|
|
Post by mastertech on Jan 21, 2022 17:32:30 GMT -5
Are you on the rail side of R7922?
|
|
|
|
Post by mmartell on Jan 21, 2022 17:42:21 GMT -5
I knew you were going to ask me that lol.
I was sure I was when I wired it up but I will remove and have a look. If I AM on the rail side anything I should do while the board is out ?
|
|
|
|
Post by mastertech on Jan 21, 2022 17:54:09 GMT -5
Not really. This is probably the last test unless we have some kind of odd result.
|
|
|
|
Post by mastertech on Jan 21, 2022 17:55:30 GMT -5
There's an internal pull down resistor on that pin not sure if that makes a difference... Quote: Pull-up and Pull-down resistors are used to correctly bias the inputs of digital gates to stop them from floating about randomly when there is no input condition. |
|
|
|
Post by mmartell on Jan 21, 2022 21:45:55 GMT -5
I was on the rail side. So what do you think is going on here ?
|
|
|
|
Post by mastertech on Jan 21, 2022 22:30:56 GMT -5
So here is what i am thinking. I expected a little drop in that voltage for this test, it just seemed a little more then I expected, but it is probably because we used a 1k resistor rather then a 33ohm one.The circuit it calculated for the 33ohm because of the 10k drain and whatever pulldown is in the CPU. I suggested the 1k for safety reasons because I didn't want to take a chance on damaging the CPU just for a test. But it looks like the voltage holds even though it is low. And the CPU changed errors again so I am thinking it is sensing ok or at least sensing something.
The DSP however now appears to have a different voltage on the FLAF0 line (2.6v) with the 33ohm resistor removed then the last time we did a test with it removed (3.3v). And there is nothing else on that line to affect a change. So I'm leaning to DSP.
Now like srt said, you have the DSP ic, FLASH and SDRAM ic's. And I am guessing you do not have an adapter to test that flash so you are kinda stuck there. But I do not think that the Flash or the Sdram can affect the value of the voltage on that FLAG0 output pin, I believe they could only tell it to be on or off. So that leaves the DSP.
Does your parts unit have a DSP ic?
|
|
|
|
Post by mmartell on Jan 21, 2022 22:41:54 GMT -5
Yes it does though I'm not certain I would be successful changing out that ic.
What do you think of this idea. What if I use a small signal transistor to use the FLAGS0 line to switch 3.3v to the mcu when it goes over 0.7v ?
Is that likely to damage anything further ?
|
|
|
|
Post by mastertech on Jan 22, 2022 10:11:23 GMT -5
Yes it does though I'm not certain I would be successful changing out that ic. What do you think of this idea. What if I use a small signal transistor to use the FLAGS0 line to switch 3.3v to the mcu when it goes over 0.7v ? Is that likely to damage anything further ? You could give it a try. Just make sure you run the 3.3v through a 33 ohm resistor. Of course just remember, even if this solved the error problem there still may be something wrong with the ic. The receiver seems to have received a charge with all the damage so far. |
|
|
|
Post by mmartell on Feb 28, 2022 11:18:17 GMT -5
So got back around to this.
The small transistor did not help as I received the same error.
I replaced IC721, HDMI switch ic, and have video output working fine except there is a strange corruption on the GUI overlays. Also the background images in the menus are displayed fine but the text is missing.
Had some trouble pulling the DSP but after repairing a few pads/traces I got the DSP fitted. Exact same error.
Either the microprocessor is damaged or more likely I think it is internally programmed with a flash that is not compatible between the current unit and the unit it came from.
The saga continues...
|
|
