[Solved]Issues with Blast City Sound, Naomi i/o

[Mugicha]

hey guys, I'll try to break this down so it doesn't become a tl;dr.

I've had the naomi running fine in my blast for a while now. Today I took it out to put in Lemony's DC padhack box. I was having an issue with button input on that, so at Lem's suggestion, I waited till after the DC was on and placed the P2 controller in, then all sound from the blast city cutout.

I tried both the jamma line and the rca connectors, but still no sound. I also remember when the rca's were live you would get a buzz if they touched something like your finger, but no buzz either.

Then in order to further test the sound, I re hooked up the naomi, only to get an error stating, The Jamma i/o board could not be found. This was surprising to me because I have never gotten this error before.

The sound issue is my bigger priority, I'm worried about that more than the naomi.

Hoping for some insight from the Blast City Club gods, thx for looking.

 

[skate323k137]

The sound amp is in the PSU right? Check for voltage on your jamma harness?

 

[Mugicha]

The sound amp is in the PSU right? Check for voltage on your jamma harness?

so something very strange happened with that. I was checking the voltage off of the 001 loom, the 3.3 was ok, but the 5v just kept dropping into around the 1.6 range. I tried to adjust the pot but it just dropped with no change. I compared it to the sun psu which ran around 5.05 then rechecked off the 001 loom and it started at about 4.7 and just gradually dropped regardless of adjustments to the pot.

 

[skate323k137]

Certainly doesn't sound good. The lack of 5v would definitely make the IO go undetected. I'm a blast noob (only had mine for a little while) but I'd think if the PSU is dropping its 5v there could be other problems with it which caused your audio to go out. Probably wishful thinking but step 1 is fuses... after that you're probably pulling the PSU unit to have a look at it. Hopefully someone else can have more useful advice for you.

 

[Tyranix95]

You need to un-load everything from the power supply. And check it. Make sure it's working fine.

(That means disconnect all the connectors that hook up to the power supply, except for the power chord. And test it.)

Get your M-M out, put your port tips on the +5v, (+12, and +3.3v) line.

Turn the PSU on, note the power level upon start up, see if it holds steady for a minute. If it does then good.

Then adjust the voltage control pot for that line, both left and right, see if the PSU responds like it's supposed to (by adjusting the power level up a bit, then down a bit). If so, then great.

Then adjust the power pot so the power level is back to the same level that you first started at.

Repeat with the other two power lines.

Basically, you're checking your PSU to see if you have a power line that is not out putting power at the level it should be (+5, +12, or +3.3) , and a line that can not adjust the power on the line like it should.

 

[ReplicaX]

Start with what Tyranix suggests. Then you can verify and start hooking up stuff one by one and checking the 5v on each piece under load and narrow it down.

 

[Mugicha]

thx for the pointers guys. Tx I can't strip it all down tonite since the wife is sleeping and it's almost time for me to get to bed too, but I will give it a shot as soon as I get off work tomorrow.

 

[Lemony Vengeance]

this is really interesting.. the DC padhack I sent to you doesn't play with the way the sound works.. It doesn't have any voltage going over it, either. With the drop in voltage, I would go with what Tyranix suggested. Check fuses in the PSU as well.

 

[Kid Panda]

I'm curious if the capacitors in the 5v area area having issues. I did have a bit of a fit with the AWSD power supply till I recapped it, then it worked like a charm.

 

[ReplicaX]

I'm curious if the capacitors in the 5v area area having issues. I did have a bit of a fit with the AWSD power supply till I recapped it, then it worked like a charm.

I'm sure it would help just from age and hours alone.

The way Mugi is describing it though seems like a load issue more than a ripple/filtering issue with caps.

 

[Mugicha]

once again, thx for the replies guys.

just tested it a bit and there is definitely nothing coming off of the 5v from the blast psu. Also it does not respond to adjustments either way on that line. The 3.3v is working like a charm and doesn't mind adjustments. I'm not sure if there is a way to adjust the 12v but it's at about 11.5 right now.

so whatever happened yesterday seems to have killed that 5v, so what would you guys suggest is the next course of action? Another question, would the 5v be giving power to the rca audio leads? I'm hoping the sound issue is also tied into this lack of 5v bizness.

 

[Tyranix95]

There is usually no +12v adj. pot. +12v adj, is tied in to the +5v adj. So when one goes up (and down) so does the other.

---

Next, you need to remove the power supply from the cab, and open it up.

Look at the power supply board inside.

You need to start looking for a bad diode or transistor or fuse on the +5v rail.

Sometimes you get lucky and the bad part is obvious, like a diode blown in half. Other times, you have to hunt all the diodes down on the board along the line and check them one at a time.

So, keep your multi-meter, de/soldering tools, and camera handy.

 

[Mugicha]

got it open, everything looks fine at first glance. I also popped out the fuse to check it, it looked ok and tested ok for conitinuity.

Tx what am I looking for in here?

 

[Tyranix95]

Does your Sega Cab have an Open Door Safety Switch?

You know, one that turns the power off, if a door is left open?

Just wondering.

---

It think on a Blast it's usually on or around the PCB Door.

And I think it turns the monitor, on/off.

---

Also, does the RED LED on the PSU turn on when you power the PSU up?

 

[Mugicha]

Does your Sega Cab have an Open Door Safety Switch?

You know, one that turns the power off, if a door is left open?

Just wondering.

yeah it does, I took care of it with zip ties a few years ago, and I've never had an issue since, the ties are still very tight.

 

[Tyranix95]

Here is a Blast Manual.

Pg 51 has the pin out for the HIROSE 32 pin edge connector, on the PSU.

----

The Big board on the left is the Power board, and

The little board on the right is the Audio Amp board.

---

White wires should be the Ground lines (Pins 3, 4, 19, and 20).

Yellow wires should be the +5v lines (Pins 5, 6, 7, 8, and 9).
Brown wires should be the +3.3 lines (Pins 21, 22, 23, 24, and 25).
Red wires should be the +12v line (Pin 26).

Audio Left+ wire should be Pin 14.
Audio Left- (Ground) wire should be Pin 30.
Audio Right+ wire should be Pin 15.
Audio Right- (Ground) wire should be Pin 31.

Jamma (mono) Snd+ wire should be Pin 16.
Jamma (mono) Snd- wire should be Pin 32.

Left Speaker+ wire should be Pin 12.
Left Speaker- (Ground) wire should be Pin 28.
Right Speaker+ wire should be Pin 13.
Right Speaker- (Ground) wire should be Pin 29.

Volume pot should be pins 10, 11, and 27 (legs 1, 2, and 3 on the pot).

AC100V IN (L) should be pin 2.
AC100V OUT (L) should be pin 1.

AC100V IN (N) should be pin 18.
AC100V OUT (N) should be pin 17.

---

...

 

[Mugicha]

ok you guys are probly gonna laugh, but basically I just cleaned the pins on the psu and where it connects, I threw it back in and instantly heard the buzz from the rca leads. Checked the 5v and it was low around 4.8 but it stayed constant, so Iw as able to get it back up to 5. I haven't tested a board yet, but I just wanted to pass this along first and I'll report back with game test results, still have to see if it will recognize the i/o for the naomi.

so fingers crossed.

 

[Tyranix95]

Clean the contacts, real well.

On both sides.

Just like a NEO.

And make sure the contacts are nice and dry before you re-test.

 

[skate323k137]

Clean the contacts, real well.

On both sides.

Just like a NEO.

And make sure the contacts are nice and dry before you re-test.

^^This

That's great news though! hopefully just dirty loom(s). If you can look for any obvious cold joints on the backside of the socket(s) too.

 

[Mugicha]

Clean the contacts, real well.

On both sides.

Just like a NEO.

And make sure the contacts are nice and dry before you re-test.

did just that and got this:

I didn't get the error with the i/o board, and I also went into to the service menu to see if it was recognized and it was indeed there. Not shown in pic: sound is also loud and clear, I can hear the attract mode as I type this. I also tested a cps2 board and it worked perfectly and also had sound, so I think all is set here!!

thanks Tx and everyone else for looking in to help mugi noob out

problem solved!

 

[kuze]

Hell yeah. Glad to see you got it working without too much of a hassle!

 

[ReplicaX]

Glad it was something simple lol.

 

[skate323k137]

 

[Mugicha]

Glad it was something simple lol.

I know right? haha

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