| Description |
So this wants to be a helpful guide to solve a problem that I’ve got with an es108a unit. I
just read this information in this group, but it was not easy to find, so I decided to do this
little guide. I can’t remember who posted it, but THANK YOU!. Feel free to correct, ask or
whatever, and sorry about my english, it’s not my first neither nor my second language.
I got three different type of error in the es108a units.
One just started to show error
intermittently, one day worked, next didn’t and just didn’t show up, and went in red in the
assigment screen. It sometimes showed up as ok in DSC screen but it had a strange
combination of leds in the front panel. So, not very trusty.
The second error just simply distorted input signal when activated. I checked that it was
not a connection problem crosspatching signals.
Third error: input signal loses volume when activated, more than 10 dbs. I also made sure
that was not a connection problem.
All this three problems got the same solution:
So as I read in this group, I just tried a simple and cheap fix, changing the VCA Chip.
There are two vca chips for each card, one for each channel, they are named U166
(channel 1) and U266 (channel
2). The chips are wisely
socketed so it’s very easy to
replace them.
Buying the chips:
The “thing” you have to buy is this little multi legged bastard from Analog Devices, claimed
to be obsolete, the SSM2018: http://www.analog.com/media/en/technical-documentation/
data-sheets/SSM2018.pdf
I found some in England and in China via ebay. I bought one in England and for the same
price I bought 3 in China. All 4 are working properly, I didn’t check for sonic differences,
apparently they work the same. The one bought in England looks original.
How to do it:
Unplug main voltage, elco multipin connectors and midi cables. There are four screws that
hold the Elco connectors input panel, just go for this ones. Take care that there’s a couple
of cables connected to this pcb, don't force them, they are long enough to put this panel
aside without disconnecting it (you can disconnect if needed, obviously)
Original from China from England
Then there’s a spacer for the 4 dynamic cards, just pull it and remember how and where it
was placed, there’s no screw for this piece. Then pull the card you have to repair, no fear,
it’s more o less the same system as the audio tower.
Once you’ve got the card out from the unit, just localise the chip depending on which
channel you are repairing, and with a small screwdriver (or special tool to “undip” chips)
and lots of care you just do “leverage” on both sides of the chip that have no legs and it will
get off the socket. Then just put your new chip into the socket. Very important: chips have
a mark on its top ( a dot or half round cut) that marks which one is considered leg 1.
Sockets also have this mark. MAKE THEM COINCIDE.
Another thing to do before placing the chip is bend a bit the legs. Place the chip like in the
picture and press a bit to bend even all the legs. And then do the other side. This is helpful
because the chips when new have the legs not doing a 90 degree angle (which is very
useful when you solder them, but not to place them in a socket). It’s not a big deal and you
can try without doing it, but this is the way I found it easier (I socketed some in my life :-) )
Put everything back and that will be it.
I really hope this thing was helpful. It’s not any rule or law. It’s my experience.
(at the end of this I just fixed another one)
Cheers and enjoy!
jordi mora
-> Have a look at "Download/Schematics/Drivers/Software"
-> 04 - Dynamics
-> Es108a_Fix
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