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G8MNY > TECH 17.12.17 10:36l 86 Lines 4115 Bytes #999 (0) @ WW
BID : 2528_GB7CIP
Read: GUEST
Subj: Mixer Eurorack1804X/ItMix PM184X
Path: IZ3LSV<I0OJJ<GB7CIP
Sent: 171217/0927Z @:GB7CIP.#32.GBR.EURO #:2528 [Caterham Surrey GBR] $:2528_GB
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Jun 17)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I have worked on both of these Behringer 10ch AF Mixers, "T Mix PM184X" has a
plastic carrying handle & a huge 375W/ch (4ê) PA amp built in underneath. The
"Eurotrack 1804X" is a mixer only & has a separate mains transformer.
ch 1 2 3 4 5 6 7 8 9 10 o/p
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
XLR³O O O O O O . . o o o o ³ 6 XLR Mic/mono Jack line +4 tone controls
Jack³o o o o o o ú ú o o o o ³
LF³ú ú ú ú ú ú o o o o o o ³ 4 Stereo 2 Jack ins +4 tone controls
Gain³ù ù ù ù ù ù o o o o o'o'o ³
³=============================³ 1 Aux Jack & 1 Phono Tape In & Out
Top2³ù ù ù ù ù ù ù ù ù ù ³
Top1³ù ù ù ù ù ù ù ù ù ù ÛÛÛÛÛ ÞÞ ³B 32 mode FX echo 24bit processor
Mid³ù ù ù ù ù ù ù ù ù ù ÛFXÛÛ ÞÞ ³a
Bas³ù ù ù ù ù ù ù ù ù ù ÛÛÛÛÛ ÞÞ ³r Aux & Separate Alt/Solo Mix functions
Aux³ù ù ù ù ù ù ù ù ù ù ³
³ ú ú ú ú ú ú ú ú ú ú||EQ|| ' ³ 7 Band Graphic EQ.
Fx³ù ù ù ù ù ù ù ù ù ù ú ú ³
Pan³ù ù ù ù ù ù ù ù ù ù ù ù :ù ú ³ All Ch have ext rear Jack effect option
³: : : : : : : : : : . . . . ³
³| | | | | | | | | | | | | ||³ XLR Bal & Jack Un O/Ps
³| | | | | | | | | | | | | ||³
³| | | | | | | | | | | | | ||³Main
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙL&R
Faders Aux Fx Alt
The 1st Mixer+Amp was not working properly, it had a broken LS screw post & a
very noisy mixer. On painstakingly opening it up, literally 100s of knobs jack
nuts & screws, (1 needed drilling out) to release the large PCB. It soon became
obvious that a CUP OF COFFEE had done it in. (Always power off/remove batts if
this happens to you!)
I photographed the PCB to show up the many small corrosion points in detail on
a PC screen & see all Surface Mount bits zoomed in to more easily check it out.
After much tinkering I found a SM dual Op amp IC with a completely corroded
away +ve pin. At this point I gave up as un-reparable for a few years.
At a Ham rally I spotted the similar 1804X "mixer only" version, for œ20, less
its external transformer, so I bought it, & made up a transformer box for it.
The mixer had a very bad 1st ch Mic slider. So I stripped this mixer down too,
unsoldered & removed the slider, opened it up, re-tensioned the wipers & put it
all back together. All tested OK.
I did not want to wreck the now "good mixer", so I went back to the Mixer+Amp
again. Removing the duff SM IC I had previously found, but the loud crackle
noises were still there, & I also spotted an overload/PFL LED would not light.
Testing further I found another SM dual Op amp IC with no +ve rail, or to the
that ch LED. This I traced to a tiny plated through PCB track bridge failure
under a component, (same as other good ch track layout) so I pieced it out on
the non component side with 2A fuse wire. All noise gone.
Now to the duff SM IC, filing it's corner off, I managed to expose enough metal
(0.2mm) to tin & solder 2A fuse wire to it. Putting it back in, a steady hand
was needed for SM ICs! Hey Presto it all worked too.
Back to the last bit, the PA Amp's broken dual post LS high current screw post,
I made a replacement part from an old similar one & made it fit.
To stop this Mixer "coffee fault" in the future, to both mixers, I added felt
rings (J Cloth washers) on each of the 79 pot shafts & glued a cloth to the
cover for the 15 sliders holes & slotted them.
Before closing up, I drilled out & re-tappped the spot welded collar's seized
screw that I had to drill off, & replaced the screw for a "Proper Job". Also
all the screw threads were greased up to enable easier re-assembly & undoing
next time!
Then it was just the matter of the 100s screws, nuts & washed clean the knobs,
etc. Then do a good test out. A very hot 2x 4R large dummy load with the
375W/Ch amp. :=)
It has now been used at a function quite reliably, so eventually it was well
worth all the hassle in the end.
Why Don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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