MX110z tuner issue

2

2020

Active Member
As the title reads, I have a MX110z and have developed a tuner problem. Hoping for advice.

The tuner on my MX110z has stopped producing any sound at all. I know most of the tubes are at least 15 years old, maybe older.

Could a bad tube cause the tuner to have no sound whatsoever?

FWIW, I'm sure I will take it to a technician to have it checked out, but they are backed up several months. It was serviced a couple of years ago for a different problem and the tuner was doing OK.

Thanks on advance for any light you can shed on this issue.
 
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Check if the tuner appears to be dead when set to FM (not MPX). If it is still dead in that position, then at least the MPX section has been ruled out. If sound appears however, then the MPX section is suspect. If it's still dead and all the tuner tubes are lit up, then make sure that the Muting switch is turned off, and/or that the muting adjustment is correctly set. If the Muting switch is turned on, and there is not some sort of antenna connected, then the FM section would appear to be dead.

Dave
 
Also make sure the Tape Monitor switch is in the out position
 
dcgillespie said:
Check if the tuner appears to be dead when set to FM (not MPX). If it is still dead in that position, then at least the MPX section has been ruled out. If sound appears however, then the MPX section is suspect. If it's still dead and all the tuner tubes are lit up, then make sure that the Muting switch is turned off, and/or that the muting adjustment is correctly set. If the Muting switch is turned on, and there is not some sort of antenna connected, then the FM section would appear to be dead.

Dave
Click to expand...
Thanks, Dave. FM is dead at either setting. System mute is not turned on and sound from other sources comes through fine. There is an antenna attached. Is there an FM muting switch that I am unaware of?
Good ideas!
 
There is a muting adjustment pot on the top side of the unit, but if you haven't messed with that it's doubtful it'd all of a sudden be your problem, plus you'd surely get strong stations to come through no matter where that is set.

Is it just the tuner that's dead? Does the unit pass signal from the aux input to the outputs? Does the fixed output produce any output even if the main output doesn't? Some of these answers might help isolate what's going on.

Bob
 
Bob the Tech said:
There is a muting adjustment pot on the top side of the unit, but if you haven't messed with that it's doubtful it'd all of a sudden be your problem, plus you'd surely get strong stations to come through no matter where that is set.

Is it just the tuner that's dead? Does the unit pass signal from the aux input to the outputs? Does the fixed output produce any output even if the main output doesn't? Some of these answers might help isolate what's going on.

Bob
Click to expand...
Thanks, Bob, for your response. I have not messed with the muting adjustment pot. Aux, tape. and phono output are fine. I have not been able to get to it to check tubes yet as discussed.

Looks like it has more tubes than I realized. I've worked on some old Dyna tube amps but am a long way from being a tech.
 
Most common cause for dead FM in the MX110 - V3, 6AB4, OSC
Click to expand...
@dewickt Terry, I recently posted a thread about the background noise pulsating at about 2Hz when tuned off of a station with an MX110. The tuning eye pulsates along with it and sometimes the stereo lamp seems to light dimly in time with it as well. Have you ever seen that before? Any ideas?

Edited to add the link ... What might be the cause of this MX110Z pulsing static?
 
Following up on this thread:

I finally took the unit out of its cabinet and cleaned the tube sockets. It seemed like a good idea and was probably worth doing, but did not have any affect on the problem. During that process I noticed the 6D10 tube was cloudy, so I ordered a replacement and also ordered a 6AB4 OSC. I tried 3 different 6D10 tubes to no avail. Soon I will get the 6AB4 and give that a try.

THANKS again to all!
 
For anyone still following, here's the latest on my mx110z issue:

I received two 6AB4 tubes and installed one. At first, the signal came in loud and clear and it sounded great. After about 2 minutes, the signal faded. Same results with the other 6AB4, but it happened faster.

I tried two different antennas with no improvement. The mute switch did not revolve the issue either.

Other source inputs (aux and phono) are fine.

Looks like the next step is to take it to a technician.

Sincere appreciation to you all for your advice.

Cheers!
 
Hello

I think that you are in front of an MX110 starting to have a dead selenium diode bridge ....
Is your power transformer very hot after some minutes of use ?
The problem with the MX110 is that the secondary winding (HV ) connected to the selenium bridge without any fuse and when the diode bridge become like a real short , the sound disapear because the HV is decreasing .

Is this unit working normally on other input than FM ?
 
Thanks for the reply, clinic-audio.

I have not noticed the power transformer being very hot, but your comment that the sound would disappear because the HV is decreasing makes perfect sense.

The unit works normally on aux, tape, and phono inputs.

Am I correct in assuming a selenium diode bridge failure would cause sound from all inputs to fade and then disappear?
 
Am I correct in assuming a selenium diode bridge failure would cause sound from all inputs to fade and then disappear ?

yes !
 
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