Question about Technics SA-DX940

3 Answers

Erratic volume on Technics SU-X911 amplifier (Class A)

Hello, was wondering if someone could advise on this problem ... Background: My midi Amp (SU-X911) is part of a Technics system (CD player, Tuner, Cassette Deck, Equalizer). The system was bought sometime in the late 80's (yes it's old). Problem: Amp volume (controlled by electronic dial) DANGEROUSLY ERRATIC - suddenly silent for 2-3 seconds, before jumping to almost max! Adjustment to volume control brings it back to normal volume. During the silent and max jump, the volume level display (eg. "-44dB") does not change. Consequences: My precious speakers risk being blown up! Remedy attempts so far: Following advice from an electrician colleague, I've pulled apart the amp, pulled out the volume control potentiometer and spray cleaned it (with electronic spray). I must say the amp was generally very very clean inside. Success? - No, problem returned after one day of amp operation. Other Notes: My colleague now suggests it could be the amp itself playing up (ie. not the volume pot). I listened to a whole CD (45mins) last night, and did not encounter the problem - interesting to see if the problem occurs using headphones as well as the speakers themselves. Any ideas anyone? Would greatly appreciate advice - perhaps there's one bit of the amp I need to look at / replace. Thanks!!!

Posted by on

  • babiuk Aug 30, 2008

    Hello, I´ve got the same problem in the same amp, it sounded ok till one day it begun to mute itself randomly and jump to high volume in the next minutes.
    A month ago the problem turned into playing normal for a few minutes and after that I just got silence.
    And nowdays it doesn´t sound anymore.
    I tried to use the headphones... but nothing.

    Please tell something about if you´ve got solved it.

    and excuse my bad english.




3 Answers

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

I have a technics su x911 linked to ars x911 and a sl pj26a and a st x 933l tuner and turntable, they are all linked to each other as is typical however, I can turn the amp on,the red light shows on and everything else will work but not the amp.there is no led display and no vulume control.

the set has not been used for many years but has been kept clean and dry.
do they have to be connected in a certain order, the remote control doesnt seem to make any difference.

Posted on Aug 19, 2009

  • Audio Service Clinic Jan 03, 2015

    Without seeing the schematic, both the volume control and illumination, may be tied togther in the power supply. This is too old a unit to use a Rotary Encodre(new style volume cotrol), so that's not the issue. Your amplifiers are not bad; it's what's controlong them that is at issue. For more information, or to inquire about haing your Technics repaired, please visit my website at You may contact me there.


  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert who has answered 20 questions.


    An expert that has over 10 points.


    An expert whose answer got voted for 2 times.

  • Expert
  • 71 Answers

Its the ic that controls the + and - voltage and there are capacitors that have leaked all the caps on that board need changing could be expensive and time consuming but its the age of it . if i was going to do that job £200 plus\

Posted on Dec 08, 2008

  • Audio Service Clinic Jan 03, 2015

    Not every issue in the world is a bad capacitor. These bad caps entered the marketplace in about 1999-2000. If they are not bad, you are wasting your time and money replacing them, just to turn it back on and have the same issue. Measure twice; replace once.


  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

My problem is the volume contorlb they use MN4030B and another MN which has blast on the circuit board.i will like to know number to replace it.This is my email you can get me on face book jerrygadogbe.

Posted on Sep 07, 2011

  • Audio Service Clinic Jan 03, 2015

    This IC, and it's complement, MN4070B/S are logic ICs, and mostly, have nothing to do with a volume control control issue.


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

Technics su-g75 amp goes to loud static after a few minutes

Hi Aawpharmd,

system control error.
please go for repair shop.

Jan 13, 2014 | Technics SU-G75 Amplifier

1 Answer

Good day i have a Technics amplifier SU-X320. Problem is it powers up up there is no sound. Checked all basic fault finding, suspect it is the volume IC.

"Volume IC" do you mean an IC that is a pre-amp and controls the volume and things like tone? Or do you mean the main power amp IC, which will be on the big heat sink?
If you amp uses the latter and not individual separate devices for the power amp, suspect that over the other IC. But if the amp has separate power amps for both channels, replace the IC.

Oct 09, 2013 | Technics Audio Players & Recorders

1 Answer

Hello I have a Technics SU-V45A amp, it's about 18

See there is a problem with the volume conroller as it is 18 years old the controller has worn out replace the volume controller with a new one and you will be able to enjoy great sound again

Dec 05, 2010 | Technics SUV500 2-Channel Amplifier

1 Answer

Su-v55a technics amp cuts off when volume up to 2. 1

poor solder connections to the volume pot It needs to be resoldered

Aug 19, 2010 | Technics SUV500 2-Channel Amplifier

2 Answers

Su-v55a technics amp cuts off when volume up to 2

usually meens it is protecting itself from destruction
check your wires and speakers for problems

Feb 09, 2010 | Technics SUV500 2-Channel Amplifier

1 Answer

Lost left stereo channel from amp. All speakers / wiring ok Technics SU-V6 amplifier. Wondering which component is most likely problem so I can cannibalise another amp.

If at full volume with the balance cutting out the right channel you can hear some music on the left (very weak), then the pre-amp is working and it's the power amp that's gone. Vice-versa if you can't anything, but say hum.
If it is the power amp check out the devices on the heat sink.
Check too for broken or burnt parts too!

Jan 21, 2010 | Audio Players & Recorders

1 Answer

Technics su z2 amp shuts off sound

hello. we cant help if we dont know what music source you are using.

Apr 13, 2009 | Technics SA-AX530 Receiver

2 Answers

About amplifier specification

sounds like you need a service or users manual...check their website,to find one

May 25, 2008 | Computers & Internet

Not finding what you are looking for?
Technics SA-DX940 Logo

2,536 people viewed this question

Ask a Question

Usually answered in minutes!

Top Technics Audio Players & Recorders Experts


Level 3 Expert

5326 Answers

Donald DCruz
Donald DCruz

Level 3 Expert

17130 Answers

Ben Armstrong

Level 2 Expert

357 Answers

Are you a Technics Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides