micle
Junior Member
Posts: 57
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Post by micle on Feb 8, 2022 13:05:28 GMT -5
Ok thanks mastertech, then the oscillator could work.
IC9001 will definitely have pins 1,3,6 at 5v if pin 18 JA9000 is 5v, right?
Before blocking the receiver switched off and switched on continuously triggering relays, which component could have failed?
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Post by mastertech on Feb 8, 2022 13:13:28 GMT -5
IC9001 will definitely have pins 1,3,6 at 5v if pin 18 JA9000 is 5v, right? Right |
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Post by mastertech on Feb 8, 2022 13:17:11 GMT -5
Before blocking the receiver switched off and switched on continuously triggering relays, which component could have failed? I read a couple posts on this receiver getting stuck at "POWER ON" and they said if they just left the receiver in the power on state that it eventually came on all the way after a few hours. I would try this just to see. It may help narrow down problem based on a symptom response. |
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Post by mastertech on Feb 8, 2022 13:32:01 GMT -5
I have had some Pioneers in the past getting stuck at the "POWER ON" position and the repair was always a power rail missing somewhere. I do not remember any other specifics other then they were repaired.
Of course your problem could also be something else causing the lockup. What we do not know is what ic's are being checked during boot up. As it is booting up it is checking for responses from various ic's and if it does not get a response from a particular ic it could freeze the boot instead of giving an error. It all depends on what the boot up is programmed to do.
But, most likely, only a component that is in the boot up checking procedure firmware would cause the lockup. Any other component failure not checked during boot up would most likely not cause it to lock up. Unless other component was shorted as to pull down a power rail supplying a component being checked. Knowing what is being checked would be nice but that information is not always stated in the manual.
So as you can see, there are a lot of variables.
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Post by serafis on Feb 8, 2022 16:28:39 GMT -5
Yes, thanks for the manual, page 75, but unfortunately "POWER ON" always appears and freezes. On a VSX-920 that I've eventually managed to fix, POWER ON appeared and then froze when not all of the tracks on the flat cable from the front panel to the digital main board were making contact. This was due to the end of the flat cable and the connector on the digital board becoming damaged due to repetitive disassembly/reassembly while trying to find many other faults. If this is a problem, you can try carefully trimming the damaged ends off the flat cable with scissors, and maybe reversing the cable. if this doesn't work, you can very, very slowly and carefully prize the plastic connector housing off the connector pins, bend the pins back to their correct shape (I used a needle and small flat spudger ) and extremely slowly and carefully ease the plastic housing back over the pins. Also on the VSX-920 and on a VSX-828, I've had the +12V regulator that is bolted to the chassis from the main board (KIA7812API or similar) have failed - delivering much less than 12V. This caused varying symptoms including not powering on, powering on and freezing, going into DC protect mode, speaker relays not turning on and headphone relay oscillating on and off. Replacing this with a standard 1.5A regulator fixed the problem (pinout may be different and insulation from the chassis is needed). |
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micle
Junior Member
Posts: 57
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Post by micle on Feb 9, 2022 15:17:59 GMT -5
During the prolonged power-up test (3 hours) I noticed that the IC800 was very hot, after a few seconds you had to remove your finger, POWER ON always remains frozen.
Thanks serafis for the indications, I found pin 23 (XSMUTE) of the CN1405 connector bent downwards which did not connect (although I have always been careful), but when reconnected it continues to lock; I remember that when powered it only makes a click and no visual signal.
I also noticed that pin 20 (ACWP5 / TEMPSD) sounded with pin 19 (GNDU), between them there are only 11 ohms, will this be normal?
Will it be necessary to check the CN1900 pin1 circuit because it is 14.6v instead of 13v?
The CP6 connector has pin12 = 12.08v and pin14 = -11.74v
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Post by mastertech on Feb 10, 2022 11:23:42 GMT -5
Will it be necessary to check the CN1900 pin1 circuit because it is 14.6v instead of 13v? The CP6 connector has pin12 = 12.08v and pin14 = -11.74v These numbers are all fine. |
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Post by mastertech on Feb 10, 2022 11:25:16 GMT -5
During the prolonged power-up test (3 hours) I noticed that the IC800 was very hot, after a few seconds you had to remove your finger, POWER ON always remains frozen. This symptom could indicate a problem with ic800. |
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micle
Junior Member
Posts: 57
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Post by micle on Feb 10, 2022 15:40:07 GMT -5
IC800 heats 40 ° / 50 ° C (measured with a contact thermometer) after about 10 minutes, then it remains like this (hottest area pin J19).
Can I heat it to 300 ° C just to re-melt the tin?
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micle
Junior Member
Posts: 57
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Post by micle on Feb 12, 2022 8:32:22 GMT -5
By heating IC800 nothing changes.
By isolating pin 12 (XOLERR) CN1405 with celophan, the receiver makes the second click (protection) and the red iPod LED flashes. If I press STANDBY it turns on after a few seconds it turns off, and iPod flashes (does not freeze POWER ON).
I also remember that before when I disconnected the posistor it went into protection with iPod flashing, while now nothing changes.
Do you have any other ideas?
Did someone have to replace the IC800 chip to fix the block?
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micle
Junior Member
Posts: 57
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Post by micle on Feb 20, 2022 5:48:23 GMT -5
Hi, I resumed the tests on the receiver while I am waiting for the oscilloscope to arrive, I am checking the IC800 chip, I see that it has as inputs the pins M24 and N1 measured respectively in vdc 1.41v and 1.69v, but apparently they are not H signals (> 2v) and L (<1v). The AB23 pin output (RYB) which should activate one of the 5 loudspeaker output relays (SBR / SBL) is 0v. Kindly someone who has the same VSX 920 receiver as serafis, can you test the above pins? It is also useful to compare pin N2 (USBPOW) which to me is 0V with pen inserted. I enclose diagram where to point the needle marked in yellow.  |
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micle
Junior Member
Posts: 57
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Post by micle on Feb 10, 2023 13:36:32 GMT -5
Hello, after a long break I have picked up this vsx-920 receiver again, I have to add more information to repair it.
I recovered another identical working receiver and exchanging only the D-MAIN 7020-06926-000-1S board my receiver started working properly again.
My bad board D-MAIN 7020-06926-000-2S seems to have some known power lock issues, can anyone else confirm this?
In the CN1405 connection the resistance on the working board between ground pin4 and "TEMPERR" pin20 is 40 KOhm, while in mine it is 19.2 Ohm as mentioned in the post of January 28, 2022.
The posistor is identical to mine with R=266 Ohm.
I don't know if it's better for me to buy from China and replace the IC800 bga chip.
Thanks for all.
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