Re: MP-1 Hum, Hiss, Troubleshooting

 new new list compose Reply to this message Top page
Attachments:
+ (text/plain)

Delete this message
Author: Kaz Kylheku
Date:  
To: Benjamin Catchings
CC: ada-mp1
Subject: Re: MP-1 Hum, Hiss, Troubleshooting

On Tue, 27 Nov 2012 13:00:05 -0800, I wrote:
> Another test: does it make a difference if something is
> plugged into the front jack or not?


By the way, these tests assume that the MP-1 is stock
in this area, and that the jack is switching properly.
It occurs to me that a current rush could weld the
switch. Just a thought.

I just noticed in the schematic there is a coupling cap
before the input JFET (Q7). That cap would protect the
JFET from DC, unless it breaks down.

If that coupler is damaged, that could be responsible for
loss of bass below 500Hz.

(Does the loss of bass reproduce through the rear jack?)