My amp becomes distorted when I turn my keyboard up. Both the Master Volume and the CH1 volume knobs are in the middle(12 o'clock). How do I keep my amp from distorting?

I'm not sure which amp you're playing thru. but generally the settings you want for a clean sound. check your drive (or Gain ) knob. You want it about half way.and your Channel volume, half way. those are good starts. then let your master volume do the rest. Also, make sure, if you have active pick-ups on your guitar. check the batteries. if they're low, it can cause distortion. if this doesn't resolve, then its internal. could be anything at that point.

It is difficult to answer your question without knowing the model no. of your instrument.
Most keyboards have a slider closer to the left side, a round knob for controlling the volume or a juggle switch in the middle which might be used for controlling many options including volume.
Switch on the keyboard and look for the word 'volume' near the controls. If you can't find it, experiment with the controls. Try one controller at a time and it won't damage your instrument.

If this ties to a keyboard, make sure the keyboard and this are BOTH plugged into the same receptacle. You should send a higher level from the keyboard (turn volume up to around 70% or so) and use less volume at the input gain of this amp. Use more at master volume if the amp has one if needed. If the hiss is there with NO input cables plugged in and input gains at 50%, that is objectionable, the amp probably needs servicing. Unused channel gains should be clear down.

Yellow should be the positive. Try plugging in and reversing. The louder of the two is the one in phase and the correct wiring. If the speaker is pushing out when playing , it is in phase and correct also.
The distortion problem could be a speaker going out. It may not be totally blown, but may be verging.
Holding your hand out as wide as you can push against the speaker lightly. If there is a rubbing or scratching sound, the speaker could be damaged.If it moves freely, and there is no scratching its okay.
Another possibility is the clean channel may have a channel volume set to high. Make sure the clean channel volume is set lower than the master volume otherwise you can get distortion on that channel too.
Good Luck.

There are many models of Marshal amps icluding 15Watt types.

First thing to try is to see if headphones have normal volume. If they do, then the headphone jack switch that connects the speaker is LIKELY bad.

If the headphones do not have any volume, LIKELY causes are:

1. Fried output power amp

2. Volume pot is broken or has bad solder joints to the circuit board.

Your amp has two channels - "normal" and "drive." When you are on the normal channel, the "volume" knob controls your gain. In the "drive" channel, the drive knob controls your gain. In both channels, the "master" knob limits how loud the amp will get.

Most likely, you are on the drive channel, so the volume knob will have no effect. Try pushing the "channel select" switch. You should notice the channel indicator lamp (next to the drive knob) turn off. When it is off, you are in the normal mode. Yellow = drive, and red = "more drive."

Experiment with different settings to get a variety of tones.

To get the most out of this amp, try reading the manual, available online here:
http://www.fender.com/support/manuals/pdfs/manuals_elec/guitarpdf/Hot_Rod_Deluxe.pdf

Have fun - it's a great amp.

Sounds like your master volume is turned up too much. The channel volume will make the squealing go away(caused by high gain and humbuckers). The best thing to do is dial in your favorite presets and change the channel volume to the correct level with the master volume where you usually keep it. I use my Spider Valve at master volume at about noon and the channel volume between nine o'clock and noon. Let me know if this does not solve the problem......

dirty dirty dirty

give the knob a ********
can of compressed air should do the ttrick remember to remove knob if posable

First make sure you have the TRIM knob positioned correctly. When playing loud the Red Led should just blink a bit so you know you're not overloading the preamp and Digital sections. The Twin Reverb Patch is a clean place to start so select that first. On this amp it's a good idea to set the MASTER to 5 and use the VOLUME control at as low a setting as you can. The GAIN control should be set under 4. You better sound crystal clear on this setting. Try turning up the volume to see how loud you can get without breaking up. It's a guitar amp so there will be some grainy distortion but it should be very light. I bet you get through this test without much trouble. After that you need to be very careful about what settings you're using since many of the presets may not mesh with your guitar pickups. You should concentrate on tweaking one highgain setting and learn about how the controls interact. The amp is so much more complicated than a 10 knob standard guitar amp. Most people need to put in some time to get a handle on it.

As far as the tubes go, typically they can get microphonic which was a problem with versions 1.1 and 1.0 of this amp so check that. Fender had a Cyber twin upgrade kit way back to fix this but if you have version 1.2 or 1.3 that's not it. Problems with this amp are typically caused by control setting more often than an electronic problem but this reponse should get you started figuring it out.
MYREL

There are 2 channels, Which means there are 2 sets of knobs ... One for clean and one for crunch. Start out with a low master volume and set up the crunch, Then the clen and switch between the 2 and make adjustments until they match volume wise ... Then turn the master up.