On Feb 23, 2022, at 14:02, Larry McElhiney via groups.io <lmcelhiney@...> wrote:

?On Wed, Feb 23, 2022 at 12:33 PM, Roy J. Tellason, Sr. wrote:

I'd appreciate it if you guys could simply put such large files where somebody can get at them, and provide a link, for those that want it, rather than forcing those of us who get things this way to download for no immediate benefit.

Hi Roy,

In your subscription to this group, go to Advanced and you will see the maximum attachment size option, below:

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Take care,

Larry

Is it possible to give the EL display backlights any new lease of life?? HP used them in a number of instruments and most ‘fixes’ I’ve seen so far mean a replacement.

DaveB, ?NZ

?

From: [email protected] [mailto:[email protected]] On Bethalf Of Harvey White
Sent: Thursday, February 24, 2022 09:46
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8594E upgrade CRT to LCD

?

From what I've seen, the displays are from a different era, and that could make a significant difference.? Modern TFT displays seem to be a lot more durable.

On the old displays, the EL backlight gives out quickly.

Also not sure about the temperature tolerance, either, although LCD displays do not really like getting too hot.

Harvey

On 2/23/2022 3:09 PM, paulswed wrote:

Stuart not to throw stones. But I have seen a fair number of tek lcd displays that have gone to heck. Normally something like crystal leakage. (I just made that up). I can think of things like the tek TDR 1503 non crt versions yet the crt versions still work.

Just saying we hobbiest users use the gear far past any expectation that it should work.

Regards

Paul

WB8TSL

?

From what I've seen, the displays are from a different era, and that could make a significant difference.? Modern TFT displays seem to be a lot more durable.

On the old displays, the EL backlight gives out quickly.

Also not sure about the temperature tolerance, either, although LCD displays do not really like getting too hot.

Harvey

Stuart not to throw stones. But I have seen a fair number of tek lcd displays that have gone to heck. Normally something like crystal leakage. (I just made that up). I can think of things like the tek TDR 1503 non crt versions yet the crt versions still work.

Just saying we hobbiest users use the gear far past any expectation that it should work.

Regards

Paul

WB8TSL

Stuart not to throw stones. But I have seen a fair number of tek lcd displays that have gone to heck. Normally something like crystal leakage. (I just made that up). I can think of things like the tek TDR 1503 non crt versions yet the crt versions still work.

Just saying we hobbiest users use the gear far past any expectation that it should work.

Regards

Paul

WB8TSL

?

@Jinxie, I did not mean to discourage you by saying that this repair is impossible without very accurate equipment that you do not have; this is not necessarily the case, and I myself have fixed many pieces of equipment with surprisingly inadequate gear. What I did want to convey to you is the fact that the 8566B is an extremely sophisticated piece of equipment that requires a precision mindset if one wants to achieve 100% success in troubleshooting it. Assuming that the 22V rail is “good enough” when it measures +1V, and the specified allowed deviation is at most 50 times less (+20mV), did not look like a promising start.

To make my point even more concrete, as Matt said, one can sometimes get rid of the YTO unlock error by performing the “13. Sweep, DAC, and Main Coil Driver Adjustments”. One of the steps in this procedure calls for adjusting the “scan reset offset” voltage to zero with an accuracy of +-500 micro-volts.
In other words, you can not assure a successful repair without accurate gear and mindset, but you may still be lucky enough and be able to fix it with an accurate mindset and less accurate gear.

As for your comment that “no way can I meet those kind of standards...”, I do not believe that this is necessarily the case given that you also say that “I have a *ton* of high-end test gear here..” --- even if it is all vintage with unknown calibration status. For example, my experience with a few used HP 3456A meters is that they are within specs, or very close to it, many years after being last calibrated. Also, even if out-of-spec, their errors are quite consistent and they still have tons of resolution which is what counts most in this case. In other words, your 34566B will function perfectly well if it is adjusted with all voltages consistently off by the same small error: the relative voltages at different points in the circuit are more important than their absolute values (within reason of course).

Finally, if you are lucky, the problem may be simply a bad electrolytic capacitor on A20, A19 or A21. Given that you have an LCR and ESR meters, why don't you start there first?

On Feb 23, 2022, at 2:13 PM, Lothar baier <Lothar@...> wrote:

?I just looked it up and your 8753 needs FW 7.68 or higher for the ECAL to work as well as the 85097B PC interface , only 85090 series ECAL are supported

?

Get an 85097 as others have mentioned. An ECAL is totally worth it. I used
them with my 8753e when I had it. I actually still have the 85097 and
cables if you're interested.