I have an Yamaha DSP-AX1 10-Channel Amplifier and the left channel sometimes turns way down, or cuts off. I can not see any blown capasators, but It smells like it, just above the cab. bank, with the dc converter. Have anyone got the schematics, or can have a solution? I hace just orderet a capasator tester, so if no one can helt I think I will try testing all (about 20) on the supply bord.
Look very closely at each capacitor to see if any has a burned look or if any shows signs of swelling. If any show these signs they probably need replaced. You should note exactly how you remove a capacitor from the circuit. To test them effectively they need removed from the circuit board. There are several different types of capacitors. If any look like a small can, this will be a canister type and most likely will be what is called polarized. These should have a line running down the side and will have a negative ( - ) sign on them. This capacitor must be replaced exactly the way they were taken out of the circuit with the neg line in the correct place. They must also be replaced with the correct size and value. The number of the value will be on the side followed with what looks like a U with an extra line on the left side. This will be the microfared value. An example is 1000uf. Also listed will be the max voltage the cap can carry, example 250v. The other types of capacitors are ceramic. They can be put back into the circuit either direction. The most important thing to remember is to replace with the correct microfared value, the correct voltage listed and the correct size. Before you start removing any electronic component from the circuit, turn the circuit board over and examine the solder joints. Each joint should be smooth and shiny. If you find one that has pits in the solder then you may have what is called a cold splice. This type of joint may be heating up during operation and the solder melting away from the wire on the capacitor and may run back to the wire after the power is removed, causing a small amount of contact until it is heated again, then the cycle repeat's self. If you find any joint that remotely looks like a cold splice, reheat them with a solder pen and recheck your device, you may have corrected the problem. It is kinda rare for capacitors to go bad but sometimes they do. I hope this helps you.
SOURCE: AMPLIFIER CENTER CHANNEL NOT FUNCTIONING
Center channel will not work unless unit is set for Surround or Pro Logic. Make sure center channel's volume is up
SOURCE: yamaha dsp a1000 left channel cuts out sometimes in surround mode, sterio works fine
The easiest way is to buy the new part online and replace it - cost about $50US.
However, if you're up to it, this problem is fixable without the need to buy any parts. The selector switch has four sets of spring contacts which need to be bent slightly to increase the pressure on the pads against which they press, but it's a tedious job and not for the faint-hearted.
Here's what you need to do:
Open the case (6 screws) and also free up the front panel (9 screws).
You'll see that the switch consists of a PCB, an aluminium box and a motor. Remove the two screws holding it to the front bulkhead. take oyr the small "L" shaped circuit board that overlays it. A plastic pop-in holds the bottom of the switch PCB and the switch assembly can then be removed entirely.
Next you will need to remove the aluminium switch box from the PCB. Firstly de-solder all the connections which hold it in place. Now pull it clear.
Here is the MOST critical part of the job: inside the switch box you'll see four circular plastic wafers - these contain the contacts you need to fix and you'll need to bend the tangs which hold the shaft assembly onto the housing and then the tags which are holding the wafers in place. Your difficulty will be making sure that the wafers go back on the shaft with the rightr alignment and that the wafers go back in the same order.
Take some digital pictures while the wafers are still on the shaft with the orientation of the KNOB included - if you mess this up (I did) the job becomes horrible! Also, mark each wafer with a number 1-4 because there are three different kinds Once you are comfortable that you can replace the wafers in the proper rotary configration with respect to the shaft, remove them individually and pop out the gray plastic cores and bend the spring contacts upwards so that they will go back pressing more firmly against the pads. Now reassemble, and good luck!
SOURCE: Own a Yamaha DSP-A1000.
problem solved
i have the same problem with my A1000 center died
problem is the magnetichal relay who has the contacts oxidated
clen thoes and ull have it like new
Testimonial: "Thank you very much. Your diagnostic was totally right and cleaning the relay fixed my problem. Thanks again - very helpful!"
SOURCE: I have a Yamaha dsp
Generally speaking, an amp attempts to protect itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.
Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.
You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.
If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.
If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'nekkid'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.
Check for loose speaker connections at the speaker as another possible root cause for intermittent shutdown.
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