Roland R-880 faulty input (and more)

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Bananahead

Member
Joined
Apr 7, 2015
Messages
5
Location
Stockholm
Hello!

I have a R-880, rarely used (because ITB) but well loved. Last weekend I noticed a fairly strong and burned smell coming out of it. So, I shut it down, opened it up and saw almost every mica-cap looking "cracked". What's up with that?

I powered it up again and.....no smell. Damage already done...... Now it powers up, doesn't smell but input 2 is peaking. At least the LED is showing full input (but no sound/data is processed and sent to the outputs) I'm guessing some circuit feeding the AD either gave in or burned up, probably both.

I used my trusty nose sniffing the inside of the chassis and locating the smell originating from the front of the unit, where the converter chips (BB PCM54HP) are located. I could easily sniff up the strongest smell from the faulty area (the channel 2 input).

Can the mica caps be replaced just like that? After all it's the analog board, through hole mounted components and I'd gladly spend a few evenings recapping the thing. But reading abouth the mica caps they shouldn't fail, at least not 90% of the ~100 mica caps on the board, right? All the elyts are looking just fine, both on the board and the PSU. All channels get their +15-15 from the PSU

Any idea what happend with my R-880?
 

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radardoug

Well-known member
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Oct 10, 2009
Messages
1,052
Location
North New Zealand
I dont think the caps are your problem. Smell indicates burning, so look for something that got hot. Did you try swapping the converter chips?
 

Bananahead

Member
Joined
Apr 7, 2015
Messages
5
Location
Stockholm
I dont think the caps are your problem. Smell indicates burning, so look for something that got hot. Did you try swapping the converter chips?
Nope, haven't swapped chips. They are soldered, not socketmounted :-/ Right now, powered on, all four chips have the same temp. No sign of overheating f ex on the print on top of the chip.
 

Bananahead

Member
Joined
Apr 7, 2015
Messages
5
Location
Stockholm
Just adding som photos of the second channel on the analog board, and what the front LED is doing without input.
 

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