# Odd reverb/FX loop issue TM36 head



## Verne (Dec 29, 2018)

My TM36 will not send sound to the speaker unless I have a patch cable (or anything) plugged into the FX loop. I have an on/off switch on my FX loop, but whether I have a patch cable or one of my old "volume" knobs plugged in or not, I can switch the FX loop off. Oddly, if I unplug the reverb switch from the amp, it acts normal. It isn't the foot switch as I tried a couple different switches and same result. The only way to get sound without something jumping the FX loop is unplug my reverb footswitch. Any idea why this is happening?

To get around it, I can jumper it or run a volume knob through the FX loop, but it'd be nice to figure out why this is happening. I have no clue if there is a master reset for the amp since it has no patches other than 3 channels. It does have a learn button I assume is for a H&K midi pedal, but I have none of that. I'm baffled.


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## Latole (Aug 11, 2020)

TM 36 ?

H&K Tube Meister 36 ?

The few time I have to fix a FX loop on amps ( not on TM36 ) ; these amps need a patch cable on FX loop to work
It was a contacts issue on FX Loop jacks.

Contacts are normaly close to send sound from iFX loop In and Out when nothing is plugged.
If contacts are bad, dirty or rusty, contacts don't work.
A patch cable by pass these contact and make amp working.
New jacks fix the issues if you an't clean contacts.

The TM36 is a programmable amp.
The problem may have nothing in common with my examples of ordinary amps I am talking about.


Owwer manual ; English page 8



http://hughes-and-kettner.com/wp-content/uploads/2014/03/TubeMeister_36_Manual_1_2.pdf



TM 36 forum;








TubeMeister 5/18/36


The unofficial guitar amp and cabinets forum for users to discuss Hughes and Kettner products.




handkusers.forumotion.com


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## Verne (Dec 29, 2018)

Forgot all about that forum. I am a member.

I have ran it before without anything in the FX loop. I sprayed contact cleaner in a couple times and took a 1/4" plug and used it in the jack as usual a few times to ensure it was getting the cleaner in the right spots. Still nothing. Just weird that I can't run the amp without a jumper loop if the reverb switcher is inserted. If I take that out, I can run the amp without the switcher and use the button on the back for reverb. Just seems odd that it's only when the reverb jack is being used. It's just started this as well.


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## Latole (Aug 11, 2020)

Verne said:


> Forgot all about that forum. I am a member.
> 
> I have ran it before without anything in the FX loop. I sprayed contact cleaner in a couple times and took a 1/4" plug and used it in the jack as usual a few times to ensure it was getting the cleaner in the right spots. Still nothing. Just weird that I can't run the amp without a jumper loop if the reverb switcher is inserted. If I take that out, I can run the amp without the switcher and use the button on the back for reverb. Just seems odd that it's only when the reverb jack is being used. It's just started this as well.


.
You can't clean the contacts by spraying contact cleaner alone. It can't work.
If the problem is with the contacts you have to replace the jacks unless they are cliff style jacks like in the Marshall. 
If you know how to do it and have the right tool (contact burnisher) you can clean them.
But only by spraying contact cleaner, it's totally useless.

And most of the time people don't use a good contact cleaner
.


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## jb welder (Sep 14, 2010)

You need the correct footswitch. You can try a dozen of the wrong type and it still won't work right. 
Requires a 2-button switch with stereo plug for each switch jack.
The footswitch must have a stereo (TRS) plug on it. Fender type with 2 buttons and mono plug will not work. One switch turns reverb on and off, one switch turns FX loop on and off.
see pg.11 of the owners manual Latole posted above.

One thing you could try if you are using a single button switch with mono plug, only plug it in halfway, to the first click. If the reverb part of the switch is on the ring, it should work right. If it's on the tip, you're going to have to use the proper 2-button switch.


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## Verne (Dec 29, 2018)

I'm using and old Randall that is hard wired at the switch. I have stereo jacks that I can use, but why won't the amp produce sound with nothing plugged into the reverb jack? The FX loop on/off is lit, but pushing it changes nothing. Should I not be able to play straight out of the amp with the jack empty? This is what has me confused.


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## Paul Running (Apr 12, 2020)

Speculating without a schematic here. Being a programmable amp, it may require a reset to factory default. Check the owner's manual here:


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## Verne (Dec 29, 2018)

@Paul Running I did try that. I don’t have the midi pedal, so I don’t think it makes a difference to the head itself.


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## jb welder (Sep 14, 2010)

In your first post you said it works properly with no footswitch.
Now you said, 'nothing plugged into reverb jack', which makes it sound like it's not working right with no footswitch.
What are you calling the 'reverb jack'?
Does the amp work properly when no footswitch is in use?


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## Verne (Dec 29, 2018)

I was incorrect in one post. The old Randall foot switch is being used to change channels, not reverb. Reverb is a single button hosa. I believe I put a new switch in it since the other didn’t work. On the back of the amp there is a jack for reverb and a jack for channels. No sound if I pull the reverb switch out of the amp. I will try pulling all switches out of the amp and nothing in the effects loop when I get home after work.


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## Verne (Dec 29, 2018)

After much cable and foot switch moving around, I have the TM36 now working properly. I can now turn the FX loop on/off as well as reverb. I believe it was the cable itself. I tried my DRRI switch and it worked right off, so I knew it was localized to what I had hooked up. I went with using the switch from my Delta Blues for the TM36. I now have the issue with the Delta Blues that I can't switch between normal and drive, but that's okay. I can't find a setting on the drive that is either not too loud, or pleasing to the ear. Weird set up with the pre and post gain knobs. Anyway, thanks for all the help guys. Something simple gladly.


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## jb welder (Sep 14, 2010)

Verne said:


> Reverb is a single button hosa.





Verne said:


> I now have the issue with the Delta Blues that I can't switch between normal and drive


You said it was the single button Hosa footswitch that was giving you trouble. If it is single type, it will not work properly with any of the 3 amps you mentioned (TM36, DRRI, Delta Blues).


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