Loud hiss from Mic Input A on Tascam DP-02CF

[andy1087]

Hello everyone

I have a Tascam Portastudio DP-02CF and am having some issues with the Microphone input on the Input A.

When the volume is turned up on Input A, there is a very loud hiss that occurs. This happens whether there is a microphone plugged in or not. Also, there is no sound from a microphone when it is plugged into the input. (The microphone input doesn’t work)

When a microphone is plugged into Input B, the hiss still happens as long as the level is turned up on Input A. The hiss goes away when the level is turned down. However, the Mic input on Input B does work and there is sound.

The only way the hiss goes away is when something is plugged into the ¼ input on Input A. (ie. a guitar)

Please see the video I have made on Youtube for a better understanding of what is going on. Link below.

Any ideas on what’s goin on and how to fix it?

Thanks for any ideas

Andy

 

[shredd]

Hi Andy - welcome to the show. We have some lovely prizes for you, just for playing!!
Sorry. I watched a lot of TV as a kid.

I don't have a definitive answer for your issue - I'm not a technician and am easily the card-carrying Village Idiot around here.
But I did watch your video and gave it some thought. He's my nickels' worth:

It appears to me that the "Input A" XLR connection - either the physical connector, or perhaps even the mic preamp - is toast; perhaps the physical connector is shorted, or the mic pre got toasted w/a power surge, bad connection, whatever...
This is apparent to me because: mic connected to Input A XLR has no signal recognized; the noise/hiss; and the fact that when you connect your git'r to the 1/4" connection of Input A, it seems to work OK.

SO: bottom line - I think Input A's XLR connector and/or something in its' connection to your signal path is fried.

I know...big help, right? But maybe it'll get you on the right track...at least until you get a reply from someone who knows whut they're talkin' about...
Good luck!!

 

[andy1087]

Hello Shredd

Thanks for giving me some clues as to what to look for.

Any ideas of how to go about testing for either the input or preamp issue. Volt meter or anything like that?

Thanks again

Andy

 

[shredd]

Hi Andy - sorry, I don't have any real guidance...like I said, not a tech...I actually have to remind myself which way the pointy end of the guitar goes.

I deduced the possible problems you're having by the eliminative process...which, by the way, was made possible by your excellent video detailing your problem!

I really couldn't address how to check mic pre's for function...but as far as the integrity of the XLR connector on that noisy channel, a good start would be to use your voltmeter's continuity tester to make sure the connections are passing through cleanly/consistently. Look for damage to the board where the connectors are attached.

Beyond that, I'm not much help...you need one of these smart-ysh doods to chime in. Or take it to someone who's got tech ability...

 

[andy1087]

Thanks anyways for the input Shredd

I tried to get the volt meter out and test some connections, but I don't know what connections to test for the mic or switch inputs.

If anyone else wants to chime in, I have added some links (couldn't upload them directly to this thread for some reason) to pictures of the circuit board and what connections to test for the mic, guitars, switch, preamps.

https://www.dropbox.com/s/h9c8z9exzuhgx1f/IMG_7922.JPG?dl=0
https://www.dropbox.com/s/2dh11slrrvthkya/IMG_7923.JPG?dl=0

 

[shredd]

Hey Andy…
All I meant in previous message was: perhaps check if the physical connector has a clean connection to the board. A bad connector might be the whole problem!?
Unless of course that Channel A XLR's mic pre is toasted…then…well…

 

[Arjan P]

@andy1087 Looking at the pictures I don't see any clue on the component side, but the other side seems to show some damage to the soldered joints in the area of the guitar jack connections and a little below.. Also looks like there's a greyish tarnish on the surface there. Maybe try cleaning that off and check those solderings/ re-solder them where they seem loose.