Marshall GU15 r cd park series reverb has no sound

https://www.dropbox.com/s/6spu98r39t2wvcr/Marshall%20G30RCD%20Schematic.pdf

Nothing wrong with the amp. Google it- these amps have extremely weak reverb. All of them are the same. It's the one weak point about these amps. And I love mine. I mic it when we gig. Sounds awesome both clean and driven. But you'll have to get a separate reverb pedal if you want "girl crush" or "pipeline" reverb. Don't listen to the above posters. It's the way these amps are.

This sounds like a DC feedback problem in the power amp. Check all the resistors R86 through R96. Verify that capacitor C80 is healthy. The right tool to solve this is an oscilloscope.

Try this website:http://tubesandmore.com/ Look under reverb tanks. Check to see how many springs your old tank has and what size it is. I think Marshall used Accutronic tanks but have a look at all of them. There are pictures and info for each. Hope this helps.

The volume control knob PROBABLY is broken, dirty or has bad soldering to the circuitry.

Use some CRC226 in the control if dirty. While you have the unit apart, check the soldering and for any circuit board cracks.

sounds like the effects module has stopped working . you could try re-working the joints around the i.cs on that board if you have a rework station. i have only managed to repair one baord this way suggest replacement is the best course of action. uk cost of panel approx £50.00 + fitting

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.

Blown speaker NO (would not get sound at all)

Bad Reverb UNLIKELY (controls would deselect reverb and it would be out of circuit)

Bad preamp tube NO (controls have no effect)

Bad rectifier and/or filter caps LIKELY

Bad power amp POSSIBLE

probably the reverb tank These coils are very thin and tent to break easily

Change the audio amplifier ic are fried