorrect image on DS1486 will cause all kinds of strange things to happen...
Strick

Mike,
I would leave the dip switches in the normal position.  I read Kellyjo's ebay ad and it would appear that he knows what he is doing. The image on the DS1486 may or may not be correct for the TDS744A, unless he still has one to test it on.  The ad indicates he tests the chips on a TDS784D, but the images for the DS1486 are very different.

So, I'm not sure the DS1486 is the problem or not.  Could you try putting the old DS1486 back in with all dip switches in the normal position and post a picture of the screen results after boot.  If it fails to show a screen, then could have a NVram problem or some other CPU board issue. 

Also, make sure that the connector board on the right side is in the proper position. It should have the part where the board extends past the plug in connector above the CPU board, not below the ACQ board.

With dip switches in normal, getting to the point where the LED is alternating and not showing numbers or letters generally indicates that all boot up checks are complete and the routine passed to the Flash memory. 

Finally, do you have a GPIB capable computer to talk to the scope?

Strick

Strick