• Nge
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  • Registered: 2022-03-15
  • Posts: 7

Topic: Fixing my FireFace 802

Hi! I'm new here, so greetings to everyone.

I bought a second hand 802 a few weeks ago and it came with mic pre number one dead.

I opened the unit up and immediately saw a bulging capacitor.

https://www.dropbox.com/s/wafh7bibpvtqpmn/IMG-20220212-WA0002.jpeg?raw=1

Changed that capacitor, not working and a few days later the new one was bulged, so it wasn't a dried cap, there must had been a problem with tension voltage, and indeed it wasn't over voltage but 6v negative volts at positive side.

https://www.dropbox.com/s/kcbu9skz9x3ja2i/20220223_164223.jpg?raw=1

I went straight to the THAT1510 IC, which is the mic pre in fact. That bulging cap works in series with a pot to control the gain. Some weird voltages were found there:

https://www.dropbox.com/s/o6driuv91nuqbdf/Screenshot%202022-02-25%20at%2011.17.45.jpg?raw=1

Only those +15V and -15V should be found on V+ and V- respectively.

2 Reply by Nge (edited by Nge 2022-03-15 19:50:15)

  • Nge
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Re: Fixing my FireFace 802

There are no schematics of this circuit, what makes repairs quite hard. I used some THAT1510 circuits to have an idea of what it should look like. Fortunately, those 4 preamps circuits are basically the same so I could measure every component and found a dead resistor:

https://www.dropbox.com/s/uc5p872e3ymr1sm/20220223_164511-Edit_03.jpg?raw=1

The little cap connected to the XLR input also gave me a weird value, but that's the side effect of measuring in the circuit (and also have a very limited knowledge).

I bought a 0805 SMD kit and made some trial in spare circuits before trying to repair my first SMD circuit and then finally changed that dead resistor with, I have to say, non appropriate tools.

https://www.dropbox.com/s/o0kmdfd1tiyv9x6/20220227_103704-Edit.jpg?raw=1

That's the circuit with the new 10R resistor. Not a piece of art but not bad at all!

Reassembled everything again, plugged it and... working perfectly!!

This is almost a miracle, I have no experience in SMD circuits, no experience with audio devices and very limited technical knowledge (most of it in tube amps). I am very happy and I wanted to share this with everyone, specially because I guess that that blown resistor has something to do with phantom power hot plug/unplug, so I guess this could be common perhaps.

Greetings to everyone. Very happy with my 802, very nice piece of gear.

  • cyrano
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  • From: Belgium
  • Registered: 2015-04-28
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Re: Fixing my FireFace 802

Thanks for detailing the repair so extensively!

MB Pro - 2 X FireFace 400, FF800 & DigiFace USB
ADAT gear: Korg, Behri, Fostex, Alesis...

cyrano's Website

4 Reply by sbcrikey (edited by sbcrikey 2022-03-16 00:11:49)

  • Registered: 2021-12-30
  • Posts: 151

Re: Fixing my FireFace 802

nice work! I agree that it's likely a little bit of a miracle that you found it and there weren't other components that needed to be replaced.

did you replace that can capacitor again after you saw it had swelled?

-Steve

  • Registered: 2019-10-01
  • Posts: 675

Re: Fixing my FireFace 802

Niiice!!

RME Gear: Digiface USB, HDSP 9632

6 Reply by Nge (edited by Nge 2022-03-16 10:23:50)

  • Nge
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Re: Fixing my FireFace 802

sbcrikey wrote:

nice work! I agree that it's likely a little bit of a miracle that you found it and there weren't other components that needed to be replaced.

did you replace that can capacitor again after you saw it had swelled?

-Steve

Yes, I replaced that 3300uF cap again.

And yes, a miracle. They are lots of stuff that is hard to check/replace without schematics: several transistors with no codes to identify them, a few ICs, hard to replace with no proper tools, and many condensers also with no codification.

Having another preamps working to compare values and measurents was very helpful.

It's kind of reckless because you're likely to end up screwing something else up instead of fixing that preamp. But I was very dissapointed everytime I saw "UFL" on that preamp totalmix meter to remind me that it was broken.

https://www.dropbox.com/s/nxr3zyoybw76c8d/6d1c420d-b232-4c0f-9dc0-720a9706df28.jpg?raw=1