HP ESG3000A backlight issue revisited....your thoughts please?
Hi HP experts,
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A few months ago I picked up an HP ESG-D3000A 3GHz sig-gen with a very dim backlight and discussed with several members on this platform where to find a schematic.
I had decided to replace the CCFL with LED's and had found a YouTube contributor who had attempted just such a modification:-
So wishing only to disassemble my signal generator once (and based on the YouTube video and your helpful comments) I designed a microcontroller based PWM driver that would be
powered from the existing CCFL inverters 5V input supply and be controlled by the signal generator's existing control voltage. (Simple, just plug and play!)
The YouTube video shows a three wire connection to the CCFL inverter which was allegedly 0V (GND), +5V (HT) and a control voltage which according to the video varied
0.2V d.c. to 4.7V d.c. from dim to full brightness. (zero to 50 HP units)
The video showed the make and model number of the CCFL inverter block as:-
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albeit with a different (I assume) batch number? (9623A vs his 9725E)
This week the backlight wouldn't come on so it was finally time to open up the beast and try to fit my new LEDs and driver.
I made up an extension lead for the three way lead to bring the connections outside the instrument. I removed the LCD panel assembly and it was relatively easy to remove the CCFL tube and carefully?
fit the strip of 18 LEDs, fixed with a tiny dab of hot melt glue at each end.
I checked that the LEDs lit up with my new PWM driver board and that the LCD display was perfectly bright enough. It was a great success, bright and clear!
So......
Now I could see the LCD display again, it was time to check that the 3 wires (that went to the CCFL inverter) were indeed 0V, +5V and the control signal I was expecting as I rotated the f/p control knob. (zero to 50)
Doooh!
The 0V and +5V are correct, but the control voltage ranges from (minus) 0.24V to (minus) 1.33V? so the control voltage is going negative with respect to the 0V ground rail!
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This of course does not agree with what I was expecting as the (measured?) YouTube control voltages, suggested a positive ranging DAC output?
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Questions:-
Does anyone have experience with the CCFL inverter control voltages in the ESG series of signal generators?
You will of course point out that the YouTube video referred to an ESG-D2000A and NOT my? ESG-D3000A, yet both seem to be using the same CCFL inverter module (E1825C) so I would have expected the voltages to be the same?
During all the 'fiddling' about I did get the CCFL to light up (out of the generator) and it's brightness REALLY is varied by this negative voltage range, so the control voltage seems correct (not negative due to a fault).
How can the CCFL inverter be working with a control voltage that only goes (outside it's supply rail) i.e. below it's GND rail, and such a small swing at that!
Have I been 'suckered' by a 'spoof' YouTube video?
What is going on?
This is very annoying....all your help and expertise will be greatly appreciated.
Thanks in anticipation......
Dave
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Re: HP 8757C/D/E Service manual
Hello Guys,
Can i calibrate the 8757D whit a external source (power meter source - 50MHz 0 dBm) ?
Thanks Ben
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Re: Troubleshooting a 8591e with opt 130
Hi Yves,
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I did the measurements all with the SA's attenuator set to 10dBm. I redid the measurements with both SA attenuator settings, see table below.
I'm still using the cal out of the SA because I don't have a more trustworthy source yet.
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| 300 MHz |
Spectrum ATT |
? |
| EXT ATT |
0 dB |
10 dB |
? |
| 0 dB att |
-15 |
-5 |
ref level 0dBm |
| 10db att |
-25,9 |
-15,7 |
? |
| 20db att |
-37,5 |
-26,3 |
? |
| 30db att |
-49,5 |
-37,9 |
? |
| ? |
? |
? |
? |
| 1500 MHz |
Spectrum ATT |
? |
| EXT ATT |
0 dB |
10 dB |
? |
| 0 dB att |
-30,8 |
-19,8 |
? |
| 10db att |
-45,7 |
-34,2 |
? |
| 20db att |
-56,5 |
-44,9 |
? |
| 30db att |
-68,4 |
-57 |
? |
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On the other images, I tried to reproduce them, I'm just taking pictures of the screen though. Are you using a GPIB interface to make those? Or can it also be done with the serial output?
The noise increase at lower frequencies doesn't seem to be there. There is an offset in the frequency though, the 0Hz peak seems to be around 580kHz
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in a broader span with the cal signal connected (through 10dB external attenuator) The 0Hz peak is near the reference level, the 300MHz signal is also quite high.?
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So i'll try to fix the attenuator and move on with another try of the selfcall from there. I'm thinking of getting a TinySA ultra to be able to do some verification.?
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Marco
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Re: Troubleshooting a 8591e with opt 130
Marco, I forgot to include these remarks ? Here are two signs of a damaged mixer that I have already noticed (blue curves): - At 0 Hz, the carrier exceeds the reference level - PRESET: ATTENUATOR = 0 dB (whether the attenuator is installed or not does not change anything). Between 0Hz and 10 MHz, the noise increases in the lower frequencies instead of remaining relatively flat. ? Yves ? 
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Re: Troubleshooting a 8591e with opt 130
Hi Marco, ? I don't know what value your Spectrum's attenuator was set to. Even if it wasn't connected, the IF gain will change according to that value. So, I did a test at 0dB and 10dB, even if the Spectrum's internal attenuator wasn't connected. I inserted a precise level at -20dBm at 300 or 1500 MHz. ? Now looking at the results, it may seem surprising that the values ??at 300 and 1500 MHz are very similar. In fact, this is normal in my case since, in the calibration table (Flatness) there is a gap of only 1dB between the level at 300 MHz and 1500 MHz, at 1500MHz the signal is attenuated by 1dB, and this 1dB is mainly due to the cables connecting the Spectrum input to the attenuator and from the attenuator to the first converter. Also, the attenuator does not have a flat frequency response. Since I connected directly to the first converter, these losses are not included in the test measurement. ? 300 MHz | Spectrum ATT | EXT ATT | 0 dB | 10 dB | 0 dB att | -19.4 | -9.4 | 10db att | -29.4 | -19.4 | 20db att | -39.4 | -29.4 | 30db att | -49.5 | -39.4 | | | | 1500 MHz | Spectrum ATT | EXT ATT | 0 dB | 10 dB | 0 dB att | -19.5 | -9.4 | 10db att | -29.7 | -19.5 | 20db att | -39.8 | -29.7 | 30db att | -49.9 | -39.8 |
? ? ? That image was very helpful! I ordered replacement components according to your values. Both for the through hole and the smd resistors. I went with thin film ones because couldn't get any specific RF resistors in the right values. They should be in early next week.?? I also got a set of BNC attenuators (Hameg HZ24 rated to 1GHz), so I hooked up the cal signal straight into the mixer, with the external attenuators.? Measured the 300MHz with the same settings you did before: correction at OFF SPAN 100kHz resBW 10kHz vidBW 100Hz MKR peak REFlevel at -10dBm ? found the following: Attenuators?? | 300MHz | 1500MHz | 10dB | -14,4 | -30,9 | 20dB | -25,3 | -41,3 | 10+20dB | -36,8 | -55 |
So the 300MHz looks quite okay I'd say and the 1500MHz is not too bad considering the 1GHz rated attenuators. Though at 1500MHz I had to use a bigger span because I couldn't get the peak centered in small span. Peak>CF would not work and manually scrolling, the frequency would change but the peak would stay in it's place. This was without proper warmup of the SA btw.? Would that mean that the mixer diodes have to be replaced asweel or would other measurements be needed to answer that??
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Re: HP 16500C Display Question
I thought I'd seen something on eevblog but didn't find that.
I think that card is another of these programmable devices but for ?20 shipped I'll give it a try. I want to do something like this for a 53310A and it might work there.
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Re: Troubleshooting a 8591e with opt 130
That image was very helpful! I ordered replacement components according to your values. Both for the through hole and the smd resistors. I went with thin film ones because couldn't get any specific RF resistors in the right values.
They should be in early next week.??
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I also got a set of BNC attenuators (Hameg HZ24 rated to 1GHz), so I hooked up the cal signal straight into the mixer, with the external attenuators.?
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Measured the 300MHz with the same settings you did before:
correction at OFF
SPAN 100kHz
resBW 10kHz
vidBW 100Hz
MKR peak
REFlevel at -10dBm
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found the following:
| Attenuators?? |
300MHz |
1500MHz |
| 10dB |
-14,4 |
-30,9 |
| 20dB |
-25,3 |
-41,3 |
| 10+20dB |
-36,8 |
-55 |
So the 300MHz looks quite okay I'd say and the 1500MHz is not too bad considering the 1GHz rated attenuators.
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Though at 1500MHz I had to use a bigger span because I couldn't get the peak centered in small span. Peak>CF would not work and manually scrolling, the frequency would change but the peak would stay in it's place. This was without proper warmup of the SA btw.?
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Would that mean that the mixer diodes have to be replaced asweel or would other measurements be needed to answer that??
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Marco
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Re: HP 16500C Display Question
I had another look for the 16500B and found this fellow ...?
I see a video port on that to. Hmmm.
On Fri, Nov 8, 2024 at 5:46?PM Damien Towning via <connolly.damien= [email protected]> wrote: I have an RGB2HDMI for another old bit of hardware.
But this is not EGA. Found a good thread over at EEVOLG :?
The mention of a board for the 16500B to output VGA as an option is interesting.?
The arcade display boards might be the way to go.?
On Tue, Nov 5, 2024 at 12:59?PM Adrian Godwin via <artgodwin= [email protected]> wrote: I had the same reaction.
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Eventually I came across some information about it. It appears there are a couple (probably more now) of devices to do the conversion and some fairly common pcbs to support them. I haven't got any further than buying a couple of PCBs but I think these are pointers to follow :
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--
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Re: HP 16500C Display Question
I have an RGB2HDMI for another old bit of hardware.
But this is not EGA. Found a good thread over at EEVOLG :?
The mention of a board for the 16500B to output VGA as an option is interesting.?
The arcade display boards might be the way to go.?
On Tue, Nov 5, 2024 at 12:59?PM Adrian Godwin via <artgodwin= [email protected]> wrote: I had the same reaction.
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Eventually I came across some information about it. It appears there are a couple (probably more now) of devices to do the conversion and some fairly common pcbs to support them. I haven't got any further than buying a couple of PCBs but I think these are pointers to follow :
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1991 HP 54600A missing text and display elements
I am attempting to repair a broken HP 54600A.
When I first powered it on the display was all solid green and squashed vertically, 3 of the tantalum caps on the motherboard also let out their magic smoke.
I have replaced the caps and the two responsible for the vertical deflection of the CRT.
It now displays both waveforms correctly but the display is missing all of the text and many other UI elements making the menus unusable.
Any help diagnosing this would be appreciated
Thanks,
Callum
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Re: HP 16500C Display Question
From looking at a schematic of the CRT it looks like they have capacitors in series to cut the dc. Going to try today some caps in series to see what happens on the R/G/B channels. It may be that rather than lifting the signal out of the connector on the mother board I lift it somewhere out of the crt past its somewhat odd resistor and capacitor setup. I was wondering if they did this to make the whole lot more tolerant to noise and interference.?
On Mon, Nov 4, 2024 at 10:34?PM Kuba Sunderland-Ober via <kuba= [email protected]> wrote: I¡¯ve used EGA sources with VGA displays in a pinch with a passive ¡°DAC¡± with resistors and a black restorer using an RF Schottky. I don¡¯t think I understand what¡¯s so special about ¡°native EGA¡± monitors. Even back when I actually had an EGA in one of my PCs in the 80s there was a little homebrew dongle that adapted that output to VGA. Many hobbyists I knew had one. I don¡¯t have the schematics anymore but it was common and cheap to put together.?
Cheers, Kuba ? From the tomverbeure reference you provided,?
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"The voltage levels for the sync signals are a standard 5V TTL (good!), but the voltage levels for the analog signals are weird, with a baseline of -1.7V and a maximum value of 125mV (WTF?), or an amplitude of 1.825V."
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I guess this would explain why you got the display to sync but with the video all black. VGA appears to be 0 to 0.7V positive, ie composite without the sync.
So you'd need to shift the levels up 1.7V and halve them to get anything displayed.
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Re: Repair of HP Logic Clips
Here, here! Everyones time and effort should be rewarded in some fashion. Often, appreciation is enough, other times, not. Some people do not have deep pockets, so trivial costs to some may be greater for others. Profit, if reasonable, is not evil in of itself.
In a message dated 11/7/2024 12:15:47 PM Eastern Standard Time, tekscopes@... writes:
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Profit doesn't have to enter into everything
I have to push back on this one: it doesn't but there is nothing wrong with making profit either. Every project no matter how small costs time and money, and honest work deserves to be compensated. To expect otherwise is to undermine the value of all that investment.
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If the author chooses to release their design freely, it should be treated as a generous gift that it is, not as an expectation.
_._,_._,_
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Re: Troubleshooting a 8591e with opt 130
Hi, ? If you have lost your calibration constants, it will be possible to rebuild them. For the moment there is the attenuator to repair... it is easily achievable according to the image. ? But I fear for your mixer, there is a good chance that it is damaged. But that too is repairable, it is only two SOT-23 components to replace (diodes). ? Attenuator values-based of attenuation. ? 
? ? Attenuator from RF input to first converter input. At left, absolute loss vs frequency, at right, VNA normalized to 0dB attenuator trace. ? 
? Yves ? ? Thanks for your reply! Those measurements look a lot more like what I expected. Took me a few days but got my hands on a nanoVNA and hooked it up to only the attenuator today. The noisefloor of the VNA at high frequencies is too high to really say something about the attenuator but at 100 and 400MHz the measurements are usable. It looks like the 10db is tilted and the 20dB is attenuating less than the 10dB. The 30dB looks ok.? i'd say this attenuator is toast, might still be more issues along the path though.? ? | Levels | ? | ? | ? | 100MHz | 300MHz | 600MHz | cable through | 1.5dB | 0.0dB | -0.1dB | analyzer off | -66dB | -53db | -64dB | 10db att | -21dB | -15dB | -12dB | 20db att | -15dB | -15dB | -17dB | 30db att | -34db | -30 dB | -30dB | 40db att | -51dB | -43dB | -44dB | 50db att | -45dB | -44dB | -49dB | 60db att | -66dB | -53dB | -66dB |
Wanted to backup the frequency response correction constants of the unit today but found out they are all gone already. So even if the attenuator and other issues could be fixed it would still need some form of calibration. Starting to feel more and more like flogging a dead horse.
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Wanted: Hp 2225 parts mule Thinkjet
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Looking for an Hp 2225 ThinkJet printer ... parts mule:
?? ( any of the 2225a, b, c, d units )
? I need the switch assembly ( Pwr / LF / FF? with LED's ) in the top upper Left hand corner.
? ?
Contact me Off-List (PM)
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thank you,
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Re: Troubleshooting a 8591e with opt 130
I went ahead and took the attenuator out. It's a JFW 50p-1120 and it was definitely abused by a previous owner. Googled the part number hoping to find other teardown pictures to find out replacement values but no luck so far
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Re: Repair of HP Logic Clips
It has never been my intention to make these boards for profit, and I'll be happy to up-load all files
I just made it for my self, because I thought it was a funny project
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Re: Troubleshooting a 8591e with opt 130
Hey Yves,
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Thanks for your reply! Those measurements look a lot more like what I expected. Took me a few days but got my hands on a nanoVNA and hooked it up to only the attenuator today. The noisefloor of the VNA at high frequencies is too high to really say something about the attenuator but at 100 and 400MHz the measurements are usable. It looks like the 10db is tilted and the 20dB is attenuating less than the 10dB. The 30dB looks ok.?
i'd say this attenuator is toast, might still be more issues along the path though.?
| ? |
Levels |
? |
? |
| ? |
100MHz |
300MHz |
600MHz |
| cable through |
1.5dB |
0.0dB |
-0.1dB |
| analyzer off |
-66dB |
-53db |
-64dB |
| 10db att |
-21dB |
-15dB |
-12dB |
| 20db att |
-15dB |
-15dB |
-17dB |
| 30db att |
-34db |
-30 dB |
?-30dB |
| 40db att |
-51dB |
-43dB |
?-44dB |
| 50db att |
-45dB |
-44dB |
-49dB |
| 60db att |
?-66dB |
-53dB |
-66dB |
Wanted to backup the frequency response correction constants of the unit today but found out they are all gone already. So even if the attenuator and other issues could be fixed it would still need some form of calibration. Starting to feel more and more like flogging a dead horse.
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Marco
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Re: Repair of HP Logic Clips
Neat project!? Well done.
If it were me, I'd release the board design and BoM* under a creative commons license and let others in on the act for personal use.? Profit doesn't have to enter into everything.? It'll be impossible to keep something like that "secret" anyway.
(* based on DigiKey / Mouser part numbers perhaps, with generic reference too, as they are largely universal world wide.)
The most expensive parts for most people (who are not conversant with ordering PCB's from a board shop) will be the two PCB's
Perhaps the only way to make a shekel on it, would be to order a batch of boards, and sell pairs them with the documentation.?? (eBay sell for free these days, at least hear in the UK, if you believe the ad's on TV.)
Regards.
Dave B (UK)
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Created on and sent from a Unix like PC running and using open source software:
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Re: Repair of HP Logic Clips
If he were instead to sell it, He may find the market really too small to be worthwhile. Probably no profit motive here otherwise.
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