Tascam 424 MK II issue in right output channel

[Oxcyde]

Hi guys, I have recently noticed there is a muffle type of scratchy sound on a certain low range of frequencies in my Portastudio 424 MK II.
I'm not running this sound through tape, just directly through the mixer.
It MAY have been happening this entire time I just haven't noticed it. I bought this 2nd hand about 6 months ago.

Anyway, I have checked cables, monitors, inputs etc.
It happens on the line output as well as the monitor output through my headphones, so whatever is happening - the issue is internal.

I have a recording of this sound I tracked out to my PC, there audio file is stereo, listen to the right channel.
again, it only seems to appear at a low freq - so any deep bass it will spaz out.

This really sucks because I love this machine so much.
I guess my questions here is - would this be fixable?
Has anyone experienced anything similar on analog machines and if you have any advice would be great!
Cheers.

I couldn't upload the file directly here, so please take a second to download from here (it's just an mp3).
bass_muffle.mp3 :: Free File Hosting - File Dropper: File Host for Mp3, Videos, Music, Documents.

 

[A Reel Person]

I'm going to guess a bit here,...

Based on the description and the sound, my guess would be an output stage chip or transistor that's blown,... or perhaps a capacitor somewhere in the signal chain has dried out or become marginal.

... assuming how I read your post that it happens on the L/R Stereo buss, the Monitor Out buss & headphones while using All main input channels, 1-4 (?) However, if it's only happening on 1 input channel, I'd look at the preamp stage of that input, as well as how it connects/interfaces to the L/R Main stereo buss.

Almost anything is fixable. The devil is in the details, tho.

 

[Oxcyde]

Damn, that sucks!
Something worth mentioning is, I bought the thing on Ebay and have been using a voltage converter ever since. (I live in Australia).

Do you think the conversion in voltages may have something to do with it?