Author Topic: What was your easiest repair ever? (Read 68294 times)

MapleLeaf · « **Reply #275 on:** August 31, 2019, 05:04:16 pm »

Looked in electronics recycling bin at work. Asus pad was in it. I thought good teardown. For fun i tried to charge it, nothing. Read on web that these pads can lock up. If you do a three finger hard reset they will come alive. So I tried it and came alive. Pad came up like it was it's first time from factory. Nice.

themadhippy · « **Reply #276 on:** August 31, 2019, 05:32:01 pm »

bss di boxes,had a couple that didnt work. Checked them with phantom power , ,nothing,try a battery ,it works,back on phantom power and it still works,look at the next one ha ha , battery connector was shorting out to the circuit board,bit of tape over the battery clip ,job done

pcmad · « **Reply #277 on:** September 02, 2019, 07:35:35 pm »

this week end i got a table saw that didnt power up turns out the brushes had a bit of saw dust jamming them pulled the out a put them back and powed up

Howardlong · « **Reply #278 on:** September 27, 2019, 09:56:48 pm »

Another nice easy one, I use an Agilent 8935 Communications Test Set as part of a production test jig, they're old, circa 2000. They work well, are usually reliable, and are cheap on the second hand market. They're also built like tanks.

Today I came to use it, switched it on with the rocker switch, but nothing happened, no life at all. I checked the fuse and integrated GFI, all good, and power was getting in somewhere as the GFI trip test worked when plugged in.

Problem with these units is that there are tons of screws to facilitate disassembly, but thankfully they're almost all the same T20 screw.

The internal standby LED was working but no other supplies.

It turns out it was the rocker switch, rated at 10A 250V, but judging from the wires on the short cable harness this is a low voltage, low current soft connection. Sure enough it was the switch, I could switch on the unit by shorting the connections.

Expecting to need to order a new one, I had a look in the switch drawer and amazingly I actually had a small stock of fit-ready replacements, albeit black rather than white.

Cubdriver · « **Reply #279 on:** September 27, 2019, 11:36:06 pm »

Quote from: Howardlong on September 27, 2019, 09:56:48 pm

Another nice easy one, I use an Agilent 8935 Communications Test Set as part of a production test jig, they're old, circa 2000. They work well, are usually reliable, and are cheap on the second hand market. They're also built like tanks.

Today I came to use it, switched it on with the rocker switch, but nothing happened, no life at all. I checked the fuse and integrated GFI, all good, and power was getting in somewhere as the GFI trip test worked when plugged in.

Problem with these units is that there are tons of screws to facilitate disassembly, but thankfully they're almost all the same T20 screw.

The internal standby LED was working but no other supplies.

It turns out it was the rocker switch, rated at 10A 250V, but judging from the wires on the short cable harness this is a low voltage, low current soft connection. Sure enough it was the switch, I could switch on the unit by shorting the connections.

Expecting to need to order a new one, I had a look in the switch drawer and amazingly I actually had a small stock of fit-ready replacements, albeit black rather than white.

-Pat

jogri · « **Reply #280 on:** September 28, 2019, 04:24:34 pm »

The easiest repair? I found a nice four channel 150 Mhz scope that wouldn't power on in the bin. Looked for the fuse, found a burnt one. Luckily it had one of those fuse holders that have a spare fuse (which was still good), changed the fuse and got a fully working scope. Not a bad price for two minutes of work.

mikeinkcmo · « **Reply #281 on:** September 29, 2019, 05:03:50 pm »

Many years ago I bought a Tek 454 scope off ebay that didn't work. I closely examined the pics, I was convinced there was most likely a problem with one side of the Vertical amplifier, Its a balanced type circuit.

Got it, opened it up, the wire connecting the top vertical plate to the amp had fallen off. THAT WAS IT, re-attached, and been working perfectly ever since.

bd139 · « **Reply #282 on:** September 29, 2019, 05:36:39 pm »

Nice looking shelf of kit that

Quick one the other day. Someone had been "at" an HP 3466A I got on eBay. Before and after fix.

Before repair

After repair

Looks like someone had replaced the RMS converter IC and put the new one in back to front. This caused the -7V rail to conduct to ground and the whole thing to go wonky. I'll admit it took me a good 30 minutes to work out this was what was wrong. Much

Falkra · « **Reply #283 on:** September 29, 2019, 06:47:23 pm »

Nice.

Cubdriver · « **Reply #284 on:** September 30, 2019, 12:07:41 am »

Quote from: mikeinkcmo on September 29, 2019, 05:03:50 pm

Many years ago I bought a Tek 454 scope off ebay that didn't work. I closely examined the pics, I was convinced there was most likely a problem with one side of the Vertical amplifier, Its a balanced type circuit.

Got it, opened it up, the wire connecting the top vertical plate to the amp had fallen off. THAT WAS IT, re-attached, and been working perfectly ever since.

I recognize that screen name! Welcome aboard, Mike, and definitely come join us in the TEA thread.

-Pat

don.r · « **Reply #285 on:** February 17, 2020, 08:17:40 pm »

Bought a Keithley 197 off eBay recently for less than $40 as a Parts unit. It was displaying "Err". Looked at the pictures of the sale and noticed the issue so I bought it. This model displays Err when the AC switch is selected with either the Ohms switch or no other mode switch selected. It works fine with any proper mode selected.

Neomys Sapiens · « **Reply #286 on:** February 17, 2020, 11:27:33 pm »

Quote from: don.r on February 17, 2020, 08:17:40 pm

Bought a Keithley 197 off eBay recently for less than $40 as a Parts unit. It was displaying "Err". Looked at the pictures of the sale and noticed the issue so I bought it. This model displays Err when the AC switch is selected with either the Ohms switch or no other mode switch selected. It works fine with any proper mode selected.

Good to know. I'm watching one.

fixy88 · « **Reply #287 on:** February 20, 2020, 05:31:04 am »

Bought an Olympus OM-D M10 with a stuck shutter recently. Opened it, reseated the shutter block flex cable and it's been working great since. Win!

kaz911 · « **Reply #288 on:** February 20, 2020, 07:35:48 am »

Not the easiest but close

2 power modules for my Agilent N6705B - bought as a for parts set.So I bought both for $150,- - and they cost a bundle as working. (It is the high precision ones) - in working condition they would have cost $1500+ each.

The power modules have parts of the circuit exposed at the bottom where it connects inside the N6705B.

Got them - and put them under the magnifying glass - and found both had been bashed so one of the big diodes on both had been knocked slightly off the board. I de-soldered both and soldered them back on - and voila - both was working again. Time taken - less than 35 minutes from delivery...

I learned there and then that out of the N6705 - one have to be careful with the power modules. Always leave the circuit board part upwards and protect it when not in the N6705.

But all of my 6705 modules have been bought as broken and fixed. But this repair was the easiest.

/k

wn1fju · « **Reply #289 on:** February 20, 2020, 08:30:39 pm »

Seller said that the "power" meter didn't move and therefore also concluded (wrongly) that there was no output. Well, yeah, if you leave the meter
switch on mA dummy!

Worked perfectly right out of the box. Not bad for >50 years old.

nfmax · « **Reply #290 on:** February 20, 2020, 08:48:37 pm »

Agilent 33120A function generator, about to be thrown out, acquired it for free. A big label on it, saying 'no output at all'. Indeed there wasn't. The soldered-in fuse on the attenuator output was blown. Hardest part was working out the current Litelfuse equivalent part number.

aeberbach · « **Reply #291 on:** February 20, 2020, 11:15:34 pm »

Motor start capacitor, clothes dryer. I can't drive by clothes dryers waiting for recycling collection any more without checking them out to see if they are better than the one I have, because they probably just need a $5 capacitor

twospoons · « **Reply #292 on:** February 21, 2020, 01:57:09 am »

I had a 22GHz TEK492 RF spectrum analyzer with a dud 30dB attentuator step. After dismantling the attenuator assembly I took the tiny 1cm square of glass belonging to the 30dB step and checked under a microscope. A tiny dot of conductive silver paint over the burnt out thin film resistor (first in a chain of 8 T sections) was all it took to get it working again. Incredibly the 30dB step was still so close to being 30dB I couldn't tell the difference.
OK, so maybe its more complex than " I changed the fuse", but it was way easier than I was expecting.

0culus · « **Reply #293 on:** February 21, 2020, 02:00:44 am »

Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well.

Neomys Sapiens · « **Reply #294 on:** February 23, 2020, 01:02:39 am »

Quote from: 0culus on February 21, 2020, 02:00:44 am

Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well.

Yep, nice one. But the moment it started ticking must have been nervewrecking.

dzseki · « **Reply #295 on:** February 24, 2020, 09:07:40 am »

Quote from: Neomys Sapiens on February 23, 2020, 01:02:39 am

Quote from: 0culus on February 21, 2020, 02:00:44 am
Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well.
Yep, nice one. But the moment it started ticking must have been nervewrecking.

For $125 I would not have expected otherwise

JohnPen · « **Reply #296 on:** February 24, 2020, 04:08:24 pm »

A B&W TV had a sizzling noise and a slightly ragged picture. With the rear cover off and in a dimly lit room observed a small blue arc into space. On closer inspection found to be a poor joint in the EHT department with a long solder whisker on the joint. A quick application of physics and a nail file rounding off the joint and all well again. Yes I did power it down first.

0culus · « **Reply #297 on:** February 25, 2020, 01:45:26 am »

Quote from: Neomys Sapiens on February 23, 2020, 01:02:39 am

Quote from: 0culus on February 21, 2020, 02:00:44 am
Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well.
Yep, nice one. But the moment it started ticking must have been nervewrecking.

Yeah, especially since it was working fine when I tried it out at the auction preview day.

Quote from: dzseki on February 24, 2020, 09:07:40 am

Quote from: Neomys Sapiens on February 23, 2020, 01:02:39 am
Quote from: 0culus on February 21, 2020, 02:00:44 am
Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well.
Yep, nice one. But the moment it started ticking must have been nervewrecking.

For $125 I would not have expected otherwise

It was working fine on auction preview day. I suspect the resistor was already loosening and act of carrying it out of the warehouse and the ride home perhaps shook it all the way loose. The whole thing is in great shape, obviously lived in a lab where the test equipment was taken care of. Microchannel plate crt is good working order.

HackedFridgeMagnet · « **Reply #298 on:** February 27, 2020, 11:45:18 pm »

Just got a call to fix 5 broken PCs after test and tagging, this was in front of about 30 people.

Waved my magic wand (voltstick) and saw there was no incoming power. The cords looked plugged in but were not fully inserted.
That took one minute and there were a lot of red faces.

NiHaoMike · « **Reply #299 on:** February 28, 2020, 04:09:42 am »

Quote from: JohnPen on February 24, 2020, 04:08:24 pm

A B&W TV had a sizzling noise and a slightly ragged picture. With the rear cover off and in a dimly lit room observed a small blue arc into space. On closer inspection found to be a poor joint in the EHT department with a long solder whisker on the joint. A quick application of physics and a nail file rounding off the joint and all well again. Yes I did power it down first.

I wonder if it has been previously repaired with lead free solder, since monochrome TVs long predate RoHS and leaded solder should be immune to developing whiskers.


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Author Topic: What was your easiest repair ever? (Read 68294 times)

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