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Free Abandoned HP 3478A 5-½ Digit DVM Repair
Free Abandoned HP 3478A 5-½ Digit DVM Repair
#Free #Abandoned #3478A #5½ #Digit #DVM #Repair
“CuriousMarc”
We repair a classic HP 3478A 5-½ digit voltmeter, and admire its ultra complicated A to D converter. HP Multislope II ADC patent: …
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I both replaced the battery and caps in my 3478a a few days back. Having a usb-to-gpib converter to download the firmware made things easier.
Man I want one of those :c. All I ever find is either insanely damaged cheapish stuff or WAY too expensive semi broken stuff
I guess as a result of this video, Wikipedia now has a nice explanation of Multislope on its "Integrating ADC" page.
@5:33 those look a lot like Apollo switches! 😍🤩
Really great repair. Thanks for your time.
Is there a reason you wouldn't solder in a socket for the battery to make it easier for the next person?
Be careful not to burn the nearby components with the hot exhaust from the propane soldering iron. Ask me how I know.
Rats you got to the HP3450 before I had a chance to get mine fully working 😉.
Nice to see you explanation on the Dual slope I guess I will have cut down on the 'Circuit Talk' part of my video and just put a link to here😊
Another 3478A back in business ,nice. I really like these meters. If I see one on ebay for cheap, I am compelled to buy it and fix it…. 😀 PS: wow never seen one with a bad switch connection, seen bad relays, bad opamp, many bad batteries and capacitors, but a switch, wow.
Another questions to your imac repair video years ago:
My imac late 2015 has the purple edges all around the black frame (well known problem without solution) . So on IFIXIT you can find "around the edge is just where you put the double side tape to fix it to the case, exactly where the inner side of the double tape makes a boundary, there are some plastic bezels or framing stuff. this plastic actually is not only a guide to mount the LCD panel in the right position, is also a kind of seal that blocks the external source of light."
– So does it help to glue this small gap between the plastic bezels or framing stuff to repair the pink edges around the screen ? I think that would be logical.
This channel has inundated me with an irrational fondness for elevator music.
I understand very little but each video I learn one or two new things and I love that. Engineering is fascinating
I get happy like a little kid when I'm notified about a new CuriousMarc video. This is the best channel when it comes to electronics as you take your time to give very good and detailed explanations about how things work. Thank you!
METRIC! 😂
The battery vivisection was pretty cool.
To build a technical giant like HP you need multiple PHDs. To destroy it … all you need is one MBA!😂
Interestingly, the Keithley 175/175A and other devices from this series use the same mechanism for A/D conversion. Its function is well described in Keithleys service manual.
I had one of those for repairs on my bench last week and it took me some time to figure out, how the conversation is done. So enjoyed your explanation how the convesion works.
Would love to see a future video adding a backlight or OLED display. I've done backlight mods when I was younger, including adding backlight to the original kill-a-watt meter.
I'm not a big fan of soldering on battery poles.
It might overheat the separator or the safety valv
Maybe it was answered somewhere already (tho I quickly scrolled thru the comments and haven't found it). Why have you soldered the battery back and not added some holder for it, so it can be easily replaced later? Or there is no standardised holder for it? I understand, it may be a bit risky, as it could potentially wiggle out of the holder, but then, you can stick it with kapton or something. And next time, nobody would need to do soldering.
Crumpets, coffee, and curious Marc, a great breakfast.
How fortunate that marc would put out this video a day after I acquired one of these for measurement automation!
Interesting 🧐. The dwell time of my mind-blown state has been increased. Good stuff, gentlemen! 👍
Oh! very pleased to see a mention regarding my 3457A backlighting mods……thanks!
You can also read our the calibration data via HPIB and restore it after the battery replacement. That is what I did, except after powering it on it still had the calibration data as if I hadn’t disconnected the battery.
Hi. I have a 3478a but I accidentally erased the calibration. When I turn it on, it flashes calibration. Does anyone knows how to calibrate it or send the link for calibration? Thanks
The HP3478 has four or five RIFA filtering caps around the transformer that are always cracked. It may be a good idea to replace them.
Marc, your timing is amazing! I'm currently trying to repair an Agilent E3634A power supply, which outputs power but voltage and current aren't displayed correctly on the front panel. I'm suspecting the A/D converter, which uses the new, improved Multislope III method. I've been struggling to understand how it works and your explanation has helped me a lot. Thanks!
9:02 egad, that’s a lot of 📈📉📉📉📈📉📉📉📉📉📉📈📈📉📈📉📈for one measurement