Sort of electronic. Fixed the darkness in my garage with some LED strip lights made to look like fluorescent fixtures. Spent a good part of the day putting in boxes, running wire, and getting them mounted. Bright as day in there now.
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What electronics have YOU fixed lately?
- Thread starter Robb
- Start date
Tram D80. Converted it from a smoke generator to a radio. Someone had apparently hooked the power up backwards, frying the reverse polarity diode. Next guy in the chain plugs it in to test it, and cooks the two chokes on the power lines. Guess the diode failed shorted. Replaced the chokes and the diode, it's happy again. Recapped it and removed the Sony bond while I was in there.
Sears "934.38260700". PLL wasn't looping, although the VCO was oscillating.
Found that the mixer for the loop downmix had two inputs, no output. Took the easy way out and swapped the transistor, no go.
Checked voltages, and the emitter was at 2.3V while the base was at 1.4V. That's not how an NPN works.
Much probing of stuff later and noticed that what was supposed to be the "ground" for the downmix oscillator signal (it's in a little can above the main board) had 2.6V on it.
Hmm... what happens when you swap these two wires? The PLL immediately got lock and it at least has receive now.
So, if you're ever working on one of these, the white wire goes to P33. The white wire with the black stripe goes to P34. They're marked "OUT" and "GND" , respectively, on the little board in the can. Just in case somebody changed the wires out with "prettier" colored ones.
Found that the mixer for the loop downmix had two inputs, no output. Took the easy way out and swapped the transistor, no go.
Checked voltages, and the emitter was at 2.3V while the base was at 1.4V. That's not how an NPN works.
Much probing of stuff later and noticed that what was supposed to be the "ground" for the downmix oscillator signal (it's in a little can above the main board) had 2.6V on it.
Hmm... what happens when you swap these two wires? The PLL immediately got lock and it at least has receive now.
So, if you're ever working on one of these, the white wire goes to P33. The white wire with the black stripe goes to P34. They're marked "OUT" and "GND" , respectively, on the little board in the can. Just in case somebody changed the wires out with "prettier" colored ones.
Recapped and retuned this oldie. The crystals seem to be dated 1965, so its likely home will end up being the ‘51 Chevy in my profile picture.
TRS Challenger 460. Bought as "guaranteed DOA." Was poking for places to put an oscope probe when it started working. Reflowed stuff around where I pressed, didn't quite fix it.
Went in with the magnifying glass and found that little circle in a solder joint that tells you it's broken. It was the anode of D1, the varactor diode for the VCO.
Which explains pretty much everything.
Reflowed that joint and now I can't make it stop working.
Went in with the magnifying glass and found that little circle in a solder joint that tells you it's broken. It was the anode of D1, the varactor diode for the VCO.
Which explains pretty much everything.
Reflowed that joint and now I can't make it stop working.
I had to replace the power supply caps for the fourth time in my old ViewSonic monitor today. Keep in mind I only use so called quality caps such as Nichicon and Panasonic. In some cases I increased the working voltage thinking that may help, but that didn’t seem to increase longevity either. At best the caps only last for about two years. I’ve been using a wide screen Dell as a backup, but the glossy screen on that one has too much glare for my liking. I would have scraped this ViewSonic years ago, except for the almost glare free screen, high contrast, and its pixel perfect (important for graphic work). While I had it apart I also replaced the ON/OFF tactile push button that was intermittent. Fortunately there was enough room on the front panel to mount an old school SPST momentary button. Tactile “pop” buttons are a pain to replace and they’re not made to last.
Circuits in a CRT monitor that filter power supply ripple at 20 or 40 kHz call for electrolytic caps made for that service. Used to just use the original part number from the failed part, rather than trying to plow through data sheets for the right cap.
Could it be the caps you're using have too much self-inductance for the frequency at which they operate?
Just a thought. Did repair CRTs long enough to watch for quirky type filter caps. Won't get me to mess with one now.
73
Could it be the caps you're using have too much self-inductance for the frequency at which they operate?
Just a thought. Did repair CRTs long enough to watch for quirky type filter caps. Won't get me to mess with one now.
73
These caps probably have trouble handling the higher frequencies, but even the originals didn’t last long (no doubt some design flaw). I’m always running the maximum refresh rate that this monitor recommended. I believe a lower rate would put less stress on the power supply, but I found the lower rates were too hard on my eyes. Anyway, I’m satisfied with having several years runtime on a new set of caps, plus I mastered the teardown sequence. It took me less than an hour to be up and running again at a cost of around $10. The main expense is the 100uf 400v cap.
Apple keyboard. The XYL doused it with a root beer float. Got very lucky that it didn't get any into the actual electronics, just all over the keycaps and part of the membrane. It was immediately unplugged and taken to the kitchen where it had water run over it to displace the root beer. Disassembled, cleaned, reassembled, works like nothing ever happened.
For the record, don't ever do this. The keyboards have lots of tiny screws. But if you do have to, get a metric hex driver at 1.3 or, as I had to do, 1.27 to get the three screws on the bottom of the keyboard out, then a tiny little Phillips for the screws inside the keyboard.
For the record, don't ever do this. The keyboards have lots of tiny screws. But if you do have to, get a metric hex driver at 1.3 or, as I had to do, 1.27 to get the three screws on the bottom of the keyboard out, then a tiny little Phillips for the screws inside the keyboard.
i just had to diagnose and replace a faulty secondary brake contactor the other day.
It's part of the brake check-back loop and one of the NC contacts is only used for digital I/O return so there's really no current running through it.
because of this they don't arc and the arc is what keeps the contacts clean.
LC
It's part of the brake check-back loop and one of the NC contacts is only used for digital I/O return so there's really no current running through it.
because of this they don't arc and the arc is what keeps the contacts clean.
LC
I took out the original coax from my sirio 5000 and replaced with LMR-240. It is fantastic. SWR at 1.1 across the 11 meter band.
I put plugs on a set of home stereo speakers & used a combiner to run both through the speaker output on my ICOM 7600 & my receive audio now sounds like surround sound.It's mono audio but I don't want stereo audio out from the receiver.I am running the speakers audio thru a ClearSpeech DSP Base Module as well.It sounds AWESOME.It was a simple project for most but I just had the speakers sitting on the top shelf above my main operating position not being used so I put them to work.It's sometimes very difficult for me because I have Severe Neuropathy in my hands which makes doing simple things very difficult if not impossible.The ICOM 7600 has never sounded better on receive for sure. {:>)
SIX-SHOOTER
W4KVW
WRMX520
SIX-SHOOTER
W4KVW
WRMX520
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