2 recent failed repairs -
1 - Rear wiper arm on VW Polo.
Plastic arm had cracked around the alloy boss.
Figured it was old & maybe brittle & the freezing weather was the last straw.
Fitted replacement arm & at last half turn of spanner, crack, same thing happened!
Seller has replaced but not sure how I'm going to fit without a recurrence.
2 - Bro's washing machine. Door interlock warning light on. Replaced interlock switch, no change. Further investigation required.
1 - Rear wiper arm on VW Polo.
Plastic arm had cracked around the alloy boss.
Figured it was old & maybe brittle & the freezing weather was the last straw.
Fitted replacement arm & at last half turn of spanner, crack, same thing happened!
Seller has replaced but not sure how I'm going to fit without a recurrence.
2 - Bro's washing machine. Door interlock warning light on. Replaced interlock switch, no change. Further investigation required.
Parasound HCA-1200II
Bad relays and they are NLA. They were cleaned and came back. They are murder to get to, the entire rear panel has to be removed and input PCB removed to allow access to the output PCB. The relays are odd units, very flat and you can't really use anything else.
While working on it, I discovered someone had used an inductive emitter resistor instead of the plate type, and they had cut off transistor legs and tacked them back together again. Pulled those and found these outputs were "dry", pulled that bank and cleaned, regreased them.
So now it works again and passes it specs. Not an impressive amplifier.
-Chris
Bad relays and they are NLA. They were cleaned and came back. They are murder to get to, the entire rear panel has to be removed and input PCB removed to allow access to the output PCB. The relays are odd units, very flat and you can't really use anything else.
While working on it, I discovered someone had used an inductive emitter resistor instead of the plate type, and they had cut off transistor legs and tacked them back together again. Pulled those and found these outputs were "dry", pulled that bank and cleaned, regreased them.
So now it works again and passes it specs. Not an impressive amplifier.
-Chris
Since this thread is usually read by repair technicians, I will post this question here.
I have a 'Sunny Boy' inverter used to convert PV panels' DC voltage to AC mains at 230V, 50Hz. It is now failing to start with an error message reading "disturbance, earthfault".
Does anyone know what this means? Online, I found it may have to do with leakages from PV output to ground exceeding acceptable values. Surrounding the DC input connectors there is visible rust. Can this be the reason for the fault? Rust can easily hold moisture creating a low resistance path where there should not be any.
I have a 'Sunny Boy' inverter used to convert PV panels' DC voltage to AC mains at 230V, 50Hz. It is now failing to start with an error message reading "disturbance, earthfault".
Does anyone know what this means? Online, I found it may have to do with leakages from PV output to ground exceeding acceptable values. Surrounding the DC input connectors there is visible rust. Can this be the reason for the fault? Rust can easily hold moisture creating a low resistance path where there should not be any.
Hi edbarx,
Well, you're right. Technicians and DIY people tend to read this thread. I wish everyone would though, because there are often hints about what to look for with a poor technician.
Rust will absolutely hold moisture and cause leakage paths. Any kind of corrosion to do with electronics or electrical is normally not good news. If you do have corrosion in a circuit where the voltage is above about 30 V AC or DC, call a professional. Not a cut-rate guy, but someone who is good at their job.
For lower voltage circuits that you feel comfortable working on, de-energize the circuit first. Check that it is de-energized with a reliable meter. Once you are positive that the circuit has no power in it, then you can begin clean-up. Depending on the problem, your choice of cleaning agent is determined for you. For rust you would normally rub or grind it off. Because this is an electrical circuit, you shouldn't use steel wool (which can burn) that may cause short circuits there or elsewhere the tiny wire lands. Once you have the area down to solid metal again, use some kind of coating to seal it against the air and moisture. It's a good idea to inspect your connections periodically. For connectors, you can use "barrier grease" designed for this job. Normally you would lightly pack the connectors (Molex kind that are open both ends) with the stuff, or on the surface (RJ-11 or RJ-45). This will protect the connections for a while. If you disconnect the connectors, wipe away the old stuff and apply some clean, fresh grease. If the connectors are corroded past cleaning, they must be replaced and you should use someone who is familiar with your equipment for this. If someone says "don't worry about it", find someone else for help. The only reason why these guys never used the stuff is because they left it to someone else to clean up some time down the road.
Best, Chris
Well, you're right. Technicians and DIY people tend to read this thread. I wish everyone would though, because there are often hints about what to look for with a poor technician.
Rust will absolutely hold moisture and cause leakage paths. Any kind of corrosion to do with electronics or electrical is normally not good news. If you do have corrosion in a circuit where the voltage is above about 30 V AC or DC, call a professional. Not a cut-rate guy, but someone who is good at their job.
For lower voltage circuits that you feel comfortable working on, de-energize the circuit first. Check that it is de-energized with a reliable meter. Once you are positive that the circuit has no power in it, then you can begin clean-up. Depending on the problem, your choice of cleaning agent is determined for you. For rust you would normally rub or grind it off. Because this is an electrical circuit, you shouldn't use steel wool (which can burn) that may cause short circuits there or elsewhere the tiny wire lands. Once you have the area down to solid metal again, use some kind of coating to seal it against the air and moisture. It's a good idea to inspect your connections periodically. For connectors, you can use "barrier grease" designed for this job. Normally you would lightly pack the connectors (Molex kind that are open both ends) with the stuff, or on the surface (RJ-11 or RJ-45). This will protect the connections for a while. If you disconnect the connectors, wipe away the old stuff and apply some clean, fresh grease. If the connectors are corroded past cleaning, they must be replaced and you should use someone who is familiar with your equipment for this. If someone says "don't worry about it", find someone else for help. The only reason why these guys never used the stuff is because they left it to someone else to clean up some time down the road.
Best, Chris
Perhaps some POR15 is in order there to deal with the rust.
POR-15 - Professional automotive & industrial coatings for permanent rust & corrosion protection.
POR-15 - Professional automotive & industrial coatings for permanent rust & corrosion protection.
This can actually be a challenge when it comes to big solar panels!
I once went through solar panel installation instructor training to qualify me to teach would-be solar panel installers. Basically, the installers were never, under any circumstances, supposed to connect the wires from individual 12V panels together...that job was to be left to a qualified electrician only. Otherwise the dangers of hooking up multiple 12V solar panels in series - working on a rooftop in bright sunlight - are pretty obvious!
The scariest part of the whole installation is when its all done, the big solar panel is feeding the AC inverter, and its time to throw the switch that connects the inverter to the mains grid. Another job for a qualified electrician only, and he/she usually does it while hiding his/her face from the possibility of a huge arc-flash that can burn your face off in a split-second if something goes wrong.
That bit was demonstrated to us without actual solar panels connected to the inverter, and without the inverter being actually hooked up to the AC grid, either. Neither the instructor nor the qualified electrician wanted to take the risk of doing it "live".
-Gnobuddy
Hi Gnobuddy,
It may be difficult to do, and a professional might be needed, but you can't work on it live! The easiest answer might be to disconnect in the dark by flashlight. I have heard of solar cells arrays delivering well over 100VDC during the day. DC is far more deadly than alternating current. I wonder if throwing a tarp over the array would drop the power enough to be safe? You have to make sure the batteries cannot back feed into the cell array where you are working.
More and more, this is sounding like a job for a professional. But once it is down and safe, take the opportunity to go over all your connection points and seal them as well.
-Chris
It may be difficult to do, and a professional might be needed, but you can't work on it live! The easiest answer might be to disconnect in the dark by flashlight. I have heard of solar cells arrays delivering well over 100VDC during the day. DC is far more deadly than alternating current. I wonder if throwing a tarp over the array would drop the power enough to be safe? You have to make sure the batteries cannot back feed into the cell array where you are working.
More and more, this is sounding like a job for a professional. But once it is down and safe, take the opportunity to go over all your connection points and seal them as well.
-Chris
Oh, I could not agree more!
A little 12V panel for an RV or something is fine. But big solar arrays are dangerous things.
I had that thought too, but if it's a grid-tied rooftop solar panel, climbing around on a dark roof and fumbling with a circuit that also connects to AC mains doesn't seem particularly safe, either!
IIRC I read 80V DC, unloaded, from a single panel on a cloudy day in Southern California. Quite enough voltage to be dangerous!
At the time I went through the training, there wasn't a universal standard for panel voltage. Some manufacturers made low-voltage panels that you had to wire up in series in groups to get the eventual voltage you needed, and then wire groups of those in parallel to get the current you needed. Other manufacturers tried to keep it simple and made panels that put out, as you say, some 100 V each, and you only had to wire as many in parallel as you wanted. But each individual panel was now dangerous by itself.
The systems I saw were "grid tied", i.e., they were connected to the city electric grid through smart electronics. There were no batteries used. (Batteries of that capacity are huge, expensive, and finicky, so only people who live "off the grid" tend to use them.)
The idea of these grid-tied systems was that when the solar panels made less power than the house was using (at dusk, say, or at night), additional power would be drawn from the city electric grid as needed. When the house used less power than the solar panel was making, excess electricity was fed back into the electric grid, the homeowner got a credit from the electricity company, and you could actually watch the meter spinning backwards!
The whole thing happened seamlessly, so the homeowner was never short of power, and didn't have to intervene in any way as solar panel output varied due to time of day, season, or weather conditions, or as ovens and air conditioning and dishwashing machines were turned on or off.
On the plus side there were no batteries to worry about, but, at least on the far side of the "smart" inverter, there was full-blown 120V, 60 Hz, residential AC power, with all its dangers.
-Gnobuddy
I had the thought too, while I was writing my original post, but I dismissed it instantly. To me, it's the equivalent of propping up your car on two cement cinder-blocks (instead of proper steel jackstands), and then crawling under it to repair something.
(Cement can crumble suddenly and unpredictably under loads like this, dropping the car onto the person underneath and crushing him/her, so this is a suicidally stupid thing to do. Some shade-tree mechanics do it, all the same.)
Back to the cloth-over-the-solar-panel idea: as just one possibility of things that could go tragically wrong, what happens if the tarp blows away in the wind while you're handling the wires?
There has to be a proper "by the book" way to work on solar panels exposed to sunlight. I don't know exactly what it is, but it's probably a safe guess that it involves the same equipment and procedures used when electricians work on live AC systems: thick protective electricians gloves (double layered, tested regularly for pin-holes by leak-test), face protection from arc-flash, and training and certification as an electrician.
I don't know what size or voltage panels Mr. Barx is talking about. If they're little 12V panels, they're as safe to work on as a car battery (meaning you still have to take care not to short them accidentally, etc.)
But if they're high-voltage, or high-powered panels, I think this is one of those cases where a properly trained, properly certified person with the proper protective gear is the only person who should do the job.
-Gnobuddy
The DC output voltage from the panels is 285V with a supported current of 7A. This DC voltage is what powers the inverter. The grid is 230V, 50Hz.
The inverter when it is powered from the panels, emits a fault code which is 5 short LED flashes equally space in time, a long pause, and then, a long LED flash. I am suspecting this implies an inverter fault. If this proves to be the case, I will have to change the circuitry, so that, the inverter is installed indoors, instead of outdoors. There is already a power cable that is used to connect the PV installation to the grid which I can use. I can isolate the panels from the cable using a purposely installed rotary switch. The grid can also be isolated downstairs by turning off the PV installation's kWh meter and main switch.
Added Later:
The fault code means an insulation fault of the generator. The inverter should be all right. At least, this is what the manufacturer's pdf states.
The major issue with this installation is warranty. Safety is the least of issues once the PV system is isolated completely. If the installation is out of warranty, I will try to diagnose the problem to solve it.
The inverter when it is powered from the panels, emits a fault code which is 5 short LED flashes equally space in time, a long pause, and then, a long LED flash. I am suspecting this implies an inverter fault. If this proves to be the case, I will have to change the circuitry, so that, the inverter is installed indoors, instead of outdoors. There is already a power cable that is used to connect the PV installation to the grid which I can use. I can isolate the panels from the cable using a purposely installed rotary switch. The grid can also be isolated downstairs by turning off the PV installation's kWh meter and main switch.
Added Later:
The fault code means an insulation fault of the generator. The inverter should be all right. At least, this is what the manufacturer's pdf states.
The major issue with this installation is warranty. Safety is the least of issues once the PV system is isolated completely. If the installation is out of warranty, I will try to diagnose the problem to solve it.
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The fault was a leakage as suspected. Due to consecutive days with sunny periods, the leakage to earth was reduced and the inverter could start to supply AC to the grid and my household.
The solution to prevent this from happening again, is to move the inverter from its current outdoor location to indoors. I will try to do this task. First, I will isolate the grid from the PV system, and then the inverter itself from the PV panels. The remaining uncertainty is whether the inverter stores electrical energy when it is disconnected from both points. With the inverter and PV panels disconnected, the PV panels' voltage can be connected to the existing cable that is currently used to deliver inverted AC power to the grid and my household.
The 3 wire power cable will be used for earth, positive and negative terminals with a DC voltage of 285V and a current of at least 7A when not accounting for conversion losses.
The solution to prevent this from happening again, is to move the inverter from its current outdoor location to indoors. I will try to do this task. First, I will isolate the grid from the PV system, and then the inverter itself from the PV panels. The remaining uncertainty is whether the inverter stores electrical energy when it is disconnected from both points. With the inverter and PV panels disconnected, the PV panels' voltage can be connected to the existing cable that is currently used to deliver inverted AC power to the grid and my household.
The 3 wire power cable will be used for earth, positive and negative terminals with a DC voltage of 285V and a current of at least 7A when not accounting for conversion losses.
Hi Ed,
Yes, electronics and outdoor installation is always going to require more maintenance than a similar system installed indoors in a cool, dry location. You have a solid plan as for your objective. We don't want to read about you in the news, so use a professional if there is any hint where this could get out of control. Over here were use 120 ~ 125 VAC grids for home power. This is slightly less dangerous than your grid voltage because we can usually let go of a live wire. You can't at these higher voltages. So choose safety over a lower cost of making these changes. You might be able to have an electrician make it all safe for you, then check and re-energize those circuits once you have moved the equipment. Here in North America, AC mains equipment (and telephone systems) are required to be mounted on a fireproof back board. This can be satisfied with fireproof paint, or impregnated wood designed for this purpose. I imagine you will need to have the changes inspected before you are allowed to reconnect to the mains grid.
Like any other major work, take the time to plan the changes and prepare a back board, as well as running any additional wire you will need before hand. Then, when the day comes for the equipment move, everything will take place smoothly and the electrician only needs to make one trip for you. The outdoor connections should be made inside a weather proof box made for that application, so your wiring can be installed and terminated in that box and you only need to move the system side wiring in and connect it. Use the same general idea for the additional inside wiring where it runs to your breaker panel (or fuse panel). Both those runs will terminate on the back board so it is easy to connect your equipment.
This is the same procedure I've used for years when moving or installing commercial telephone systems. Do all your prep work first, and once it is done without problems, you can install the equipment with a minimum of problems. Do this any other way invites disaster.
-Chris
Yes, electronics and outdoor installation is always going to require more maintenance than a similar system installed indoors in a cool, dry location. You have a solid plan as for your objective. We don't want to read about you in the news, so use a professional if there is any hint where this could get out of control. Over here were use 120 ~ 125 VAC grids for home power. This is slightly less dangerous than your grid voltage because we can usually let go of a live wire. You can't at these higher voltages. So choose safety over a lower cost of making these changes. You might be able to have an electrician make it all safe for you, then check and re-energize those circuits once you have moved the equipment. Here in North America, AC mains equipment (and telephone systems) are required to be mounted on a fireproof back board. This can be satisfied with fireproof paint, or impregnated wood designed for this purpose. I imagine you will need to have the changes inspected before you are allowed to reconnect to the mains grid.
Like any other major work, take the time to plan the changes and prepare a back board, as well as running any additional wire you will need before hand. Then, when the day comes for the equipment move, everything will take place smoothly and the electrician only needs to make one trip for you. The outdoor connections should be made inside a weather proof box made for that application, so your wiring can be installed and terminated in that box and you only need to move the system side wiring in and connect it. Use the same general idea for the additional inside wiring where it runs to your breaker panel (or fuse panel). Both those runs will terminate on the back board so it is easy to connect your equipment.
This is the same procedure I've used for years when moving or installing commercial telephone systems. Do all your prep work first, and once it is done without problems, you can install the equipment with a minimum of problems. Do this any other way invites disaster.
-Chris
Considering the educational level of students who opt to become technicians, my educational level is better at their required subjects of Mathematics and Physics. In my A-Levels I obtained the highest possible grades, and I sat for these exams in one examination session. These people understand mathematics and physics on an inferior level than me, therefore, if I opt to hire a technician to do the job, I will be hiring someone who understands the required concepts on a lower level.
The issue is not an issue of safety, but of a hegemony, which is the deep ingrained assumption that educational institutions, and hence, formal courses are the only form of acquisition of knowledge and skills. This is not true: there are other methods of acquiring knowledge and skills. By other methods, I am referring to methods that include self learning by studying using reputable text books. I am definitely not referring to learning from experience without any effort to understand concepts.
Many western countries do not provide a system of examinations for lone learners who opt to study on their own without having to attend courses. Having to attend courses is now tied with examinations and one cannot sit for examinations without attending some course. This is an injustice.
I know what I am talking about as I possess a degree in education. The present system of tying exams with courses is blasphemy. Its only advantage is of allowing private teaching firms to increase their earnings through making students having to attend courses, otherwise, they wouldn't be allowed to sit for exams denying them qualification.
The issue is not an issue of safety, but of a hegemony, which is the deep ingrained assumption that educational institutions, and hence, formal courses are the only form of acquisition of knowledge and skills. This is not true: there are other methods of acquiring knowledge and skills. By other methods, I am referring to methods that include self learning by studying using reputable text books. I am definitely not referring to learning from experience without any effort to understand concepts.
Many western countries do not provide a system of examinations for lone learners who opt to study on their own without having to attend courses. Having to attend courses is now tied with examinations and one cannot sit for examinations without attending some course. This is an injustice.
I know what I am talking about as I possess a degree in education. The present system of tying exams with courses is blasphemy. Its only advantage is of allowing private teaching firms to increase their earnings through making students having to attend courses, otherwise, they wouldn't be allowed to sit for exams denying them qualification.
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