No sound out of MX110 tuner

[joss2178]

Found a few web pictures for similar model, that have the C28 cap installed, so I am gonna continue investigating.

I am wondering, at TP2, I am always getting 0v, whenever I am at a strong radio frequency or not.

For TP1, I get only negative voltage, around -10v for strong radio frequency and around -0.6v for nothing.

Those voltage seems ok ?

 

[joss2178]

Finally got some sound! I found in part my problem.

In the latest version of mx110z, they replaced resistor R42 2.2k with a Zener diode (it is written 758 on it). This diode seems dead. If i test with a resistor, i get music! So now I am wondering if I should put back a working Zener diode?

Also, maybe it is the cause of my diode being blown out but on the 6cs6, instead of getting around 29v on pins 1,2 and 7, I get around 130v. I am not sure why it is that high and where to look for. Pin 6 of v8, is around 90v. Pin 5 of v6 is around 130v. My psu have been recapped and test around 10% higher.

 

[joss2178]

In fact, my voltage tests on the 6cs6 were before replacing the dead Zener diode with a resistor (only put 1.1k for now). With the resistor I am getting around 17v. Yeah, so my problem should be solve.

 

[joss2178]

So - if I put back a Zener diode 758, will it die because of the 10% increased voltage of the psu (recapped, new Silvio on rectifier) ?

On the latest mx110z schematic, voltage at 6cs6 should be 10v, not 29v for the first mx110z version.

So should I consider putting dropping resistor on psu to go to original voltage?

 

[joss2178]

Ok - read more about Zener diode. It is used as a voltage regulator in the MX110z context, so putting a 10v zener (the 758 that was in) will max out voltage to 10v, exactly the specs of latest schematic. So just ordered some of them, will let you know when I get them.

 

[Treyphan]

Is your MX110 working on other high level inputs ? or quiet on every ?

Sorry to awake an old thread...however I’m having an similar issue with my MX-110z. I run it with a couple for Mc240’s.

Up until today, all was well. No all of a sudden, after carefully cleaning the top gain lots for Ph 1, PH2 and Aux, the pre-amp is extremely quiet, with a barely any gain. I could Max the volume and not be at 70db I bet. Though I’m not.
However, through the Tape monitor sounds PERFECT?
Volume and gain where they should be?

I read that the tape monitor does not go through the 6D10 tube. Could this be the issue? It doesn’t seem to be working. No glowing, or warmth at all. Even after listening for an hour.
Of course I can’t find the spare I have.

I sure hope cleaning the gain pits didn’t do something. I’ve cleaned a bazillion pots before, and never had an issue. They weren’t even that bad, just a bit scratchy in a few spots. So I wanted it the best. Used a very small drop per pot. Followed by deoxit Fadelube.

Plugged it in, and this is what I got. The gain pots work to attenuate the volume, and the music sounds fine. Just very very quiet. Where the sources through the tape monitor are rockin! And sound great.

Is this a faulty 6D10? I’ve got those and some NOS 6U8s on their way already. So hopefully I can swap it soon.


I just don’t get it. However, it seemed like @clinic-audio was getting ready to explain what may cause my issue, however the OP didn’t have the same problem.

Any hel is Greatly appreciated! Thanks in advance

 

[dshoaf]

You've nailed it, Treyphan. IF there are not 3 distinct glowing filaments in the 6D10 tube, at least one of the 3 triodes in the glass bottle are not working.

With the power off, pull it out and clean the pins a bit. Use the thin edge of a flap from a cardboard box - you don't really need to do much more than burnish the metal pins. Then, plug it back in with a gentle wiggle as the pin are pressed back in then turn it on again to see if there's any change.

I've had one 6D10 tube go bad on my MX-110 and it was, indeed, a filament that went open (means it didn't light up).

Also, you might want to start a new thread so others can see this new conversation. Click on Report at the bottom of this panel and ask the moderator how best to do that. They're good guys!

Cheers,

David

 

[Treyphan]

You've nailed it, Treyphan. IF there are not 3 distinct glowing filaments in the 6D10 tube, at least one of the 3 triodes in the glass bottle are not working.

With the power off, pull it out and clean the pins a bit. Use the thin edge of a flap from a cardboard box - you don't really need to do much more than burnish the metal pins. Then, plug it back in with a gentle wiggle as the pin are pressed back in then turn it on again to see if there's any change.

I've had one 6D10 tube go bad on my MX-110 and it was, indeed, a filament that went open (means it didn't light up).

Also, you might want to start a new thread so others can see this new conversation. Click on Report at the bottom of this panel and ask the moderator how best to do that. They're good guys!

Cheers,

David

@dshoaf David,

Thanks you Sir! Got home after work, yanked that 6D10 out and went to town with some deoxit gold and cardboard, result....my Mc is back!
Can’t wait to pop the NOS GE compactron I ordered in when it shows up Monday. I also ordered a sleeve of both NOS GE and RCA 6U8’s. Odd thing is I ordered these “just Incase”. Then 8 hours later these issues arose. Odd.
I think these 6U8’s need replacing anyway, I know they’d ethe most failure prone tubes in the MX-110z. They’re some Realistic replacements, and the Compactron is a Raytheon. All the AX7’s are Tele’s that tested above NOS on my TV-7 a few weeks ago. Well before it stopped working last weekend. Not a good week...but looks like I got out of this with just tubes. So I feel lucky.


Thanks again for your help! It is much appreciated. Just got a second matched quad of RCA Blackplate 6l6’s for my second 240. I was really digging my setup with them in Mono with matched tubes, then that happened. Talk about Bummer. So the re-assurance was verywelcomed, as I eagerly anticipated getting home from work.

Any Recs on your personal favorite 6U8? Also....I thought I read GE was the only 6D10 manufacturer. So is the Raytheon that’s in there just a rebrand?


Again, I really appreciate your help and the advice to contact a mod, had your solution now covered my issue.

Long live McIntosh sound and quality!

 

[clinic-audio]

Well done !

 

[pjrengineer]

Ok - read more about Zener diode. It is used as a voltage regulator in the MX110z context, so putting a 10v zener (the 758 that was in) will max out voltage to 10v, exactly the specs of latest schematic. So just ordered some of them, will let you know when I get them.

A few years later did this solve your tuner problem? My tuner likes to go out after I clean all the tube sockets. Shouldn’t have messed with the tuner tubes. Last time I cleaned the tube sockets the tuner went out for a few days then started working again. Last night I cleaned them because the phono had static and shouldn’t have messed with the tuner tubes because fm went out again. Arghhh.