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obstacle-man

Help diagnosing Jaguar issues

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Hey Guys,

 

My Jaguar starts up slow and doesn't have sound.

 

I already replaced the reg1 / u38 hoping that was the problem and it did nothing.

 

I've done a lot of searching and I'm either not using the right keywords or no one has posted these same symptoms.

 

When you turn it on with a cart inserted the red jaguar logo zooms in quick and then it takes a long time (~5-10 seconds) for the 3d letters to start falling into place. The entire boot up process takes a long time here but once you are in game everything seems to run proper other than the fact that there is no sound.

 

I've used both coax and A/V outputs, there's only one spot on the board where it looks funny and that's some of the pins on the DSP. I've attached some photos and can take more.

 

post-67430-0-49270600-1548952958_thumb.jpg

post-67430-0-87629700-1548953010_thumb.jpg

 

Thanks for any assistance.

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Boot time sounds pretty normal.

 

What's the voltage at TP6? That's the output of the audio regulator (REG1). Check you're getting a sensible value here (I'm not actually sure what audio vcc is, but it will be more than 0v ;))

 

TP11 and TP14 will give you the right and left audio into the audio amplifier sections. See what they're giving.

 

Also U5 is the I2S chip which takes digital serial audio from the DSP and generates the left and right audio outputs.

 

If you have a scope you can check the data going in (BCK/WS/DATA) and then data out (RGHT/LEFT)

 

You also have U10 which gates the WS signal to the I2S chip to mute the sound, pin 9 on that is WS out. It should be toggling at a high old frequency to get any audio out of the I2S chip. You could just test this with a multi-meter, anything non-zero should be "working". But again, better with a scope.

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Boot time sounds pretty normal.

Maybe I need to do an actual time... because it's way slower than any video I've ever seen.

 

What's the voltage at TP6? That's the output of the audio regulator (REG1). Check you're getting a sensible value here (I'm not actually sure what audio vcc is, but it will be more than 0v ;))

I measure it at 4.97

 

 

TP11 and TP14 will give you the right and left audio into the audio amplifier sections. See what they're giving.

I think I need some help with finding these?

 

Also U5 is the I2S chip which takes digital serial audio from the DSP and generates the left and right audio outputs.

BCK: 2.46

WS:2.47

DATA: 0.31

GND:0

Vdd:4.98

IOL: 3.27

Iref: 0.67

IOR: 3.28

 

If you have a scope you can check the data going in (BCK/WS/DATA) and then data out (RGHT/LEFT)

Sorry, I don't have a scope. :(

 

You also have U10 which gates the WS signal to the I2S chip to mute the sound, pin 9 on that is WS out. It should be toggling at a high old frequency to get any audio out of the I2S chip. You could just test this with a multi-meter, anything non-zero should be "working". But again, better with a scope.

Pin 9 is reading 2.47

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Oh it's slow starting up, nothing unusual. The larger the game, the longer it takes as it checks the whole rom for integrity.

 

Looks like the i2s chip is working given it's giving some reasonable readings for in and out data. Can't be sure without scoping it, but I'd say it seems ok.

 

Do the iol and ior values of the i2s chip vary with what's happening on screen?

 

It's worth checking tp11 and tp14 and the output of the amp section next.

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Lol, ok, there is slow starting up and completely buggered frame rate and rendering! Yours is the latter.

 

I can't remember if the cart is hashed by the dsp or gpu, but it's running enough to start up.

 

Could be a buggered dsp...

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Ok, the DSP does check the cart. So that's at least *running* as such.

 

Yeah, this isn't going to be an easy fix! :_(

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Well at least you're better along than me, I have no video OR sound after replacing all that stuff :skull:

Hopefully you can figure out the problem.

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The pins on that IC look burnt which is rather odd, it may just be flux residue in which case a careful scrape with with a craft knife blade and/or a rub with a q-tip and dipped in isopropanol should clean it. Whatever it is, if it is causing a problem I would expect it to either be an issue with all games or at least all 3D games (assuming the boot screen is using 3D objects).

 

Your video briefly shows the Raiden intro screens appearing to run OK but does it play through ok (i.e. at the correct speed, no control issues) and what about 3D games like Iron Solder and Cybermorph do they also appear to play ok?

 

I may be wrong but I have a vague recollection that you can slow it down the boot screen with a code, or button press in a similar way that you can change the spin speed/direction of the cube. If that recollection is correct does it do the same thing without a controller connected?

Is this a Jaguar you have recently acquired or a working one you have for a long time that had recently gone bad?

 

May be worth monitoring the main 5V supply voltage to see if it drops during the boot screen and recovers afterwards.

Edited by Stephen Moss

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Those dodgy looking pins seem to be the section heading off to the 68000, so I'm not sure if they are relevant or not. Does look a bit dodgy though.

 

I did wonder if this unit had been plugged in with the wrong polarity / voltage plug pack and things got fried as the main voltage reg was replaced.

 

The intro button combo thing was to be able to rotate the cube, it doesn't kill the frame rate. Something really odd is going on. The video is stable, so it appears the OLP is getting updated every frame, so it seems the rendering code is waiting on something which just isn't happening correctly.

 

Makes me think buggered blitter perhaps... but then, that's on TOM not JERRY.

 

Really odd.

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Ok, so I tried cleaning it up more with some isopropol and qtip. It looks a bit cleaner, although still looks like it's covered in something the unit no longer passes the red jaguar logo.

 

Sometimes the logo is white and it just sits there, sometimes the logo bounces up and down, sometimes it's cut in half with the right side starting at the top of the screen and the left side starting at the bottom and they both fly up and away...

 

Sorry Saint, I didn't measure the IOL/IOR before cleaning it so I probably can't answer that question.

 

It did play Raiden and Iron Soldier properly before I cleaned it.

 

This is a unit I bought on ebay over a year ago which was supposed to work just fine. But I didn't try it right away, and when I did I got convinced by the seller that I could just get A/V cables (came with rf) and the sound would work. The unit came with the original power supply and neither of the chips I replaced looked like they had any problems. I only replaced them because I was starting to get excited by the upcoming flash cart and everything I was reading/watching online indicated that was probably the problem. After replacing them things didn't change.

 

I think this is going to be outside my abilities to fix based on the comments here.

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Ok, that's very interesting -- if cleaning around the DSP where it looked dodgy has changed the behaviour then that's very promising.

 

I'd get some sticky flux, liberally apply it around all DSP pins, then take a soldering iron and reflow all the DSP pins with a bit of extra solder. Any bridges which may form can be easily removed with a bit of extra flux or some solder wick and then a bit more flux to clean up.

 

Finally clean it all up with more IPA and cue tips.

 

Its weird as it sounds like you're getting more GPU type issues, yet dodgy looking connections on the DSP.

 

Dont be intimidated by reflowing the joints on the DSP. Sticky flux is awesome. If you can solder at all, you'll be fine. ;)

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I'm wondering given the weird slow down of the letters if perhaps there is a clock issue to one of the CPUs.. Not all games use all CPUs which may also explain why some work and others don't (and maybe why Raiden looks to run). Perhaps either a bad joint, or damaged track?

 

1st I have ever seen of a jag doing that before, hope you get it fixed.

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I meant to post an update a while ago, but haven't done so.

 

Basically I cleaned that area up and reflowed it and I'm at a point now where Raiden works (minus sound) without any speed issues on startup, but everything else that I have seems to fail on starting up. I had a fair amount of trouble getting that done and I think that repairing this jaguar is outside my abilities. I may sell it for parts and look to the MISTer fpga project jaguar core to be my solution going forward.

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