C64 Porer supplies...
I have a box full of C64 P/S's ...I sell them for $18 plus S/H, 60 day
warranty. Got cables and manuals and lotsa software, too.
I don't have any 128's. Anyone wanna get rid of one cheap? Trade a slightly
used Panasonic HHP for one :>
> >The next question would be, is it worth trying to repair a C64's power
> >supply? I got two of them yesterday, both powersupplies are dead. It
> >looks like the 5V line is shorted to ground. I did get a copy of the
Old &
>
> if it is potted, NOPE. some are unpotted and can be fixed.
>
> >New style users manuals, and a copy of "Troubleshooting and Repairing
your
> >Commodore 64" yesterday (I love Powells Technical Books!) so I've got
some
> >documentation. It's been too many years since I worked as an
Electrician,
> >so my skill level is pretty low (wasn't very high to begin with, which
is
> >why I switched to computers).
> >
>
> I have these manuals too and I must say that it leaves no tern left
unstoned.
>
In a message dated 97-07-15 13:32:57 EDT, you write:
<< IMHO the ST-4096 FH 80 MG was the most reliable of this era. I spent over
600.00 for this drive new and used it for more than 20 years, and ended up
selling it to a business for 50.00 to replace their dead st-251.
>>
hmm, my experience is just the opposite with this drive. I had 6 out 7 fail
in less than 6 months back in 1990. The 4096 was just hideous.
Kelly
I dug out the PC-jr Techref (in order to look up details on the joystick), and
I also looked at the PSU diagrams (page B-23 in my edition). We had a thread on
this about a month ago, mainly about the external transformer unit which I
don't have.
Now, the input connector is a 3-pin thing. The centre pin is connected to
shield ground, and then via L3 and L4 on the system board to logic ground. It's
thus a DC connection to the system ground.
The outside 2 pins go through a filter to the AC terminals of a bridge
rectifier (CR7 - CR10) and the output of this goes (via the power switch) to a
1500uF 25V capacitor (C13). The -ve side of this capacitor is also connected
to system ground.
Thus, IMHO it makes no sense at all for the transformer to be centre-tapped
with the tap going to pin 2 on the connector. If it was, the winding would
be paritially shorted out by the diodes in the bridge rectifier, which would
cause a lot of damage. Also, since C13 is only rated at 25V, the maximum input
rms voltage is 25/sqrt(2) volts, which is a lot less than 34V. I therefore
still believe that it's a plain 17V transformer between the 2 outer pins on
the connector.
Incidentally, the +12V output comes from a standard linear regulator, the
+5V output from a switching regulator (Z2 is the control IC, Q2 the chopper,
and L1 the switching inductor). The -12V output is supplied by a secondary
winding on L1, which is then rectifier and smoothed.
It's always possible that IBM used several versions of the PSU card, but the
schematic in my Techref seems to agree with the one in my machine.
-tony
> Haven't found a IBM cassette recorder either but I did pick up an IBM
> joystick (had IBM logo on it and the word "Joystick") plus it had a funky
> square connector which looked like it goes to the PCjr.
I've dug out the PC-jr Techref, and there's some info in it on the joystick.
> (MS-DOS machines) since about 1983 and I have yet to see one. Another
> thing I've been looking for without success is an IBM Cassette recorder
> for the IBM PC cassette interface. I've heard they really do exist.
Now that's something I've never seen.
One interesting point is that the pinout of the cassette socket on the PC
(although not on the PC-jr) is the same as that on a Tandy Model 1/3/4/Coco/etc
It is rumoured that IBM intended you to go down to the local Radio Shack and
buy one of their recorders + cable.
-tony
>
Somebody in the Berkeley area might want to answer this call to duty.. I'd
be thrilled to get the Sun 1 clone, but it'd cost several hundred
dollars to ship up here.
ok
-r
---------- Forwarded message ----------
Date: 15 Jul 1997 07:39:46 GMT
From: Paul Leondis <leondis(a)slip.net>
Newsgroups: misc.forsale.computers.workstation
Subject: antique computer blowout
I'm looking to get rid of some stuff, let me know what you think:
I've got a huge amount of old S-100 bus stuff, almost all of it with
technical manuals and software on diskette, that was working the last i
knew. Most is Godbout stuff, some Morrow, some Dual, etc. Lots of 8"
floppy drives and diskettes. I have most of the processor boards that were
released by Godbout, including 8088, 8086, Z80, 8080, 68000, and i even
have some of the National Semiconductor 32000 series cpus on S-100 cards.
I have all the stuff like CP/M 68K with the associated assemblers and
linkers etc.
I also have a complete working [?] Sun I clone: yes, that's right, the
first SUN design was public domain (did you know that?? At least that's the
way i understand it...) and a company called Forward Technology made clones
of that design. It has a 68K cpu running in a multibus one chassis, and i
have lots of peripherals for it, including 9-track tape drive and 1/4"
tape drives and disk controllers for several interfaces. I've got all the
relevent software, inc. V7 unix and a mess of compilers. I have the (at
the time) very high res monochrome monitors that went with the system.
It's a real wrench for me to let go of this stuff, if you were in this
field 10 or 15 years ago you know what i paid for some of the stuff. But
i'm tired of hoarding it all. So, i will take the best offer i can get for
all of the stuff. My reserve bid is $0, that is i will give it away if
that is the best offer. I will probably be most moved by someone that may
actually get some pleasure out of the stuff and esp. someone that would
want to take the whole lot. There is a free city dump day coming up in my
part of town on July 19th, so i'd like to settle the stuff by then so i can
dispose of whatever is left at that time.
Paul Leondis
leondis(a)slip.net
510-649-0993 phone
Berkeley, CA
IMHO the ST-4096 FH 80 MG was the most reliable of this era. I spent over
600.00 for this drive new and used it for more than 20 years, and ended up
selling it to a business for 50.00 to replace their dead st-251.
----------
> From: jpero(a)mail.cgo.wave.ca
> To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
> Subject: Re: What Classic Computer are All About - A Lovers
> Date: Tuesday, July 15, 1997 7:59 AM
>
> Allison,
>
> I gently disagree with this assertion that ST251 series is good than
> ST225 series. I got too many dead ST251 series compared to ST225's
> due to weaker structral design, pushed design by driving steppers too
> hard byond 40ms average and not as rugged as ST225's.
> I noticed the relationship between higher stepping rate and
> terrible high failure rate on many hard drives such as ST251's,
> Miniscribes and early 40meg western digital drives compared to
> very slow stepping rate on most drives did last long time byond its
> goal set by designers. If one wants faster seeking time, go voice
> coil! I am dreaming wishing that ST251 drive was fitted with voice
> coil instead of stepper and better motor design...sigh.
>
> Those ST225, ST250 are really best consumer's drives and ST251 series
> might be a mistake at cutting corners well as ST277, ST296 are same
> design.
>
> I wished that segate designed ST251 case
> more rugged and used internal spindle motor with bearings on outside
> and one screw on top of cover to stablize the motor from top. Then
> this ST251's would be possible to be expanded to 100 or 120 size
> reliably. Whole problem was that design of this ST251 spindle motor
> is ill-designed to begin with in my opinion: Trying to fit all the
> coils and one bearing INSIDE that spindle results in weak axle that
> gets bent easily due to this design and the bearings failure rate on
> this one is high too.
>
> Recently I pulled this ST225 out of dumpter and fixed
> up the XT with this hd and LLF'ed it. Gave whole thing to poor guy
> to use vax at college. Still works.
>
> I tore down all kinds of drives from old and 3 years old types for
> post-failure analysis which gave pretty good info for me.
>
> > ->X-Sender: cerebral(a)michianatoday.com
> Snip!
>
> > First off why bother withg the st225s? They are slow (st251s are
> Snip! Tales of positive things about cooling...
> > If the fan isn't noisy it isn't moving enough
> > air past them, seriously!
> Actually, all drives old and new benefits from cooling and boards
> likes the flowing cooling air.
>
> > Also if they are in the smae box as all the
> > other hardware they raise the other components temperature lowering
their
> > life. Heat is not your friend, this is why computer rooms are air
> > conditioned an usuialy under 70 degrees F.
> We have no choice as many does not have AC so they ran in warm air
> but if you are careful, enough fans to make hurriance out of it and
> put a fan or two on monitor as well. My 17" needs two otherwise the
> HOT transistor will pop again. ARRGgghhh.
>
> > Allison
>
<PC500
<RCD31
<
<The PC500 seems to be a display with a 5.25 inch floppy drive and some
<electronics. It is mounted on top of the RCD31 unit which is in a pizza
<box style case. Is this some sort of PC clone or maybe a DecMate?
It's called a Vaxmate. what it is is a PC/AT clone(sorta) with a 8mhz 286
and most had 2meg of ram, wd1003 HD controller, an st225(rd31) or
st251(rd32) and a Lance eithernet interface. The floppy is RX33 (1.2mb).
These are nice machines and were aimed at running as a diskless workstation
to vaxen on eithenet using PCSA and later Pathworks networking. It will run
dos3.3 and 5.0 that I know of.
Allison
Typo was intended to be 10, but it was still undauntingly reliable.
----------
> From: jpero(a)mail.cgo.wave.ca
> To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
> Subject: Re: What Classic Computer are All About - A Lovers
> Date: Tuesday, July 15, 1997 8:34 AM
>
> > Date: Tue, 15 Jul 1997 12:07:09 -0500
> > Reply-to: classiccmp(a)u.washington.edu
> > From: "Bill Girnius" <thedm(a)sunflower.com>
> > To: "Discussion re-collecting of classic computers"
<classiccmp(a)u.washington.edu>
> > Subject: Re: What Classic Computer are All About - A Lovers
> > X-To: <classiccmp(a)u.washington.edu>
>
> > IMHO the ST-4096 FH 80 MG was the most reliable of this era. I spent
over
> > 600.00 for this drive new and used it for more than 20 years, and ended
up
> > selling it to a business for 50.00 to replace their dead st-251.
>
> Had to ask! Are you kidding? :) None 5.25" hds came out til after
> '82 when lot of hds bigger than 8" was king. !!!! 20 yr old
> ST4096? Impossible! More like 8 or 9 years.
>
> Seagate started on this design after 1986. Is this one of yours
> that only have one board on bottom with only platter cover painted
> black? That is last generation of this design which is finally
> reliable. Earlier ones had teething problem of all kinds, no
> kidding. All the way back to early first linear voice coil of ST4025
> between 1985 through '88. I pick them up all the time are almost
> always dead due to bearing failures. These drives are best left
> running horizontal right side up.
>
> Jason D.
> The PC500 seems to be a display with a 5.25 inch floppy drive and some
> electronics. It is mounted on top of the RCD31 unit which is in a pizza
> box style case. Is this some sort of PC clone or maybe a DecMate?
No, I suspect it's a VAXmate. The VAXmate is a 286 PC clone with some
special DECness (Ethernet, included software to do DECnet).
Roger Ivie
ivie(a)cc.usu.edu
PS: Rumor has it that the VAXstation 2000 folks were really pissed that
the name 'VAXmate' was already taken...
