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View Full Version : FW-1884 Opamp replacement



D
08-19-2009, 10:16 AM
Installed the new opamps on my FW-1884. Tried to sleep, but couldn't (as usual), so I got up and figured I'd do the job. It took about 45 minutes to disassemble, maybe 20-30 to put it back together, about 30 minutes to remove the old ones, and another 45 minutes to install the new ones.

The old ones were 8 pin SIL (Single In Line Package) and the new ones were 8 pin DIP (dual inline package, most integrated circuits use the dual configuration). These require an adapter and I installed sockets on the adapters in case of future chip failures.

These sound 200% better than the cheap ones Tascam puts in at the factory (JRC NJM4580). I was having some problems with noise from my SY77, and it is now almost completely gone. DAMN! These sound great.

One problem. I either made a mistake soldering on chs 5 & 6, or that particular opamp is defective. I ordered an extra one just in case, so I am going to pop that one in and see what happens, AFTER I check my soldering again.

BIG job. Lots of tiny parts, screws and ribbon cables. This is not a job for someone with a poor memory, unless you're willing to take pictures and document every step. Fortunately, I like to test myself from time to time on jobs that I am completely unfamiliar with. 100% on the reassembly - everything worked the first time (aside from the issue on 5 & 6), no extra parts. The nice part is now this is a piece of cake for me. I am quite familiar with the mechanical and electrical layout of the boards, so it will take much less time to check chs 5 & 6, as I don't have to remove quite as many parts.

D
08-24-2009, 09:31 AM
The problem with channels 5 & 6 turned out not to be something I did wrong. I looked everywhere for a stray bit of solder, cleaned and checked all boards several times. In the end, I put one of the old opamps back into that slot and everything worked perfectly.

I've also tested for problems with the SIL-to-DIP converter board, and that appears to be okay as well, although I did desolder and remove the DIP socket before I tested.

So now I have one of the old opamps in that slot, I plan on doing an A/B test. I'll post the results when that is done.

Another interesting note: after re-assembling everything, I was having some problems with the unit syncing up to the computer. After about 20 minutes it synced up fine. I wonder what the issue might be here. It seems that the unit required a 'history' of sync before it would consistently sync up. Very strange IMO.

stealthl
09-15-2009, 02:43 AM
Thanks for the info. I would like to try on mine some day.

dementedchord
09-17-2009, 07:44 PM
so what op-amps did you go with??? did they need extra decoupling and phase compensation caps????