Error 585 on AM503B with A6304XL Current Probe

[IDEngineer]

I've got an A6304XL "gun style" current probe that I'm using with an AM503B amplifier. I have two AM503B's and they both work fine with my two A6302 probes so I'm confident the amplifiers are working.

When I press the degauss button on the AM503B, I often get an error code of 585 on its display. I don't get this error with the smaller probes, and I don't get it 100% of the time with the big gun probe either. Pressing any button clears the error from the display, the degauss button remains red, yet the A6304XL does work in the sense that passing current through a conductor is measured and displayed on the scope screen.

EDIT: When I press the degauss button the various "interesting" degaussing waveforms are visible on the scope screen, just as they are with the smaller probes. So the degaussing operation at least starts, it just appears to find something it doesn't like before completing and turning off the degaussing light.

I haven't found any documentation that lists errors of triple digits, other than the 2xx error you get when the AM503B isn't connected to a 50R input.

Anyone know what this 585 indicates? Even better, is there a list of known triple digit error codes?

Thanks!

[TERRA Operative]

Page 3-18 in the AM503B/AM5030 manual (070-8766-05) says this:
https://w140.com/tekwiki/wiki/AM503B

Error occurred during internal automatic adjustment. Repeated errors in the range 550–594 indicate the Amplifier needs repair. 580 and 581 indicate that the Amplifier was unable to complete a probe offset adjustment. See the DC Offset Adjustment procedure for the particular probe you are using.

Might be time to give things a bit of a tweak with your tongue at the right angle... 

Too bad the manual isn't forthcoming with the actual descriptions of the error codes, maybe a post on the Tekscopes groups.io page will yield some info if not here. I've had luck catching a Tek engineer who worked on these products in the past.

[IDEngineer]

Error occurred during internal automatic adjustment. Repeated errors in the range 550–594 indicate the Amplifier needs repair.

Interesting that it thinks it's an amplifier error, when neither of the other two probes cause it to happen. That strongly points at the A6304XL probe as being the culprit.

My present theory is that the A6304XL was being difficult in successfully completing the degaussing operation, but perhaps got a bit closer with successive attempts until it finally resolved. I'm going to let it sit unpowered overnight and try it again tomorrow. It had sat unused for a very long time before my work with it today (I don't often work on multi-hundred amp circuits). I did notice that the degaussing operation took MUCH longer on the Big Mombasa probe than either of the little probes.

[alm]

The degause operation does not just degause but also do the zero and balance adjust. Those knobs you had to regularly adjust on the AM503 because it would keep drifting. From the description it sounds like the problem is more with the zero adjust than degausing. I'm not sure if the amplifier get any feedback on the degausing.

[IDEngineer]

After letting everything sit overnight, here is the latest info.

* The (big) A6304XL probe repeatedly degaussed without issues this morning.

* It also degausses properly on the second AM503B that we have. Behavior is identical.

* Both AM503B's also operate properly with the smaller A6302 probes.

* The A6304XL takes at least 3X the time to degauss compared to the A6302's. True on both amplifiers. You can see the waveforms on the scope and hear the relays clicking, just as with the A6302's, but each phase takes a bit longer. The real delay comes from how the process seems to stall on certain steps with the big probe. It sits there for so long, with the red light still on, that even when I know it takes longer it feels like it's going to fail. But patience pays off, and eventually it advances to the next step in the sequence. This happens at several points along the way and the cumulative time is quite lengthy.

My conclusion is that the much larger ferrite mass in the A6304XL requires more time to degauss and balance/zero. The AM503B's must be watching feedback signals during the process and on the big probe it just takes longer for those values to get where the amplifier deems necessary before proceeding to the next step. As for the initial failures, it may have been sitting unused for so long that the core took on a large bias that required multiple sequences to finally zero out. For now, I'm just thankful that it all appears to be working properly.

TLDR: Be patient and retry the degaussing sequence, several times if necessary.

Hope this helps someone in the future!