[slowpogo]

 
Quote:

42.  
 
 
 
That's going to be difficult to quantify, don't you think?

You cheeky monkey, you. I was thinking along the lines of either, "If there is a difference it's pretty small, the sigma is probably overkill." Or, "It sounds much better, a totally worthy upgrade!"
 
I'm not a very hard sell so I'll just go for it. Maybe I can use the current TREAD setup to power the Hiface I am probably getting....I can never escape DIY for too long. Damn you, head-fi!

 

[Dan55]

Hi all, 
 
I'm attempting to upgrade my y1 full and can't even pass the initial test! I'm getting considerably less than 3.3V at that test point. It was at first 1.81V, and after I reflowed U2 I am now measuring just over 2V. I have an extra regulator and will try to replace U2 unless there might be another culprit. Does anyone have any ideas? Sorry for the lack of pictures and the newbie question.
 
Many thanks,
Dan 
 
edit: After doing some more reading, I think the problem is likely attributable to solder bridges on X1, U4, or U5. I think I need some more desoldering braid!
 
edit 2: After attempting to clean up X1, U4, U5 and measuring the same voltage at the 3.3V test point (~2V), I've concluded that I have absolutely no idea where the problem is...

 

[Dan55]

I probably shouldn't have posted the above just before the holidays. Is replacing U2 a decent approach or way off base? The continuity at each pins seems fine, so I'm not sure what the problem might be, but I'm also not sure where else to look. Thanks!

 

[jdkJake]

Pictures? Lot's of light, as much focus as possible.

Really, really helps.

 

[Dan55]

Sorry about that. The only camera I have at the moment is on my camera, and I'm still trying to figure out how to upload to my computer. Someone forgot to mention that in the 200 page manual. 

 

[PScal]

Check the marking on the voltage regulator in question.  I had Mouser send me the wrong part on the 3.3v regulator. 

 

[Dan55]

I believe it says PHUI, though I imagine that's not of much help. The packaging indicates 3.3V.

 

[amb]

 
Quote:

I believe it says PHUI, though I imagine that's not of much help. The packaging indicates 3.3V.

 
See the γ2 website "Instructions" section, there is a table of markings on these SOT-23-5 devices.  PHUI is a Texas Instruments TPS79333DBVR.
[size=smaller]TPS7933T3DBVR[/size]

 

[pterodactilo]

From the gamma 1 thread
Quote:

This should really be in the γ2 thread now that you're debugging that board, but anyways...
Thes second 5V test point (VBUS) will read low if the USB cable isn't connected to the computer.  So that's probably normal (if you're only using wallwart power).
The fact that the first 5V test point (VCC) has 4.86V means that the voltage regulators U1 and U2 are getting the correct input voltage, but your 3.3V and 4.5V test points show that they are not producing any output.  Make sure that you have the correct chips installed in U1 and U2 locations (what do the markings say?).
 
EDIT: I assume your two 5V test points are as I described (VCC and VBUS).  If they're the opposite, then it would be a different problem.

 My bad,  I forgot to specify which 5V test points I am refering to. It's the opposite: 5V (VCC) reads 1.38Volts and 5V (VBUS) 4.87V. I used the USB cable only to power the boards. If I connect the wallwart too I get the following voltages:
5V (VBUS) : 5.09V 
5V (VCC) :1.34 V 
3.3V :  0.03 V
4.5 V: 0.00V
 
With external power only:
 
5V (VBUS): 0.03V
5V (VCC): 1.34V
3.3V: 0.02V
4.5V: 0.00V
 
The markings on the regulators: U1 is PHJI and U2 is LPKL.  I double checked that the pin headers and receptacles that correspond to VCC make contact . The DMM reads around 2 ohms in J1 and J5 .

 

[amb]

pterodactilo, what you observe seems to point back to a problem on the γ1 side.  If you measure only 1.34V at γ2's 5V (VCC), then U1D on γ1 board isn't putting out enough voltage.  You could verify this by measuring the voltage at the γ1 5V (VCC) test point, as well as U1D pin 7.  They are probably all measuring 1.34V, when it should be 4.8xV according to your VBUS reading.  I know we've been down this path before and you've replaced U1D (and verified R13D, R15D and R16D values), but it's got to be something around there.  As I said, there is not much there that could cause this.  Look at the schematic diagram (and the TPS2115A datasheet) and think about why this is.

 

[pterodactilo]

Quote:

pterodactilo, what you observe seems to point back to a problem on the γ1 side.  If you measure only 1.34V at γ2's 5V (VCC), then U1D on γ1 board isn't putting out enough voltage.  You could verify this by measuring the voltage at the γ1 5V (VCC) test point, as well as U1D pin 7.  They are probably all measuring 1.34V, when it should be 4.8xV according to your VBUS reading.  I know we've been down this path before and you've replaced U1D (and verified R13D, R15D and R16D values), but it's got to be something around there.  As I said, there is not much there that could cause this.  Look at the schematic diagram (and the TPS2115A datasheet) and think about why this is.

What puzzles me is the fact that this only happens when y1 is mated to the y2 board. I've tested y1 alone and when dac and usb sections are connected with wires all test points give the correct values and U1D's pin 7 sends the correct voltage: 4.80 volts or so when USB cable is connected and 5.10 with external power.

 

[amb]

The only possibility for that to happen is U1D went into current-limiting protection mode, dropping its output voltage.  Something on your y2 board is drawing too much current, and the most likely cause is a short somewhere.  Could you post clear, high-res photos of your y2 board, top and bottom?

 

[IPodPJ]

Quote:

The only camera I have at the moment is on my camera,

Huh??

 

[Dan55]

Haha. That should say my phone. I wrote that in a hurry this morning and knew something was wrong, but I just couldn't put my finger on it. 

 
Thanks, amb. I guess I can't blame the problem on Mouser. 

 

[pterodactilo]

Quote:

The only possibility for that to happen is U1D went into current-limiting protection mode, dropping its output voltage.  Something on your y2 board is drawing too much current, and the most likely cause is a short somewhere.  Could you post clear, high-res photos of your y2 board, top and bottom?

 
Thanks for your help, I know that without pictures it's hard to say where the problem  may be but right now I  only have my nokia 5800 which makes horrid photos .   I've shorted JP2D(3-2) and in this case gamma1 works with gamma2 mated to it. This apparently points to U1D once again, but then the  gamma 2  board should function while it does not. Test points give : 3.3V -> 0.02V, 5V (VBUS) -> 4.84 V, 5V (VCC) -> 4.84V, 4.5 V -> 4.75V. I've already replaced the 3.3 voltage regulator , the one with  a "LPKL" marking on it. Given that now both inputs are correct it should output 3.3Volts and not 0.0V. Ok. I'm leaving  it here until I get a proper camera.