|
|
Post by tibimakai on Oct 2, 2019 10:15:08 GMT -5
I have picked up this receiver, which looks like it is brand new, with box and all the accessories, for $40.
Usually, when there is a bad channel, it is easy to find, because there are shorted final transistors.
On this one, they are all good. It does the amp diagnosis and shows Check SP Wires, at the end.
Sometimes, it turns on normally without entering in this test and then it shuts down in like 30 seconds, or so.
Other times, there is no display at all, because as soon as it turns on, instantly shuts off.
I have tested all the semiconductors, at the amp and preamp section at all channels, and did not find anything bad.
Maybe, there is a bad resistor, or capacitor somewhere?!
I would need some ideas, on how to narrow it down to the bad channel.
Also tested idle current, at each channel and I did not notice anything out of ordinary.
Any help would be appreciated.
|
|
|
|
Post by mastertech on Oct 2, 2019 10:34:04 GMT -5
Usually in a situation like this I would be testing the protect lines at the CPU to see if there is something triggering a protection..
|
|
|
|
Post by tibimakai on Oct 2, 2019 21:46:22 GMT -5
It is hard to find a sm for this model. It is in TX-RZ610.
Do you refer to the two diodes(D7002/D7003) at the MCU?
I'm measuring 0.24V, respectively 0.13V.
To me, it seems like when the speaker relay turns on, then when the unit shuts down. After the amp diagnostic,it stays on, because the relay is not turned on.
|
|
|
|
Post by tibimakai on Oct 2, 2019 22:00:29 GMT -5
In the service manual it shows that, if it comes up with Check SP Wire, that means that it is all good.
But next time, if I reboot it, after a few seconds it will shut off. Than next time when I turn it on, it will check again the amps, that means that something caused it to do the test, right?
|
|
|
|
Post by mastertech on Oct 2, 2019 22:42:54 GMT -5
I would test right at the + speaker terminal for short to ground. I once had a new in box unit that had a factory assembly error where a speaker output metal strip was touching the chassis inside where it was hard to see.
|
|
|
|
Post by tibimakai on Oct 3, 2019 9:59:02 GMT -5
I will try that too. But if it enters the test mode, those terminals won't be active. I will reboot it few times, and hopefully I will manage to get it in normal boot up mode, to test it that way.
|
|
|
|
Post by mastertech on Oct 3, 2019 14:33:11 GMT -5
You do not need it powered on for that test. You do not even need it plugged in, lol.
|
|
|
|
Post by tibimakai on Oct 3, 2019 23:39:24 GMT -5
I thought, that I should test for positive DC, at the speaker terminal. I did not see anything wrong there, except a few millivolt max.
I have measured, at MCU pin #38(thermal) 3.28V. I haven't checked yet, what that means.
|
|
|
|
Post by mastertech on Oct 4, 2019 14:02:11 GMT -5
As I indicated in my first post here, you are testing for short to ground, not for DC.
|
|
|
|
Post by tibimakai on Oct 4, 2019 23:39:11 GMT -5
No short.
For a few minutes I thought that is all good, I have listened to some Tune in music, I have even upgraded the firmware.
At the next reboot, it went blank display again, just a click on and off.
I have managed to get to the description screen, and it was showing Protection: I.
|
|
|
|
Post by tibimakai on Oct 10, 2019 23:39:43 GMT -5
Any more ideas?
|
|
|
|
Post by tibimakai on Oct 10, 2019 23:40:13 GMT -5
Any more ideas?
|
|
|
|
Post by tibimakai on Oct 17, 2019 21:41:34 GMT -5
This is weird.
Yesterday, I have listened to music for a few hours and it worked flawlessly.
Today, I turn it on and it shuts down instantly. Than it makes an amp diagnosis, and it comes up with Check Speaker Wire result, which if I'm not mistaken, on this model that means that everything is OK.
After that, I turn it on again, and it runs very well again.
|
|
|
|
Post by tibimakai on Oct 25, 2019 9:54:33 GMT -5
It seems like that "sensor", on the big heatsink was loose. After retightening it, ran it for a few hours for like a week and it was still working great.
|
|
