Epson PF10 problems

[Tony Duell]

> > There are part diagrams to explain the various sections, and these are a
> > lot easier to follow. THe PSU is not at all simple (and depends on the
> > NiCd to act as a shut regulator on the main logic supply line). Heck,
> > there's even a 4-bit microcontroller and a 6 bit ADC in the middle of it
> > all.
> >
> > But I can try to talk you through it if you want me to.
> 
> Let me see what I can get a hold of.

I've jsut cured a problem with the PSU section of my PX8. The fualt with 
mine  was that you connected power (actually a 5V bnech supply to the 
battery connector [1]), turned on the power switch and pressed the 
sub-CPU reset button (in the ROM compartment), and it came up fine, 
everything worked. But if you turned it off at the power switch, it 
wouldn't come on again unless you did the full reset (clearing memory, etc).

It turned out there is a supply line that is always-on, to keep the RAM 
(actually DRAM!), its controller, the PSU-control micro, etc alive. This 
can be switched between the main battery and a backup battery on the PCB, 
and one of the transistors in that circuit was open-circuit base-emitter. 
A new BC807 (first SMD PNP transistor I found) got it going again. 

[1] If anyone needs to make up a battery pack for the PX8, or a cable to 
link the battery connector to a bench supply, sockets to fit the 
connector on the PX8 mainboard are available from RS components in the 
UK. Use 311-6209 housings with 311-6439 terminals


> > It's not the same, but there are various drive emulators for PCs. The
> > 'serial' port on the PX8 is at RS232 levels, and the disk drive just uses
> > the TxD and RxD pins (it's a subset of the pinout of the RS232 port
> > alongside it, you can use the same cables, essentially). It runs at 38400
> > baud.
> 
> Just being able to get info into and out of that machine would be nice.

Talking of that, is the protocol used by FLINK documented anywhere? 
(FLINK is a program in the utilities ROM of both the PX4 and PX8 that 
seems to do file transfer over the RS232 port). I've heard rumours for a 
version in C for unix machines, but can't seem to find it anywhere.

Anyway, the disk emulaotr program I found was called vfloppy13.tgz. The 
archive is vig (about 300K) becuase it includes 3 disk images that you 
might need. The linux part of the system is GPLed (no flames, OK...)

> 
> > I've downloaded a disk emulator for linux.
> 
> Pretty much what I run here -- which distro do you use?

Very old Debian. 

> > > > I had to make up my own cable, but I have checked and double-checked
> > > > it, and anyway it works fine to link a PX8 to a PX4 via the RS232
> > > > interfaces (essentially the same pinout as the 'high speed' serial
> > > > interface to the disk drive). In fact what I did was make up a cable
> > > > from the 8 pin nini-DIN plug to fit the PX8 to a DB25 plug,, wired as a
> > > > DTE and a second cable with a DB25 socket to a 8 pin mini-DIN, wired to
> > > > do the right swaps and jumpers.
> > >
> > > I got a couple of connectors a while back,  but my eyesight isn't what it
> > > used to be,  so I never did make up any cables.  Do you have specific
> > > cable wiring info,  assuming I can get this thing working?
> >
> > I regard mini-DIN plugs as one of the offspring of Satan  :-).
> 
> :-D
> 
> > I really hate wiring them, and the type you can wire (as opposed to moulded
> > ones) are often too large tor fit through the hole in the case to mate with
> > the socket.
> 
> I do believe these will fit,  and better yet, they appear to be Switchcraft.  
> I still don't want to have to wire them,  though.
> 
> > What I did was buy 3 cables from RS components which had an 8 pin
> > mini-DIN plug moulded on one end and bare wires at the other.

FWIW, the RS cables are 463-518

> 
> I might have something around here I can chop...
> 
> > I wired 2 of them to DB25 plugs, so that you got a DTE pinout on said plug.
> > And the last one I wired to a DB25 socket with the apporpiate crosses and
> > interconnections so that when I pluged that one one of the first type of
> > cable, I got  a crossover mini-DIN to mini-DIN cable which will like 2
> > PX8s (or PX4s), or link a machine to the PF10.
> >
> > I can look up the wiring colours used in those RS cables if you like, they
> > are in the catalogue/on the web site, but I buzzed them out anyway just
> > to be sure.
> 
> Just the pin-to-pin connections would be of great help.


The PX8 serial port conenctions are pretty sane, actually, and sort-of 
follow the RS232 order. I think the pinout is in the user manual (it's 
certainly in the the technical manual), as are diagrams for the standard 
cables (again, those are certainly in the technical manual.

Anyway, here are the pins (and the colours of that RS cable I mentioned)
PX8 pin      Signal           Colour         RS232 Pin
1          Signal Ground      Black            7
2          TxD                White            2
3          RxD                Red              3
4          RTS                Yellow           4
5          CTS                Purple           5
6          DSR                Blue             6
7          DTR                Green            20
8          CD                 Brown            8

The pin numbers are actually the same as on the HX20, which used a 
full-sized 8 pin DIN plug. It made a lot of sense on that machine, 
because 3 pin, 5 pin (type A) and 7 pin DIN plugs will fit the 8 pin 
socket. A 3 pin plug gave yopu Gnd, TxD, RxD, a 5 pin plug added RTS and 
CTS, a 7 pin plug added DSR and DTR, and finally the 8 pin plug added CD. 
Every possbile connector gave a useful subset of the signals.
 
> > [Note for US readers. RS is not Radio Shack. It's a large UK distributer
> > of electronic components, tools, materials, etc. Look at
> > http://www.rswww.com/]
> 
> I've heard that before.

If you want to annoy them, call them 'Radiospares'. They started out 
with that name many years ago, but changed their name in 1972 (I think) 
to RS components because they wanted to get away from the iamge of only 
supplying parts to fix radios. But every old-time engineer and scientist 
in the UK will call them 'Radiospares'.

-tony