Repairing devices at an electronics level

[psynegy]

Our science department approached me recently, as I have some experience in repairing electronics, they wanted me to look at some of their broken equipment. We're talking signal generators, oscilloscopes, bench power supplies, that sort of thing.

 

It got me to thinking, what are the limits of what I am allowed to repair in this manor? What happens if a repair I did results in injury?

 

Another example of a repair that I've been asked to do, is the music department piano keyboards. The kids snap off the power connector. It's a piece of cake and costs next to nothing to repair. The keyboards are only 12v, so even if I soldered someones tounge to the board, apart from the burns and confusion, they'd still be okay.

 

Am I allowed to replace the fuse in our signal generators? I have to remove 4 screws to get to the fuse as it's on a little plastic fuse holder on the PCB... What if I accidentally put the wrong fuse in?

 

It seems crazy to be throwing these things away, but am I leaving myself open to problems later down the line?

[noelmm]

If you repair anything to that level you should at the very least do a PAT test on the item and bench test for 24 hours where possible. At the end of the day you can only test equipment to a certain level within a normal environment.

[NetworkServices]

I've often asked myself the same question. Whilst I'm confident in my ability to service electronics it does mean that my name will be tied to that device should anything else go wrong with it in a decade's time even if any future issues are not related to anything I've done. Of course once SLT get wind of your ability to do this kind of thing you will find that you become the go-to-person for anything with a plug on the end and they won't want to pay you any more for it.

[Fazza]

It got me to thinking, what are the limits of what I am allowed to repair in this manor? What happens if a repair I did results in injury?

 

Repairs should be undertaken by qualified/experienced persons and then a PAT test/inspection needs to be performed before being put back in to service. With regards to injury, your School should have liability insurance in case any member of staff or a student injures themselves at work. If you did the repair correctly you'll be OK, if you bodged a repair then you wont as you should only repair things you are competent at repairing.

 

Am I allowed to replace the fuse in our signal generators? I have to remove 4 screws to get to the fuse as it's on a little plastic fuse holder on the PCB... What if I accidentally put the wrong fuse in?

 

There are no laws as such that say you can or can't it's down to your Schools policies or line manager etc. What happens if a repair company puts in a wrong fuse?

 

It seems crazy to be throwing these things away, but am I leaving myself open to problems later down the line?

 

Only if you don't know what you're doing. My advise is to only repair something you are competent at repairing.

 

 

We do the PAT tests/inspections in our Academy and we failed over 50% of all the Science departments kit! The Science Technician repaired the ones she felt competent in fixing and got an outside company in to repair the ones she wasn't and binned (WEEE) the rest that weren't worth repairing or were to complex to repair.

[Chris_Cook]

I think common sense is needed here, as has been said above. Anything low voltage is OK. Fuses and plugs should be fine if replaced with correct and quality parts. Anything else that's field serviceable or modular. I've re-soldered boards with bad joints, and replaced usb sockets on keyboards before.

 

Issues normally arise when things are bodged, overloaded or not done to a standard. E.G. Bare wires, sharp bits, poor quality components that fail etc. If you're returning it to how it was when it came out of the factory, then it shouldn't be a problem.

 

If its going to be left on 24/7, then you may want to think about how good you are at repairing.

 

A second opinion never hurts, and if you arn't happy with someone else inspecting it, then that's a good sign the repair job isn't up to it.

 

Check with the insurers and the pat tester.

[difinity]

I had a similar question when I worked in a school. I was told I could repair low voltage stuff but not mains. USB sockets, DC jacks were ok, anything in the power supply was not.

[synaesthesia]

The risk level is negligible for a competent technician, the problem comes down to liability should something go wrong even if it was more dangerous to start with. Saying that, I do it all the time including very high voltage equipment.

[jmak]

The risk level is negligible for a competent technician, the problem comes down to liability should something go wrong even if it was more dangerous to start with. Saying that, I do it all the time including very high voltage equipment.

I found out the hard/stupid way that inside digital cameras can be very high - although not too harmful.

[AlanD]

I am (or at least was) very keen on electronics...and yes, I fixed everything from TVs, monitors and oscilloscopes to board level repairs on early microcomputers (like the BBC Micro). But to be honest - its really hard to justify financially. While you can (and I often did) work without circuit diagrams - they can be hard or impossible to get hold of. And before now, I found myself building complete mini circuits on Veroboard to replace ICs which are often unobtainable as parts. With something unfamiliar it can take half a day just to dismantle and investigate. Yes there is enormous self satisfaction when you resurrect something from the grave and management can be very impressed...although they should be thinking what a waste of your time.

 

The only time I would justify this now, is when there are lots of the same devices that all start to fail. And once you have spent the time once to fix the fault - its quick and easy to fix the rest. For example we had a some monitors where the power diodes were in parallel and inevitably one takes a little more current than the other, gets hotter, takes more of the current and eventually dies...the other then works for a while before it too dies. Replacing both diodes (cost 50p) with a higher rated replacement and monitors have lasted another 5 years. But a one off device...I wouldn't want to waste my time on.

[mikeprice]

My question would be - exactly what qualifications do you need?

 

I have been working with computers - including fiddling with th einside bits - since 1981 and yet I have no formal qualifications

I would never mess around with the mains voltage stuff as I am scared of it and very scared of doing something that may hurt someone else. However, if a case went to a court.......

 

Anyway - when I started doing stuff with computers there were no courses around unless you worked for a major manufacturer like IBM

[Fazza]

My question would be - exactly what qualifications do you need?

 

I have the City and Guilds 2240 Electronics Servicing Parts 1, 2 and 3 qualifications where I was taught how to safely work on high voltages (up to 25KV) all the way down to a few mV. I was even taught how to fix a motherboard down to component level.

[mikeprice]

I am sure there are many on here with excellent qualification - but are they all relevant to everything

 

and what about those of us who have loads of experience but no actual qualification - which will include many of the older people - like me

 

So if you have qualification in e.g. fiddling with a network - but are employed in a school on your own so you do everything - or you have no formal qualification at all - if something goes wrong are you vulnerable??

 

I suppose - in my opinion - this is one reason why I would say that any IT tech should be a member of a union just in case.

[Chris_Cook]

I guess like any risk in a school, you need to risk assess it and work out if its worth it.

 

If you have a good work flow, and can make a good case as to how you repaired something then it should be fine. For example, not doing the repair when you tired, taking steps to make sure you use the right value fuse and looking on the case or PCB for the actual value, rather than whatever the last person used.

 

A work log, or job sheet might be a good idea for this - give you some level of backup if there is a query. Would only take one line for something like this - "Fused replaced on PCB. Value checked against markings on PCB". If there was an incident, then the remains of the equipment could be checked against this. After a certain number of months it would be difficult for anyone to prove it was you who did the last repair. Like with PAT testing, anything can happen 5 mins after its been tested. The important bit would be showing you had a good system of work in place.

 

What happens if there was a fault that wasn't the result of the repair? Or if an outside technician makes a mistake? The school is still responsible for the equipment it gives to employees and students.

 

As adults in schools, we either need to know what we are doing, not do it, get someone in, or get training.

[Andrew_C]

Aside from what's gone before:-

 

Techlab Ltd - not used them, but have been recommended.

Harding Scientific Instruments Ltd - Home - used them, slow and not cheap.

[synaesthesia]

An annoyingly large amount of device failures in schools will be down to a few things; vandalism, failing capacitors, loose wearing items (cables, knobs, buttons etc). Very few of those will be dangerous, vandalism is typically cosmetic and results in a visual PAT failure. Caps are an easy job, not entirely safe for DIY replacement unless in the right hands but safe for use (replace same value, higher voltage rating, same temp rating) and wearables may need replacement parts. Those science power supplies are nearly always capacitors, have one at home as a bench supply.