FW-1884 channel 5 input damaged???...


New Member
Oct 12, 2012
Gear owned
Tascam FW-1884 Tascam DR-680
I am not really sure if my FW-1884 is actually damaged or is there is something I am not doing right....
Everything was working fine and I had a dynamic microphone connected to channel 5 input XLR, with phantom power turned on.

Without turning phantom power off and without turning the mixer off, I unplugged one microphone from the XLR cable and plugged in another one. It may be totally unrelated but I noticed then that channel 5 was not passing the sound of the microphone. Instead it had a static sound like "rain". A "Sshhhhhh..." kind of continuous sound, if you understand what I mean.

I have tried unplugging everything from channel 5. I have tried unplugging the XLR and plugging a sound source to the unballanced jack input. I have also tried turning phantom power on and off... No matter what I try, the loud static sound "shhhhh" is always there.

I noticed that if I change the Monitor source to "Computer", instead of "inputs" or "Both", the sound vanishes so, the problem seems to be in the input.

What can this be?.... Is the channel 5 input damaged? Can it be fixed?...

Finally and since we're talking about damages, one of my Firewire inputs is not working (for some years now). Can this be fixed somehow? I'm afraid the other Firewire input stops working and the FW-1884 will become obsolete, specially as DAW.
Ahhh,you broke one of the cardinal rules-never plug or unplug a mic with the phantom power on.You probably blew the input op-amp.
Holy cow.... But I thought that wasn't a problem. I actually had read on the following web page that at worst, it could harm the microphone but even there it was very rare and only with ribbon microphones. But reading that I would never imagine it could hurt the mixer input:

http://socialsounddesign.com/questions/ ... ower-is-on.

But anyway... Now that it's damaged, how do I go about for fixing it? Is it fixable? Do you know if it can be sent for repair and replaced or fixed? :confused:

EDIT: I found a forum where people are providing a solution for the repair. Is this the procedure? http://www.gearslutz.com/board/geekslut ... 884-a.html

I also contacted Tascam tech support and should expect a reply in 2 working days... :(
Great to see this forum back.

The really helpful area about this is at http://deeringamps.com/fw1884/index.htm

Look especially for the pdf about the machinator mod (unfortunately I believe that the person who was machinator died), and the Tascam pdf about the capacitor mods.

There is also a Tascam pdf about firewire cold starting, but I don't think that will help much with your firewire problem.
Thanks a lot for the links and the reply! The Machinator PDF seems very interesting and may help me repair the FW-1884 without needing to take it to the local Tascam representative. However I am very little experienced with electronics and may not be ready for the task, despite the pdf information. Maybe if I handle the pdf to a friend who understands of electronics...

What I find puzzling is that my serial number seems to be amongst those which already came with the diodes for op-amp protection... (#0120089). :confused:
Wasn't it supposed to be ready for unplugging mics with phantom power on (even if accidentally)?
I would have to be very certain of the abilities of any friend before I let him loose on my 1884!

I am an old engineer from the days when all good mixers had transformers on the mic inputs.
I am quite wary of all modern transformerless inputs. I worry about static electricity from carpets etc. (we used to water the carpets in some studios that I worked in, others had carpet tiles with metal threads ) as well as the phantom power. so I am extremely careful with any recent mic inputs.

I also think Tascam support is rather erratic. I've had a good response (from Germany) to one question I asked, another support query about a different usb device fell into a black hole.
In my case they replied telling me that it was not a good idea to unplug mics with phantom power on... And that it was common practice on all studios not to do so. I almost replied telling them to take a hike. I found their reply quite imbecilic... If in the 8 years that I have my FW-1884 I never had a problem... That's because I obviously know that. Now, sometimes people make mistakes and sleeping 3 hours a day during a week doesn't help. That's what repair services are for: To repair when something goes wrong. Not to tell you what you shouldn't have done, or to give elementary school teacher kinda sermons!.. To which I don't recognize them the moral authority.

Anyway... They provided me with the contact of the representative in my country and said nothing else about whether it is repairable or how much it could cost to replace the op-amp. They didn't even send me any documentation to support the repairing process or any links to anything that could help.

I'm already predicting the guys from here saying that they don't know how to repair or that it will cost more than a new one!
I'm interested to hear if you got it fixed and how much it cost.

To go back to your next-to-last post, yes, your serial # looks high enough that it was supposed to be built with the protection against the unplug-with-phantom-power-on problem. This makes the lecture from Tascam doubly annoying.
Actually I haven't fixed it yet because the guys from Tascam redirected me to the representative here in Portugal, who told me that I had to send it to Germany since they don't fix it here. The alternative he told me, is to know exactly the name of the part that got damaged and import that part from Germany. then I need to have someone (trained electrician) to replace it here for me.

In your opinion... Is this too difficult for a trained electrician?

I may not be needing it replaced right away but, I don't intend to have it damaged forever.
I think we have to be clear in the translation here. What you want is not an electrician, but an electronics technician (or engineer) used to working on equipment down to component level.
I used to do this, but age and eyesight now would make me look for someone to do this for me. Locally here I know of a pro-audio dealer who has a service department and I also know a local small shop who have been around from the early days of mobile phones before they were throw-away items, and who have branched out into building and maintaining advanced alarm systems.

Perhaps a local college might have lecturers who could advise on a suitable person?
It doesn't look to me as if the work would be too difficult, and a good person would almost certainly know how to get hold of the components at a good price.

My limited experience with Tascam themselves indicated that the German people were helpful and, I assume, competent when you got through to them.
To clarify:The reason why you don't plug/unplug mics while phantom power is on is because you get a BIG FAT minimum +48 volt spike,(look up back EMF), on the inputs.The mic preamp is running off of +/-12 volts D.C.,being hit by that kind of voltage above the supply voltage,(and maximum voltage rating of the transistors), will take out the input transistors and/or input opamp.The input diodes usually block any spike higher than .6 volts above /below the power supply rails.Those diodes can take number of spikes,but like anything else can fail after being hit with repeated BIG FAT +48 volt spikes.It's not rocket science- I can't believe there isn't a competent tech that can't use basic troubleshooting techniques to repair it in your country.
Of course... I'm sure there is. I'm just not sure where to go at this point. There is a good house for this in Lisbon. But I live 100 km from Lisbon and don't go there all the time. It's probable that there is someone here where I live too... Just not sure where. I'll look...

But first there's an important issue... Do I have to identify the damaged part myself?.. No, right? If the technician is competent enough, he can do that too, I suppose.

@Billaboard: Yeah, that's what I meant: electronics technician. Thanks!

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