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SE/30 Motherboard: UB10 & UB11 SONY Sound Chip Voltages


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2 hours ago, ttb said:

I measured that 5.81 V p-p at the internal speaker header with the [stock] speaker connected.

 

Thank you for clarifying.  Now I am more confused about what @aeberbach said about having measured 12V "peaks".

 

@aeberbach Can you please clarify that you did indeed measure 0-12Vpeak voltage at the pin-10 output of UB10 & also UB11 respectively using your scope?  And if you put both pin-10s on a scope at the same time, were those 12V peaks in-phase (directly beneath each other on the scope)?  If you measured 0-12Vpeak on both pin-10s and if both peaks were in-phase, as per my simulation, the op-amp would double those voltages to be 24v, which seems very wrong.

 

Also, @ttb, a measurement of only 5.81Vp-p at the output of R10 with the internal 63Ω stock speaker connected implies only a 2.9v signal at each pin-10, assuming both peaks were in-phase and double their respective amplitudes at the output of R10.  Hmmm...

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If I have a couple hours this week I will open it back up and probe the rest of the circuit while playing the tone to provide the full picture. I'd imagine there is some difference from the fact that @aeberbach was playing a different sound, but that can't explain all of it.

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The sound I played is the ascending tones that happen when you press the programmer's switch button. I'm a bit limited in what I can do because I do not have a booting system set up at all at the moment. I took measurements from the positive side of C3 and C4 - sorry but I'm not going to get the chance to measure again until early January, a holiday is happening.

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4 hours ago, ttb said:

If I have a couple hours this week I will open it back up and probe the rest of the circuit while playing the tone to provide the full picture. I'd imagine there is some difference from the fact that @aeberbach was playing a different sound, but that can't explain all of it.

Thank you very much for your kind willingness to do that extra testing, @ttb.  Please also try pressing the Programmer's Switch so as to perform the exact same test as @aeberbach.  Curious if you see those +12V (0-peak) voltage spikes too.

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5 hours ago, ttb said:

If I have a couple hours this week I will open it back up and probe the rest of the circuit while playing the tone to provide the full picture. I'd imagine there is some difference from the fact that @aeberbach was playing a different sound, but that can't explain all of it.

 

I re-read all of @aeberbach's previous posts.  He said he measured:

 

• 5v on the positive side of C3, C4 and C5, individually

• 12v peak voltage on C3, C4 (but he didn't mention if it was also on C5)

 

It is very important that we know if all 3 of those caps see 12v, even if that 12v is merely a transient now and then.  And yes, measuring on the positive side of each of those 3 caps is important, using a scope.

 

@maceffects, thank you for your kind words and for following our discussion! :-) 

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Alright, these measurements are from my other SE/30, recapped with the same caps. All are waveforms of the ascending tones played when the interrupt switch is pressed. I changed the system volume to 7/7 before testing. 

 

Note: These are all with respect to ground. I also measured across the components directly and the signals were substantially similar.

 

C3 sees a max of 8.56 V:

 

scope_0.png.ccb3a5734dde896ff3e72eb3f38970ef.png

 

C4 sees a max of 8.67 V:

 

scope_1.png.c1dcb68bcf2b3d6ae8971f72177a87e8.png

 

C5 is a constant 5 V (plus a fair amount of noise):

 

scope_2.png.807eadacf14110896b51bd9b0ca3a198.png

 

C6 is a constant 1 V or so:

 

scope_3.png.e1209e973f0bbbfa30911d1c69b69e2b.png

 

And finally this is the output at the speaker jack (J11):

 

scope_4.png.22cf0f190a09ab8478c552491900b6e8.png

Edited by ttb
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Thank you for the extensive testing @ttb.  Again, I cannot remove my motherboard like you, but I am able to take scope voltage readings from the J11 speaker connector.  The video below shows exactly how I tested the stock 63Ω speaker and a MacEffects 8Ω speaker.  As I expected, the 8Ω speaker has substantially less voltage across it because the audio circuit simply cannot supply enough current.  Also note that your measurement at J11 appears to be 2.30V.  I assume that is 0-peak.  Even if you double that to get 4.6Vp-p, it's still much less voltage than I am measuring when pressing the Programmer's Switch to get the death chimes. As shown in my video, my highest measurement was 8.24Vp-p (63Ω speaker, solid tantalum recapped MB).  

 

I also measured a 13.9V transient at J11 upon power-on, followed by the boot chime showing just under 1.5Vp-p.  

 

All voltages were much, much lower with the speaker.

 

So while this doesn't give a comparison with your capacitor voltages, unfortunately, it does show that I am getting higher peak-to-peak voltages at J11 than you are for some reason.

 

 

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Very interesting. Your peak voltage is similar to mine, but the your minimum appears to be much lower, resulting in the large p-p measurement. I believe that may be because you are pressing the interrupt switch repeatedly (e.g. from a sad Mac). The first signal captured by your scope is therefore the single chord of the sad Mac chime rather than just the ascending tones which is what my wave forms are. For my testing I always hit the reset switch, armed the scope, then hit the interrupt switch to only capture the ascending tones @aeberbach spoke of. 
 

My guess is that if you do the test from a non-sad Mac screen you’ll see measurements substantially similar to mine. 

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19 hours ago, ttb said:

I believe that may be because you are pressing the interrupt switch repeatedly (e.g. from a sad Mac).

 

Actually, I got the highest peak-to-peak measurement on my very first press of the Programmer's Switch, prior to getting any Sad Mac.  That measurement at J11 (stock 63Ω speaker) was 8.24Vp-p.

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I decided to solder some test wires to UB10-pin10 (capacitor C3), UB11-pin10 (C4), Pin-15 (C5, both chips are tied together here), C9 & C10.  Below are my measurements and a short video of the pin-10 testing. Speaker was the MacEffects 8Ω.

 

C5: 5v constantly, with or without sound, even during the power-on thump, bong, and programmer's switch press.

C3 & C4: 11v with the power-on thump, and 10.2v with programmer's switch press & chimes.

C9: -12.3v

C10: 12.31v

 

As such, 16V Solid Tantalum capacitors should not be used at C3, C4, C9 or C10.  (16V Polymer Tantalums are fine though.) The other six 47uF caps can be 16V solid tantalum (or Polymer) because they only see 5V.

 

 

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