-
For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.Subscribe Now
820-01700 A2141 ppbus 12,3v
- Thread starter Bravo2001
- Start date
Check UPC_I2C_INT_L.
Also check the pull-up resistors on the corresponding bus (page 51).
Be sure to get correct voltage and diode mode to ground on both SCL/SDA lines.
Also check the pull-up resistors on the corresponding bus (page 51).
Be sure to get correct voltage and diode mode to ground on both SCL/SDA lines.
Ok, weird enough all diode mode readings look good. But when I check voltage I see some weird stuff.
I checked UPC_I2C_INT_L 0v
R5246 1=1.8v 2=0v
R5200 1=1.8v 2=1,4v
R5201 1=1.8v 2=1,1v
On working board all voltages are 1.8v So looks like something is pulling them down. How can I find out what is?
I'm guessing one of the CD3217's... But which one?
I checked UPC_I2C_INT_L 0v
R5246 1=1.8v 2=0v
R5200 1=1.8v 2=1,4v
R5201 1=1.8v 2=1,1v
On working board all voltages are 1.8v So looks like something is pulling them down. How can I find out what is?
I'm guessing one of the CD3217's... But which one?
Last edited:
So actually what I see is
R5200 is connected to other resistor R3021 and RB241.
R3021 is the going to U3100 & U3200.
RB241 is going to UB300 & UB400.
same for R5201 is connected to other resistor R3025 and RB242.
R3025 is the going to U3100 & U3200.
RB242 is going to UB300 & UB400.
Is it possible that disconnect R3021 and R3025 that will isolate U3100&U3200. Maybe if the voltages to R5200 & R5201 will come back, at least I'll know which side the problem will be? Or do you think there is another way... or this won't work
R5200 is connected to other resistor R3021 and RB241.
R3021 is the going to U3100 & U3200.
RB241 is going to UB300 & UB400.
same for R5201 is connected to other resistor R3025 and RB242.
R3025 is the going to U3100 & U3200.
RB242 is going to UB300 & UB400.
Is it possible that disconnect R3021 and R3025 that will isolate U3100&U3200. Maybe if the voltages to R5200 & R5201 will come back, at least I'll know which side the problem will be? Or do you think there is another way... or this won't work
T2 MUST talk with U3100/200 and UB300/400; you can't isolate SCL/SDA lines.
If one CD3217 pulls down UPC_I2C_INT_L, will still keep it low if you separate its SCL/SDA lines from that bus.
Unfortunatelly, there's no way to isolate UPC_I2C_INT_L from a single CD3217 chip.
You should compare diode mode readings around all CD3217 chips and also on J3300 and JB500.
S-UEM2 tester can help you...
If one CD3217 pulls down UPC_I2C_INT_L, will still keep it low if you separate its SCL/SDA lines from that bus.
Unfortunatelly, there's no way to isolate UPC_I2C_INT_L from a single CD3217 chip.
You should compare diode mode readings around all CD3217 chips and also on J3300 and JB500.
S-UEM2 tester can help you...
I tested all four CD3217 chips with diode mode... Every single point on them! (Hell of a job!) All 4 are same as know good board.
What I noticed is that UPC_I2C_INT_L is 13 Ohm to ground when power is connected. So It looks like is being pulled down. When I look with thermal imager only thing which gets a little bit hot 29degrees is T2 chip.
When I got 1 CD3217 chip off, R5246,R5200 &R5201 Got back to 1.8v! I got 4 working CD3217 from a donor a2141and TBT rom's. Changed all , but still same...
HELP!
What I noticed is that UPC_I2C_INT_L is 13 Ohm to ground when power is connected. So It looks like is being pulled down. When I look with thermal imager only thing which gets a little bit hot 29degrees is T2 chip.
When I got 1 CD3217 chip off, R5246,R5200 &R5201 Got back to 1.8v! I got 4 working CD3217 from a donor a2141and TBT rom's. Changed all , but still same...
HELP!
Last edited:
"UPC_I2C_INT_L is 13 Ohm to ground when power is connected."
Checking ohm scale, or diode mode with power applied to the board???
Oh god; PLEASE stop doing that!
Just an idea; try removing CD3217 chips one by one.
Check when/if UPC_I2C_INT_L goes high.
Input can't switch to 20V if one CD3217 chip is missing, but may help to locate the channel which pulls down the signal.
Checking ohm scale, or diode mode with power applied to the board???
Oh god; PLEASE stop doing that!
Just an idea; try removing CD3217 chips one by one.
Check when/if UPC_I2C_INT_L goes high.
Input can't switch to 20V if one CD3217 chip is missing, but may help to locate the channel which pulls down the signal.
I tested while one chip was removed and then got 20v on the other side. And UPC_I2C_INT_L was high... But doesn't this mean there is no communication between the chips. That's why it's not getting pulled down. I'm thinking as soon as the communication begins it's getting pulled down. With only 3 chips there is no COM.
I followed the link @tcampell34 https://logi.wiki/index.php/CD3217_and_T2_Power_on_Sequence#820-001700_CD3217_Compatibility_issues Where is said to change all CD3217 and TBT rom...
But still same... I'm running out of ideas
I followed the link @tcampell34 https://logi.wiki/index.php/CD3217_and_T2_Power_on_Sequence#820-001700_CD3217_Compatibility_issues Where is said to change all CD3217 and TBT rom...
But still same... I'm running out of ideas
Put back that chip and remove another; from the other board side.
Check if same thing happens.
That is an interrupt request and can be activated (0V) at any moment.
Check if same thing happens.
That is an interrupt request and can be activated (0V) at any moment.
I don't understand this part...
If any CD3215 detects a problem on its area, will pull down the signal; no matters there is communication (or not) on the corresponding bus.