20 Most Recent Laney A1 65-Watt Acoustic Amplifier with Digital Multi Effects, Black Questions & Answers

What is the impedance on the devices? It sounds to me like the amp and the pickups are not rated for each other.

I would check C37 & C38. If one is loose or bad connection, there will be 100/120HZ noise.

First, plug your guitar and cable into a different amp to make sure the problem is the amp. Then check to see if you have output from any headphone jack or effects loop. If so your problem is in the power amp section. If not, it's likely the preamp section. Whichever section it is, it will most likely need to go to the shop.

There is a heat sensor on the heatsink (to cooling IC / transistor) which decides current / voltage, in case of overheating. This is indeed to secure IC / transistor power of destruction. The cause of the excessive heat, the impedance mismatch between the amp to the speakers. It is also possible that parts already exist within the amplifier that is almost / half broken, for example, changing the resistor value, electrolytic capacitors are bulging or dried, isolation transformer windings were charred, solder joint cracking etc. Should be checked, before the fatal damage. Heatsink on the amplifier (the picture is owned Connelectronic):

The most likely case is that one of the main output transistors (if which there are many) is shorted. When the protect circuit senses DC on the final output, it will not allow the output relay to come on to protect the speakers from raw DC. With the power removed, you can check between each outputs Emitter and Collector and you will probably find close to zero ohms. From that point you need to unsolder each of the pins of the bad channel until you find the shorted device(s) and replace them.

'pianoforte'

BREV. N. 838420

See page 22 troubleshooting of this manual. It may help you. dd501 (yamaha.com)

Depending on the model, there are four around that date, it could be the insert jacks are tarnished reducing the signal flow between the pre amp stage and digital power amplifier. It could be the power amplifier has failed. It could even be customer error in wiring. This assumes there is the correct level of signal entering the input sockets of course.

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It's a Line 6 and probably requires a software update from Line 6.