This was my very first repair. Awhile back I was a happy owner of a Toshiba Satellite laptop. I did practically everything on it. So it came as a high disappointment when one day my computer failed to turn on. As everyone knows, your machine is your sanctuary because you keep everything about you in there. I was living in an attic of a house at the time and I never stopped to think how bad that was. Winters as well as Summers were pretty extreme. I learned that it was because of high temperatures why my laptop failed to turn on. Because I had sensitive information on it, I declined to have it service by anyone else but me. With a little bit of help from online resources I proceeded to take the entire computer apart. It was a tedious job because of so many small parts that I couldn't mix up.My line of reasoning initially was to save myself some money. However, as I continued on I became more and more curious, about repairs, electronics and innovation. I really felt very accomplished after those 10 plus hours. It answered many questions that you can't unless you get your feet wet. Therefore, I'm glad for this experience. This i know will allow me to undertake much more interesting and harder tasks.

When I was 14 (1979) My grandfather was given a few broken video games by the manager of the local woolworths and as he knew I loved to take things apart and repair them he gave them to me.  There were 3 broken 'pong' games out of them i managed to make 3 working controllers, 1 left and 2 right. The circuit boards of the games were all cracked and snapped along with the cases.  I carefully cut the circuit boards so I had 4 pieces made from the 3 consoles and using paper templates I managed to cut them so I could join them back together.

I cleaned off the green laquer from the copper tracks and soldered wire bridges where they were needed. I used car panel repair fiberglass and reinforced the circuit boards. Using more car repair fibre glass I repaired a case so that I could house the circuit board. I was over the moon when I tried it and it all worked.  It was the first large scale electronics project I undertook and have been a hobbyist ever since and enjoy doing small projects.

Hi ever since the kids were young, they are now 27 and 24, we had an electronic Father Xmas that moved and sang when the start button was depressed. I will give the details of song and dance later, but in the meantime try to reflect and guess, I guarantee all the warmth and amazement of the season. Anyhow the year our last offspring left home to work away, we unpacked the Xmas decorations as usual at Xmas, and the singing dancing Santa was lifeless, I changed the batteries nope, cleaned the dirty terminals no joy. However dissapointed the 'kids' would be it was sad but not tragic. I vowed to repair it next year, in a manjana manjana type of way. This year our first grandchild was born, a little girl, aptly named Ellie, not after Element 14 unfortunately   . So I got the soldering iron out, every joint was dry, every wire rotten. Battery box corroded, but I vowed to repair it for Ellie, and this year on Xmas Morn Ellie can watch Santa raise his arms whilst Singing Hands up, baby hands up give me your heart baby give me your heart baby baby. My kids loved it and thought it was hilarious that Santa sang a song made famous by Ottowan https://m.youtube.com/watch?v=XWsvzko1fkY

My employer was upgrading the access control system for the whole office, but wasn't replacing the old card readers. The installer said everything was compatible and they'd done it before so they got started replacing the controllers. After a few hours the engineer came to see us to set up the software so we could test the readers. We could see data from the readers but it didn't represent anything identifiable we could use. With the help of my boss we ended up hooking up his oscilloscope to read the data direct from reader as a card was scanned, this helped us to decipher the bit sequence the card was using and configure the software correctly! We saved our employer about £5000.

I fix all my broken charges and leads by stripping and rewiring the wires. Also I can charge the old-school battery phones with the wires attached to two sewing needles hooking the negative and positive to the battery terminals. Dangerous maybe but I've never had a problem.

Sounds like a great toy. I wonder where you can get one now?

Dubbie

https://www.eevblog.com/forum/projects/fan-replacement-on-the-rigol-dp832/msg1023425/#msg1023425 Hello gents , I just bought the DP832 and it's extremely annoying ,the fan noise , it's as i have a mill near by , i can't work like this !

So i have google for a silent fan and found this post .

I tried to replace the fan with the Noctua NF-A8 FLX but this supply it's a " smart " one. The curent it's monitored, doesn't let me to use this fan.

Tried the method described by johndoe271828 on youtube and the fan speed its decreasing , i need the air out and to benefit the fan silences.

SO again like on many other things i went in to reverse engineering this part of the supply.The original fan it's consuming around 186 mA at maximum speed and 110 mA at lower speed. Apparently  has 2 modes , low speed and fast speed , i measure the voltage at both modes on R 44 which it's used as current sense resistor  . On first i have around 0.8 V on R 44 and 1.5 V on second speed.From my analysis the power supply doesn't control the RPM of the fan , just it's  making  sure it's running , and it's checking that by reading the voltage from U 15 TLC 072C OPAMP on FAN_FAIL test.

The new fan  Noctua NF-A8 FLX it's not hungry like the original one SUNON, it's needed just 48 mA to run at full speed . I have checked the voltage that is on the R 44 and it's not good , it's triggering the power management ic to show that messages on the screen about "fan fail " .

So did some math and calculate the value of the new current sense resistor R 44 with 48 mA at 1.5 V and i got around 32 Ohms . I have replace the R 44 with the closest that i had , a 27 Ohms at 2 W .

The fan it's running now with no prompt of failing fan and it's silent .

I mentioned that this power supply has 2 modes of running the fan , the first one it's around 8 volts where my fan it's fully silent and the second mode at 12 volt in full speed it's noise it's bearable . Now it's doing the job, taking the hot air out  in silence .

My buddy asked if I could solder a chip back on his kid's key fob. He went to replace battery and popped of the chip. I repaired the fob(chip) for him.

It really wasn't that big a deal.

I just remember how great it felt to help my buddy and his kid.

Most stressful success story would be building installing test and commissioning of a Vsd setup controlling fans to reduce rpm and make the sound levels produce safe for human occupation. Doesn't sound like much but I had 12 hours before a newly delivered ship sailed interstate and the space had to be manned at all times. Required a lot of work and troubleshooting to get it done and integrated properly. Best bit was the captain personally taking the time to come down and watch and tell me how impressed he was definately a good day on the tools.

Where to begin, there are way to many to put here but OK here is one most recently during lockdown.

A Samson Servo 200 power amp blowing fuses. Most would assume Mosfet failure or something along those lines however all the power amp circuit was fine, all filter capacitors were fine and so was all the rectifier and regulation circuit.

The toroidal transformer continuity tested fine however the inrush current limiter was burnt and cracked like a BBQ coal, the surge capacitors were exploded. Replacing these items made no correction to the fuse eating goblin Amp so a trick of the trade was needed.

I placed an incandescent bulb in series with the mains input, yes making up a temporary circuit with some 2.5mm2 flex cord and a socket and patress on a plywood board then powered up the amp this way, the fuse did not blow and the bulb lit up. This told me the Toroidal transformer although testing fine with continuity and showed no short circuits obviously had a fault.

I then began to unwind the toroid transformer winding by winding counting each winding one by one until I got down to the primary windings. There were no shorts, no broken enamel, no scorch marks at all anywhere in the transformer however, there it was the fault for anyone to see. The large thick gauge secondary copper windings were configured with the centre tap but instead of the copper windings being a continuous copper wire the centre tap was made of two separate windings with the centre tap being twisted and soldered together, the solder joint they used during manufacture had formed a dry joint. This is what caused the high current inrush, took out the surge suppressor and the inrush resistor and was eating up fuses.

Cleaning up this joint, then using a 40w iron and some high quality flux and high content silver solder fixed it. The pain came when one had to wind all the turns of wire back onto the toroid one turn at a time and re-wind all the mica film tape, oh the finger blisters.

Old amp which was discontinued and the part not available for purchase now repaired and tested working perfect. Just to make things more frustrating however, the manufacturer finally got back to me with the circuit diagrams indicating all the operating voltages to the input of the Power Supply board, so I could have had a toroid made to the now obtained specs, damn it.