Music Man 210 HD, Tremelo issues

[Ginridge]

Hi Folks,

My first posting here! I have a Music Man 210 HD guitar amplifier that was my main road amp for years in the early 80s, but has been in storage for the past 15 years or so (gone acoustic!). As I recall it had this issue at the end of the time I played it out on the road. The tremolo function doesn't seem to work. It is extremely weak in the low levels, and created a rhythmic whomping sound at higher levels and faster speeds. I have read about the multi-functional nature of the tremolo on these units, (above 5 on the intensity creates a sound that is meant to emulate a Leslie speaker) but this is clearly not a functional sound.

I've located the schematic and owners manual and will be sharing them with a local tech who is looking into this, but I hoped that perhaps someone here on the forum might have some thoughts or information about what's going on. Thanks!

[J M Fahey]

Share it with us too, so we all talk the same

[Ginridge]

I assume you mean the manual... Here it is: https://drive.google.com/file/d/1nZT...ew?usp=sharing

[TomCarlos]

Here is another link to the schematics (and one per page and might be easier to see) - https://el34world.com/charts/Schemat...0_2275_130.pdf

And the rest of the amp? Pots all clean, no crackling, ample volume? Just the tremolo is the issue?

Do you have anything connected at the rear end Tremolo jack?

[Helmholtz]

Some useful info contained here: https://music-electronics-forum.com/...issues?t=12356

[Ginridge]

I dropped the amp off at the local tech yesterday, but I did drop by with a guitar and test it today. It sounded very good. He cleaned pots, but there were no other issues other than basic maintenance he found besides the tremolo issue. It currently has it's original tremolo/reverb foot pedal connected which has a noisy connection but even when I get the connection making good contact, the basic issue remains. You can run this unit without the pedal connected as well and I tried that and the result is still the same.

Helmholtz, I looked at that link and while it's beyond my pay grade, I bet this would be excellent for my tech to see. Thanks!

[g1]

Unless you've identified it as such, chances are your amp does not have the tube phase inverter like the version of schematic in the manual you posted.
The more common schematics with the solid state phase inverter can be found in the links in posts #4 and 5 above.

[Ginridge]

More identifying info:
Serial Number: B003987.

Here's a shot of the amp ID tag:

[g1]

How many tubes are in it, 4 or 5 ? (for amps with 5, one is smaller than the other 4)

[Ginridge]

Hi G-1,

This amp has 4 tubes.

[g1]

Hi G-1,

This amp has 4 tubes.

Ok, so the schematic in the manual you posted is not correct for your version. The schematic on pg.2 of the pdf in post #4 above would be correct for your amp.