Tektronix CSA802A - anyone familiar with repairing this unit?

unately it developed a fault in transit, and the extended diagnostics are s howing the following faults :-

ROMs anyway) and have checked all the supplies and all inter board cabling. All socketed IC's have been checked for correct seating. From a visual i nspection there is nothing obvious. The unit was very well packaged, with no damage to the packaging on receipt, and I'm confident that it was workin g when sent.

he unit and can advise on the probable problem. Given that there isn't sch ematics available for these they are a pain to trouble shoot. I suppose it 'll be cheaper in the long run to find a donor unit and swap boards until t he faulty board is identified, rather than reverse engineering the unit.

Unfortunately it developed a fault in transit, and the extended diagnostics are showing the following faults :-

anyway) and have checked all the supplies and all inter board cabling. All socketed IC's have been checked for correct seating. From a visual inspection there is nothing obvious. The unit was very well packaged, with no damage to the packaging on receipt, and I'm confident that it was working when sent.

unit and can advise on the probable problem. Given that there isn't schematics available for these they are a pain to trouble shoot. I suppose it'll be cheaper in the long run to find a donor unit and swap boards until the faulty board is identified, rather than reverse engineering the unit.

That's the comm version of the 11801?

I think there are a pair of battery backed ram memory chips on the timing pc board (bottom of unit). With the power off, make a measurement of the voltage between pin 14 and pin 28 on both of those chips (they are installed in a Dallas battery backup socket). If the voltage is less than 2 volts, you will need to replace both memory chips.

If that is your finding, report back and I'll post a source for a replacement device.

tm

tunately it developed a fault in transit, and the extended diagnostics are showing the following faults :-

PROMs anyway) and have checked all the supplies and all inter board cabling . All socketed IC's have been checked for correct seating. From a visual inspection there is nothing obvious. The unit was very well packaged, with no damage to the packaging on receipt, and I'm confident that it was worki ng when sent.

the unit and can advise on the probable problem. Given that there isn't sc hematics available for these they are a pain to trouble shoot. I suppose i t'll be cheaper in the long run to find a donor unit and swap boards until the faulty board is identified, rather than reverse engineering the unit.

Yes, on the hardware side two of the plug in slots supply power only, and i t has an additional wide bandwidth prescale trigger. The direct trigger ha s higher sensitivity than the 11801, and has a higher bandwith. Software w ise it has some standard inbuilt masks for pass/no-pass testing.

Yes, I should have mentioned that I checked all the internal batteries and they are all good (battery backed RAM sitting at over 2.9V).

tunately it developed a fault in transit, and the extended diagnostics are showing the following faults :-

PROMs anyway) and have checked all the supplies and all inter board cabling . All socketed IC's have been checked for correct seating. From a visual inspection there is nothing obvious. The unit was very well packaged, with no damage to the packaging on receipt, and I'm confident that it was worki ng when sent.

the unit and can advise on the probable problem. Given that there isn't sc hematics available for these they are a pain to trouble shoot. I suppose i t'll be cheaper in the long run to find a donor unit and swap boards until the faulty board is identified, rather than reverse engineering the unit.

Just for interest here's a photo of the prescale trigger hybrid

John

Unfortunately it developed a fault in transit, and the extended diagnostics are showing the following faults :-

EPROMs anyway) and have checked all the supplies and all inter board cabling. All socketed IC's have been checked for correct seating. From a visual inspection there is nothing obvious. The unit was very well packaged, with no damage to the packaging on receipt, and I'm confident that it was working when sent.

unit and can advise on the probable problem. Given that there isn't schematics available for these they are a pain to trouble shoot. I suppose it'll be cheaper in the long run to find a donor unit and swap boards until the faulty board is identified, rather than reverse engineering the unit.

I sure wish some ex-Tek person would smuggle out a set of schematics for the

Of course, Tek doesn't want those wonderful old scopes to get fixed.

That causes a timebase error code, E5322 or something like that.

The Maxim/Dallas parts are obsolete, but there is an ST module that works great. I may have been the first person to publish that error fix; one of my engineers figured it out.

Agreed. It's like they killed all the people that knew anything.

It really is a wonderful scope.