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Re: HP Agilent 8753ES VNA repair [Help]
Hello Yves,
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Thank you for your screenshoot. Here is what I got on my board.
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TP20 B (with look cable between port 1 and port 2):?
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TP18 A (OPEN loop between port 1 and port 2):
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TP16 R:
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I check the TP1 5V and the voltage is OK here.?
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Two points here :
- The IF frequency seems to be off, I have 22 KHz instead of 4 KHz. Do I have a problem with one of the final OL ? Perhaps it is why I have nothing on TP7,8,9. There is some LC filter in the board. ? - I had to put the probe level in x2 mode in my scope to measure the same voltage than you in peak to peak mode. The voltage I measure initially was divided by two. I don't think this is important.?
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Re: Service manual scan post processing
Don't know where I read this, but it said: better use high resolution with JPEG compression than low resolution without. For the same file size, that is.
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My experience: 300dpi is largely sufficient even for schematics, with compression. If the original is bad, has exceptionally small lettering or such, I take 600dpi as a precautionary measure. Of course JPEG does the artefacts around sharp contrasts, but as long as its perfectly readable I prefer that to humongous files that take minutes to open... cheers Martin Using JPEG for those will result in nasty artifacting around the text, border box, etc. I'd not recommend that at all. |
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Re: HP Agilent 8753ES VNA repair [Help]
开云体育Sorry, test point TP12, TP10 and TP11 are ground from sampler…no signal on that. Input signals are on TP16, Tp18 and TP20. Output R, A and B are -6dB lower than input (TP 9,8 and 7). ? Signal at TP16 R: 1.18Vpp Signal at TP18 A: 3.75Vpp (no loop cable) Signal at TP20 B: 3.51Vpp (with loop cable) ? PRESET SWEEP SETUP CW FREQ (defaut 1GHz) SWEEP TIME 10sec ? ? ? ? De?: [email protected] <[email protected]> De la part de Yves Tardif via groups.io ? If the three signals are absent, there would have to be a common point between them, so there is the local power supply. ? Signal A, B and R on DIGITAL IF come from of the 3 outputs of samplers at 4kHz via motherboard. Check TP12, TP10 and TP11 connected to input lines from mother board. ? If there are no signal at theses points, problem is near samplers? ? ? |
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Re: Service manual scan post processing
I should have said:
[...] scan 600dpi, ==greyscale== .tiff-s !!ONLY!! I don't want to have to dig for that so give me a link, I'll postBill @ PEARL, Inc. |
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Re: Service manual scan post processing
I don't want to have to dig for that so give me a link, I'll post process and get back to you.
I have long since and flat out mastered document scanning and restoration, I've done 1,000s upon 1,000s of pages and brought documents back from nothing to virtually as printed appearance. You need Acrobat 9.xx, Photoshop 7.01 with some well configured filters, scan 600dpi .tiff-s !!ONLY!! , use Acrobat to assemble the Photoshopped.tiff-s then Clearscan OCR. Don't worry about the .tiff file sizes, ClearScan will reduce the size about 10-fold. I use an Epson V600 that talks USB2 and the companion Epson software and a Canon DR-4010C that talks USB2 and SCSI, which I use, and it's companion driver and software. It'll duplex 24-bit color @ 600 dpi at about one second per face. I would be interested in feedback from members as to how well their post processing for .pdf works with these files.Bill @ PEARL, Inc. |
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Re: HP Agilent 8753ES VNA repair [Help]
开云体育If the three signals are absent, there would have to be a common point between them, so there is the local power supply. ? Signal A, B and R on DIGITAL IF come from of the 3 outputs of samplers at 4kHz via motherboard. Check TP12, TP10 and TP11 connected to input lines from mother board. ? If there are no signal at theses points, problem is near samplers? ? ? |
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Re: Service manual scan post processing
On 2/28/25 17:50, Tom Gardner via groups.io wrote:
Reducing the pictures, e.g. *19.tif, to a two level bitmap is unlikely to be successful. To reduce the size, I would try reducing the XY resolution to largely remove the "grain effect", then convert to a .jpg format.Using JPEG for those will result in nasty artifacting around the text, border box, etc. I'd not recommend that at all. -Dave -- Dave McGuire, AK4HZ New Kensington, PA |
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Re: HP Agilent 8753ES VNA repair [Help]
开云体育Hi, ? To make a short summary: You have tested several RF paths, <300kHz, <16 MHz, CW 1GHz, sweep up to 6GHz. In all cases the signal is noisy for all S parameters, but always PHASE LOCKED. You have done tests on samplers A, B and R. Even if B seems weak according to the measurement you have done, this would not affect the other possibilities. The only common point between all these paths is the DIGITAL IF. ? Do the oscilloscope tests for channels R, A and B on the DIGITAL IF. Here again there are separate paths for these three signals, but they have common power supplies and a switch leading to the ADC. ? Out of curiosity do TEST 17 ADC LIN. This test activates a precision ramp at low frequency and tests the ADC. ? Here is a picture of a DIGITAL IF PCB, does your PCB look like this version. If so, you have the schematics available for that, here is the DIGITAL IF section. ? ---------------- CW mode 1GHz, test on DIGITAL board. ? ? ? ----------------------------- ? 1 GHz, 0 dBm, SPAN 0 mode, PORT 1 output:??? your signal is OK, with same setup, similar result (I have 1D5 option, high stability ref). ? ? R output power verification at 1GHZ, SPAN 0 mode :? nominal -16dBm, it’s OK ? ------------------ ? ? |
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Re: Service manual scan post processing
On 2/28/25 17:11, Dave_G0WBX via groups.io wrote:
I've had a play with GIMP on Linux, and I can (to my eye anyway) sharpen things up quite nicely.I didn't bother with any sharpening; the original scans really aren't too bad. One example of a page in that document that has a schematic is page 20. I did a quick pass in GIMP on each TIFF file, to determine the most reasonable approach on a per-page basis. Then I threw together a quick script that used ImageMagick to apply those functions per file, concatenate them to a PDF, then do the OCR pass. Some of those pages would benefit from some manual editing, like cropping, etc, but they're perfectly readable as they are, at least to me, and having the text layer underneath the page image is good. -Dave -- Dave McGuire, AK4HZ New Kensington, PA |
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Re: Service manual scan post processing
On 2/28/25 16:18, Peter Brown wrote:
Looking at the service manual for the Canon MS-8000 reveals the followingI sure would like to get my hands on one of those scanners. -Dave -- Dave McGuire, AK4HZ New Kensington, PA |
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Re: Service manual scan post processing
On 2/28/25 10:00, Peter Brown wrote:
Any other takers for trying to post process the 256 level .tiff files? -? found atI took a whack at it and didn't get anywhere near as much of a size reduction as you did. But, the file looks great, passes a PDF/A validator, and has been OCRed. And, no embedded ads. ;) I've put it in the directory with the TIFF files. I applied a binary threshold to all of the text pages, and posterized the pages with graphical content at varying levels, mostly 24 and 32, to preserve the image quality. -Dave -- Dave McGuire, AK4HZ New Kensington, PA |
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