Marshall vs265 65w valvestate amp reverb not working

To many possibilities. The reverb unit or the reverb preamp or the reverb output amp.

First check the preamp valve in that curcuit

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.

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.

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

I believe that your model uses a 12AX7 tube for the pre-amp section. The tube is bad and needs to be replaced. Start there.

Dan

There could be a short in the rectifier diodes or in the transformer itself. Can you take some measurements inside the unit?

Let me know.
Dan

Hi chagzuki, you are right, but only when the valves are used as outputs, You amp has transistorised outputs, and a single tube used for distortion/gain. You will get a very long life out of this tube also because its supply voltage that is is used in the valvestate preamps is really quite low. Just enough for it to work really, so the tubes life can be expected to be much longer than normal. It is also a preamp tube, not an output tube, so they rarely need changing. If you ever did want to change it(dont bother), it is located on the PCB inside the unit. You have to slide the sleeve off to get at it. Get yourself a JCM800=the best guitar amp ever built(imho), then yo got pure Marshall tone, and output tubes that need changing every 6 months or so. Now go RIFF OUT and dont worry about your valvestates' "valve"

regards
Graeme