What is wrong with this pic - Number IV
- Thread starterMayhem
- Start date
Oops - forgot to say Correct to the Soundman's identification of smoke and haze particles causing potential shorting problems when combined with dust in electrical environments. Remember, this is not just an issue for amplifiers but for ALL electrical equipment including lights and dimmers.
Not sure how duct tape would get into a fixture and mix with the dust but nothing would surprise me in some places that I have worked.
So well done to Soundman and avkid for picking up on smoke and haze as sources of moisture in an electrical environment.
Now – how do we go about keeping amps (for this example) clean and in good working conditions?
Not sure how duct tape would get into a fixture and mix with the dust but nothing would surprise me in some places that I have worked.
So well done to Soundman and avkid for picking up on smoke and haze as sources of moisture in an electrical environment.
Now – how do we go about keeping amps (for this example) clean and in good working conditions?
Heres a qucik little guide;
1. one clear workspace. I have an old white towel I use when I take apart things, the white shows little screws and springs better and prevents them from rolling.
2. ground yourself. Those little $2 wriststaps can save your $200 doller amp. If you dont have one touch the metal case while the amp is still pluged in and avoid shuffling your feet on carpet
3.Open it up. If need be write down where screws go and any wires you need to unplug go.
4. Gett the dust/crud out. If it looks like a fur ball in there a pass or two with a vacum might not be a bad idea, then to get the rest of it out blow it out with compressed air, try to avoid high power compress air because that could probly wont but could strss a joint or shoot a piece of dirt into some where it shouldn't be.
5. Put back together. Throw away any extra pieces and write your name and date on a piece of tape and stick it on the amp. That way your boss knows who screwed up or that the amp was cleaned last week and dosn't need to be done agian.
1. one clear workspace. I have an old white towel I use when I take apart things, the white shows little screws and springs better and prevents them from rolling.
2. ground yourself. Those little $2 wriststaps can save your $200 doller amp. If you dont have one touch the metal case while the amp is still pluged in and avoid shuffling your feet on carpet
3.Open it up. If need be write down where screws go and any wires you need to unplug go.
4. Gett the dust/crud out. If it looks like a fur ball in there a pass or two with a vacum might not be a bad idea, then to get the rest of it out blow it out with compressed air, try to avoid high power compress air because that could probly wont but could strss a joint or shoot a piece of dirt into some where it shouldn't be.
5. Put back together. Throw away any extra pieces and write your name and date on a piece of tape and stick it on the amp. That way your boss knows who screwed up or that the amp was cleaned last week and dosn't need to be done agian.
Good work Soundman.
Just be careful if you leave the amp plugged in that the recepticle is switched off. No matter how experienced you are, you don't really want to be poking around in an amp that has power flowing to it.
Before I comment on other aspects, does anyone else have anything to add or discuss?
Just be careful if you leave the amp plugged in that the recepticle is switched off. No matter how experienced you are, you don't really want to be poking around in an amp that has power flowing to it.
Before I comment on other aspects, does anyone else have anything to add or discuss?
Now everyone is getting all excited about cleaning their amplifiers just a reminder about SAFETY!!!
As you all know the amplifiers connect to the electricy supply so everyone remembers to unplug them from the wall.
But unless you know about how the inside of an amplifier works you may not be aware of the electrical hazard that maybe present even when the amplifier is unplugged.
The power supplies in the sort of amplifers we use in theatre use quite high voltages. Between the positive and negative supply rails the voltage can easily reach 100 volts which can give you a nasty shock and in some cases maybe fatal if you come in contact with it. Also if you accidently short circuit the supply with other parts of the amplfier by accidently touching it with things like a screwdriver, the metal part of a vacum hose etc you may literaly blow parts of your amplifier to Kingdom Come. Transistors may melt, printed circuit board tracks may lift which definetly means a servicemans bill and a please explain from the principal.
Because the amplifier needs large amounts of electrical energy quickly to reproduce loud pieces in the music there are a number of large capacitors to store this energy. And because they store it, when you have turned off the power these high voltages will remain for quite some time. So never turn an amplifier off straight away and start working inside. Leave it for a couple of hours to bleed off the energy. If you are comptent with using a multimeter you can use that to check the power supply voltage has gone to zero.
Some people will have diffrent ideas on the length of time that it will take for the energy to drain away. This is just a general guide so feel free to offer suggestions on the length of time you find necessary. Obviously different amplifiers will become safe at different rates.
To be honest only people who really know what they are doing should ever open an amplifier as there is too much chance of doing more harm then good.
Also things to remember if you take the lid of your amplifier are:
It may be against school policy and drop you in it.
It may void the warranty on gear.
The best thing is to try and get your school to send all the gear to a qualified serviceman once a year for a clean and check.
As you all know the amplifiers connect to the electricy supply so everyone remembers to unplug them from the wall.
But unless you know about how the inside of an amplifier works you may not be aware of the electrical hazard that maybe present even when the amplifier is unplugged.
The power supplies in the sort of amplifers we use in theatre use quite high voltages. Between the positive and negative supply rails the voltage can easily reach 100 volts which can give you a nasty shock and in some cases maybe fatal if you come in contact with it. Also if you accidently short circuit the supply with other parts of the amplfier by accidently touching it with things like a screwdriver, the metal part of a vacum hose etc you may literaly blow parts of your amplifier to Kingdom Come. Transistors may melt, printed circuit board tracks may lift which definetly means a servicemans bill and a please explain from the principal.
Because the amplifier needs large amounts of electrical energy quickly to reproduce loud pieces in the music there are a number of large capacitors to store this energy. And because they store it, when you have turned off the power these high voltages will remain for quite some time. So never turn an amplifier off straight away and start working inside. Leave it for a couple of hours to bleed off the energy. If you are comptent with using a multimeter you can use that to check the power supply voltage has gone to zero.
Some people will have diffrent ideas on the length of time that it will take for the energy to drain away. This is just a general guide so feel free to offer suggestions on the length of time you find necessary. Obviously different amplifiers will become safe at different rates.
To be honest only people who really know what they are doing should ever open an amplifier as there is too much chance of doing more harm then good.
Also things to remember if you take the lid of your amplifier are:
It may be against school policy and drop you in it.
It may void the warranty on gear.
The best thing is to try and get your school to send all the gear to a qualified serviceman once a year for a clean and check.
After being overwhelmed by the response on the basic steps to service an amplifier, here are my thoughts on the topic.
cutlunch raised some good points about safety and I want to reinforce that statement. The aim of this topic was not to turn you all into little amplifier, dimmer, sound board, lighting board, moving light etc service technicians, nor was it to have you attack such equipment in your school or theatre. The aim was to get you to think about the problems that dusty equipment can cause. I used an amplifier as an example, purely because I did take some pics of one that came through my workshop. It could have just as easily been a dimmer.
Once you had thought of the complications of having ‘dirty’ gear, I wanted you to then think about what common causes of moisture could be found in the theatre environment that could really cause some problems with the circuit boards that are now not only dusty but moist as well. It took a while and some prompting to come to the conclusion that:
dust + (smoke/haze fluid or humidity) = bad news
Given that we now knew the reasons to keep equipment clean, I was looking for a quick rundown on how to do this. Soundman made a very good start but no one really took up the challenge to add to this. cutlunch raised the safety issues and I have held off responding to these posts to see if anyone else wanted to add anything. However, I feel that the time has come for me to respond with my method. Now this is not to say that mine is right or wrong or any better than the next person. Although, I do hope that it stimulates some additional discussion.
In his post, cutlunch made comment about the capacitors that are used to store energy to ensure that the lower frequency sounds do not draw too much on the mains power. They essentially act as a reservoir. Some people that I know discharge the caps before servicing an amplifier and if you are measuring the ESR of a capacitor, they need to be fully discharged anyway. I use a discharge probe for this purpose.
I would be much more concerned with people leaving the power plugged in (although soundman did clarify this point this is a caution to other people) .
The steps that I would use are:
1. Visual inspection of all external connectors, plugs, switches, pots etc
2. Discharge capacitors
3. Dust with a vacuum cleaner and small brush (I have an attachment for a vacuum cleaner that has brush nozzles and other attachments that are about ½” in diameter)
4. Using low pressure compressed air, blow out any areas that cannot be accessed during step 3
5. Inspect fans for broken blades or resistance to turning (do not 'spin up' using compressed air as it can damage the fans) and clean the blades
6. Inspect components, boards and wire for any physical faults (such as dry joints, discoloured heat transfer compound etc) and repair/replace as necessary
7. If necessary, clean circuit boards with a circuit board cleaner
8. Clean and lubricate switches and pots
9. Ensure that any wires or connectors removed are replaced and in the correct position and that any internal fuses are secure in their holders.
10. Replace cover and test.
I power up for the first time using a variac and a clamp meter (to check for any shorts) and then run the amplifier up on a dummy load with a signal generator and check the wave forms on a CRO but I doubt that many of you will have these resources.
Some people initially suggested covering up amplifiers and/or placing materials in front of fans. This is fine for equipment that is not in use, but please do not do this if it is in use. First off, you will be reducing the ability of the equipment to dissipate heat, which can lead to component failure. Secondly, you will restrict air movement through the fans. Remember, some equipment use fans that suck air into it, some use fans that blow air out of it and some use both. Some manufactures actually do place filters on their fans and this is ok because they have calculated this into their design.
Once again, I am not advocating that you run out and pull the covers off of your school equipment. My aim is to ensure that you understand the value of regular servicing and the potential hazards of simple things like dust accumulation on circuit boards.
cutlunch raised some good points about safety and I want to reinforce that statement. The aim of this topic was not to turn you all into little amplifier, dimmer, sound board, lighting board, moving light etc service technicians, nor was it to have you attack such equipment in your school or theatre. The aim was to get you to think about the problems that dusty equipment can cause. I used an amplifier as an example, purely because I did take some pics of one that came through my workshop. It could have just as easily been a dimmer.
Once you had thought of the complications of having ‘dirty’ gear, I wanted you to then think about what common causes of moisture could be found in the theatre environment that could really cause some problems with the circuit boards that are now not only dusty but moist as well. It took a while and some prompting to come to the conclusion that:
dust + (smoke/haze fluid or humidity) = bad news
Given that we now knew the reasons to keep equipment clean, I was looking for a quick rundown on how to do this. Soundman made a very good start but no one really took up the challenge to add to this. cutlunch raised the safety issues and I have held off responding to these posts to see if anyone else wanted to add anything. However, I feel that the time has come for me to respond with my method. Now this is not to say that mine is right or wrong or any better than the next person. Although, I do hope that it stimulates some additional discussion.
In his post, cutlunch made comment about the capacitors that are used to store energy to ensure that the lower frequency sounds do not draw too much on the mains power. They essentially act as a reservoir. Some people that I know discharge the caps before servicing an amplifier and if you are measuring the ESR of a capacitor, they need to be fully discharged anyway. I use a discharge probe for this purpose.
I would be much more concerned with people leaving the power plugged in (although soundman did clarify this point this is a caution to other people) .
The steps that I would use are:
1. Visual inspection of all external connectors, plugs, switches, pots etc
2. Discharge capacitors
3. Dust with a vacuum cleaner and small brush (I have an attachment for a vacuum cleaner that has brush nozzles and other attachments that are about ½” in diameter)
4. Using low pressure compressed air, blow out any areas that cannot be accessed during step 3
5. Inspect fans for broken blades or resistance to turning (do not 'spin up' using compressed air as it can damage the fans) and clean the blades
6. Inspect components, boards and wire for any physical faults (such as dry joints, discoloured heat transfer compound etc) and repair/replace as necessary
7. If necessary, clean circuit boards with a circuit board cleaner
8. Clean and lubricate switches and pots
9. Ensure that any wires or connectors removed are replaced and in the correct position and that any internal fuses are secure in their holders.
10. Replace cover and test.
I power up for the first time using a variac and a clamp meter (to check for any shorts) and then run the amplifier up on a dummy load with a signal generator and check the wave forms on a CRO but I doubt that many of you will have these resources.
Some people initially suggested covering up amplifiers and/or placing materials in front of fans. This is fine for equipment that is not in use, but please do not do this if it is in use. First off, you will be reducing the ability of the equipment to dissipate heat, which can lead to component failure. Secondly, you will restrict air movement through the fans. Remember, some equipment use fans that suck air into it, some use fans that blow air out of it and some use both. Some manufactures actually do place filters on their fans and this is ok because they have calculated this into their design.
Once again, I am not advocating that you run out and pull the covers off of your school equipment. My aim is to ensure that you understand the value of regular servicing and the potential hazards of simple things like dust accumulation on circuit boards.
MOONLIGHTING
Member
Great stuff.
In many cases the filters can be removed and cleaned in warm soapy water. Sometimes they are too sticky to clean with a vacuum. Must be completely dried before installing again, of course. Or you could just replace them with the same kind....
Mike
In many cases the filters can be removed and cleaned in warm soapy water. Sometimes they are too sticky to clean with a vacuum. Must be completely dried before installing again, of course. Or you could just replace them with the same kind....
Mike
