Pioneer SC-LX81 - loudspeaker terminals

[Clunche]

Hello everyone,

I am currently working on a Pioneer SC-LX81 amplifier and I successfully ran a firmware upgrade fixing the network issues. I have found the file here.

The problem I am having comes from a defective 3-terminal loudspeaker connector whose previous owner destroyed the PCB connections. I don't know how this happened because I don't think the guy ever opened the received - never seen such a complicated architecture with numerous stacked boards and flat ribbons! -and the plastic is secured from the from panel.

After almost an hour for removing all the boards, I could finally access the amplifier assy and this is a 7-channel class-D amplifier driven by an ICE chip and a bootstrapped high-side driver also marked ICE. I removed the loudspeaker connecting terminal and it is well affected with most of its connection torn down (see attached pictures). The brand is Jalco and Pioneer lists it as AKE7138-A in the schematic diagram or AKE7138 in the bill of material. I've tried to ask for a spare part in a Pioneer repair station in France but the guy told me that Pioneer Europe no longer stored the part. I've tried searching the internet and found a few approaching parts on eBay but not this exact version. I can try to fix the connector by adding long wires and gluing it to the PCB but I would prefer to replace the terminal by a new one. If you gents have suggestions on where I could find this type of connector, I'll happy to read your comments. Thanks a lot in advance.

Cheers, Christophe

[stj]

Re: Pioneer SC-LX81 - loudspeaker terminals

common problem with japanese amps.
is the plastic o.k.?
if it is then i would connect it with copper wires!

[Clunche]

Re: Pioneer SC-LX81 - loudspeaker terminals

Hi Stj, thank you, this is actually what I did as the plastic was ok and it worked. One of the banana screw thread was dead so I managed to secure it with a nut inside so the only connection means now is via a 4-mm banana plug but it seems to work now.

The new problem I've found is pretty weird and I don't know if it was there before I dismantled the whole thing (what a mess!): it works well when operated in any configuration of Dolby for a long time. Then, if I suddenly switch to Advanced surround, there is a kind of low-frequency oscillation appearing in the loudspeakers. If I push direct stream or simple stereo mode, then it disappears. It goes up and down with volume. When I return to Advanced surround, then it comes back again. It's only if I change the Dolby mode on the fly because it can operate for many hours while in Advanced surround (Rock style for instance) and if I toggle for another choice and return to Advance surround, then it oscillates again. Sometimes it is hung completely and despite changing sources, there is no sound at all. Turn the amp off, back again and sound is back ok until the next toggling event. This beast features Freescale DSPs and not the TI ones having lifetime problems.

The problem with with this amps is that you can't probe any signal without the jig cables. If you believe this is due to a bad contact I created when remounting the whole thing, I am willing to reopen it and secure all connectors again but I am doubtful this is it considering what I observe. If you have a clue... thanks a lot.

[frankusb]

Re: Pioneer SC-LX81 - loudspeaker terminals

Try a factory reset?