Great video, this was 11 years ago and the quality of sound has greatly increased, audiophiles are now understanding how good they can be. A genius invention in my mind.
I realise that this video is over 10 years old, but my method may still be of use: I haven't seen this complete video yet but what I have always done to get an accurate 10Mhz reference is by using the cesium atomic clock driven carrier signal from WWV, by adjusting my oscillator to this carrier frequency using the beat frequency method. This is even more accurate than a rubidium frequency standard. The method I used was by tuning into WWV 10Mhz signal using a short wave radio then the device that needed its oscillator adjusted was brought near to the short wave radio and its oscillator was adjusted to provide a zero beat signal. I was located in New Zealand , so had to wait for the best time of day/night to get the best signal from WWV of course.
Thanks so much for this video. Do you happen to still have those photos you took of the connections from the transformer to the power connector? I thought I took enough, but it appears I didn't.
@@gerrysweeney No problem Gerry I eventually got it sorted out after a few blown fuses haha. Mine had almost the same issues as yours just not as fried. I found the original shut resistor in china which works well. Just had to replace that, the 33 ohm resistor, the fet (q5 only) and an OP7 op amp and I’m back in business!
Wow. It's been a long while since I've watched a technical video from end to end... but this was worth it! Thank you! I would've just been happy for a plain 'old signal distribution box!
Nice work! One quick comment, the 75ohm BNC connectors are different from the 50ohm version; the mismatch in not an issue here, but the 50ohm center pin is thicker and might damage the 75ohm connector over time.
Thank you for the video, however I took the longer road and disassembled the display entirely. It is cumbersome and tedious, but I could not imagine to solder it the way you did. After disassembling the frame and everything I was able to disassemble the and isolate the left part of the backlight LED strip. With this in plain sight I was able to re solder the connector again nice and clean. For those that come her and look for solutions.
The data sheet for my Accubeat rubidium standard does state a max temp for the unit. So yes, it does need to dissipate some of the heat so it does not overheat. You don't want the unit getting too hot. You might want to keep it below 80° F.
Ib know this video is 10 ys. old and it's been 20 years since i worked with extron but I'll share my if the top memory. The green channel should be 315mhz bandwidth, red and blue somewhere between 50 and 80 mhz and i think 100 mhz for H & V. The green channel on extron hardware is designed to carry the composite video including chroma and luma and any sync info. Awesome to see you using it. It's been a long time.
Nice :) yeah the video amps in there are more than capable of the 10Mhz so a very good re-use of an old bit of kit that in todays digital world would otherwise end up in landfill
@@gerrysweeney this was the first time I've seen extron on you tube. Man I used to be drowning in that stuff. I still have one or 2 extron tweekers (flippable micro screwdriver that came in every box) around here.
Your comments about enclosures really rings true! I have found a good technique is to find off-the-shelf enclosures then get some laser cut aluminium/stainless panels done for the connectors and controls.
So I attempted this operation. One of the pads that you solder the wire to came off! I take it I out of luck with getting full LED light working on my auria monitor that uses the same LG panel inside as the macs?
... Hi Gary, after 10 years, you may have answered this question... nevertheless, I'd like to know this ... why is canal 1 AC coupled and canal B, DC coupled .?
Assuming your simplified circuit diagram @33:00 is accurate enough I think there might be another (much smaller) design flaw: the secondary voltages use the big +-rail as GND but it's connected after the shunt resistor while the main switching mosfet(?) is bevor the shunt. Wouldn't it be better if both were on the same side? - so if/when the shunt fails the PSU doesn't kill itself because most/all parts are still referenced/connected to the same GND (only when an external load is connected)? With the failed shunt it's kinda split-GND isn't it?
Great info even 9 years later. Having already done the "bake the graphics card" trick I just assumed it was that failing again, but no.. It's a new failure to deal with. I'll probably do exactly what you did. Thanks very much.
It's amazing how small amps have become for their power. I used to work at a music shop in the early '90s and we had a used 500w+500w class AB amp from the late '80s for sale and that thing was an absolute beast, it was only 2U high but nearly 3 feet deep. Had two massive toroidal transformers and rammed with MOSFETs and needed two people to lift it. I don't think anyone ever brought it in the end 😆
This is the fault of the layout engineer and all his colleagues who allowed that preposterous trace width to connect a giant three-hole component. Reliability by design... fail.
Very informative video, but it is worth remembering about other distortions that Otala discovered and were related to the slew rate of the amplified signal and the depth of the amplifier's feedback.
Very useful video, Gerry. Thanks. Can you please clarify where that red cap came from? Is that from the banana end of a test lead? It’s only shown for a moment without much explanation. Also, what is the part number for that switch? Thanks again!
"Can you please clarify where that red cap came from?" the red cap is just a protection cap you find included with typical 4mm meter lead. I don't have a part number to hand but those switches are very common, you can eyeball them easy enough. Something like this: www.ebay.co.uk/itm/183739838385
I find it staggering that the Keithley 2015 is the only multimeter that measures Thd. It costs around 7000 UK pounds new, serious money. If other manufacturers brought out cheaper meters with this on, I am sure they fly off the shelves.
You can use modern replacements for those oven-based TCXOs. If you want to make a board anyway, you might consider to chose a modern part. Better accuracy, smaller, way lower power consumption.
For anyone else doing the 75 to 50 Ohm conversion. If you don't have 50 Ohm resistors, then a 150 Ohm resistor piggy backed onto the original 75 Ohm resistor will give you 50 Ohms.
MOSFET can have either positive or negative temperature coefficient depending on Vgs. Look at the IRF250 datasheet : Id as a function of Vgs. It has a negative temperature coefficient for Vgs < 7v. And this dummy load is only 150W, its maximum current setting is rather low so Vgs is most likely in the negative temperature coefficient range. which can lead to the thermal runaway without those current balancing resistors.
Love your videos! This one in particular was exceptionally inspiring to me. I've been running a GPSDO in my lab (I did purchase a couple of your TCXO boards for the HP/Agilent frequency counters), but because of this video I've purchased the Rubidium standard, and also a couple of the Extron D/As (two came in a rack mount duplex configuration). I've modeled the Rubidium standard, as well as a rectangular hole for a lighted rocker switch and CNC machined all the holes into the front panel. I also opted to not gang all 18 outputs together, but rather keep them in sets of 6. The top one I removed the BNC and installed a right angle BNC on the inside of the PCB so as to provide a connector inside the chassis to the standard. I then made two short RG-316 jumpers to jump the other two sets of outputs to the main section. Next I'll be CNC machining the fan holes and building the auxiliary PCB with the PIC for the LED control. Work in progress, but I owe you so many thanks for putting out this video.
Nice Video Gerry. I have been doing similar things lately. Following Dave Jones video, I bought a Rubidium oscillator several years ago and only used it a little. More recently I've invested in some older but quite high spec equipment and have been curious how accurate they were even though some have included calibration certificates. Just recently I also purchased one of the second hand OCXO's pulled from equipment and I too found them to be very good. I have video's some of my findings but not edited the clips yet. One other comment why not just use one of your oscillators, maybe even the rubidium standard and distribute that to all of your equipment? I would be interested in how you would tackle it. I am thinking of taking the 10MHz input and using some buffers for multiple outputs and distribute that to my various pieces of test equipment, counters, spectrum analyzers etc. One other thought, do you need to convert the sine wave output to square wave for any equipment? and is there a min/max voltage range required for your equipment, I know some must not exceed certain levels.
Ahh thats nice, I went to work and that has most definitely taken over my life. I do hope to get back to the electronics and YT, I have literally a whole room full of stuff to mess with. Thank you for sticking around the channel though. I appreciate that.
@@gerrysweeney thank you for the update. I look forward to your eventual return. Don't come back early just to appease me; do it when you're ready, of course.
Very interesting indeed! I discovered that thanks to you. However: Why make it simple when you can make it complicated... Instead of destroying the plastic contactor, I put a drop of WD4O, for electrical contacts, two small wedges (mini nails) to force the contacts towards the welds. Adhesive, reassemble the screen, test, bingo!
Both your videos are informative and I’m grateful for them. I did find it a little paradoxical that you’re happy to take the thing to bits, but left the protective film on the display, bubbles and all. Has the meter held up for you over the years?
Yeah I tried to keep it as new, and to be honest, since I shot that video the meter is still in its box and has never been used. I have a lot of meters!
