Noisy bugera

[harrisxr650]

Hi. i got a Bugera 333xl-212 combo. it doesnt count more than 30 hours of play and haven't turn volumes above 3-5 yet...and its out of waranty

issue a): yesterday at the rehearsal I've notice a small hum on clean channel while i was playing with no effects ( i only use clean channel as i get my sounds from pedals). hum gets stronger when i turn master volume or clean channel volume up...what should i start checking?

issue b):i also notice a whistle noise on Crunch and lead channel only, which gets louder only by turning volumes up ( not gain) also crunch and lead channel has Hum...\
the whistle goes away when i use my pedals or clean channel ( hum on clean channel remains)...at a gig last week i didn't had any whistle problem only hum ( which isn't annoying and its hard to hear it when master volume is under 6-7 or if its not quiet and not traceable or bothering while playing but it should be quite i think). the whistle is really annoying since i start to like a lot the crunch channel of this amp and its really important to fix it..i will appreciate any help you can give me

yesterday also the Standby led in the front panel went dead...which i guess it should be easy to be replaced by me...
i have some basic electronic knowledge so i think i will proceed to the repair my self if someone can guide me
again i will appreciate any help given and i thank you in advance

[Enzo]

Do this first: Turn the volume control on the guitar to zero. How much of those noises remain? Now unplug the guitar completely, nothing in the input jack at all. How much of those noises remain?

[harrisxr650]

first of all thanks for replying.
second ..i made a mistake since my English are not so good... :S its nut a hum its a little hssssss i turn the guitar volume to zero and still the hssss remains...note that i did that with both clean channel volume and master volume cranked up to 10 and the hsssss was too little...i did that without my guitar plugged in the amp and still the same. note that crunch and lead channel got a noticeable and really annoying hssss (with and without the guitar plugged in) i dunno if this is a problem or not to be honest...now the whistle problem persist only when i plug my guitar through my pedal board ( with no pedals on ofcurse , just the amps effects). i get no whistle when i plug my guitar direct to input ( low or high gain) but hsss remains no matter what.
once again thanks for replying

[Enzo]

Ah, well, his is a side effect of gain. The amp was not really intended to be operated with ALL the controls at maximum. Set like that, it would be dificult to keep teh amp stable and also to get a reasonable tone.