Emax

You can adjust the digital volts by turning the pot in the PSU, i do 
so until 5,30 volts....but no change in the machine, finally there´s 
a problem on some IC, who knows what are the SSM´s chips??? and the 
PAL, or the scanner MPU???? i can´t locate in the mobo....



--- In emax@yahoogroups.com, ted Summers <djtbs1@...> wrote:
>
> I need more description (do the connectors have labels next to 
them  
> like CN14 or J1), to tell you what the connectors are for. Picture  
> Files do not show on the group email, but you could post them to 
the  
> files and then we could see what you are talking about, also.
> 
> Thanks,
> Ted
> 
> On Apr 29, 2007, at 1:18 AM, RICARDO JUAREZ wrote:
> 
> > Well...
> > I clean all the unit,everything was removed, and found
> > nothing special, nothing but a few problems with some
> > "Light leds" in the push buttons, there was one with a
> > "cold soldering", and some contacts with several
> > wearing, I repair it with some glue and new metalics
> > contacts, ONe Question: There´s a pair of "sort of
> > jacks" (white and light-Blue) in the back of the
> > keyboard plaque, in one side and the other side, is
> > there any cable attached to they??? because my unit
> > has no one........I will check the soldering in the
> > PSU...
> > Saludos
> > Ricardo
> >
> > --- Wayne Griffin <ingsoc_1979@...> wrote:
> >
> > > I agree about the 5.05V and the idea of a voltage
> > > drop
> > > across the digital board.
> > >
> > > orange = +12V
> > > yellow = +5V (5.05V)
> > > purple = -12V
> > >
> > > The +10V on pin 3 of Q2 is also fine because that's
> > > either to drive the DC/DC converter for the LCD
> > > backlight or maybe something pertaining to the
> > > EPROM.
> > > [w]
> > >
> > >
> > >
> > > --- ted Summers <djtbs1@...> wrote:
> > >
> > > > Well, my opinion is that there is an issue with
> > > the
> > > > power supply.
> > > >
> > > > The 4.92 volt is SUPPOSED to be at 5V. A little
> > > > variance is ok, and
> > > > higher (5.05V) especially in an older unit would
> > > > feed better as it
> > > > went across the board. 4.92 is a bit low. Most
> > > chips
> > > > like 4.95 at
> > > > least. And remember the farther you measure across
> > > a
> > > > board, the more
> > > > the volts will drop lower. In fact, if you knew
> > > the
> > > > correct pin to
> > > > test for on the farthest chip physically across
> > > the
> > > > board from the
> > > > power supply, and measure the volt reading on the
> > > 5
> > > > volt pin, it
> > > > wouldn't surprise me if it is actually much lower
> > > > than the 4.92. This
> > > > can cause very strange behaviour in logic systems.
> > > >
> > > > It is possible to attach a PC power supply and
> > > test,
> > > > without making
> > > > it "permanent". Not an ATX, but an older AT style
> > > > power supply.... I
> > > > would have to see schematics, but am not sure why
> > > > there would be a 10
> > > > volt, it seems that should be twelve. If the power
> > > > supply is putting
> > > > out 10v on a 12v line, then that would be another
> > > > issue.
> > > >
> > > > Be aware that power supplies have what are called
> > > > 'rails'. Each rail
> > > > is a separate voltage. So the power supply may
> > > have:
> > > > 1 x 5 Volt rail
> > > > 2 x 12 volt rail
> > > >
> > > > for an example. One 12Volt rail could be ok, and
> > > the
> > > > other bad, then
> > > > the bad side can pull down the power on the good
> > > > one.
> > > >
> > > > I looked at the power supply in my emax when I
> > > > first got it. They
> > > > used diodes to "crowbar" the voltage regulation
> > > > circuit. Not an
> > > > uncommon practice back then, but not done often
> > > now
> > > > (there are better
> > > > ways to do this). What I did on my power supply
> > > when
> > > > I first got the
> > > > emax was remove it, and resoldered all the
> > > > connections to the parts
> > > > on the power supply. There were a couple of "cold
> > > > solders" which are
> > > > solders that have small cracks in them (sometimes
> > > > require a
> > > > magnifying glass to see them). They will arc and
> > > > connect part of the
> > > > time, then lose connection momentarily at which
> > > > point the circuit is
> > > > broken and no longer works properly. This could
> > > > cause the lower power
> > > > output as well as the strange behaviour. You can
> > > > resolder all the
> > > > parts on the power supply, then if that doesn't
> > > seem
> > > > to help, get the
> > > > PC power supply and hook in place of the original
> > > > supply to do a test...
> > > >
> > > > Just a couple of thoughts.
> > > > But what do I know. Having worked as a repair tech
> > > > for 17 years on
> > > > electronic equipment.... I don't know anything ;-)
> > > >
> > > > Thanks,
> > > > Ted
> > > >
> > > >
> > > >
> > > >
> > > > On Apr 26, 2007, at 8:51 PM, RICARDO JUAREZ wrote:
> > > >
> > > > > Yep!,I still need a method for verify the 5v of
> > > > the
> > > > > digital, Why we need to measure VR1?????, and
> > > how
> > > > you
> > > > > do that????
> > > > > Más Saludos
> > > > > Ricardo
> > > > >
> > > > > --- ted Summers <djtbs1@...> wrote:
> > > > >
> > > > > > That IC is still available (just google it-
> > > > someone
> > > > > > will sell you a
> > > > > > single one- may have to do a bit of email to
> > > get
> > > > it)
> > > > > > and one bad IC
> > > > > > can cause others ICs to heat up as well....
> > > > > >
> > > > > > But I would still verify the Power Supply
> > > > first.....
> > > > > >
> > > > > > Thx,
> > > > > > Ted
> > > > > >
> > > > > > On Apr 26, 2007, at 6:28 AM, RICARDO JUAREZ
> > > > wrote:
> > > > > >
> > > > > > > Hi!:
> > > > > > > Here´s what a found: IC 14(NS32008) gets
> > > very
> > > > hot,
> > > > > > IC
> > > > > > > 14 , 9 and IC 17 gets hot, also when you
> > > play
> > > > the
> > > > > > > keyboard there´s is sound, not in scale,
> > > > > > additionally
> > > > > > > as you play, the menu´s system changes going
> > > > from
> > > > > > > everything to everything
> > > > > > (master---traspose---change
> > > > > > > patches---select, etc)even performs a
> > > sequence
> > > > on
> > > > > > the
> > > > > > > diskette and blocks the keyboard....tottally
> > > a
> > > > > > mess.
> > > > > > > When you push a button in the panel the
> > > system
> > > > > > crash
> > > > > > > and no sound and changes, hanging the last
> > > > > > > note.....despite all this stuff, the patches
> > > > > > sounds
> > > > > > > very good. Really there´s some processor not
> > > > doing
> > > > > > > well its job, i don´t think i can find one
> > > of
> > > > > > these
> > > > > > > IC´s nowadays, is there any method for
> > > > reseting
> > > > > > this
> > > > > > > devices.
> > > > > > > Saludos
> > > > > > > ricardo
> > > > > > >
> > > > > > > --- Wayne Griffin <ingsoc_1979@...>
> > > > wrote:
> > > > > > >
> > > > > > > > What are the IC #'s on the chips? What do
> > > > the
> > > > > > chips
> > > > > > > > say on them??? Did you also reseat
> > > > *everything*,
> > > > > > > > todos
> > > > > > > > on the second board, attached to the
> > > > > > motherboard?
> > > > > > > > [w]
> > > > > > > >
> > > > > > > > --- RICARDO JUAREZ <cheju_99@...>
> > > > wrote:
> > > > > > > >
> > > > > > > > > Wayne:
> > > > > > > > > Could you be more specific about the
> > > test
> > > > of
> > >
> > === message truncated ===
> >
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> 
> 
> 
> [Non-text portions of this message have been removed]
>