On 10/24/2015 5:56 PM, Adrian Graham wrote:
On 24/10/2015 19:18, "John Robertson" <j...@flippers.com> wrote:
On 10/24/2015 5:43 AM, Adrian Graham wrote:
Hi folks,
PET4032 repair continues with all ROMs, video RAM and dodgy sockets removed
thanks to a hot air gun. Holes cleaned and I have new turned pin sockets for
everything I've removed which I'll be fitting this afternoon.
Since the ROMs came out OK I'm trying to dump them using my Pinmaster48
programmer, being from the 90s it doesn't read 2332/2532 PROMs but it WILL
read a lot of variants of 2732 so I've made an adapter as found thanks to
google and USENET:
2332 pin 18 to 2732 pin 21 (A11)
2332 pin 20 to 2732 pin 18 (Chip enable/Power Down)
2332 pin 21 to 2732 pins 20 and 24 via diodes with banding at the 2332 end
(2332 Vpp)
Wiring checks out and the diodes are aligned correctly so pins 20 and 24
don't interfere with each other, however the pinmaster continually gives me
"continuity error on pin 20"
Have I goofed somewhere?
Cheers,
You just tie pin 21 of the 2332 to Vcc (+5) - Pin 24 of the 2732 - to read.
There are only two modifications needed normally for reading a 2532/2332
in a 2732 socket.
2332
Pin 21 - Vcc (2732 Pin 24)
Pin 18 - A11 (2732 Pin 21)
If your reader coughs up a /OE error then use diodes:
2332
Pin 20 - 2 Diodes, one to 2732 pin 20, the other to 2732 pin 18. Banded
end to these pins, and you will also need a pullup resistor on the
2532/2332 socket pin 20 so /CE (2332/2532) goes high when not selected.
2K2 would do fine. Anything from your junk box between 1K and 4K7 should
work though.
I don't think you will need the diodes though.
John :-#)#
Hi John and others,
Thanks for that. I removed the diodes and wired 2332 (21) to 2372 (24)
leaving the A11 swap in place, the programmer complained about pin 18
missing. The adapter in front of me is now wired like this:
2332 (18) to 2372 (21)
2332 (20) 2x diodes to 2372 18 (band) and 20 (band)
2332 (20) 2k2 resistor to 2332 (24)
2332 (21) to 2372 (24)
Now I get "reverse insertion" hinting I've wired something upside-down which
isn't the case. I can read 27256 and 2764's no problem so I'm mounting
things the correct way.
Further digging into available eproms that the programmer can read reveals
it CAN read 2532s, specifically the MCM2532 which the datasheet tells me has
the same pinout as the 2332. I still get "reverse insertion error" so I'm
guessing my PROMs are toast.
Cheers,
Reverse insertion may just mean you are drawing more current on the /OE
and /CS than expected.
How about this - go back to my original suggestion (no diodes) and this
time add a small resistor to the 2732 pin 18 and Vcc to act as a load.
Try larger resistors if the reader still complains - and try reading
with NO 2332 in the reader (all FFs). Once you can trick the reader into
reading air as highs then try your 2332 again with the working resistor
values for the unused select.
Oh, and what reader are you using? Did you check with the manufacturer
(or archives somewhere - archive.org?) to see if they have a trick for
reading 2532/2332s?
John :-#)#
--
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Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
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