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I accidentally had the AVR on and touch the digital coax from the preout to the back of an external amp. Now the AVR immediately turns off after I turn it on.
Everything I checked seems to measure fine. I still replaced the voltage regulators in the amp and a few resistors on the amp and 5V PSU. It didn’t fix the problem.
I removed the preout board and all in/out boards to see if I could isolate the problem or produce a different outcome but the problem is the same.
I would trace back the signal from the S/PDIF connector to the first active component (likely an S/PDIF tranceiver). The failing component is probably that then. Please share a photo of that chip and surrounding parts, if there is a challenge to identify it.
Also, it always helps to share the maker and model of the AVR.
Cheers, heke
Here are some pictures of the SPDIF board. The red box is the front preout I was connecting to an external amp when I shorted it. Around that area are some ICs labeled in the picture.
The first is labeled X25, which I’m not sure what it is. I’m guessing the JRC chips are opamps? There’s another IC that looks like TC4052 (guessing zero). I’m not sure what that is.
On the bottom are a couple chips marked BD3473KS2 but I’m not sure if they have anything to do with the preout. I think there is a transformer marked 25 on the opposite end of the board. Aside from that there are smd resistors and a few smd capacitors. I don’t see a way to identify the smd caps.
How would one go about testing the IC out of circuit? Nothing looks visibly damaged. It might be easier to simply replace everything.
Thank you for the pictures.
The output in question is apparently not a digital S/PDIF, but a classic analog line instead. Presumably this is part of a Pioneer product? Can you provide the model?
I wonder, can you take a close-up picture of the “X25”? It’s probably a Toshiba’s transistor, but need to “see” it.
However, as you say that the whole unit won’t start up, the problem can be somewhere else. That Rohm’s BD3473 is the first suspect.
Cheers, heke
This is the output section to the speakers. Nice Nichicon caps in there. I’m not sure there would be a problem here since I was hooking it up to an external amp, although the internal menu was still set to use the internal amp.
Thanks for the additional info.
It sounds like the unit is turned off due to diagnostics.
The “X25” transistors are IMX25 by Rohm.
However, even in a case that the transistor is gone, the unit should power up (the transistor is merely used for muting the output).
The opamp driving the line out (IC3101) may be the damaged one. Could you try measuring (while power is OFF) conductivity from supply pins (8, 4) to other pins on that IC and between them?
When powering ON, can you see +12V at pin 8 and -12V at pin 4, even briefly?
Cheers,
heke
Thanks for that info. It sounds as if some kind of bootup programming konked-out. Normally the front display would show an error message but it doesn’t even get that far.
I don’t have the tools to test IC3101 while it is powered outside the chasis and I can’t test this board in the chassis because the A/V board sits tightly above it. But while it’s OFF, there’s only conductivity between pins 1. A Output and 2. A - Input, also between pins 7. B Output and 6. B - Input. This is the same for the remaining NJM4580 opamps.
Also R3202 (270 Ohm) measures 282 Ohm (boxed in red). The remaining 270 Ohm resistors measure within a couple Ohms.
I might just order a handful of ICs and resistors from the front channel X25 to the other end of the board and see how it goes.
Yes, the first thing I checked was for continuity in any fuses I saw. They were good. So I moved on to the amp.
I didn’t see any issue but I replaced all but two of the voltage regulators (not stocked). It doesn’t look too complicated and I figure for the age it’s easier to just replace everything I could identify.
There are a couple Rohm 2SD2400A 2SB1569A transistors boxed red that weren’t stocked that weren’t replaced. The ceramic caps weren’t replace since I couldn’t make sense of the markings. There were a few resistors I replaced for tighter tolerances.
Hi @hp-je513l ,
I think you can test the power supply board by itself (just connect the transformer) and measure all the voltages that are printed to the PCB.
If it helps, there is a service manual available online
Thanks, much appreciated. It looks like I identified the boards wrong but it won’t stop my from going gung ho replacing parts until it works, as long it it doesn’t involve unmarked smds.
I’d have to put it all back together to complete the power flowchart, but from memory, the wireless light continues to blink so it’s getting power from the primary and main boards. I remember checking the pins on the primary board and those were good too. Short of checking the display and display bridge, that’s probably inferring the problem in the main board.
Hi @hp-je513l ,
That pin is driven by a couple of open-drain comparators, thus should be either near 5V or 0V. +4.3V may indicate that the line is pulsed. Check the XRESET with an oscilloscope. If it is pulsed, then check which supply V+5_EV (CN7903, pin 1) or V+5R6_EV (CN7902, pin 39) is unstable.
… Or, resistor R7906 is damaged (unlikely).
Cheers, heke
