Hello everyone,
First off, I should say that I'm a relative neophyte when it comes to
all things Neotek (and console tech-ing in general), so hopefully I
don't ask too many silly questions...
Short story is that I'm starting work on slowly sprucing up a 24 ch.
(20 ch. currently installed) Elan that belongs to a friend of mine
(Casey Rice...he posted here before Christmas about the meters on some
channels spontaneously switching between peak and VU modes.). IIRC,
the console was built in '91.
First up on the list of things to do is to give the power supply a
good going over. Until last weekend, the console was running off a
PS3-01 that is now getting a bit tired (I say was, as it is now
running off a PS4-01 that was purchased a while back as a spare - by
the way, do the PS4s generally run a bit hotter than the PS3s? This
one certainly seems to, though I didn't really check exactly how hot
the PS3 was before so that's a subjective observation...)
The PS3 appears to be in original condition with little or no work
done on it. As mentioned, it is still operational, but no longer quite
up to scratch. Adjusting the +/- 18V trimpots to their maximum
settings gives me +16.6V and -16.33V, with the console connected.
However I have not tried adjusting the over voltage protection trimpot
as I didn't have the 15k resistor handy to set it as described in the
documentation.
The phantom supply looks good (reading 48.6V) but the logic supply is
also down a bit; -22.5V instead of -25V.
The unregulated meter supply is reading 34V but has a 100Hz,
approximately 2Vp-p sawtooth ripple on it.
I guess this is causing the occasional random meter problems described
in the other thread. AFAIK it hasn't happened again since I switched
over to the PS4.
Noise/ripple looks good on all the other supplies though when checked
on the scope though and the console noise floor seems to be fine.
There's not a whole lot of evidence of serious overheating or much
burnt out except for the 0.1uF ceramic capacitor across the input to
the logic supply, which has split open and also the 1N5401 diodes
across the TIP35/36B transistors look a bit toasty (especially on the
+ve supply).
The plan is to replace all of the electrolytic capacitors, the burnt-
out ceramic, those 2 diodes, renew the heatsink compound on all the
silicon and then re-calibrate (and also check short-circuit
protection) per the documentation.
Basically just wanted to ask if anyone has any advice or
recommendations on other things check or replace? Or does this seem
like an appropriate first (and hopefully last) step?
Also, I was planning to stick with Nichicon caps; thinking using the
PW series (low impedance, long-life, 105degC):
http://au.mouser.com/ProductDetail/Nichicon/UPW1V472MHD/?qs=V4Q4DNvfnliPoJjHSDt1Yg%3d%3d
Obviously they are physically much smaller than the original caps and
have a smaller lead pitch (will probably put a drop of silicon under
each one to help support them). Is this a good cap choice, or should I
consider upsizing them? My inclination would be to do so as a matter
of course, but it looks like the PW series tops out at 4700uF in 35V
and anything larger that I could find wasn't "Long Life". Happy to
accept suggestions for other caps - this was the best I could come up
with after a while of bouncing between the mouser and nichicon websites.
Thanks in advance and best regards,
-Matt.
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