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1 Jan 2020 18:06:15 UTC
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#60 - Zoom R16 repair fail
This Zoom R16 was picked up on eBay for parts or repair. It was described as not powering up. It turned out that both the external power supply and the R16 itself were dead. The NEC D78F0536 microcontroller seems to be faulty. No replacements are available and no firmware too. No way to proceed at the moment.
Power supply repair: https://youtu.be/wySRf2b0Low
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https://www.youtube.com/watch?v=3QJDH4LFgnQ
Power supply repair: https://youtu.be/wySRf2b0Low
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https://www.youtube.com/watch?v=3QJDH4LFgnQ
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#27 -
27-m-audio-axiom-61-keyboard-usb
This Axiom 61 keyboard (2nd generation) needed a new USB connector. The process of replacing it was shown in detail. It is quite simple given the right equipment and some experience.
Axiom 49 (1st gen) repair: https://youtu.be/GAeNwjgq0Qw
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https://www.youtube.com/watch?v=SJzhA-PmbIE
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#39 -
39-agilent-66321b-troubleshooting-and
Troubleshooting of a faulty Agilent 66321B Mobile Communications DC Source from eBay. It seems like the calibration memory was corrupted somehow. After going through the calibration procedure the unit appears to work just fine.
User's guide: http://cp.literature.agilent.com/litweb/pdf/5964-8184.pdf
Repair of Agilent 66309D: https://youtu.be/3kg7LIYbYLQ
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https://www.youtube.com/watch?v=OqyC8DkskaI
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#34 -
34-tektronix-tds-540a-oscilloscope
This scope suffered from the classic problem for this line: leaky electrolytic capacitors. All 96 capacitors were replaced, and a few broken PCB traces restored. A backup of Dallas DS1650Y NVRAM was made as well.
Schematics: http://hakanh.com/dl/kits.htm
Service manual: http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%20TDS%20520A,%20524A,%20540A,%20544A%20Service.pdf
Discussion: http://www.eevblog.com/forum/testgear/tektronix-tds-540a-repair/
Followup video: https://youtu.be/iJt2O5zaLRE
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https://www.youtube.com/watch?v=7V0LCL4mL-8
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#3 -
3-canon-battery-testing-part-2
I bought another battery to try: TechFuel NB-2L 850mAh.
Same equipment: Array 3710A electronic load (a re-branded unit), some programming in Python using Eclipse to log data from the electronic load, and a tiny bit of power of GNU Octave for plotting data.
Previous tests: http://youtu.be/hUCnEbOAP3A
After I finished the video it occurred to me to try a gentle discharge at 150mA. It took 207min, which translates to 518mAh. It is essentially the same as measured at 400mA.
Update (Apr 22 2014): the seller invited me to send the battery back to them for a refund, and I must pay the shipping. I don't like this, but I will send it back. I don't need one more useless battery sitting around.
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https://www.youtube.com/watch?v=yXYKc9gMNO4
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1 month ago
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#50 -
50-audio-technica-atw-d70-antenna
I needed an antenna and power distribution system for Shure wireless microphones, but Shure UA844 is too expensive, so I picked up a really cheap Audio-Tecnica ATW-D70. It is an old model with the frequency range of 728-750MHz, which is useless in the United States. I wanted to find out if it can be modified for use in the range of 470-698MHz, which was legal in the US for such purposes until recently, or at least 470-570MHz, which is going to stay legal going forward. I am talking about the FCC auction of the 600MHz band (570-698MHz). So it seems that such a modification is possible. Two filters (one per channel) need to be replaced, which was done. Frequency response after the modification was measured and was found acceptable.
Filter used: http://www.mouser.com/ProductDetail/Taiyo-Yuden/FI212L062003-T/
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https://www.youtube.com/watch?v=Ga0E2HHvPro
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#94 -
94-fluke-scopemeter-keypad-followup
A few hours after publishing my previous video I realized that there is a very easy fix for the problem with the mirrored connector. How come It did not occu...
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https://www.youtube.com/watch?v=ug27Y1bNSw8
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#33 -
33-yamaha-clavinova-clp-860-pedals
I got this digital piano with the pedals removed from the stand, screws and a spring in a plastic bag. Someone decided that something was wrong, but I didn't find anything. The circuit was traced, and the operation of the pedals was explained in the video. I hope it can be useful to someone.
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https://www.youtube.com/watch?v=mD2vjOtW-4M
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#37 -
37-a-look-inside-of-an-agilent-e4400b
Another lucky find from eBay. This Agilent E4400B generator has some problem with fractional PLL. It seems to be unstable, so the instrument periodically shows error 508 "Frac-N Loop Unlocked". The synthesizer was inspected, the block diagram was discussed and the blocks were located on the board. Unfortunately, there was no definite solution to the problem due to lack of appropriate equipment at the moment. If there will be any developments, another video might follow.
Calibration guide: http://literature.cdn.keysight.com/litweb/pdf/E4400-90325.pdf
Document with the block diagram. It is for a different model, which seems to use the same synthesizer:
http://cp.literature.agilent.com/litweb/pdf/E4400-90014.pdf
Discussion: http://www.eevblog.com/forum/testgear/a-look-inside-of-an-agilent-e4400b-signal-generator/
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https://www.youtube.com/watch?v=JPEmbvUx0JQ
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#79 -
79-channel-update-new-scope
A generous donation from Shahriar of The Signal Path channel: Keysight DSOX1102G oscilloscope. Thank you very much!
The Signal Path channel: https://www.youtube.com/channel/UCKxRARSpahF1Mt-2vbPug-g
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https://www.youtube.com/watch?v=8PMGVik7-_w
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