12 Jan
2012
12 Jan
'12
4:49 p.m.
I have two working Defender board sets that I'm almost ready to start building
cabinets for. I'm scoping out new power supplies (I have the linear ones they came
with but no giant transformers for it; I've been using PC power supplies but would
like to use something with no moving parts). Does anyone know the approximate rail
requirements for it? They don't seem specced in the drawings/theory of operation
manuals anywhere. An old 230W AT power supply seems to work fine, but I don't think I
need anything that heavy-duty.
I know the 5v is going to pull a lot because it's used for most of the logic, and the
regulated 12v and -5v are probably somewhat heavy since they power the sense amps for the
24 4116s. As far as I can tell, the unregulated 12v is only used to power the audio amp
and the -12v (unregulated) is only used for the negative reference on the audio DAC; am I
missing anything? I haven't measured current draw per rail yet, mostly out of
laziness (and missing a few sizes of .156" plugs).
BTW, the Apple color monitor they sold with the IIgs works great as an arcade monitor in a
much smaller size if you can set the sync polarity correctly. Fortunately, Defender has
solder jumpers for selecting that.
- Dave
8:21 p.m.
On Jan 12, 2012, at 7:27 PM, Alexandre Souza - Listas wrote:
Because the fan is making noises like it won't work for long. In general, I'd
rather have no moving parts in there, since a fan is much more likely to fail over time
than old logic (I got these boards off Ebay and only had to replace a total of 8 chips,
only one of which was not a 4116, and that's on a 30-year-old board).
Also, I only have one power supply between the two sets.
- Dave
requirements
for it? They don't seem specced in the drawings/theory of operation manuals anywhere.
An old >230W AT power supply seems to work fine, but I don't think I need anything
that heavy-duty.
If it is working, WHY MESS WITH IT??? :o) 
9:30 p.m.
Because the fan is making noises like it won't
work for long. In general,
I'd rather have no moving parts in there, since a fan is much more likely
to fail over time than old logic (I got these boards off Ebay and only had
to replace a total of 8 chips, only one of which was not a 4116, and
that's on a 30-year-old board).
Have you tried to use the AT PSU without the fan? Sometimes the current
used is so low, it can turn the fan off
Also, I only have one power supply between the two
sets.
But an ATX power supply is SO cheap...Do you need any help hooking it up
directly to the board and measuring current?
13 Jan
13 Jan
12:42 a.m.
On Jan 12, 2012, at 9:30 PM, Alexandre Souza - Listas wrote:
Wasn't in the mood to open up the power supply. I'm not a huge fan of using the
AT power supply to begin with; I had to chop off the ends to stick 'em in .156"
headers anyway (which I don't feel too badly about because they're cheap generic
PC supplies, not an actual vintage item).
I could use an ATX supply if I wanted to put a soft switch in. At some point, I'll
have to make a board to wire up whatever supply I use to the .156" pins anyway, so
why not? They are, in fact, cheap. But I also like the dedicated, fanless ones.
Sometimes it's a matter of aesthetics.
- Dave
Because the
fan is making noises like it won't work for long. In general, I'd rather have no
moving parts in there, since a fan is much more likely to fail over time than old logic (I
got these boards off Ebay and only had to replace a total of 8 chips, only one of which
was not a 4116, and that's on a 30-year-old board).
Have you tried to use the AT PSU without the fan? Sometimes the current used is so low,
it can turn the fan off Also, I only
have one power supply between the two sets.
But an ATX power supply is SO cheap...Do you need any help hooking it up directly to
the board and measuring current?
7:48 a.m.
Wasn't in the mood to open up the power supply.
I'm not a huge fan of
using the AT power supply to begin with; I had to chop off the ends to
stick 'em in .156" headers anyway (which I don't feel too badly about
because they're cheap generic PC supplies, not an actual vintage item).
I use them in all kind of projects, and have no problems.
I could use an ATX supply if I wanted to put a soft
switch in. At some
point, I'll have to make a board to wire up whatever supply I use to the
.156" pins anyway, so why not? They are, in fact, cheap. But I also like
the dedicated, fanless ones. Sometimes it's a matter of aesthetics.
It is up to you, but ATX power supplies are cheap :) You don't NEED to
put a soft switch. Short the green wire with a black wire, and key the AC
supply. It works :)
9:22 a.m.
On Jan 13, 2012, at 7:48 AM, Alexandre Souza - Listas wrote:
I don't have a problem with the power supply itself, it's the chopping up that
makes me nervous. It's not a technical thing, it's a guilt thing. :-) An
entirely misplaced one at that, I'll admit.
True, and I do that often enough. About half the ATX supplies out there have a mains
switch built into the back, too (would be nice if they still had the passthrough for the
monitor plug that the AT supplies used to have.
- Dave
Wasn't in
the mood to open up the power supply. I'm not a huge fan of using the AT power supply
to begin with; I had to chop off the ends to stick 'em in .156" headers anyway
(which I don't feel too badly about because they're cheap generic PC supplies, not
an actual vintage item).
I use them in all kind of projects, and have no problems. I could use an
ATX supply if I wanted to put a soft switch in. At some point, I'll have to make a
board to wire up whatever supply I use to the .156" pins anyway, so why not? They
are, in fact, cheap. But I also like the dedicated, fanless ones. Sometimes it's a
matter of aesthetics.
It is up to you, but ATX power supplies are cheap :) You don't NEED to put a soft
switch. Short the green wire with a black wire, and key the AC supply. It works :)
9:29 a.m.
On Jan 13, 2012, at 7:48 AM, Alexandre Souza - Listas wrote:
It is up to you, but ATX power supplies are cheap :)
You don't NEED to put a soft switch. Short the green wire with a black wire, and key
the AC supply. It works :)
Hm, looking into it, though, it looks like modern ATX supplies have done away with the -5v
wire (which makes sense, since there's not much that uses it that can't use the
-12v through a switcher/LDO these days). Perhaps I'll just have to be picky. :-)
- Dave
9:45 a.m.
Hm, looking into it, though, it looks like modern ATX
supplies have done
away with the -5v wire (which makes sense, since there's not much that
uses it that can't use the -12v through a switcher/LDO these days).
Perhaps I'll just have to be picky. :-)
Yes, they did. -5V was used only in ISA/EISA buses, seems that PCI
doesn't use that anymore (I may be wrong). Anyways, you can take -5V
from -12V, a 7905 may help you :)
I try to keep "period correct" my old computers. But sometimes (did I
heard "Commodore 64 and the big brick of death!" on the back???) if you use
te puter everyday, it is better to put a beefy, stable and NEW PSU.
12 Jan
12 Jan
7:50 p.m.
On 1/12/12 1:49 PM, "David Riley" <fraveydank at gmail.com> wrote:
I have two working Defender board sets that I'm
almost ready to start building
cabinets for. I'm scoping out new power supplies (I have the linear ones they
came with but no giant transformers for it; I've been using PC power supplies
but would like to use something with no moving parts). Does anyone know the
approximate rail requirements for it? They don't seem specced in the
drawings/theory of operation manuals anywhere. An old 230W AT power supply
seems to work fine, but I don't think I need anything that heavy-duty
http://www.mikesarcade.com/arcade/manuals.html
There are defender theory of operation manuals there. Old and new boardsets.
Towards the end there is information on the overcurrent levels of the
powersupplies.
13 Jan
13 Jan
12:43 a.m.
On Jan 12, 2012, at 7:50 PM, Geoffrey Reed wrote:
http://www.mikesarcade.com/arcade/manuals.html
There are defender theory of operation manuals there. Old and new boardsets.
Towards the end there is information on the overcurrent levels of the
powersupplies.
I have those, but I guess I hadn't been reading them closely enough. They do indeed
detail the overcurrent mechanisms; doesn't specify the load they expect to see, but I
should be able to extrapolate a bit.
- Dave
12 Jan
12 Jan
10 p.m.
On Thu, Jan 12, 2012 at 4:49 PM, David Riley <fraveydank at gmail.com> wrote:
I have two working Defender board sets that I'm
almost ready to start building cabinets for.
Nice.
I know the 5v is going to pull a lot because it's
used for most of the logic
Sure.
and the regulated 12v and -5v are probably somewhat
heavy since they power the sense amps for the 24 4116s0.
Not so much current there... if you can't find official specs, I
_know_ the 4116 datasheets aren't hard to find. ISTR it's a few mA
per chip for -5V, and I think it's a bit more of +12V. I do remember
that I wanted to replace a 7905 with an ICL7990 charge-pump negative
voltage supply and it was way too small for 16 4116s.
One thing to be careful of is that 4116s are sensitive to the order
that rail voltages are applied and removed. Some classic memory
circuits explicitly control the order, but others I've seen are less
stringent, depending on, I think, charging a large electolytic cap on
the rail that is supposed to be brought up last (can't remember the
proper order - someone else here might, or it should be in the
datasheet). You should be able to find the schematics for the
Defender power supply - be on the lookout for any parts that look odd
or look like they might affect on/off or rise time.
Good luck!
-ethan
13 Jan
13 Jan
12:45 a.m.
On Jan 12, 2012, at 10:00 PM, Ethan Dicks wrote:
One thing to be careful of is that 4116s are sensitive
to the order
that rail voltages are applied and removed. Some classic memory
circuits explicitly control the order, but others I've seen are less
stringent, depending on, I think, charging a large electolytic cap on
the rail that is supposed to be brought up last (can't remember the
proper order - someone else here might, or it should be in the
datasheet). You should be able to find the schematics for the
Defender power supply - be on the lookout for any parts that look odd
or look like they might affect on/off or rise time.
Good to keep in mind. It's worked fine with the AT supply so far, and I don't
remember seeing a sequencing requirement in the datasheets, but it's possible I
overlooked it. Jameco still sells replacements fairly cheap, but I don't relish the
thought of having to replace 24 of them. :-)
- Dave
4:13 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of David Riley
Sent: 13 January 2012 05:46
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Defender power requirements?
On Jan 12, 2012, at 10:00 PM, Ethan Dicks wrote:
There is some times a statement that the power voltages should never cross
which implies there is also a power off requirement as well...
One thing to be careful of is that 4116s are
sensitive to the order
that rail voltages are applied and removed. Some classic memory
circuits explicitly control the order, but others I've seen are less
stringent, depending on, I think, charging a large
electolytic cap on
the rail that is supposed to be brought up last
(can't remember the
proper order - someone else here might, or it should be in the
datasheet). You should be able to find the schematics for the
Defender power supply - be on the lookout for any parts
that look odd
or look like they might affect on/off or rise
time.
Good to keep in mind. It's worked fine with the AT supply so
far, and I don't remember seeing a sequencing requirement in
the datasheets, but it's possible I overlooked it. Jameco
still sells replacements fairly cheap, but I don't relish the
thought of having to replace 24 of them. :-)
- Dave
4608
days inactive
4609
days old
13 comments
5 participants
participants (5)
-
dave.g4ugm＠gmail.com -
ethan.dicks＠gmail.com -
fraveydank＠gmail.com -
geoffr＠zipcon.net -
pu1bzz.listas＠gmail.com