I have resolved that to get my H7874 PSU working better I am going to have
to bite the bullet and replace some electrolytic capacitors which cannot be
desoldered from below, at least not without some significant surgery on the
board (there are components soldered to the underside of the board and
attached to a large heatsink, all those components would have to be
desoldered so that the heatsink can be removed to get access to the
underside of the board).
I have had the suggestion to pull the old ones out from above, and then
solder in the new ones from above. These are relatively small radial types
(330uF, 25V).
I am sure the pins will just pull out of the bodies of the capacitors,
leaving me to desolder the pins from above, which should be OK. But, I am
worried about doing damage to the board by just pulling them "cold". Are
they really just going to pull out of the capacitor body, or does anyone
have any tips for doing this in the least damaging way possible?
Thanks
Rob
looks good Todd!
wall art is good to have!
Ed#
In a message dated 12/28/2015 10:54:47 A.M. US Mountain Standard Tim,
tsg at bonedaddy.net writes:
For what it's worth, I bought myself a Christmas present of:
http://www.ebay.com/itm/151918395795
Which is a print of a PDP-1 system (well, part of one anyway) on canvas.
It's not inexpensive but the ePay auction has a %-off "sale" going on
and the web site has coupons available to reduce the list price.
If you don't want to deal with ePay then you can check out their web
site at http://www.greatbigcanvas.com.
No connection and I can certainly understand that people might want to
spend the not inconsiderable amount on real hardware but I was pleased
with the result when it arrived today.
Todd
is this Evan?
if
In a message dated 12/28/2015 11:33:10 A.M. US Mountain Standard Tim,
cctalk at snarc.net writes:
> or who ever was supposed to get it done!
> Ed#
I don't know what "plaque dedication" you're talking about.
Email me privately / off-list.
Hi Mike,
A few corrections:
1) Some disk OEM's produced 3340 compatable diskdrives in the 70's.
The OEM manufacturer connected their equipment direct to the internal S/3
channel.
I have only seen 1 CPU at a scrapper which had this.
2) The BUS/TAG connector/cables are the same as used by IBM for 360/370
channel, but are used between the IOP and the 3340 disk string.
They do not carry 360 channel signals but special IOP --> disk signals.
3) CPU --- int chan ---> IOP ---> IDE/SCSI drive. (IOP has modified HW & FW)
See:
http://www.mirrorservice.org/sites/www.bitsavers.org/pdf/ibm/370/fe/3125/SY3
3-1063-1_3125_Processing_Unit_Input_Output_Processor_Nov73.pdf
Regards Henk
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~
On Sun, Dec 27, 2015 at 10:29 PM, Henk Stegeman <h.j.stegeman at hccnet.nl>
wrote:
> Hi Mike,
>
> Here are the options to attach 3340 DASD emulation to an IBM System/3
>
> 1) direct connect to the internal channel of the S/3. Some disk OEM's did
> this.
> Requires a FPGA with at one side MST-1 interface logic and at the other
side
> IDE or SCSI interface.
> The availabe IBM documentation is complete enough to finish this project.
> You need good IBM HW & VHDL knowledge.
Oh interesting - I had no idea! Do you have names and product numbers
for those OEMs? Any more info? Ever seen one?
If they were sold commercially by OEMs then the project already IS
finished so to speak; it's just a question of *finding* one! Or
finding the documentation and using that as a basis for re-creating
the OEM solution.
It doesn't require any hard-to-perform or reverse changes to the S/3?
No backplane rework or wire wrap? It was just a case of plugging OEM
cards into appropriate slots?
> 2) direct connect to the BUS/TAG interface connector.
> This needs a 8+P bit stream. You have to do some reverse engineering to
> figure out what the exact format is.
> I have no idea if the HW must be implemented in a FPGA (for timing
reasons)
> or if an AVR processor will do the job.
> Advantage is that you don't have to modify anything inside the S/3.
And the other advantage is that it could be part of a more
generalizable device that could be used to replace other Bus/Tag
peripherals on other IBM systems... if some of us were to start a
home-brew project that might be the best approach to take.
> 3) IBM has implemented an IOP (I/O Processor) between the S/3 CPU and the
> 3340 drives.
> This IOP is a modified version of the ones used in the IBM 370/115 & 125.
It
> is a powerfull multi thread capable beast.
> With small HW modification you can connect an IDE or SCSI drives to it.
> The difficult part is modifying the firmware of the IOP. This requires a
> special assembler (to be written) and very good assembler skill's.
If IBM have already implemented it then ready to use IOPs exist or at
one time existed out there in the wild... your reference to modifying
IOP firmware... do you mean to connect to the S/3 - or to attach IDE
or SCSI? Or both? Does this IOP have an IBM model number? Was it a
separate box or a set of cards and backplane that could be installed
in the 370? I hope to be getting a 370/125 next year...
Fascinating info Henk; I had no idea any of this stuff existed. I
thought the only options for S/3 5415 were real hardware 3340s or
nothing.
Mike
I have the following backplanes, most have all the boards with them.
DB11-A bus repeater
DH11-A 16 chan com
DP11-PA
DR11-B general purpose interface
DV11-
RK611- I have one put aside for another list member
RM11-A massbus
TM03 tape formatter
Several DD11-D backplanes- 9 slot spc
Please contact me off list if you have any questions or interest. There may
be a few more later. Shipping from 61853
Thanks, Paul
or who ever was supposed to get it done!
Ed#
In a message dated 12/28/2015 10:32:51 A.M. US Mountain Standard Tim,
cctalk at snarc.net writes:
> Did they ever get the plaque dedication video finished Evan?
> Ed#
They?
For what it's worth, I bought myself a Christmas present of:
http://www.ebay.com/itm/151918395795
Which is a print of a PDP-1 system (well, part of one anyway) on canvas.
It's not inexpensive but the ePay auction has a %-off "sale" going on
and the web site has coupons available to reduce the list price.
If you don't want to deal with ePay then you can check out their web
site at http://www.greatbigcanvas.com.
No connection and I can certainly understand that people might want to
spend the not inconsiderable amount on real hardware but I was pleased
with the result when it arrived today.
Todd
Did they ever get the plaque dedication video finished Evan?
Ed#
In a message dated 12/27/2015 10:45:51 P.M. US Mountain Standard Tim,
cctalk at snarc.net writes:
Good news! A bunch of old VCF East/West videos are going onto YouTube,
thanks to ANTIC / Atari Podcast's Kevin Savetz stepping forward to do
the grunt work.
The first batch are talks from VCF East 6.0 (2009). YouTube playlist is
at https://t.co/yYRr7rP7R4.
We also asked Jason Scott to bring the videos into Archive.org as they
go online.
> From: Mark Matlock
> either 11/23 or 11/73 CPUs (limited to 256KB by the MINC Q18 bus)
Have you thought about upgrading the backplane/bus to 22 bits (shouldn't be
too hard) - or do you want to keep it original?
Noel
