Teardown and Repair of a Racal-Dana 1992 Frequency Counter
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- Опубликовано: 15 сен 2024
- In this video, I did some repair on a Racal-Dana 1992 frequency counter. I also covered some fundamentals of frequency counters in general. Pictures of the teardown can be found on my website www.kerrywong.c...
Nice instrument! Judging from the front panel I wouldn't have expected it to have such advanced functions and diagnostics.
Excellent troubleshooting and step-by-step explanation. Very well done. And the end result! 👍🏻
Beautiful instrument. I had a counter like this a few years ago
I gave this a thumbs up. When troubleshooting it allway good to check for socket chips as this is a give away that the part may have been replaced before. If all the chips are socketed well c'e la vie.
Thanks Joseph. The only down side of putting chips in sockets I suppose is that overtime the contacts could be oxidized and causing failures. But that could be solved by wiggling and reseating ICs.
Nice find Kerry! Agree on installing a socket but sometimes a component really needs to be down flush to the board for RF purposes although most often not. When you're working with your diagrams you may want to change the camera to a fixed focus on the page as it kept changing between the diagram and your hand and made it a little hard to watch; I don't remember that being an issue with your previous videos. Thanks for the explanations, always learn something new on your channel!
Thanks for the suggestion. Yeah, I am still getting used to the new camera (Sony A6000). I will be sure to use manual focusing the next time when I am doing explanations on paper.
Great repair and explanation! Thanks as always!
Got a Racal Dana 1998. I like the stirdy housing, it is really rugged.
Nicely done. Excellent video. Joel
Thanks Joel!
I have one Dana instrument- a 3-1/2 digit multimeter from the early 1970s with Nixie tube display...
This one is not as old, it was from 1990.
It looks like it has the same MOS Vic chip for video output ore display output as the Commodore 64 had.
Nice video. Well explained.
Thanks!
nice troubleshooting skills!
Thanks!
Hey I’m having trouble finding a part number for channel C fuse. Any idea on what it could be ?
I have one and channel C is not working. Does anyone know where the fuse is located for channel C? Thanks!
Where did you find the service manual for this unit? I'd like to have a copy of that for mine.
I don't remember where I downloaded from, but if you PM me I can send you a copy.
@@KerryWongBlog Thanks but I found one.
Channel A doesn't work on my unit either. It also has a crystal oven but none of the resistors look burned or broken and there was no rework, the seal on the cabinet was not even broken. Channel C works but the freq. reading is a bit off. Did you have to calibrate yours?
I didn't calibrate mine afterwards as the frequency reading was close enough (a few milihertz off if I recall correctly).
@@KerryWongBlog Got the A input fixed. It had an open 100 ohm resistor R160 and a shorted protection diode, D5. Oddly there is only one protection diode that is connected from the signal path to the -11.2 volt buss. The unit is also missing a couple of gray buttons but Racal_Dana is listed as the supplier so I may have to 3D print those.
Great! Thanks for the update.
@@KerryWongBlog Finding a replacement for the protection diode D5 was a problem. They used a special low capacitance diode type JPAD50 that has only about 2 pf. of capacitance that seems to be rare and expensive. I tried a regular diode with 50 pf capacitance but it loaded down the signal too much. The original D5 looks just like a small transistor with one lead clipped off so I tried a 2N3904 connected base to collector and it seems to work OK.