Musical Fidelity 750K Manual Do Utilizador

 

 

 

 

 Issue 

3 

 

 

Basic problem-solving with an amplifier is similar to troubleshooting other electrical or electronic equipment.  Always check the 
most obvious possible causes first, such as the following examples: 

No power when POWER switched 
turned on 

Mains power plug is not fully inserted 
into rear socket 
No mains power 

Plug in securely 
 
Check socket with another appliance 

No sound 

Wrong input selected 
 
Wrong connections between input 
sources and the unit 
 
Speakers not connected, or incorrectly 
wired 
 
Mute on driving amplifier enabled 

Move input XLR/RCA and 
LINE/SPEAKER input switches to the 
correct position 
Check correct input has been wired in 
(loudspeaker or line input) 
Check speaker cables at both ends. 
 
 
Check and disable mute function. 

Sound is not precise, lacking in bass and 
stereo image (when used in conjunction 
with other unit(s)) 

Speakers are connected out of phase, i.e., 
connections to one speaker (+ and -) are 
reversed on  one or more units 
 
 
 
Speaker level inputs incorrectly wired 

Ensure speakers are connected correctly 
on all units: 
+ terminal on amplifier goes to + terminal 
on speaker, 
- terminal on amplifier goes to – terminal 
on speaker. 
If using speaker level inputs, check the 
connections are correct at both ends as 
above. 
Note: Most cables have polarity markings 
to help get this right.  

Unit cuts out, orange LED lit 

Overheating 
 
Short circuit in speaker (output) leads 
 
 
Problem in speakers 
Grounded via speaker 

Make sure unit is situated to allow free 
air circulation.  
Check speaker leads connected to 
SPEAKER OUTs on 750K and speaker 
ends for stray strands or short circuits. 
Check speakers 
Both the + and – speaker output terminals 
on this unit are “live”, i.e. carry 
substantial signal. Some speakers e.g. 
active subs and electrostatics have 
“grounded” inputs. Such speakers are 
incompatible with the 750K. 

Unit cuts out, red LED lit 

Clipping 
 
 
 
 
Grounded via speaker  

Reduce volume level on driving amplifier 
Switch off unit using rear panel mains 
switch 
Wait 30 seconds before switching back 
on, and apply music source. 
Both the + and – speaker output terminals 
on this unit are “live”. Some speakers e.g. 
active subs and electrostatics have 
“grounded” inputs. Such speakers are 
incompatible with the 750K.   

Hum 

Audio connector plug not fully pushed in 
Cable Fault 
Unsuitable Cable 
(e.g. cable grounds not connected) 

Insert plug securely 
Check cable is connected at both ends. 
N.B. some esoteric cables have internal 
wiring intentionally 
disconnected/modified. For best results 
on all inputs, please use good quality 
fully screened coax; signal connected 
both ends and earth/screen connected 
both ends. 

If none of these actions affect a cure, please contact your dealer, or an authorised Musical Fidelity service agent.  Remember; never 
open the case of the 750K yourself, as this will invalidate the guarantee. 

 

Page 9 of