Shure M62V Level-Loc Repair Questions

[MrG]

Excellent - worked great, thank you!

New problem: this unit is now passing audio through the box but it is not compressing... Do any of you have suggestions on where to look in this compressor circuit to look for the culprit? I’m new to compressors so I don’t know what to look for.

Thanks much,
Mark

 

[scott2000]

no compression even without bypass?

 

[MrG]

no compression even without bypass?

Sadly, that is correct. And it’s not just the compressor not releasing - zero compression motion.

A few questions I’ve come up with:

-My wallwort is putting out 14.27v upon entry - could I be feeding it too much?
-Could this be a problem with a transistor or several?

Thanks,
Mark

 

[scott2000]

Not sure....... I'm guessing the circuit would be set up for the 9v.....

That sounds a bit high for a 9v wart???? Haven't tried a battery yet??

 

[MrG]

Not sure....... I'm guessing the circuit would be set up for the 9v.....

That sounds a bit high for a 9v wart???? Haven't tried a battery yet??

Yes it seemed a bit odd to me. It’s a Korg 9v DC with 600ma. I’m going to try a dunlop one with 9v 200ma next.

This is all reminding me:

Its designed to run on the battery at 9 volts. There is a 10K resistor in series with the input socket. You could remove this resistor and feed 9 volts in across the battery terminals. Polarity is important. The 9 volt supply needs to be very well filtered and provide a reasonably accurate 9 volts. Lots of plug packs wont be suitable. Let me know how many hours you spend on it, and whether it was worthwhile in the end.

I did not blow off this post, however, I didn’t know what you were getting at. Could this be the issue - does the compressior or do the transistors rely on a very certain 9v? Also, even though the box is working, and I replaced the battery leads with this 9v DC cable, do I still need to removed that 10k resistor? To be clear it is not in series with my connections, it’s parallel between my inputs and that 28v input jack.

Thanks!
Mark

 

[scott2000]

Yes it seemed a bit odd to me. It’s a Korg 9v DC with 600ma. I’m going to try a dunlop one with 9v 200ma next.

The warts will usually be a little high until the  supply is used ...but it seems high......and the fact that it's not using current is concerning...like you said, nothing is working so this could make sense......

Your unit may have issues??? or your wart is not working???

This is all reminding me:

I did not blow off this post, however, I didn’t know what you were getting at. Could this be the issue - does the compressior or do the transistors rely on a very certain 9v? Also, even though the box is working, and I replaced the battery leads with this 9v DC cable, do I still need to removed that 10k resistor? To be clear it is not in series with my connections, it’s parallel between my inputs and that 28v input jack.

the 28v input jack is for a different set up.... It takes 28v and drops the voltage down with that resistor..... you don't really  need to remove that resistor ..... As long as you're not feeding your wart to that section before the resistor, and are feeding to the battery instead, you should be fine.....

circuits are set up to run at their specified voltages obviously.....operating points,etc.....I'm not sure what levels of abuse or mistakes they can take before checking out. That would depend on the ratings of various things in the circuit.....


Maybe test some of the transistors....those caps too....????
you could actually shotgun replace all the electros and transistors in that thing pretty quick and probably be good if there was damage I'd imagine...

Also, even though the box is working

???

 

[MrG]

The warts will usually be a little high until the  supply is used ...but it seems high......and the fact that it's not using current is concerning...like you said, nothing is working so this could make sense......

Your unit may have issues??? or your wart is not working???



the 28v input jack is for a different set up.... It takes 28v and drops the voltage down with that resistor..... you don't really  need to remove that resistor ..... As long as you're not feeding your wart to that section before the resistor, and are feeding to the battery instead, you should be fine.....

circuits are set up to run at their specified voltages obviously.....operating points,etc.....I'm not sure what levels of abuse or mistakes they can take before checking out. That would depend on the ratings of various things in the circuit.....


Maybe test some of the transistors....those caps too....????
you could actually shotgun replace all the electros and transistors in that thing pretty quick and probably be good if there was damage I'd imagine...

???

Ok thank you very much. I’ll look into all of this.

I mentioned the box “working” just meaning signal passes in both bypass and Level-Loc mode, input trim works, distance selector works - it just seems like the compression circuit is not being entered or threshold triggered. I don’t know. I’ll test power options first.

Thanks,
Mark

 

[radardoug]

The clock is ticking....... Hehe!  It is clear to me that you are not technical at all, so how are you going to approach this repair? You cannot understand the purpose of the series dropper resistor from the socket. This is very elementary. If you have to give this box to a pro to fix, what will that cost you?

 

[scott2000]

If you have to give this box to a pro to fix, what will that cost you?

LOL....You obviously haven't looked at where he works.....

 

[radardoug]

LOL....You obviously haven't looked at where he works.....

Well, they have reel to reels, someone must maintain them. They could flog off one of those guitars to pay the bill!

 

[MrG]

Well, they have reel to reels, someone must maintain them. They could flog off one of those guitars to pay the bill!

Hey radardoug,

Thanks for the questions. I am, in fact, a highly technical person. I am also not too prideful to enter an arena in which I’m not well-versed and take a little heat in order to learn new fields, which is what I’m doing here. As scott noticed, I’m a studio owner, producer/engineer, mixer,  mastering engineer, songwriter and a multi-instrumentalist. I’ve interconnected and created multiple studios over the years, and design and build various transformer boxes for myself and others. I’m also a computer programmer and an avid cook lol. I take all of this to the max of my abilities and am a constant learner.

So again, I am here to learn, and learning implies not knowing all. My fundamental electronics knowledge is lacking (I believe I wrote this in my first post here but maybe not).

I do understand the concept of that dropper resistor as it applies in series, however, I didn’t know if it would affect the other power input from the battery with something like a load concern. I was shooting in the dark here based off of what you’d said and trying to solve an issue. Apologies for being pedantic - I’ll improve as I progress.

Good news is that I tried other wallworts and after metering them, they almost all output 9.4v.  So I plugged one of those in and voila, compression now works! Sounds lovely. If you want to hear a cool snippet of this and another old Shure comp in action, here’s an instagram post: https://www.instagram.com/p/Bp7dEoABXyk/?utm_source=ig_share_sheet&igshid=30omypd9vh60

To complete this saga, I’ll just say that I did learn that the wrong amounts of power supplied can still pass signal, but render some components (I’d assume transistors at least) unusable for their designed purposes. I had thought perhaps that it would only use the amount of power it needed but clearly this is incorrect logic. So now the only issue is that the mic output isn’t working. But the aux line out is working, and sounds great.

Thank you all very much for your help!

Best,
Mark

 

[mjrippe]

Measure the transformer for the mic out.  The first Level-Loc I ever bought had an open secondary on one of the transformers.

 

[craigmorris74]

I've noticed a few comments on this thread critical of the OP for wanting to fix the Level-Loc.  Yes, it is a cheap piece of equipment, and for many types of music, probably junk.  However, the Level-Loc has a very unique sound that many producing modern music enjoy.  The Level-Loc is used by many high end engineers to give them a specific tone that can't be had elsewhere, whether you like that sound or not.

Kudos from trying to keep one more piece of electronics out of the landfill!
Craig

 

[dmp]

I built a pair of level loc clones and in parallel they are pretty awesome sounding -  drums for sure.  The clones have a wet/dry mix on them, but I don't think the originals do. 
They're more an effect than a high end studio compressor