Alesis power supply type P4 (1622 mixer)
ChrisK
My good old 1622 mixer's power supply (PSU) just died. I need to urgently
build a replacement to continue my work this week-end. Could someone please
give me information about the pin layout of the DIN connector, and the
voltage and current specs ?
Any help greatly appreciated.
Best regards,
Christian Knecht
Switzerland
Scott Dorsey
>
>My good old 1622 mixer's power supply (PSU) just died. I need to urgently
>build a replacement to continue my work this week-end. Could someone please
>give me information about the pin layout of the DIN connector, and the
>voltage and current specs ?
Wouldn't it be easier to fix the old one? With the old one, you should have
two regulator circuits that are mirror images of one another, so you can
track through and compare the two one stage at a time.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
ChrisK
Yes, it could be. The first problem is opening it up: they are built never
to be opened. Then I am surprised you talk about regulators : are there
really regulators in the external power supply itself ? I though they would
be in the device. What exactly do you know about this P4 type power supply :
should I be able to measure anything on the 4 pins of the DIN connector or
is one of the pins used to switch the power on ? I ask because I can't
measure anyhing at all (seems all high impedance). And I ask also because I
know the 1622 mixer's power switch has been working not very well sometimes
in the past.
[pause]
I just disassembled the 1622 to get access to the power connector and power
switch: it is clear now that the board is supplied with only a single 9V
power line. Actually, from the 4 pins of the DIN connector, two are
connected to ground, and 2 are connected together and rounted to two el-caps
before going to some regulator circuits (difficult to see precisly).
[pause]
I finally disassembled the power supply using brute force and found that
there was a soldered fuse in there, which had burned through. As a quick fix
(yes, absolutely *not* recommended), I removed the fuse and I will use the
power supply without fuse for the time needed to order a new one.
Here is the answer to my own questions:
Pin layout and voltage : if you look at the DIN connector with the mark at
the top, the left two pins are wired together, and the right two are wired
together. These two pairs supply the 9V AC (measured 9.9V AC, not loaded) :
they are directly connected to the secondary of the transformer.
Christian
"Scott Dorsey" <klu...@panix.com> wrote in message
news:cg5cuk$3na$1...@panix2.panix.com...
Scott Dorsey
>
>I just disassembled the 1622 to get access to the power connector and power
>switch: it is clear now that the board is supplied with only a single 9V
>power line. Actually, from the 4 pins of the DIN connector, two are
>connected to ground, and 2 are connected together and rounted to two el-caps
>before going to some regulator circuits (difficult to see precisly).
Man, that is nasty. No bipolar supply at all?
OR, is there AC coming in from the wall wart supply with a center tap,
and it gets rectified on the board and turned into two supplies?
>I finally disassembled the power supply using brute force and found that
>there was a soldered fuse in there, which had burned through. As a quick fix
>(yes, absolutely *not* recommended), I removed the fuse and I will use the
>power supply without fuse for the time needed to order a new one.
It could have been due to shock. It might not be due to shock and it might
be due to something on the secondary side of the transformer failing. Go
to your local auto parts store and pick up a pack of 3AG fuses.
>Pin layout and voltage : if you look at the DIN connector with the mark at
>the top, the left two pins are wired together, and the right two are wired
>together. These two pairs supply the 9V AC (measured 9.9V AC, not loaded) :
>they are directly connected to the secondary of the transformer.
Okay, so the wall wart is _just_ a transformer, not the whole power supply.
Is there a center tap on it?
Mike Rivers
> Here is the answer to my own questions:
Good work. It's nice when people do that, perhaps after a little
encouragement, rather than wait for someone else to do it for them, or
try to make sense out of 20 guesses from people who have never seen
the equipment.
Running without the fuse may cause something else more expensive and
harder to replace to act like a fuse.
--
I'm really Mike Rivers (mri...@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo