Hey, Been messing with a few ps1's just for fun recently and hit a weird problem, The problem is if I put mm3 on a chip and disconnect wire 2 from my socket I get perfect results and all backups boot 99% of the time, If I leave wire 2 connected I get the same results as mayumi 4, chips used for mm3 were 12c508a and 12f508. Now mayumi 4 on either a 12f508,12c508a,12f683 99% of the time wont boot anything, with a certain disc I may get to the black splash screen then hangs but most of the time to the home screen with the cd stopped spinning and in the past also being read as a music cd,Tried using the oscal value and no oscal on 12f508 and makes no difference. I'm using a k150 but have had zero issues with this one always reads/writes/verify every time and the same chips reprogrammed with mm3 with 7 wires boot perfect. Any ideas?
Check the routing for the clock wire (pin 2) - make sure it's kept as far as possible from the low-level CD stuff like the RF amp chip. As much as possible run it directly over a ground plane.
Only difference is pin 2? I've tried using a socket and no socket just something I will have to live with, I may one day when I'm bored try a different model I think I have every model except 1.
I believe on MM3 pin 2 is used to connect to an access led, but it is necessary to modify the program http://christophe.mahe.free.fr/PSX/psxpuce.htm http://christophe.mahe.free.fr/PSX/logpsx/Mm3eur.zip
On multimode 3 pin 2 is not used (even the led feature was removed), on mayumi is used for external clock. MM3 or mayumi 4 share the same code, the only difference is the use of the external oscillator on pin 2 for the mayumi to clock the microchip. So if you use mm3 modchip you must not connect the pin 2 (i don't remember if setted as input or output pin, but if it is the second case you can also damage the psx!) About the non working mayumi the problem lies on your programmer which, i'm pretty sure, it won't backup osscal value correctly...
I thought mayumi didn't need the oscal? and mm3 does which is why it doesn't use pin 2. I've always read the chip first,note the oscal, load the hex and then insert the oscal and change the fuse code protect to disable I then verify which is successful then re=read the chip to make sure the oscal is there which it is. Have tried mayumi with and with out oscal,mm3 obviously is always programmed with the oscal and works flawlessly aslong as I de solder pin 2 to make it what it should be a 7 wire install so I believe my programmer is working correctly.
only reason for soldering pin 2 in the first place is I use a socket for switching chips so going from mayumi to mm3 i just desolder/solder pin 2, I wasn't sure if pin 2 being connected would effect the mm3 code but it does, or I've soldered pin 2 wrong every time which seems unlikely as i've re done it 3 times
Yeah, the only difference is pin 2 - in fact, the code used in MM3 for the PU22/PU23/PSone boards seems to be a direct copy of the Mayumi code. Connecting pin 2 when using the MM3 code will result in boot failure because the chip will drag down the clock signal and crash the mechacon MCU. Also make sure to keep the wires clear of the area around the RF amp chip (that little SOP device just below the FPC connector for the CD pickup) - it's very sensitive to RF pickup and a fast rise-time 4MHz signal like that clock can screw it up really badly. If you have access to a scope, try looking at the eye signal from the optical pickup (it's in that test point field below the connector - I think it's CL704) and see if it's degraded when pin 2 is connected. The signal should look something like this: The more jitter and noise there is, the wider the bands on the screen will be (note that the persistence has been set to a couple of seconds so that you get an average of many readings). If the jitter gets so bad that the diamond shaped holes (the "eyes") in the signal around the zero on the Y axis close then the data becomes impossible to recover and you get read errors.
You just further confirm my lack of knowledge lol ,alot of what you said went straight over the top of me, The chip socket may actually be located on said amp chip if it sits just below where the cd ribbon cable plugs into the board,is this just pin 2 it interferes with?
Oh man, the PSX RF eye patterns are so ugly to look at. It must be the worst "CD Player" that was mass produced in this barely working state. I have to use my best CD burner to get the jitter low enough that it works reliably. Still looks all mushy on the eye pattern though :/ @TriMesh in case you want some eye bleach? Code: https://www.youtube.com/watch?v=TFG2yNynq4A&feature=youtu.be&t=4m25s That's what we'd like to see on our consoles, eh?
Yeah, you should avoid that area as much as possible - really you don't want any wires around there, although the other signals are lower frequency and cause much less significant interference. In my experience, they are much nicer in x1 mode, especially if you are using a well mastered pressed disc (like YEDS-17) - but in the case of x2 using a CDR it does tend to look pretty nasty This is probably a better indication of what you should expect using a decent analog scope and a well-mastered disc - not the best signal I've ever seen, but not something the hardware would have any problem decoding.
I know it's not needed but i hate finding a thread without conclusion and better late then never. It was exactly as Trimesh said and was all down to chip/wire location, I just re stumbled across this Thread and thought it may help others in the future.
