Offline

the last post in this thread: http://chipmusic.org/forums/topic/5765/ … cart-guide is more than 3 months old, so I couldn't just add a reply there

I know that I'm late to the party, but I'm trying to build a few carts for a friend of mine.

for the first one, I'm attempting to make a PR8 cart out of an FF1+2 famicom cart

he's sent me the FF1+2 cart and I've unsoldered the program mask rom from it. it was my assumption that all I needed to do was split the PR8.nes rom using ucon64 and then burn the .prg portion to the eprom
we are using M27C2001 eproms (which I believe are 256mb), so do I need to double up the .prg binary first using the "copy /b" method?

additionally, do I need bend the legs and add jumper wires (pins 1,2,16, 24, 30 and 31) to the FF1+2 cart or can the eprom be directly plugged into straight soldered socket?

Last edited by jmratkos (Mar 14, 2013 2:50 am)

Offline
Jelly Stone park, MD USA
jmratkos wrote:

... it was my assumption that all I needed to do was split the PR8.nes rom using ucon64 and then burn the .prg portion to the eprom
we are using M27C2001 eproms (which I believe are 256mb), so do I need to double up the .prg binary first using the "copy /b" method?

The 27c2001 is a 128Kx8, http://www.sycelectronica.com.ar/semico … 7C2001.pdf
So you will need to locate a 27c020  a 256Kx8 eeprom, as per
http://hackitup.tumblr.com/post/1920173 … rom-to-run
Go thru the 'Hack It UP' site';  ne7 has pioneered the method, but there are others that have done a few conversions also and maybe they will pop in here.
TSC had a great deal of issues with the NES carts, and gained some in-sight  with the MMCs. There seems to be an issue with the mappers on the NES carts that can complicate things. So hearing success stories would help some.
I haven't moved forward with my own cart; the ease of the PowerPak and the ability to use 'saves' on a SD card makes allot of sense for a tracker. I've been reluctant to spend more money and time, (trying to get the cash together for a PPak), before I order more parts for the conversion. Don't want to be a buzz kill, but getting PR8 to run on a NES cart seems like a crap shoot  :-|
Keep us updated on how it goes, would really like to hear a 'success' :-) Can you list some of the stats of the chip set on your cart, I.E. the MMC  labling, so we can have a record of what works and not?

Offline

yogi:
thanks for your reply. both the 27c2001 and 27c020 are 256Kb x 8 eproms (the link that you provided shows this for the 27c2001).

however, since the .prg images for both PR8 and NTRQ are only 128Kb in size, I believe that I must use the binary copy to double up the image size prior to burning it to fit the 256k eprom size (this is mentioned in the 2nd link that you provided smile. I'll give that a shot tomorrow and see what happens

here are some images of both the FF1+2 board and the other board that my friend provided me with to produce the mod tracker carts for him

Offline
Jelly Stone park, MD USA

Oh my bad! You are correct, it is a 256K DOH!. Anyways, yes you split with ucon64 and then double the PRG image for a 256K hex file as per ne7. Definitely want to go thru ALL his pages on the chipping, his blog is very helpful!!

Thanks for the photos. You are way out front with the SXROM board, the easiest to re chip. Is the SNROM board for parts? If not you will have to add the few parts to upgrade it for battery back up. Not very hard, but there is a solder bridge that you need to remove for batt backup. Looks like its at the upper right hand corner of the board, near pin 1 of the WRAM chip, a large solder blob. If you want the parts values I can post them, 3 resisters, 2 diodes and a coin batt..

On a side note, both boards have Sharp MMCs so that's a big plus for you.
Yogi

Offline

no worries. I re-programmed another set of eproms (while waiting for the original set to be erased) and attempted to mount the NTRQ eprom directly onto the SNROM board (this time adding the wires to jumper thru-hole 1 to pin 30, thru-hole 2 to pin 31, thru-hole 24 to pin 2, and tacking a wire from the nub of pin 24 on of the eprom and running it to pin 16 for ground), but I have still not been successful in getthing anything other than a grey screen to appear when powering up the famicom sad

I have not taken the steps to add the CR2032 coin batteries (still waiting for those to show up in the mail). I would be very appreciative if you coulld post the values for the resistors and diodes that I need and where they go.

I've gone through all of the pages on his blog, but unfortunately I still feel like I'm missing something

Offline

additionally, I wasn't clear but I'm trying to make 2 carts from my friend. the FF1+2 will ultimately run PR8 and the smaller board is to run NTRQ

Offline
Jelly Stone park, MD USA
jmratkos wrote:

no worries. I re-programmed another set of eproms (while waiting for the original set to be erased) and attempted to mount the NTRQ eprom directly onto the SNROM board (this time adding the wires to jumper thru-hole 1 to pin 30, thru-hole 2 to pin 31, thru-hole 24 to pin 2, and tacking a wire from the nub of pin 24 on of the eprom and running it to pin 16 for ground), but I have still not been successful in getthing anything other than a grey screen to appear when powering up the famicom sad

Oh no!
Your jumper description is correct. So considering that you are are using Famicom HW and following ne7's guide, it should work; the NTRQ mod seems the easiest of the two.  The only advice I can offer is general tips:

1.Clean the board, removing any flux.  I use rubbing alcohol, 90% grade. Did the cart work before the mod? Clean the card edge contacts, they can never be too clean.

2. Recheck you work. Verify all the wiring, more then once I have made a bone headed mistake swapping connections. Wiggle the wires a little, could be a broken wire at the place you stripped it. Don't trust yourself, VERIFY EVERYTHING wink

3. Use a magnifying glass and look for solder bridges and shorts. Clean up with solder braid.
Are any board traces damaged? De-soldering can be ruff on circuit boards, excess heat can lift or break a trace. If this is the case, you can carefully repair it with some 30 gauge wire. Follow the bad trace a little ways back, to a good place to solder. Clean the solder mask off and tack the wire to that spot . Connect the other end to the component.

4. Cold solder joints can 'look' OK, but still not work. Some times you can tell because they are dull and do not 'flow' to the soldered parts. You can try testing the continuity with an ohm meter. Probe on either side of the joint, I.E. from the copper on the board to the component lead; so you are testing through the solder joint. 0 ohms=GOOD. The short cut is to assume there is a cold joint and go back re-heating all the joints, use solder braid to remove the bulk of the old solder, use new flux and if needed a bit more solder. Then goto to step 1.

5. If all of the above fails, then you need to consider that the EPROM wasn't programmed correct. In which case you are back to square one, so this is a last ditch effort. Do make sure that all the above steps check out before starting over!

With all of the above, you can pop the cart back into the Famicom and try it as you go. With a large project, I like to do these checks as I go, after a build session. Troubleshooting a whole board with >100 solder points can be a night mare tongue

With PR8 there is an issue with the save state in the ram having bad data at first boot, but I don't think this is the case with NTRQ

jmratkos wrote:

I have not taken the steps to add the CR2032 coin batteries (still waiting for those to show up in the mail). I would be very appreciative if you coulld post the values for the resistors and diodes that I need and where they go.

I'll gather the info and post to this thread soon, have to look over your photos closely.

jmratkos wrote:

I've gone through all of the pages on his blog, but unfortunately I still feel like I'm missing something


Not to worry, you'll get it tracked down, just takes a little time!

Offline
Jelly Stone park, MD USA

OK, the battery back up:
The min needed are two diodes and a resister D1, D2 & R2.. The diodes only allow current to flow in one direction, Anode to Cathode. R2 limits current flow from the battery. The extra resisters are 'pull downs' that are connected to the MMC. Of the boards that I've looked at: they are on the ones with a battery and not on the ones without. You judge

What you need:
2- diodes, 1n914 should be fine. Stripe marks the Cathode end
R2- 1K resister, Brown Black Red
Add:
R1- 10K resister, Brown  Black Orange
R3- 27K resister, Red Violet Orange
Coin battery with solder tabs.

Prep the Board:
With the card edges down, the W Ram will be in the upper right corner. To the right of the W RAMs pin 1, there is a 'blob' of solder, this is a shunt that must be removed. De-solder it.
Just below this shunt are two silver pads (through holes ). Between them is a printed symbol for a diode, triangle with a bar.  De-solder these holes. You will install D2 here following the symbol. The 'bar' on the symbol corresponds to the stripe on one end of the diode package.
Now look over by the battery area. You should find another diode symbol between two pads, also 3 resister symbols between pads, R1 R2 & R3. Clean out all of these pads.
Install D1 just like D2,
Install the 1K at R2
Install the 10K at R1
Install the 27K at R3
Compare your board with the photo at ne7's NTRQ page, same SNROM board.
Looking at your SXROM board, you only need to add the battery, so you'r good to go!
Best of luck