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  1. S

    Help - ceramic disc capacitor

    Typically, when an MOV fails, you get the catasrophic damage you see. A word of warning, while I have seen MOVs fail by themselves, it usually indicates another problem in the circuitry that CAUSED the MOV failure. MOVs are installed to prevent voltage spikes from damaging sensitive circuitry...
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    No sound from radio speaker, but can hear from headphone jack

    There might be a problem with the speaker itself, but as Bluejets said, the headphone jack is usually the problem. When you have no headphone plug installed in the jack, the jack wiring leaf spring supplies the signal to the radio speaker. When you insert the headphone plug, the leaf spring in...
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    Help - ceramic disc capacitor

    It's probably not a capacitor, it's probably an MOV (Metal Oxide Varistor). Read the lettering on the good one, and that will probably confirm it.
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    1967 sears am/fm phonograph; only tweeter speakers work not 12"

    You asked for ideas, so here's mine. The minimum problem you have is dried-out electrolytic capacitors, due to the age of the stereo. Might be the only problem, might not be if the over-stressed caps damaged other semiconductors. Like tedstruk said, I've never had a problem finding a schematic...
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    Need help with wiring 120 to 220 all schematics here

    I'll give you my logic-reasoning explanation below, but it looks to me like your unit IS ALREADY wired for 240V mains, as is: I checked the drawings the mfgr sent you, they were written by different guys, and it's obvious to me that they were not using the same correlating data on the...
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    Need help with wiring 120 to 220 all schematics here

    I'm back. Sorry nobody else joined the conversation to help you out while I was gone. I'm working my job right now, but I'll take a look at what you got from the manufacturer in my down-time. This will take a while, but wanted to let you know I'll get back to you on this as soon as I can. I...
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    Need help with wiring 120 to 220 all schematics here

    Good, sounds like they want to help. It's also good that they say they all use the same transformer, so it's a matter of finding the correct terminal diagram, as the original Figure 3.2 you showed does not match what the board is wired for. So. Do you have the Model SPM2, SPM3, or the SPM 220...
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    Need help with wiring 120 to 220 all schematics here

    The numbers on figure 3.2 are supposed to match the numbers on the transformer picture. When you flip the board over to where the transformer is soldered to the printed circuit board, you're supposed to cross reference the corresponding numbers on the transformer to the solder points under the...
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    Need help with wiring 120 to 220 all schematics here

    The figure 3.2 seems pretty clear to me, what don't you understand? You're in the UK (240V mains), so I assume you bought the unit wired for operation in the US (120V mains). If I'm correct in that assumption, you need to remove the jumpers between terminal 1 & 4, and 3 & 6; and then install a...
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    Rhino air hockey scoreboard

    Can you give us any information from any manufacturer's identification plate on the unit? Is there anything specifying the manufacturer, model number, or any other useful information we might be able to use to track down information on your specific unit?
  11. S

    Accessing embedded electrical contacts with PCB or other terminals

    Since you're compressing the copper between two fiberglass boards, and you only want a terminal block or connector on one side of the boards, .... Why can't you install your electrical connections to the copper BEFORE compressing the two boards together. Make your electrical connection, just...
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    Accessing embedded electrical contacts with PCB or other terminals

    I'd check the Mill-Max website and see if they have any application data. What you're doing is generally referred to as a multi-layered printed circuit board (even though you only have one layer, apparently). What usually happens to make the electrical connection, is that a hole is drilled and...
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    Need Help Repairing Amplifier with Possible Corrosion

    Yes. The first most obvious thing to do, is to check that you HAVE power to the unit. You'd check the 12VDC (set meter for DC voltage, greater than 12V), 'hot' wire, and chassis ground of the vehicle if an actual ground wire is not wired into the unit. The two fuses in the amp are probably...
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    PIR operated DC motor project odd behaviour help

    Do you have a part # or data on your Passive Infra-Red sensor? You might have a 'switch', but you might instead have a 'sensor'. If it's a sensor, it will have varying degrees of sensitivity associated with it, not an 'on-off' 'switch' function.
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    4 awg lug connector for 5/32" terminal?

    Thomas & Betts makes a lot of the large AWG (and small) terminals. You might want to Google them for size matches. An electrical (for electricians) supply store should stock what you need. Example of a T&B compression lug in your size is part #54106. (Just remember, you need a proper crimp tool...
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    Need Help Repairing Amplifier with Possible Corrosion

    It sounds like your amp took a hit, but I'd recheck all of your original rewiring, just to make sure something in your new installation was not wired incorrectly. When you said 'neither fuse was burned-out', did you mean the fuse in the amp and the fuse in the new unit? Did you check the fuse...
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    Repair Keyboard Rubber Contacts?

    Typically, the 'conductive powder' you wiped-off, is carbon from the carbon disc on the rubber push-button itself. Contact is made between the sqwiggly lines on the printed circuit board, by the carbon disc on the bottom of the push-button. Usually, your failure is due to the carbon disc...
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    Repair Keyboard Rubber Contacts?

    Can you post a picture of what you're seeing?
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    8 channel ultrasound pulser

    I doubt I can help, but if you can post a schematic of what you've got and what you want, somebody here can probably try to help you.
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    Transistor Power

    Yes. 50W is supposed to be the maximum package dissipation wattage. It's in reference to the transistor package itself.
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