A quick look at a few problems I found with this power supply. Are some of them just defects of my particular unit? The encoder problem is clearly shared with my electronic load of similar design. Leave a message if you have the same issues or if you checked and found no issues. Thanks.
Setting up a metrology lab on a small budget.
Datron 1071 repair: https://youtu.be/jcCC867gKXE
Fluke 341A repair: https://youtu.be/mxz3-fGs1Lk
EDC 520A repair: https://youtu.be/pkMySlkpTJk
Thermometer build: https://youtu.be/pj1HOM35vH4
KX Voltage reference : https://xdevs.com/article/kx-ref/
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https://www.youtube.com/watch?v=80ypF-Ix2p8
Repair of Shure PG2 wireless microphone.
The switch on DigiKey (part number 450-1140-ND):
http://www.digikey.com/product-detail/en/FSMSM/450-1140-ND/
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https://www.youtube.com/watch?v=Z2ag9VrgRLg
The instrument had a couple of faults: some flicker and jitter on the display, and some noise in the signal in VNA mode mostly visible at lower frequencies. The flicker disappeared after reconnecting some internal connections. The noise was traced to a cracked soldering joint in the VNA module.
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https://www.youtube.com/watch?v=nmXqApz3ETk
In this episode the project was completed. A few extra features were added such as LCD display and current measurement. Everything was fitted into an enclosure. The temperature inside the enclosure was measured after about 30 minutes of charging Nissan Leaf at 16A.
Part 1: https://youtu.be/JVhBMvj4KuA
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https://www.youtube.com/watch?v=to4eYCJ4ZfM
A good old HP 8590A spectrum analyzer, which was picked up from eBay for parts or repair. It turned out to have a bad mixer in the first converter. A matched pair of schottky diodes was dead. A replacement was found and installed. The analyzer seems to be back in business. Perhaps, it will need some adjustments though.
Forum:
http://www.eevblog.com/forum/repair/hp-8590a-spectrum-analyzer-repair/
Service manual:
http://www.keysight.com/upload/cmc_upload/All/8590AServiceGuide.pdf
Avago (Broadcom)HSMS-28xx datasheet:
http://www.mouser.com/ds/2/678/AV02-0533EN[1]-908864.pdf
Diodes on Mouser:
HSMS-2802 - the ones I used:
http://www.mouser.com/ProductDetail/Broadcom-Avago/HSMS-2802-BLKG
HSMS-2812 - the ones I think I should have used:
http://www.mouser.com/ProductDetail/Broadcom-Avago/HSMS-2812-BLKG
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https://www.youtube.com/watch?v=kV4BOf3Oqk8
The piano had non-working B4 key. The keyboard was taken apart and fixed. The problem was found to be with a rubber contact pad that got stuck in a strange twisted position somehow.
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https://www.youtube.com/watch?v=_Tpe7UYVOqc
This unit had 4 broken input combo TRS-XLR connectors. A few samples were obtained from Amphenol and installed.
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https://www.youtube.com/watch?v=r1O4gXvh7uo
This unit produced wrong output amplitudes. The problem was traced to a faulty ceramic bypass capacitor affecting one of the attenuation stages. After replacing the capacitor the amplitudes looked much better, but still off. Apparently someone tried calibrating the unit while the hardware was misbehaving. Fresh calibration fixed the problem.
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https://www.youtube.com/watch?v=PTLeZTKU8jk