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 Post subject: JBL ESC 200 - Sub Output
PostPosted: 07 Jan 2017, 11:26 
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Joined: 07 Jan 2017, 11:19
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Hi folks, this is a bit of a long shot, but if you don't ask you don't get ..

I have a pretty old JBL ESC 200 Surround System. It was all in pretty good condition and working nicely until recently. It never gets thrashed and has always had low level clean signals. Just recently i switched it on and there was no Sub Output. The speakers including the sub are all passive, so i connected the sub to an alternative output to ensure the problem doesn't lie within the sub.

All other outputs work fine also the problem seems to lie in the actual sub output, which obviously leaves the system sounding pretty weak.

So i would like to attempt to repair this. I have a small amount of knowledge and i'm fairly handy with a soldering iron, but i have no idea where to start to isolate the problem.

I'm looking for any advice or tips and i can certainly post images of the internals of the system.

Any help would be greatly appreciated.

Many Thanks


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PostPosted: 10 Jan 2017, 11:10 
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Joined: 05 Aug 2016, 14:35
Posts: 143
[quote="Tascam424"]

I have a pretty old JBL ESC 200 Surround System.

So i would like to attempt to repair this. I have a small amount of knowledge and i'm fairly handy with a soldering iron, but i have no idea where to start to isolate the problem.

I'm looking for any advice or tips and i can certainly post images of the internals of the system.

>>Various Snips<<

Start with:
a) Hunt down a schematic for this system. JBL is still in business, and may be helpful. HiFi Engine may be another source, or a plain internet search.
b) What you can do without the schematic: Look for any blown fuses. Quite often these devices have internal fuses that are not accessible from the back. They are usually board mounted and quite visible when the guts are removed. The fuses may also be in a small black holder - so look for that as well. The schematic will also indicate fusible links - which do not look like fuses. Look for any mechanical problems - broken wires, loose connectors and such. Quite common as it happens, especially in stuff made in the early days of RoHS compliance.
c) Marginally possible without schematic: As the sub-woofer is driven from a single amplifier module, it is quite possible that this is blown. These modules are pretty basic and shared in common and shared amongst many devices. The schematic will tell you voltages and give you the pin-out, but if you can establish that it is bad, you may be able to replace it from the part number stamped on it. It will be a fairly large chip connected to a heat-sink.

This is not rocket science, but it does require intelligent diagnostics to prevent wasting time doing shotgun substitutions.

Owner's Manual here:

https://www.manualslib.com/manual/79188 ... sc200.html

Service Manual (possibly) here:

http://www.eserviceinfo.com/downloadsm/ ... SC200.html


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