Amplifier problem- digital wattage readout no longer lights up.
I recently acquired a used Amplifier that was very dirty. I am no stranger to cleaning out dirty audio gear, and so I took my trusty Hoover and carefully vacuumed out all of the fuzz and lint I could see. I also used a small paintbrush as a miniature whisk broom to get in the tighter areas.I was very, very careful not to disturb any wiring connections.I carefully put the top cover back on and used the amplifier for acouple of days with no problems whatsoever. But now I have noticed that the digital wattage readout on the front of the amp no longer lights up. I believe that it did light up normally after I re-assembled the amplifier, but I still can't help wondering if I did something to break a connection somewhere. Does anyone have a schematic for this amplifier? Is this a common problem on these amplifiers?
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Re: Amplifier problem- digital wattage readout no longer...
It's very hard to say, if the unit has been sitting around for a long
time, it's possible you operating it may have kicked out a bad cap that
just was aged, and the minor heat you were generating did it in.
I don't know what type of display you have how ever, if it's a
fluorescent display, you may have a bad electrolytic cap in the
inverter section that supplies the HV low current for the display..
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First determine what the material of your digital piano keys are. Many digital pianos now days have plastic keys but if you have those ebony black and ivory white keys, you need to clean them with extensive care.
1 - Use a damp cloth for cleaning your keys and make them dry.
2 - Use a small amount of liquid soap with a damp cloth.
3 - Clean dirty keys with this cloth. Your grip must be firm but rubbing must be light.
4 - Gently rub keys until they are completely clean.
NB: These steps can be followed for plastic keys but for ivory keys, you would need to get ivory scrapper
Use this in Google to fine manuals and schematics: Epiphone junior amplifier manual Google zoeken
Most resistors are 1/4 watt, unless something is added in the schematic.
You also can deduce the wastage, because for every size is a wattage, or the other way around.
When you are not sure, and it fits, use a bigger resistor. The same resistance (ohm) but a higher wattage is no problem as long as it fits in the housing.
It could have a capacitor failing in the amplifier section, or primary oscillator section. it might also be a failing output transistor on the amplifier. If the amplifier has gotten noiseir, suspect a faulty transistor.
One of the two contacts for that key is not working. This could be dirty or damaged contact. They use a conductive rubber pills that the key presses against circuit board traces. One contact makes before the other and this is how velocity is sensed. Unless you are adept at this repair, I would recommend you take it in for repair. Chances are any part cost is negligible... mostly labor to open and access the contacts for cleaning. Clean ONLY with 99% isoprophyl alcohol and Q TIps... VERY GENTLY.
The board is a mixer only, not an amplifier. A mixer simply, well, mixes audio sources into a line output which then goes to the amplifier.
Your question really has no answer since wattage is determined by the amplifier used. Essentially, it can "push" as many watts as the amplifier can deliver.
Please check the wattage of the replaced speakers, now check the cross over in the speakers, if the capacitors are short the voltage might flow into the tweeter coils to burnt them out. Also you can try and reduce the high frequency and also see if the tweeters heat up . If so use high wattage super cooled tweeters.
Check finally for fault in the amplifier output- high voltage/current.
the "nobs" that have the noise is what we call a "dirty pot" Some can be cleaned others are to far gone to ever work well again. To clean a "dirty pot" you need to get into the internal area of the amplifier. Most amps have screws in the bottom that hold the unit into the wood frame. unplug everthing from the amp. turn the unit upside down and remove the retaining screws. that should allow the guts" of the unit to slide out. don't force anything. then you should be able to see the "pot" from the top. If you can you get electric contact cleaner (I use the NAPA brand) and the spray stick (red tube) that comes with the can of contact cleaner. In a safe area (no flame or heat) you spray the contact cleaner on the top and sides of the "pot" then work the knob back and forth all the w ay to each end of the allowable movement but never try to go beyond where the knob wants to stop. repeat this at least three times. take care not to let the contact cleaner drip onto anything as it could leave a stain. I usually try to use a lot of newspaper under the unit and be careful not to use any more spray than you need. You should feel the pot getting easy to move as it gets cleaner. Let everytthing dry off before you reinstall the amp into the outside frame. Move slowly and take your time. If it works it will save you a lot of repair cost as changing out the pots is not fun and could cost almost as much as the amp is worth
try a differrent speaker of suitable wattage and ohmage (displayed with a number next to a ? symbol on the back of the speaker),
remove the original amp speaker and gently push in and out on it, checking for uneven resistance or scratching. the speaker should retract and return smoothly, without any scratchiness or uneven resistance from within, and if there is any of this scratchiness or uneven resistance from within, the speaker is likely damaged from too much wattage or distortion.