Issues with main bus left channel on Model 16

[Hmurphii]

Hi fellow Tascammers,

I am having an issue with my Model 16 where sometimes signal that is routed to the left channel on the main bus either doesn’t come through at all, is very quiet, or makes a crackling sound. This happens on the stereo channels with the pan pot central and the mono channels when panned hard left.

From some troubleshooting I’ve found the following:

1) The mixer is getting signal on all channels (sig LED lights up)
2) When recording to internal SD and during playback, I see the signal on the left panned channels on the screen but there is no audio output when this issue is occurring
3) This issue occurs with the headphone output, control room output, and the main mix but not the SUB bus.
4) Sometimes if I crank the gain on the problematic channels to an unreasonable level and back down again the signal “breaks through” and temporarily resolves the issue.

Any idea what may be going on here? Of course I can use the SUB bus as a workaround but not being able to use the meter is a drag.

 

[shredd]

I don't have a Modelxx -wouldn't, even at gunpoint - but your problem seems like it might fall into a coupla categories:

It's possible, of course, that the unit has an internal flaw/failure - a bad amp, internal connection, or flaw in some other electrical or mechanical part (jacks, pots, whatever). That's a Tascam-service issue, unless you're one of those rocket-surgeon types.

I'd also encourage you to consider your signal-chain/flow and make sure that everything ELSE in the chain is OK...just as ONE example, whut if your M16 was producing L channel signal just fine...but the cable feeding your L monitor was bad? Or your headphones had a bad cable, bad driver, yadayada???

One of the ways to explore this is the ol'-fashioned "elimination" method, whereby you check/test each "link" in the signal chain, all the way to your ears, to see if you can isolate the flaw/break in the signal flow. We're assuming your left ear works OK...

This issue occurs with the headphone output, control room output, and the main mix but not the SUB bus.

This 'symptom' is a curious one...I'm no rocket-surgeon (or even a studio wiz) - but my bb-brain went to things like a mis-set compressor/limiter, or something else in the signal chain that DOESN'T include the [SUB] bus...
Time to study that block diagram...and mebbe check some of those things that might limit/cut off the signal?

To be honest - sounds to me like a blown something...but I'd go down all those other roads before calling Tascam...

Good luck - let us know how things wash out, in case this ever comes up for others...

 

[Max Relic]

Any news @Hmurphii ?

 

[Hmurphii]

Thanks for the thoughtful (and funny) response @shredd .

I've checked the other parts of the signal chain and everything is solid. The only part of the block diagram the SUB and MAIN buses don't share is the Master EQ.

Just now when the issue was occurring I toggled the Main/Mon1,2 switch and EQ in/bypass switches in the Master EQ section and it went away. I'll keep messing around today to see if the issue returns and if playing with the Master EQ section keeps making any difference.

If it does indeed come back , this to me would seem like a Tascam service issue. I have some experience fixing these sorts of things myself but without a service manual this is probably one for the pros.

I'll report back if the issue returns.

 

[shredd]

Thanks for the followup!
Pretty odd - it just reappears like that, punching a coupla buttons...but suggests that either those buttons (specifically, where they were set) were the source of your original problem (might wanna peruse the Block Diagram?!?) - or perhaps one of said buttons is going floopy and not passing signal consistently?