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- Опубліковано 23 лип 2024
- In this episode Shahriar takes a close look at an EG&G DSP-Based Lock-In Amplifier. This instrument provides excellent sensitivity for both voltage and current inputs and is based on a fully digital architecture. The instrument's LCD screen is dim and unreadable. Furthermore, a few lines are missing from the LCD pointing to a failed zebra strip.
The instrument's block diagram is examined and explained. The teardown reveals the structure of the LCD screen, front-end blocks and internal PLL. The CCFL back-light inverter is located and replaced with a low-voltage DC-DC converter for use with an LED strip. The instrument's functionality is verified through a few experiments including measuring the 3dB bandwidth of an RC filter as well as measuring the photo-current induced in an LED using a synchronized infrared light source.
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Seeing the new LCD backlight was already good, then seeing the LCD without any missing lines was satisfying. However, seeing the Chinese DC/DC converter module fitting like it was made for it... Really, really satisfying...
That display mod worked great. However the hotbar connection of the display will most likely fail again. I have lost count how many of these displays I have replaced. These displays are still available today. The good thing: They don't use hotbar connections anymore, they addded 16 connections to each side of the 4 zebra strips to make up the 64 line connections. When I replaced the displays I went for Winstar (w/o BL) and Bolimyn FSTN with white BL. The only "problem" now is that the T6983 controller is obsolete and has been replaced by a compatible type from China.
I think it depends on the display brand (or more precise, the glue brand) if the bond-on-glass repair is more permanent. The glue has conducting "ball's". By applying the right temperature and pressure the ball's "break" and form a conductor between glass and cable. I think that displays with this problem are going bad because the pressure or temp were wrong during production. If there are enough balls left the repair will succeed. I have reworked this several times with succes. I use 165 degrees celcius.
About those bloody zebrastrips, I once read a report from a LCD manufacturer that was made after analyzing a batch of displays that failed in use. The cause was the cleaning with IPA during assembling.
@@pa4tim I have had at least 5 manufacturers over the years with hot bars. All failed within a few years. Then we went to zebra only and none failed. After that I designed a display myself with zebra strips. No zebra fails. We use silcone based zebra strips not that cheap TPE stuff. Silicone based are IPA resistant which we also use for cleaning before assembly. That manufacturer has chosen incompatible compounds. For TPE you need to clean with water based solutions that do not work as good. TPE stips are only about 1/3 the cost of silicone based ones. Also silicone based zebras are more temperature stable.
@@ChipGuy Thanks, that is interesting info about the zebra strips. Hard to find good info about this subject. I repair test and calibration gear (and industrial stuff) for a living. The cases I did the hotbar thing there was no alternative. But low numbers, like 1 or 2 a year. I try to avoid these repairs because it is often a lot of work and I can not guarantee it is permanent.
Do you have an adres where I can buy replacement zebrastrips ? Are there standard zebra strips sizes (regarding height, width, length, pitch) Or is it all custom made ?
@@pa4tim I get the zebra stips custom made by a german company, but I am sure they get them in China somewhere. Asking some supplier at AliExpress might help.
Loved the cat's reaction: "It's just a back-light replacement fix.." :)
Note to the remarks to your loverly cat, Egyptions Worshipped Cats as they were special to bring them good luck ! "Great Repair" you have to thank your cat for that, Iam getting my EG&G 7265 in the door today, I do have the analogue version in my store as well, I must admit it looks a very impressive kit to own, & yes the unit needs a LED strip & PSU perhaps you can guide me to the units for this modification, thank you in advance for that,
I love your cat, but can't have animals in my apartment, I have to move to a Bungalow I can say that for sure, due to a bad life changing spinal accident last year :(, I keep on with my pastime hobby as such, used to work in a UKAS laboratory years ago in the UK, I guess that I won't ever stop enjoying electronics,
19:28 "Why do you disturb me, mortal?" - the cat, probably.
Excellent video. Hard to look at other videos and not compare them to your exquisite content.
Is this the same EG&G that makes that made the cameras that photographed Nuclear Explosions including some of the earliest ones ? [edit]Just searched. ... indeed it appears to be. Very cool
Yet another piece of equipment I wish to have on the bench to work on diod arrays for atomic absorption.
Excellent!
the cat shot is awesome :)
Keep up the Good Work!.
19:29 :)
Thumbs up Indiana USA.
I love how so often all you need is a backlight! JK...LOL I love your videos Shahriar. Also thrilled to see over 61,000 subscribers!
Any documentation on how to use the pots inside the faraday cage to calibrate? My 7265 reports an R that is 170% when directly connected to oscillator.
featuring The Signal Cat
👍👍
Nice repair and demonstration of LI applications.
Anyhow, LI are used for ultra-sensitive phase / frequency locked measurements, like well down in the nV /pV AC-ranges, and maybe having a high dynamic range of SNR, dependent on the AC gain setting.
These LI are not that 'precise', maybe on the order of 0.1% only.
Did you watch his first video? Did you know he works at Bell Labs? I think he probably knows what LI are for ;)
What is the output impedance of the oscillator? Should this not be added onto decade resistor setting when calculating the RC time constant?
I used that device in a lab like 10 years ago. IIRC the output impedance of the oscillator is 50 ohms. The manual is available online, check page A-4, or 114 in raw pdf page number at www.ameteksi.com/-/media/ameteksi/download_links/documentations/7225/190491-a-mnl-b.pdf . I repeated the calculation for 1.59kOhms (1.54k from the decade box and 50 Ohms output impedance). The corner frequency is 1000.97Hz, so just 0,1% off the target 1kHz. As you notice, the indicated phase shift is not 45°, but 45.03°, so it *also* is nearly 0,1% off. It seems like the lock-in amplifier is not the weakest link here.
Oops, google screwed me. That's the manual of a related instrument. The correct manual is w0.rz-berlin.mpg.de/pc/labview/wp-content/uploads/2014/08/190284-A-MNL-C.pdf , its page 172 in that document.
A video Request Please Could you show how to measure the internal impedance of a Li-Ion Battery using a AC signal like what is shown on Data sheets for batteries please
19:23 Holyshit i had a jumpscare from that unexpected alien gaze at me! Wtf
dawww! what a handsome kitty :3
Thumbnail at 19:28
Running power to a CCFL trough standard ribbon cable? That's insane in more ways than i can count ... Silly engineers.
Exactly. They designed such a complicated instrument perfectly (I guess), then included a crazy thing like this. All of these standard ribbon cables I've seen are rated for 300V maximum. The peak voltage can be *much* higher on a CCFL, especially during startup. Also, the converter should be on the front panel PCB. Running a high frequency, high voltage signal that far can cause a lot of radiated interference, especially if the output of the converter is not pure sinewave. It should be sinewave to be gentle on the tube, but I'm pretty sure it has quite high THD. So high that this might be the cause of the tube to die early. This one doesn't seems like a high hour unit, it's very clean inside, even the fan is completely clean.
uk designer did it because the hv backlight was an afterthought hence the hv in the ribbon cable, which we thought was daft also, but who listens to test techs....we built these in ireland by the way
Still teaching RF at Columbia?
Yes.
Just got my EG&G today, same fault backlight, everything else works ok, but I will change the 160mm? 2mm or 3mm? Cold cathode JKL Components Corporation for a new keeping things as much to the same state without removing the main PCB & fitting a DC to DC, I will use a Either Digi-Key, Mouser or Arrow,
I know its probably a long time ago do you remember the actual size length - width in mm of the Cold Cathode tube, it looks to be around 160mm?
I am reluctant to strip down & leave around in bits, until new parts arrive, 3mmx160mm ccfl part number is BF3160-20B
Can you assist with tthe actual side of the CCFL please.
Thank you in advance
I don't actually remember the exact size. But these LED replacements can be cut to various sizes. A CC driver can then be adjusted to appropriate value for the number of LEDs.
Where did you get the LED strip for this?
eBay, there are tons of them. Usually ship from China.
We didn't expected DC measurements here. 😃 I thought even you lab PSUs have at least 10GHz ripple, just in case... 😃
How did you change the percentage in the R value at the beginning, to mV?
I'm curious how the measurement limits of the digital unit compares with the analog. Is vinyl a meme?
For lock in amplifiers, digital definitely is better than analog. Analog units are almost nonexistent due to dynamic range limitations. It appears to be much easier to make a linear ADC than a linear analog multiplier.
این ویدیو حتما عیدی سال جدیده : )
یک عدد از این تقویت کننده مبتنی بر دی.اس.پی ناقابل به عنوان عیدی قبول می نماییم! خواهشمندیم جهت ارسال، بابل-رپ و هارد باکس شده باشد :)) هاها
@@mahdimahdavi , مهدی مهدوی، به یاد داشته باشید حمل و نقل اضافی است! بلند خندیدن
Do you always source the instruments from E-bay?
Iceteavanill, Where else would you get a bargain like this unit?
@@BruceNitroxpro Maybe some local guy who doesn't know what it really is....
19:23 I almost fell of my chair..
Dr. Pooch... :)
I would like to talk with your supervisor
Meow :3
didn't mikeselektrikstuff tear down a baggage X-Ray machine from EG&G?
Can We measured I vs V Characteristics from using lock-in amplifier
Are you interested in another Anritsu Spectrum Analyzer 100mhz-3ghz? This one is unused.
who else skipped to 19:25 first!
الان دو تا ویدیو با شماره ی 146 تو کانال هست ؟
از کجا 146 کانال دریافت می کنید؟
Can you please give a link to your other video you mention?
ua-cam.com/video/rzzliN_vTKs/v-deo.html
Can you give the c programming to connect this
Can we connect this amplifier with pc
Sir will you help me in repairing 7260 DSP lock in amplifier