I remember working for a company that imported cheap radios. I took my seat with the other 20 or so techs repairing radios. Most quotas were in the 20 range while I was only repairing 3 or 5 radios a day. Thinking I would be handed my pink slip I asked the tech next to myself how he was repairing so many radios? He pointed to my draw where I had saves some diagrams off the back of some of the radios. There is your problem he said. You are over th inking wasting time. You can measure 6 transistors faster than you can thin k if they are RF , audio or IF. In short stop thinking and start measuring. When I looked around I could see that the other tech were measuring not th inking. I took his advise and my quota when up from 3 a day to 10. A lesson I did not forget and still use today. I would like to know if others have found this to be true.
Well, in my field (arcade game repairs - video, pinball, etc.) we (the industry) used to trouble shoot monitors looking for the exact problem. Then some lazy tech started simply replacing all the electrolytic capacitors in the monitors - and the service rate went from a few monitors a day to five or more. In 90% of the cases replacing the caps and the HOT (and fuse) fixed most problems, changing the caps, HOT and LOPT/Flyback fixed most of the rest. Leaving 5% as dogs that one could spend a day on - if the customer thought it was worth the money.
Mr & Mrs. Gilbreth (Cheaper By The Dozen) who in their Time Management process would often watch the laziest employee as he (she) would usually have the best way of doing the job with a minimum of effort or fuss.
John :-#)#
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John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
Back in the 60s I worked for a year as an electronics troubleshooter. As I recall, the quota was testing 80 circuit modules per day. The quota was how many modules were tested, not how successful was the troubleshooting of failed modules!
Repair records traveled with each module. I noticed that other technicians would trace a signal, and have the first transistor replaced where the signal stopped. Sometimes the same transistor would be replaced multiple times. Once I noticed that the problem was actually caused by a wrong part, a backwards diode or parts mounted in the wrong holes, I learned to visually check the modules before testing. My quota increased dramatically.
I suppose a quota system is necessary, but it does encourage shortcuts.
As always there are many ways to attack a problem. If equipment has a history of some part or parts failing , look at that first. Especially if it is easy to replace those parts and they do not cost very much. Then if it still does not work go on to other methods. At work we had some equipment that 99.9% of the time it was one of two things, About 80% was a relay, the other large percentage was a circuit board that we did not repair in house, but changed out. The relay was easy as it just plugged in. Took about 5 seconds to change. The board took about
30 minuits to change. For the ones that knew the equipment would take one voltage reading before changing the relay, for ones that did not know the equipment and called some one they were told to change the relay.
For something like radios ( I repaired the CB radios back when they cost around $ 200 and up ) I used the devide by two method if nothing stood out at first glance. Start about half way and inject a signal or listen for a signal. From that point go about half way to the end and so on.
seat with the other 20 or so techs repairing radios. Most quotas were in th e 20 range while I was only repairing 3 or 5 radios a day. Thinking I would be handed my pink slip I asked the tech next to myself how he was repairin g so many radios? He pointed to my draw where I had saves some diagrams off the back of some of the radios. There is your problem he said. You are ove r thinking wasting time. You can measure 6 transistors faster than you can think if they are RF , audio or IF. In short stop thinking and start measur ing. When I looked around I could see that the other tech were measuring no t thinking. I took his advise and my quota when up from 3 a day to 10. A le sson I did not forget and still use today. I would like to know if others h ave found this to be true.
A friend of mine has an old school arcade machine. No CPUs or monitors in t his puppy. Just a pile of relays and paddle wheels. Great stuff. I could no t find the tilt detector?
I found a short cut for flat electrolytic condensers in monitors and switch ing power supplies. First check if condensers that are rounded on top. Fai ling this use an impedance meter to measure the condenser impedance in circ uit without un soldering it. Not un soldering it saves a lot of time. Any c ondenser with a impedance higher than a few ohms at 10 KHz and you found yo ur problem. The down side is they do not sell condenser in circuit impedanc e meters so you have to make it yourself. Not a big deal as it just require s 10 KHz at a low impedance with about 100 m volts then monitor the current .
Good question. While the ohms meter is still in your hands from measuring t he transistors you touch the volume control. If you hear a click from the s peaker the audio is okay. Then the IF and RF with a RF injector probe. With practice it all happens so fast that you quickly know where the problem is . If it turns out to be a dog then the golden rule is switch your dog for s omeone else's dog. Often my dog is an easy fix for someone else and their d og is an easy fix for me. Not sure why it is like this. Maybe taking a fres h look at a problem from different shoes.
Yes I know what you mean. With new boards anything can be wrong. Memorizing all the resistors . diodes and transistors can save a lot of time by quic kly troubleshooting with your eyes only.
y seat with the other 20 or so techs repairing radios. Most quotas were in the 20 range while I was only repairing 3 or 5 radios a day. Thinking I wou ld be handed my pink slip I asked the tech next to myself how he was repair ing so many radios? He pointed to my draw where I had saves some diagrams o ff the back of some of the radios. There is your problem he said. You are o ver thinking wasting time. You can measure 6 transistors faster than you ca n think if they are RF , audio or IF. In short stop thinking and start meas uring. When I looked around I could see that the other tech were measuring not thinking. I took his advise and my quota when up from 3 a day to 10. A lesson I did not forget and still use today. I would like to know if others have found this to be true.
.
s
ly
in this puppy. Just a pile of relays and paddle wheels. Great stuff. I coul d not find the tilt detector?
itching power supplies. First check if condensers that are rounded on top. Failing this use an impedance meter to measure the condenser impedance in circuit without un soldering it. Not un soldering it saves a lot of time. A ny condenser with a impedance higher than a few ohms at 10 KHz and you foun d your problem. The down side is they do not sell condenser in circuit impe dance meters so you have to make it yourself. Not a big deal as it just req uires 10 KHz at a low impedance with about 100 m volts then monitor the cur rent.
Indeed, I've been selling those meters since 1999 when I first starting chatting with Bob Parker (Dick Smith K-7204 kits in those days). Great ESR meter that works in circuit for roughly values between 4ufd to about
1000ufd.
John :-#)#
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John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
It's true, but only if you have a production line environment. During the late 1960's, I worked for a company that did warranty service on mostly consumer tape recorders. We would get the rejects and returns from the distributor. We had 4 people working the line. One to unbox and machine and organize the paperwork. One do to nothing but diagnostics. Me to tear it apart and do parts replacement, more testing, and reassembly. One more to do more paperwork, a final check, and reboxing. Anything that couldn't be fixed in 10-15 mins was put aside for later troubleshooting. Anything with more than 5 faults was deemed not worth repairing. It was quite efficient. As I vaguely recall, we could do about 4 to 10 machines per hour.
What was interesting was the general lack of test equipment. As you noted, it takes far too much time to setup and probe. For audio, putting a finger on the base of a transistor and listening for hum worked well. To make it quick an easy, we had cardboard templates, with holes punched for all the common injection points with notes on what to expect.
Head alignment and channel balancing was a different story. For that, we had a separate test fixture near final check. It had an audio generator and oscilloscope, but with a good ear, the scope wasn't really necessary. Unfortunately, this doubled the cycle time adding an additional 4 to 10 minutes.
After you've worked on several hundred of exactly the same model tape recorder, you see patterns of failure. For example, if some component was inserted backwards on the first 10 or so units, it's a fair guess that the rest had the same problem. So, pre-emptive replacement was possible and worked well.
Fast forward 30 years and I'm now doing marine radios and data transceivers. Over about a 10 year period, I was either involved or watched at least 5 different product test and QA systems. The one that worked best was visual inspection. I brought some of the assemblers into test to do the inspection. They couldn't read a resistor color code, but they could spot anything that had changed quite easily. The worst was a complex series of bench tests required by the customer, which involved a large pile of test equipment. I did a quick time-and-motion study and found that 30% of the test time was in setup, changing setup, and teardown. This would have been a great candidate for computer driven ATE (automagic test equipment) except that the PC of fashion at the time was an Apple III and RS Model II. We tried, and failed. So, we continued to use a pile of test equipment for test and troubleshooting. After about 3 years of this, some of the rotary switches on the HP equipment started to fail.
Somewhat later, I had changed company and now had a product with sufficient quantity to justify ATE. The PC of fashion was the HP 9816 with an HP-IB(IEEE488) bus. It controlled a rack full of HP RF test equipment. I don't have time to go into detail on the setup. When it worked, it was great and could test, align(tune), print measurements, print reports, and live test amazingly quickly. When it didn't work, everything came to a grinding halt. I recall having 4 techs at idle while someone furiously drove to Fry's to buy a replacement part. I wanted to build a manually operated backup test line but management vetoed the idea. Getting all the equipment calibrated at the same time was tricky, but reduced downtime. ATE would have been a marginal failure had I not been able to "borrow" test equipment from the engineering dept.
However, that was production test, not troubleshooting. When the manual or ATE test line declared something worthy of troubleshooting, it was NOT done while there were units waiting to be tested. If the products were cheap enough, they could just be "remanufactured" which means tear them apart down to the board level, run them back through board test, and build a "new" unit. This worked well with radios that had plugin cards. Eventually, there was a backlog of boards to be troubleshot. Usually between production runs and contracts, someone would decide that it's time to clean up the backlog. However, instead of having the test techs do the troubleshooting, the engineer who designed the radio would be sentence to overtime diagnosing the boards. Yeah, that was usually me. Unless the problem was trivial, I would only tag the likely parts, borrow someone that could do the soldering, retest the board, and send it on to production test. This worked well when we needed 25 identical board immediately, and was a total waste of time for 5 or less boards that took too long to setup.
Today, much of what I see is ATE run by techs that only know how to push the buttons. Troubleshooting is done partly with BITE (built in test equipment). Parts replacement and soldering is outsourced to a contractor, specialty shop, or refurbisher. In short, there's nobody on the production line that knows which end of the soldering iron to grab, much less how the product actually works. The rule is that production must continue unimpeded by any form of troubleshooting or repair. If there is any troubleshooting, it's to fix the production line and ATE, not the actual product.
Might as well say something about bugs and fixes. With todays fairly short product lives (typically about 6 months), it's not uncommon for a company to have 3 or 4 generations of replacement products in development at the same time. If something is found lacking or defective in the current product, it is cheaper and easier to simply wait for the next model to appear in production, and replace it with a later version. What this means is that NOTHING gets fixed in production, even when it's a known problem, easy fix, or major enhancement. If you see products with known design flaws that continue to be manufactured with the flaws, you now know why.
Of course, there will still be independent repair shops (like mine) that fix things one at a time. They're a dying breed mostly because of the declining cost of modern electronics. As the retail price of new hardware declines, the amount of money that a customer is willing to pay for a repair also declines. As a rule-of-thumb, most customers will buy a new replacment instead of repairing something when the repair cost exceeds 50% of the replacement cost. So, if someone drags in an out of warranty laptop that cost them $500 about 3 years ago, my maximum bill (parts+labor) cannot exceed $250. Assuming no parts were replaced, that 3.3 hrs at $75/hr. The number of things I can fix in under 3.3 hrs is rapidly shrinking. For example, I have an APC XS1300 UPS on the bench that can be purchased new for about $125. In order to replace one lousy bulging electrolytic capacitor, I've already burned 2 hrs and I'm not done. Can I bill the customer $150 to fix a $125 UPS? Nope.
So, the question isn't as much how to troubleshoot, but whether it's worth you time troubleshooting in the first place.
Happy end of the tax year.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I "repaired" early digital-type equipment in the Air Force.
Quotes because it turned out that all we did was find the failed circuit boards and replace them - leaving the actual repair work on the boards to the old-timers.
We were told "Follow your nose".... and that proved to be the way almost all of the time.... you could locate the board with the failed component by smell and then visually verify after the board was pulled.
I don't suppose that monkeys could be trained to do that.... but I am pretty sure than anybody with a room-temperature IQ could....
Six months of technical training at taxpayer expense down the drain.... Oh well.... -)
Sounds like you touched a lot of bases in the service life. I took a simila r path ending up self employed for about the last 25 years. It has changed so much from the old days walking around with a tube caddy cleaning TV tune rs. I now walk around with a laptop pinging IP addresses. How did that happ en? I think the writing is on the wall. How many shoe repair and watch repa ir shops do you see. The electronic repair tech could meet the same fate. J ust the other day I saw a flat screen monitor sitting in a garbage bin. To see the rain falling on it was too much so I took it inside. When I plugged it in everything worked and it had a VGA plus DVI input! What was that doi ng in the garbage. My only guess is someone wanted a wider flatter monitor so he or she tossed it out. I am typing on that monitor as we speak. How ca n one make a living in service with this going on. It is so bad that I have to work on 50,000 dollar LED displays boards. They will still fix those at that price. Just about everything else is disposable. However I have no re grets as electronics has been an existing ride with technology changing so fast that there is never a dull moment.
t everything else is disposable. However I have no regrets as electronics has been an existing ride with technology changing so fast that there is never a dull moment.
There is always arcade game repair. There is enough interest in that that most cities need a few people who do house calls.
John :-#)#
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(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
In my checkered past, I once helped design two direction finders for the USCG AN/SRD-21 and 22. After shipping a fair number of these radios, I was given a tour of the local repair facility on Treasure Island in SF Bay. Sitting pilled in one corner was about 50 radios, in various stages of cannibalization. So much for spare parts.
Yeah, I do the same. I would prefer an FLIR infrared imager, but the nose will do for now. I also have a NIKKEN #1394 "air wellness air quality monitor". It's a nephelmometer which uses light scattering to detect airborne dust particles. Overkill: It's been useful for finding what is burning in the office and locating the component producing the smoke. I've also used it to chase down the source of a white dust in a customers air ducts.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
** I find Bob's ESR meter useful with electro caps anywhere from 1uF to over 15,000uF. It also checks the ESR of tantalum electros. film caps from about 0.47uF upwards - for shorts and opens.
Another use is with batteries, particularly Lithium button cells plus any type of AA, AA and 9V battery.
As with caps, known good examples are your reference and ESR readings rise as the cell goes flat. A 20x3mm Lithium reads about 10 ohms when new rising to 100 ohms or more at end of life.
milar path ending up self employed for about the last 25 years. It has chan ged so much from the old days walking around with a tube caddy cleaning TV tuners. I now walk around with a laptop pinging IP addresses. How did that happen? I think the writing is on the wall. How many shoe repair and watch repair shops do you see. The electronic repair tech could meet the same fat e. Just the other day I saw a flat screen monitor sitting in a garbage bin. To see the rain falling on it was too much so I took it inside. When I plu gged it in everything worked and it had a VGA plus DVI input! What was that doing in the garbage. My only guess is someone wanted a wider flatter moni tor so he or she tossed it out. I am typing on that monitor as we speak. Ho w can one make a living in service with this going on. It is so bad that I have to work on 50,000 dollar LED displays boards. They will still fix thos e at that price. Just abou
has been an existing ride with technology changing so fast that there is n ever a dull moment.
I noted you are from Vancouver. I grew up there until about 14 then Montrea l and now Toronto. Fond memories of biking down to Kitsilano beach.
I'm a mechanical engineer but I've been in management a long time, I don't get to do much technical stuff.
This week I got called to a gas leak. The emergency response and the mecha nics had already been there and confirmed safe to reoccupy, but somebody wa sn't so sure and called me.
These things are 80% one problem and 9% the other. The crew that showed up found and fixed the 80% problem, but it wasn't actually causing the leak. The leak was somewhere else. Just because one thing is broken doesn't mea n something else isn't broken too.
Once a problem is identified, attentional blindness sets in. Contrary evid ence is not just ignored, it cannot be seen.
In this case the pilot light was out in the kitchen, and they assumed the g as smell came from it. They shut off the gas to the kitchen and authorized the building to be reoccupied.
They ignored the evidence the real leak was somewhere else - well, they wer e incapable of seeing that evidence because they already knew what was wron g.
When I got on scene it took little time to find where the smell was coming from. Partly that's from my bias to try to avoid assigning the cause until I've looked at all the evidence, but partly it's from knowing human nature and knowing if it were the usual problem they would have fixed it the firs t time, and it obviously wasn't.
I sent the mechanics back and told them where to look, and the second trip they fixed it correctly. Of course I had to keep quiet my part in it, ther e's always politics in these things.
So yes, fix the most likely fault first, but bear in mind the potential cos t of it being something else.
hanics had already been there and confirmed safe to reoccupy, but somebody wasn't so sure and called me.
up found and fixed the 80% problem, but it wasn't actually causing the leak . The leak was somewhere else. Just because one thing is broken doesn't m ean something else isn't broken too.
idence is not just ignored, it cannot be seen.
gas smell came from it. They shut off the gas to the kitchen and authoriz ed the building to be reoccupied.
ere incapable of seeing that evidence because they already knew what was wr ong.
g from. Partly that's from my bias to try to avoid assigning the cause unt il I've looked at all the evidence, but partly it's from knowing human natu re and knowing if it were the usual problem they would have fixed it the fi rst time, and it obviously wasn't.
p they fixed it correctly. Of course I had to keep quiet my part in it, th ere's always politics in these things.
ost of it being something else.
I hear that. I remember being stuck on a problem so I asked a friend for a fresh look at it. He looks around then thought about it for a minute. He th en looked at me and said " if you touch your head and it hurts and you touc h you arm and it hurts and you touch your toe and it hurts maybe it is your finger that is the problem ". That was a strange way to put it but he was
100 percent right as I had my scope probe on 1 to 1 instead of 10 to 1 caus ing a loading problem. It is always a good idea to get a second opinion whe n you are spinning your wheels.
Another unrelated problem. You being an engineer will enjoy this one. The c ity has a water leak. They are not sure where the leak is. They can not dig up a whole city block to find it so they use a clever trick. They put two microphones about 50 feet apart where the leak seems to be. Then then recor d the random sound of water hissing out of the pipe. The two microphones ar e wired to left and right channel of the recorder. By adjusting the time de lay of the right or left microphone they can find the sweet spot where the random noise from one microphone matches the random noise of the other micr ophone. Once the delay is know they know where the leak is within 1 or 2 fe et. That is a clever trick.
There is a similar trick in cabling. You send a pulse down a cable that is about 80 percent c propagation speed. If you hear an echo you have a proble m. By timing the echo at 80 percent c you know where the problem is.
e city has a water leak. They are not sure where the leak is. >They can not dig up a whole city block to find it so they use a >clever trick. They put two microphones about 50 feet apart where the >leak seems to be. Then then record the random sound of water hissing >out of the pipe. The two microph ones are wired to left and right >channel of the recorder. By adjusting the time delay of the right or >left microphone they can find the sweet spot w here the random noise >from one microphone matches the random noise of the other >microphone. Once the delay is know they know where the leak is >with in 1 or 2 feet. That is a clever trick. "
HA, HAHAHAHAHAH
HydroTDR
Water Domain reflectometry
Feel free to add your own, this could be fun. Water Wave Technology.
Oh, and sound is so much faster in water, but then that gives alot more acc urate transmission, which os probably necessary to make this possible.
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