PSone sync problem

[VEGETA]

Here are new pics: https://slow.pics/c/r79azsii

what happened:

- I soldered all ground pins of scart cable together, nothing happened.
- added 330R and 75R resistor divider on input csync to opamp, now it is about 600mv.
- after this attenuation, its output is a bit cleaner due to skew being ok... but it is unloaded. once loaded, returns to be the same.
- I probed power supply and ground, some periodic stuff are there.

I am really frustrated by now. this should not be like this, I mean no need to do all these tests for mere csync mod or running it via ossc. this should have been much easier! All I can do now is return it to the way it was then connect it to a TV using CVBS cable to see what happens. this should indicate it very well since seller did this and was perfectly fine.

I feel like it has a serious problem down to chip level, but signals seem ok except for that super-imposed ripple!

I don't want to do any filtering and so on, this should not be the requirement for running a PSone via OSSC!

If none of that ever worked, then I can send it to one of you guys to check it out if you are interested to crack this down.


Finally, here is a picture of the board itself if you wanna see it, maybe has something interesting: https://slow.pics/c/vzgsQr5O

thanks

[Syntax]

IC 203 has a bent leg, and a chip in PsONE can cause issues with sync and games that are out of region as that model has a bios check too that needs patching, Pretty sure that patch code doesnt fit on a ATtiny chip your size so yeah youll get the PS1 logo load then black for out of region games. If its an American system then disregard my comments.

Fuse has been jumped so the system took a hit from something, and what is that random purple wire going off screen for? Oh powering that silly op amp I see.

[VEGETA]

IC 203 has a bent leg, and a chip in PsONE can cause issues with sync and games that are out of region as that model has a bios check too that needs patching, Pretty sure that patch code doesnt fit on a ATtiny chip your size so yeah youll get the PS1 logo load then black for out of region games. If its an American system then disregard my comments.

Fuse has been jumped so the system took a hit from something, and what is that random purple wire going off screen for? Oh powering that silly op amp I see.

I burned the fuse by mistake, accidentally shorted it but it is ok now. if it worked again I will replace the fuse.

notice that this system was tested to work fine by seller. he showed me the video.

Originally, I had an arduino pro mini (or similar) that I wanted to implement PSNee in it, but couldn't get to this since the system has the noise issue. yes PSNee requires you to do the PAL bios patching.

the problem in this thread has nothing to do with region blocking or so, just video noise for no reason so far. can it be the chip causing this noise? then why it works fine with the seller?

I need 2 weeks to return home to test it on TV using composite video exactly as seller did, and will get my ossc as well to test it too with the scart cable.

anything you know that can help?

thanks for following so far, aren't you a bit frustrated? xD

[Syntax]

I find it pretty funny you pulled out the scope, made an op amp, and did a weeks worth of poking around talking theory BEFORE testing the system via composite video OR removing the installed modchip/modifications.
Do you enjoy pain?

[VEGETA]

I find it pretty funny you pulled out the scope, made an op amp, and did a weeks worth of poking around talking theory BEFORE testing the system via composite video OR removing the installed modchip/modifications.
Do you enjoy pain?

well I told you the seller sent a recent test video showing it to be fully functional. console starts, game starts and picture is perfect using composite video on flat LCD TV (no scaler). this doesn't count?

if the seller didn't verify this, then I should have done it myself as you suggest. He used to play copied discs via these very old mods for sure.

hmm so I will try tomorrow to remove the mod chip and re-solder lifted legs of ICs, return CVBS capacitor, then try my luck again. please notice that my other fat PAL PS1 also had a modchip but still worked out of the box using the exact same setup! this is what baffles me!

but anyhow, can the mod really affect the system so much? then how can you explain the same system worked for the seller using composite video?

[Syntax]

I just noticed your pads around the CXA RGB encoder IC502 are cooked and missing, there seems to be a jumper for one but the other one which looks to be a ground does not appear to have a jumper.
It seems most damage is in that area with the messy cap and IC203 with the bent leg.

I'd call it a junk system if running jumpers don't fix it, who knows what's been done to the poor thing before you received it.

Here's a nice HiRes of what the traces should look like. https://upload.wikimedia.org/wikipedia/ ... rboard.jpg

[VEGETA]

I just noticed your pads around the CXA RGB encoder IC502 are cooked and missing, there seems to be a jumper for one but the other one which looks to be a ground does not appear to have a jumper.
It seems most damage is in that area with the messy cap and IC203 with the bent leg.

I'd call it a junk system if running jumpers don't fix it, who knows what's been done to the poor thing before you received it.

Here's a nice HiRes of what the traces should look like. https://upload.wikimedia.org/wikipedia/ ... rboard.jpg

Don't worry about these 2, I cooked them due to repeatedly soldering on them. Bad move by me but no effect on board or performance. These 2 are csync but now I got csync from elsewhere by soldering a wire to it that I use.

[NewSchoolBoxer]

I'm glad Syntax can practical and I can be theoretical. It's possible seller videoed a different PSOne from what you were shipped. I've had more blatant scams run on me.

Pic9 looks good but voltage spikes up when you put console under load by connecting to Scart cable right? The noise on power filter looks bad but if it doesn't get worse than 154 mVpp at 5V out then that's not too bad. Could add a bypass capacitor to reduce the rippling. I'm sure at least one is already there but at over 20 years old, may have reduced capacitance and higher ESR and be in need of replacing. In other words, replace the one or two bypass capacitors you see at the voltage regulator or filter with same kind and values.

I've seen a noisy power supply mess up the video like I was saying on 9V DC to Super Famicom. I haven't seen a video chip do it when video is its purpose but you're pulling ~15 kHz csync that it wasn't designed to put on the multiout and therefore wouldn't likely have the correct bypass capacitor(s) to smooth over. The sync on composite video and luma from the video chip is encoded on a carrier wave in the MHz range and therefore not damaged by the low kHz noise. Watch at least the first 11 minutes of this video explaining bypass capacitors: https://www.youtube.com/watch?v=BcJ6UdDx1vg Dave the EE master says it's possible for chips to spike voltage like what you're seeing, so good enough for me.

Basically, a capacitor resists sudden changes in voltage. You turn off a 5V battery, the capacitor resists that sudden drop and outputs the charge it was storing to help slow said drop. Conversely, turn on a 5V battery and the capacitor resists that sudden rise and stores charge to help slow said rise. This is actually where you'd want to consult a capacitor's datasheet to find its ESR but a 10uF capacitor in parallel as close as possible, but not directly on, the csync pin (or multiout pin?) would be a decent first guess. Probably 100uF max. Can put 2x 100uF in series to make 50uF with higher ESR. Risk is you filter out the spike at the cost of flat part of the square wave decreasing from capacitor recharging. May be able to get away with that. Edit: I saw OSSC has "Analog sync Vth" setting which sounds like the minimum voltage level you're treating as sync so I think you can definitely get away with it.

I'm not against looking over your PSOne but at more than $10 shipping each way it's not worth it. Consider buying Japanese consoles. Only cheap option left.

[VEGETA]

so you think it could be a problem with PSU due to caps?

as for the seller I can be sure he is honest.

I may try to put extra elec. caps in parallel with those on the board for PSU section to make sure enough capacitance is there, then power on the system.

I think now we can be sure that OSSC, SCART cable, and so on are not the problem. the problem has to be inside the PSone itself.

I have smaller ceramic caps (forgot the value) that I can salvage from a new board I have, I can add them to the power pins of the video DAC IC.

your theory about the IC taking more current than it usually takes due to csync mod is viable but still should not be this far... also, even by returning everything to its original form of CVBS signal it still makes the same thing.

so adding caps or recapping if possible (I have few elec. caps of few values) is the only thing I can test for now. will do it sometime next few days.

[NewSchoolBoxer]

That's cool you can rule out the seller giving you a non-functioning console and narrow down the focus to console maintenance. I think the PSU problem is almost certainly due to caps. The purpose of caps on a PSU input or output is to filter the ripple voltage. Ripple shortens electrical component lifespans by making them hotter and can mess with the video chip by being noise in the operating frequencies.

Not saying smoothing the power supply voltage fixes everything but it's easy to fix and apparently a common enough maintenance task that Console5 sells capacitor kits to do it. PSU in need of recap is the most logical explanation left because it's when console is under load, i.e. pushing the PSU the hardest, that voltage spikes go crazy. The FFT proves the spikes are in the sync and luma bandwidth.

Reasonably good video overview of a PSU cap replacement on a PS1 here: https://www.youtube.com/watch?v=Ledxj3Hz0bA
I posted in other thread how I'm against paying a surcharge for widely available capacitors but I realize saving the shopping time is worth $5 to some people to buy the kit.

I think that's a good idea to put another cap or two in parallel. Near end of life capacitors have maybe 10-20% lower C and much higher R. If you don't have the exact value and type to replace then an extra cap in parallel raises the effective C and lowers the R. Just check the voltage and temperature ratings on the ceramics.

I can't tell the exact mod chip you're using but I don't think it's significant. Datasheets for PIC 12F508 and 12F683 used as mod chips show standby currents of almost nothing and operating current of 220uA or less. At 2V, that's a low 0.4 milliwatts. Way I understand it, modern day mod chips go idle after the region check so that the games that check for the chips don't detect them.

[VEGETA]

Kindly check the video here: https://gofile.io/d/o5oNTA

this time I hooked it up via composite to a TV which supports composite and 240p\480i signals, and the result is exactly the same as before! so can we safely assume that the console is broken?

I made sure to return everything to its previous status, CVBS cap and taking op-amp off.

[clairobskur]

i own a psone that won't sync with OSSC no matter what setting or scart cable i use. but mine is a japanese one, not PAL. it works perfectly with a CRT TV. years ago i've asked for help at the OSSC forum, but no one had a clue. they asked me to try some specific settings, but none of them has worked. i eventually gave up trying.

[VEGETA]

i own a psone that won't sync with OSSC no matter what setting or scart cable i use. but mine is a japanese one, not PAL. it works perfectly with a CRT TV. years ago i've asked for help at the OSSC forum, but no one had a clue. they asked me to try some specific settings, but none of them has worked. i eventually gave up trying.

my PSone doesn't work on regular HDTV which supports 240p composite... gives the same wavy noisy image. therefore, I think it is faulty.

I will try to find another local PSone which is guaranteed to work, then will try it with OSSC. so first step is to be working fine with regular TV using composite.