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Louie
Louie, Technician
Category: Home Theater-Stereo
Satisfied Customers: 11421
Experience:  Have been in the business 25+ yrs., down to component level.
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Pioneer VSX-84TXSi System powers up, no odd displays or error messages

Customer Question

Pioneer VSX-84TXSi System powers up, no odd displays or error messages. No delay inrush or speaker protect relay sound (should there be?). As best I can tell, there appears to be no internal audio or visual switching taking place though the display reports correctly. No relay sounds during source switching (should there be?). Silence from speaker outputs and phones, including FM and AM hiss (speaker protect relay never closed?).
Submitted: 1 year ago.
Category: Home Theater-Stereo
Expert:  Russell H. replied 1 year ago.
Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I don't think the protect relay is the problem, not necessarily - if there is such a thing in this device. Rather, you have an undiagnosed electronic problem with a component (or components) in the audio amplifier portion of the circuitry. What this is, would need to be determined.
One way to determine whether there is a fault in the amplifier, is to measure along the signal path through the audio amplifier, and see where the signal becomes reduced or absent.
But first one ought to measure the power supply's voltages, as supplied to the circuitry when the Pioneer device is live.
To do those steps properly, a service manual would be ideal - it would show test points, and expected values. It also would provide diagrams, and procedures. Would you like me to search for a source for such a service manual for your model?
Or would you prefer a recommendation to a service shop in your region, that would service-repair your Pioneer device?
Customer: replied 1 year ago.
I have the primary service manual and am a component level tech. Just have no experience with consumer electronics so am looking for someone with experience with this particular unit so I don't have to waste a lot of time learning what someone knows from experience..... I know its not the speaker protection. but there's no v to any of the relays, including the relays related to the input device selection....just figuring that its not booting completely. BTW, voltage traces through the power supply.
Customer: replied 1 year ago.
Another tech told me he thought this unit had internal diagnostics but we can't find anywhere that talks about it.
Expert:  Russell H. replied 1 year ago.
I may not be experienced enough with this particular device to help you with this problem.
If it's not booting up completely, not initializing, then internal diagnostics probably wouldn't work. So I can only give the advice I have already stated - check that no voltages from the power supply are either absent or off-specification (e.g. loaded down owing to a short, perhaps).
And, since it is late (11:45 p.m. in my time zone), I regret having to give up the case, but I have: I have Opted Out, opening the case to other Experts in this category.
Customer: replied 1 year ago.
Thanks Russel.
Expert:  Louie replied 1 year ago.
Hi and welcome back to JustAnswer,
Thank you for the question and your patience. Should you still need assistance for information purposes only...
Initially, consider / try the 'release mode' (if have not been done). This would serve as both an attempt of a fix and as a test. If still a no-go, then the internal hardware issue is confirmed.
If so and based on the above description of "...there's no v to any of the relays...", then check for the presence and consistency of V+12V at pin 5 of connector J4009 of the SP/PS ASSY. Follow/trace this +12 line from a connector board (Trans Side Assy AWX8652) and check the coupling inductor/resistor L4405/R4405. Also check for potential cold solder or loose connection/connector pin. And finally to regulator IC6104 of the Local Supply Assy (AWX8671).
Customer: replied 1 year ago.
Hi Louie. I'm not familiar with the "release mode" you speak of, so please explain. The following may be helpful to you: late last night, I discovered that the service manual I really needed was the one for the VSX74 (the 84 that I downloaded was merely an 80 page supplement which explains why it wasn't telling me anything useful), so through the night, I printed the entire 74 manual and found/ran the section 7.0/7.1 Diagnosis/test mode starting on page 189 and everything reported normal except the microcomputer tests on page 190. DSP microcomputer returned version Dx.xxxx (no version). The 2 DSP firmware tests also returned "x" versions. In the notes, it's suggested that the "x.xxxx" indicates "failure in comms between the m/c's or failure of the corresponding microcomputer is likely". It was getting close to sun-up, so I called it a night and haven't done anything since that test. Thanks for your response. Does this help at all? Your thoughts?
Customer: replied 1 year ago.
Since writing last, did your tests as suggested and found 12Vdc at all points. Also, check the connectors and followed Vdc around the DSP block per the diagnostic instructions on page 196-197 checking all 3.3vdc and 1.2vdc points. All tested good.
Expert:  Louie replied 1 year ago.
Appreciate the additional information.
Please note that the release mode is a technician's bypass and is a double-edge action as it would equally serve as an attempt of a fix (if it were a glitch) and as a test by process of elimination (the faulty part may exhibit burning). Please see if either Service Manual is RRV3477P or RRV3197 and check p.191 for the release mode.
Customer: replied 1 year ago.
Found the issue...... Before it came here, the previous owner took it to his local "expert" so I knew somebody had been in it before me....so just 'cause.....I like the line....trust, but verify, I started to check his re-assembly and sure enough, found a pair of connectors to the DSP block that were reversed. Corrected the discovery and she fired right up. I now have a decent receiver for a very reasonable price.
Expert:  Louie replied 1 year ago.
...would have never guessed a prior work on the Pioneer
Still, Great! Good to hear that the issue has been resolved, congratulations.
Good luck and thank you too for the opportunity to be able to exchange information.
Customer: replied 1 year ago.
I might have lied.... Had it all working. Put the DPS shield back in and the bridge connector back and retested...good. Disconnect power, put the cover back on and......retest, nuts, we're back to same problem. So.....right now, got it all apart again; tested again, bad. Tracing through bridge connector for cold solder joint and then point to point beyond the connector. Damn thought I had it. I suppose it could also be a bad microprocessor that decided to come back to life for a minute just to annoy me..... any other ideas would be much appreciated.
Customer: replied 1 year ago.
Looks like it came back to life momentarily for reasons unrelated to what I was doing. Anyway, the VSX 74 manual I have is marked "provisional" and the manual marked VSX84 is RRV3477. What next?
Customer: replied 1 year ago.
The only page 191 I have is in the "provisional" manual and doesn't discuss a release mode. Its a page that explains error messages reported by the display on start-up. Meanwhile, would I be correct to assume this is looking like a issue with the DSP block? I'd sure like to know for sure before replacing it. I'll keep trying stuff if you direct me to do so. Thanks again.
Customer: replied 1 year ago.
And last......found version RRV3197 and release mode. Pushed the 2 buttons as instructed and....nothing. Doesn't turn on or anything.
Expert:  Louie replied 1 year ago.
Sorry to hear the "relapse".
If the release mode was not corrective, then there is a fault but not major nor related to the amp / output circuitry.
Please re-check the rear screws; all of them as well as the circuit boards they screw into inside. Pioneer uses the rear panel as a common GND BUS.
Customer: replied 1 year ago.
OK.....going to do the backplane now. Done. Sure does act like a intermittent connection, but........I sure can't find anything. Have reseated all the DSP connectors many times now. Also note, refired it about 50 more times (without changing anything) with a signal on the CD channel and the selector set to CD. The system "kicked in" twice and the display shows the input 192Khz stereo instead of CD. It continues to work until I shut it off, then we're back to ground zero.
Customer: replied 1 year ago.
OK....5 more fires and now its working again. This time I'm just going to pour a drink, think about this and let it cook for a bit. I have a digital source signal on the RCA digital jack (2) routed to the CD channel playing stereo.......
Expert:  Louie replied 1 year ago.
Let's focus first on the grounding (even if just to eliminate is as a suspect). Use alligator clips with wire to carefully connect the ground trace ALL the circuit boards to the back panel.
http://tinyurl.com/k2u9t7l
The 192K would likely point to DSP2 / MCACC Port Processing being falsely triggered or a firmware glitch.
Customer: replied 1 year ago.
Well, I switched the source and lost it again. I need to take a break for a bit. I do have enough test leads with ACs to tie it all together so will do that in a bit or morning and report back. This thing sounds super...when its working, so at least I don't have multiple issues.
Expert:  Louie replied 1 year ago.
I understand; later then or when able.
Customer: replied 1 year ago.
One other note, when I turn it on and its going to work, I get several front panel lamps such as Phase Control, MCACC, Speaker selection and Surround selection. I can operate the functions of each,also. When I fire it and its not going to work, I don't get any of the lights and the function buttons do not respond. Will write after a tie the boards to ground.
Expert:  Louie replied 1 year ago.
...another to try / check would be reset IC IC104, its peripheral circuit including C126 & C 102 as well as crystal X101.
Customer: replied 1 year ago.
Tied and cross tied the ground every which way and double checked with resistance checks to the back plane and ground near the P.S. Reseated all the ribbon cables and connectors. At least now, we can be reasonably confident its not a lifted ground. Just now seeing your last comment about IC104 and the caps and crystal. What do you mean by reset? Think (hope) I'm done for tonight unless I start obsessing. Thanks for all your help.
Expert:  Louie replied 1 year ago.
Agree on the ground connections now.
And yes, there is a reset IC the produces a reset pulse every time that the Pioneer is turned on. This is a low-level reset that starts the CPU and syncs with the time base produced by the crystal.
Post an update when able.
Customer: replied 1 year ago.
Headed to bed but when you get a chance how would I test these? Supply v and cap? I don't have a scope for testing the xtl or do you mean something else?
Expert:  Louie replied 1 year ago.
Yes:
• +5V on pin 2 of IC104;
• a pulse at pin 1;
• a very low voltage difference between the 2 outer legs of the crystal.
Customer: replied 1 year ago.
Hi Louie,I plan on getting back on this later tonight or tomorrow. What do you mean by a pulse on pin 1 of IC104? Should I expect a single pulse at power up or should I expect something like a clock pulse say every second or few seconds or ???? And last, just to confirm, you asked that I check Vdiff on X101. I see crystal X301 which looks like the only crystal on the DPS board. Am I missing something? As always, thanks for your patience and help.
Expert:  Louie replied 1 year ago.
The low-level reset would be a single pulse.
X101 would be tied to the main/SYSTEM CPU IC101 PEG116A.
Customer: replied 1 year ago.
OK....moving to the Main CPU board (Digital Mother Assy), IC104 Pin 2 (Vdd) tests 5.2. Pin 1 (Vout) tests constant 5.1. Cycle power and pin 1 fires up clean to 5.1v and holds at 5.1v each time. Crystal with the meter across the crystal, drops to absolute zero. Not even any noise voltage.
Customer: replied 1 year ago.
Additional info: When the receiver is in standby mode, both Vdd and Vout sit at 4.8. When the receiver is switched on, v at both pins rise as described above. When power is completely removed (receiver unplugged) both pins slowly drift to zero as if tied together. Upon power up, both pins rise again as if tied together. 4.8 when in standby, 5.2 when on.
Expert:  Louie replied 1 year ago.
Thanks.
Could you please try cleaning the solder pins of IC104 and IC101 preferably with plastic safe / non-staining DeoxIT DN5 or LPS 03116 Contact Cleaner or equivalent and an old toothbrush.
And if available, carefully re-solder using a hot air soldering station.
Customer: replied 1 year ago.
I have some Deoxit around here somewhere. Good stuff. I don't have a air station. I have the right gear and feel comfortable resoldering the setup chip, but not the CPU.... I'll Deoxit everything and try power again. If still a problem, I'll reflow the setup chip and try again. If still having trouble, I have a good loupe and will look over the CPU. I'd probably tackle a single pin if I saw something specific but beyond that, think I'd be pushing my luck. One thing I'd be curious about. If this is the issue, and the above stuff doesn't work, remove the setup chip and manually pulse the output trace with 5v once the receiver is on. If that works, replace the setup chip ($3 at Digikey). If not.......on to whatever you suggest I do next? I'll be back tomorrow night. Thanks again for all your help.
Expert:  Louie replied 1 year ago.
I understand and would look forward to an update.
Customer: replied 1 year ago.
OK.... Deox'd both chips and resoldered the setup chip. I was momentarily hopeful as all 4 solder points were cold, but reflowed nicely, No change. Remeasured v flow and Vout still follows Vdd from 5.2 down to zero and back to 5.2. If I understand the circuit correctly, when Vdd falls below the designed threshhold, Vout should drop to zero (turn off or normally off depending on circuit design). Then, upon powerup or return of correctly system voltage, Vdd rises above the threshhold, triggering a pulse from Vout; resetting the CPU. As best I can tell, there's no such activity at Vout. It just mirrors V in. So.......what next?
Customer: replied 1 year ago.
Unless, of course there's some level of feedback voltage coming from the CPU back to pin 1 of the reset ic, but I just exceeded my technical threshold.
Expert:  Louie replied 1 year ago.
No feed back. The schematics shows an arrow indicating the signal flow from IC104's pin 1 to the CPU's pin 17 through a 100Ω resistor R112.
Agree with you on the reset IC's operation, consider:
• pin 1 is reading logic HI due to pullup resistor R164 [VOUT = VDD = V+5UM];
• internally, IC104 would clamp VOUT to GND upon startup even if momentarily;
• the pulse then is a negative going signal - logic LO.
Would you venture momentarily shorting to ground pin 1? ...and observe any change in the display?
Customer: replied 1 year ago.
Sure. Will power down. Clamp pin 1 thru a jumper to gnd. Power up. Wait for Vdd to settle and release pin 1 by lifting jumper. Should emulate the setup function. Will report back later. Thanks as always.
Expert:  Louie replied 1 year ago.
Would look forward to an update then.
Cheers.
Customer: replied 1 year ago.
Ok.....Pin one jumpered to ground: receiver won't start. Lift jumper, leaves IC 104 connected normally and previously known condition. Start receiver and just touch pin 1 to ground and receiver shuts off. Tried various "timing" steps and no difference. Do you feel that IC104 is the problem or probably just a step? If so, consider this. Remove IC 104 (thinking it's the issue) which would leave the trace to the CPU at 0 volts and create a pulse manually by putting 5v on the pin 1 trace once the receiver has started. Or.....something else?
Customer: replied 1 year ago.
IC104 is showing a direct short from pin 1 to 2, so I'm guessing the receivers protect logic would see the above test as Vdd short and self protect.....
Customer: replied 1 year ago.
Also, R164 confirmed 100K.
Expert:  Louie replied 1 year ago.
Try de-soldering IC104 and repeat momentary grounding R112.
And the shorted pin 1 to 2 would of course necessitate replacement.
Customer: replied 1 year ago.
I tried a few things. Nothing worked, but I'm thinking they're probably invalid tests. With the chip out, jumping ground to R112 shut the receiver down (receiver still sees 5.2v through R164 so with the chip out, R112 still sees the supply v swing from 0-5.2 (Obviously, I'm missing something as I don't understand how IC 105 is supposed to shunt Vout when R112 has full access to Vdd through R164......so I'm guessing the chip was possibly OK all along???). Meanwhile, I ordered a couple new chips from Digikey as the one I took out is toast. I'm way over my head now so have no idea what to do next.
Expert:  Louie replied 1 year ago.
Could you try de-soldering / temporarily removing either R164 or R112 out?
Customer: replied 1 year ago.
Sure, will tackle manana and let you know. Have a nice evening.
Expert:  Louie replied 1 year ago.
You too.
Customer: replied 1 year ago.
So.... bypassed R164 and the receiver starts, but issue still exists. Played with different combinations of pulsing R112 or releasing it and no real difference however the receiver seems to "think about it" more before shutting down, but whatever it decides to do, I can't duplicate the response twice in a row. I was looking at an ap note for the setup chip, but will need to look more at it later when I have time to see if I can understand the circuit more. Initial glance seems to suggest (using education from 40 years ago) a logic circuit that low-high on the output is something like 4v to 5v with a single ms duration pulse at a threshhold of about 4.8v, so I'm guessing my on/off emulation probably just confuses the works. I looked, but on the internet but didn't see an ap note or spec sheet on the Pioneer CPU saying what it wants to see on the setup pin. Also, checked Vdd and Vcc pins on the CPU and all seems good. Meanwhile, DigiKey sent an email this morning saying the replacement chips have been shipped 1st Class mail. Any thoughts? I'll check back after the morning chaos settles down.
Expert:  Louie replied 1 year ago.
I understand and would also run a search for any app/other circuit for the BU4842F.
Customer: replied 1 year ago.
Sad to report......got the new BU4842F installed (noting correct placement of pin 1 and checking afterwards for garbage) and it meters out as before and last double checked the traces and resistor I lifted and.......same.
Expert:  Louie replied 1 year ago.
Sorry to hear of this.
Does the new BU4842F also show "...a direct short from pin 1 to 2..."
Customer: replied 1 year ago.
No, but I suspect I got a false positive the first time because I didn't realize that R164 existed between pins 1 and 2. Unfortunately, I broke the first chip taking it out so couldn't confirm it's condition after removal.
Expert:  Louie replied 1 year ago.
At this point, there are just too many variables that can/would cause the CPU to go to auto-protect or simply fail to cycle/start. And the RESET IC104 would have been the simplest to check.
"Shotgun approach"; i.e. test any and all voltages. Should you elect to pursue further tests, determine the presence of the different voltages starting with the Digital Mother Assy including (but not limited to) the V+5_6ST, V+5_6U, V+5US, V+5UMIN, V+5UM...
Customer: replied 1 year ago.
I kinda suspected that was going to be the next step. I'm going to set it aside for a few days and reclaim my dining room table. I'll let you know after I've created a list and the results. Thanks again....I'll be in touch.
Expert:  Louie replied 1 year ago.
When able please; thanks too.;