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Post by tibimakai on May 7, 2019 10:10:41 GMT -5
A coworker gave me the whole set for free, this receiver with the bad HDMI and a bunch of speakers and bad subwoofer(different thread here and badcaps).
HDMI IC was getting very hot. He installed a fan there, and that way at least he was using it without HDMI.
I assumed that that IC is shorted, since it was getting so hot.
Though the 3.3V, 1.8V at the HDMI, IC and 5V at pin #18, at the HDMI were there.
I have replaced the HDMI IC, and now does not turn on, it only clicks on and then off, continuously.
Any ideas, where to start with this?
It is not really worth dealing with this receiver, it is very old, but it is just a personal challenge.
Any help would be greatly appreciated.
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Post by tjmotter on May 7, 2019 14:35:23 GMT -5
There is not a lot of circuitry in the HDMI section of this receiver. If you are sure the Q8101 part is good the only things I can see to check are the transistor pairs connected to the Hot Plug Detect lines (Q8111/Q8112 - HDMI 1, Q8113/Q8114 - HDMI2, Q8115/Q8116 - HDMI3, Q8117/Q8118 - HDMI4.
There is also a small "dual diode" device (Q8347) on the HDMI out port that you should check as well.
HTH
Todd
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Post by tibimakai on May 7, 2019 15:03:55 GMT -5
Yes, it is pretty simple and the DSP IC has legs(!).
I'm wondering, why it would not turn on, with a new IC?
Supposedly the IC is good, I got it from ali.
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Post by tjmotter on May 7, 2019 17:11:45 GMT -5
not sure. did you double check to make sure you don't have any solder bridges or poor joints?
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Post by tibimakai on May 7, 2019 20:36:41 GMT -5
I'm doing a good job now. I have a microscope, I have purchased that tip, that you have showed me. I'm going over like three times to be sure, that everything is OK.
One trace it was ripped off(lifted like two inches long), from the beginning, but I have managed to solder it back.
The only thing that could be, is that the IC from Ali, is bad.
The previous owner has replaced this HDMI IC, but since I have already purchased a replacement IC, and it was getting very hot, I thought that it's a good idea to replace it.
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Post by tibimakai on May 9, 2019 0:41:11 GMT -5
It is hard to diagnose something, when it keeps turning on and off.
The transformer has on both pins 40V for a second.
At JL901B connector(page 37), the 12V, 10V and 12.9V(Mpower) are there stable.
At JL801B th 5.2V and 12V are not there. They show something like 0.58V and 0.8V.
I have even removed the HDMI IC(Q8101) and nothing has changed, still clicking on and off.
The Micom is bad?
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Post by tjmotter on May 9, 2019 14:33:57 GMT -5
Is it possible that a channel blew sometime during this process? Can you check the power on voltages at the two protect diodes next to the CPU (IProtect and VProtect)?
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Post by tibimakai on May 9, 2019 16:36:01 GMT -5
I'm not aware of such an event, but at this point anything is possible.
I will check them later on.
Thanks, Todd.
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Post by tibimakai on May 10, 2019 0:17:45 GMT -5
I have removed the pre-amp board, tested the final transistors for short, but they are all good.
I ended up unplugging most of the ribbon cables from the speaker board, HDMI board and it was still clicking.
The only thing left connected on the HDMI board, it was the JL901B.
After removing the ribbon from that connector, the clicking has stopped.
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Post by tjmotter on May 10, 2019 15:13:47 GMT -5
Makes sense. That connector supplies all the voltages to the HDMI board. The only thing I can think of is that the HDMI chip you got from Ali is bad. Not common but it does happen....
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Post by tjmotter on May 10, 2019 15:49:22 GMT -5
Can you do a quick check on Q746 and Q273 to make sure neither has the output (pin 5) shorted to ground? Also check D182 and D183 to make sure they aren't shorted.
The MAIN CPU may be detecting a voltage issue and is shutting down because of it.
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Post by tibimakai on May 10, 2019 20:01:08 GMT -5
On this board, the Micom is under the board, so I can't really measure those two diodes. Only if I would solder some wires to them.
I will check those. Thanks
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Post by tibimakai on May 12, 2019 13:58:27 GMT -5
Those components are not shorted.
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Post by tibimakai on May 13, 2019 16:59:33 GMT -5
The voltages at JL901B are fluctuating, with only that connector connected.
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Post by tjmotter on May 13, 2019 17:08:17 GMT -5
Did you check D702 and D701? If you aren't seeing any obvious shorts on pin 4 and 2 of JL901B, it might make sense to take a quick look at the power supply board. Specifically:
D930, D931, D923, D921, D924, D922, D925, C930, C922. Also try to measure R921 to make sure it is 47 ohms. If it is below 45 ohms, change it out.
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