Marshall 15 Watt Guitar Amp - Answered Questions & Fixed issues
Vs232 has power and makes noise when you plug in
Check that you have 15 volts across C19 and C20.
If either are bad, suspect ZD1 and ZD2 regulating Zener diodes.
Check the soldering and condition of the input jack as these are chronically bad due to damage of yanked cords.
Okay i need to know how to get inside my amp to
One can overtighten the input jack and "un-rivet" the jack. They are not made very well !!! OFTEN when they appear loose, they HAVE un-riveted the threaded sleeve from the metal inside the jack... that USUALLY requires REPLACEMENT of the jack itself.
The cabinet backs on a lot of these have to be PRIED out as the Tolex covering often makes them tight.
The amp portion is often retained by screws from the top and or sides AND even the two holding the handle on... there are many different configurations. Sometimes the amp comes out the front, sometimes the back. It is easy to shear off the speaker wires when removing some of them.
I need the schematics for a Marshall MG-10KK
Most of the problems with the small guitar amps are blown power amp chips. They usually use chips like the TDA2030 which look like a power transistor.
Most other problems involve broken connectors, bad solder joints or cracked circuit boards. The power supply area is so simple one doesn't need a schematic for that part which is usually just three terminal regulators for +/-15 volts. Schematics are often hard to find.
Try this site, although this is a different model, much of the schematic will likely be the same.
http://elektrotanya.com/marshall_valvestate10_10w_8001_8010.pdf/download.html
Why dose my guitar amp make a high pitch sound
If you have an instrument plugged into the amp, then you need to turn down the volume of the amp before turning on the amp. Otherwise you risk permanent damage to your speaker. Also, the instrument cord may be defective. The hot and ground wires may be shorted together. You need an ohm meter to test your cord. With the cord unplugged and detached, put the positive (red) lead of the ohm meter on the tip of the plug and the negative (black) lead on the sleeve of the plug. You should not have any reading at all. If you get a reading then you have a bad cord with a short.
I have bought a second hand guitar amplifier, and
First and foremost make absolutely sure you know what you are doing. If the amp is in good working order you should be O.K. The biggest safety check you can do is make sure that no one has removed the ground prong from the power cord. If it doesn't have one then you should take the amp to your nearest qualified amp repairman who can do a certified repair on your amp. For instance if it is a Marshall product, take it to a Marshall dealer. This type of repairman not only has the training, tools and schematics to work on your amp he will also be able to tell if someone has done a safe mod to your amp. Not only that he can be held contractually responsible if you are injured through the correct use of the amp after he has done the repair. Read your service agreement carefully before allowing the work. Amplifiers can kill you.
Hi I have a marshall haze15w amp and stack, the problem seems to
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.
What kind of el34 for my jtm610 marshall to obtain
It is UNLIKELY you will notice any difference trying different brands of tubes.
The sound will be most affected by the audio output transformer and especially speakers. The transformers in many of these have too little iron in them resulting in saturation. You can spend a lot of money on new tubes and any apparent change you notice will probably be psychological rather than actual.
The design of vacuum tube amps will often result in a softer high ends... If you want more than that, go to the solid state amps. Sustain is affected by the overall gain which is mostly in the preamp and reverb functions AND a large part on the quality of strings on your guitar...
Mp3
The problem is that a CD has a stereo signal and the Marshall is mono.
You could make a simple mixer cable with resistors as a completed cable is not something you will find easily.
Take three 1K resistors joined at one end and connect the open ends of those one each to the three terminals of a stereo plug that fits you CD player.
Connect a mono plug and cable with "hot" to the joined connection of those resistors. Connect the ground shield of that cable to the barrel connection of the stereo plug that one of the resistros is also connected.
NOTE: if you use the "line" output of the CD player, then use 10K ohm resistors instead of 1K.
While playing, the volume cuts up and down in all the channels.
Fiirst check if your input connector is bad. Move the cable right at the connector and see if the volume jumps... HOWEVER before doing that even, verify your guitar is not the problemm using another amp.
If it is definetly the Marshal, it will likely need servicing.
It could be a bad volume control or a cracked circuit board.
Hi my Marshal G15 is making an echoy twang
I suspect the vibration when it is loud is vibrating a reverb tank within the unit.
Test this bylistening with headphones and see if you get same sound.
It may be the reverb has a resonance or the cabinet does that is sensitive to your E chords.
The shock mounting of the reverb may have failed to isolate the reverb tank from speaker vibrations... hence the headphone test.
Hi have been given a Marshall MBB15 amp to find
Dead resistors? The evidence would be if the resistors are cracked OR if their is evidence of smoke/fire around them.
In either case, there would LIKELY be damage at least one or two layers deep beyond those resistors if in fact they are fried. If they are cracked physically, teh circuit board also may be cracked due to physical bending. Tripping over an inpout cable can do this.
Causes of this would be shorting the input to power line voltage or the output of a high powered amplifier.
I question that the resistors are "dead".
THE USUAL cause of failures of these small amplifiers is frying of the output power chip which is often in the TDA family of 5/7 terminal amplifier chips in modified TO220 packages.
Another less common problem is failure of the rectifier and filter capacitor combination.
No sound through marshall amp
The best thing would be to take it to an audio repair tech. Could be anything....Not something you can fix without taking apart and using a multimeter.
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