TDS540 spc fail error 2260

[Dmoff]

Good morning, ive got a tektronix TDS 540 that fails signal path compensation Error 2260 Repet cal failed. when testing all channels it passes everything to spec. is there something i should be looking for that i wouldnt see otherwise. is it a nvram on acq board problem. its operating perfect to my knowledge other than that spc failure. Thank you in advance.

[TERRA Operative]

Is the fault specific to one channel?
If so, you can try swapping the input hybrids between channels to see if the fault follows. If so, you might be due for a new set of relays. It's one of the most common causes for SPC failures.

[Dmoff]

it dont believe it is. all 4 channels are reading in spec. i messed with all 4 channels switching vertical scale to activate relays for about 3-4 minutes per channel. besides that spc fail im not seeing any out of tolerance reading or indications its effecting those 4 channels.

[shakalnokturn]

If all channels seem to make sense both for amplitude and frequency on all timebase settings and input sensitivities with an external source, I'd look towards the internal signal used as calibration reference.
If the acquisition isn't reading back the expected values due to a reference signal out of range the scope should throw an error.
Of course knowing the model the first thing to look for is SMD capacitor electrolyte leakage.

[TERRA Operative]

Yeah, as shakalnokturn mentioned, if the fault is common to all channels, I'd be looking at the internal signal generator for problems, after doing the leaky capacitor dance.

Also, I'm not 100% sure, but if the 500 series is similar to the 600 series in that all channels end in a single acquisition chip (rather than one per channel as in the 700 series) that's another potential point of failure that could affect all channels.

Easiest next step after doing the capacitor thing is to grab the schematics and poke at the internal signal generator. You might even have a corroded trace or two, it's not uncommon with these leaky capacitors.

[shakalnokturn]

Also, I'm not 100% sure, but if the 500 series is similar to the 600 series in that all channels end in a single acquisition chip (rather than one per channel as in the 700 series) that's another potential point of failure that could affect all channels.

No, the 500 series are not CCD based and don't share the common FISO ASIC as on the 600 series.