OK, I will try and get back to you, hopefully with progress
roman-hartwig
Member
Last Activity: 07-29-2023, 04:06 PM
Joined: 04-14-2023
Location: Berlin
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Re: Onkyo TX-NR828 - popping sound every 5 min
OK, I will try and get back to you, hopefully with progress
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Re: Onkyo TX-NR828 - popping sound every 5 min
The phenomenon I described is more of a "bang" and occurs about every 5 minutes. So it is louder and more abrupt. Ok, let's assume it's a similar problem, then the fault is in one of the transistors shown in the attached picture? I imagine a diagnosis with cold spray as in the linked article difficult, since it is not present all the time. Would such a transistor have to have measurable variances to identify it, or does one in the schematic catch your eye directly? And thanks already for the hint....Leave a comment:
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Re: Onkyo TX-NR828 - popping sound every 5 min
When you talk about a "bad transistor", do you have a specific one in mind? Because basically the channel is still giving a clean sound, it's just that it's making cyclic pops. Wouldn't a bad transistor prevent the channel from working at all?Leave a comment:
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Onkyo TX-NR828 - popping sound every 5 min
Object: Onkyo TX-NR828
Problem: Popping noises in the right surround channel every ~5min
Service manual: available
After I was able to bring my beloved Onkyo back to life (total failure of the power amplifiers) and it has now been doing its job for some time without any problems, it is now ailing with a new problem. It still works fully, but after about 5min it "pops" in the right surround speaker for about 0.5 sec very loud (100% volume). I am almost scared to death - sounded like a battery exploding or something. It sounds like something is discharging - a... -
Re: Onkyo TX-NR828 - Repair assistance wanted
After almost a week of daily use, without further incidents, I would say everything is fine again. Thanks again to all involved for your help and support in troubleshooting.Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
Both are discontinued and according to the data sheet are designed for up to 150°C. On occasion, I will look again if there is an exchange type that perhaps does not get so warm, or to what extent I can mount a small heat sink to simply improve the heat dissipation....Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
Okay, I may not have expressed myself very clearly. Sorry. They all get equally warm, you don't want to leave your finger on them - so warm. There is no difference between the channels. The actual power amp can be seen in the second schematic for the left channel (first post). If you like I can also just provide the manual.
In the meantime I have also put the amp back into operation and it does what it is supposed to do. I replaced the fan with a higher quality one and checked the idle current again. Everything was still...Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
and they also all get equally warm.Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
These are not mounted on heat sinks. These respective pairs stand freely on the board without heat sinks. You can feel the heat emission with your hand if you only hold your hand over the open AMP....Last edited by roman-hartwig; 04-23-2023, 12:42 PM.Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
I have now measured the resistors and their voltage drop and calculated the resulting current. For comparison, I measured the right channel.
The results are as follows:
[B]
Left Channel:[/B]
[U]R5370:[/U]
R = 2.3 Ohm
U = 25,7 mV
I = 11.17 mA
[U]R5380:[/U]
R = 2.4 Ohm
U = 25.6 mV
I = 10.66 mA
[B]Right Channel:[/B]
[U]R5371:[/U]
R = 2.3 Ohm
U = 26.6 mV
I = 11.56...Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
You're right, I overlooked them. Thanks! But since they are marked green, I have measured them as intact. Don't get around to it today and won't tomorrow either. So on Sunday I will measure the voltage drop and then calculate the current. But what can I deduce from that? Whether they are running within their specification, or is the set point of the current known?Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
A day later and after normal use, everything works as usual. I also measured again and could no longer find any deviations. The heat generation still takes place. Said "larger" transistors ( first post => preamp-pcb-front.jpg ) are still a bit warm for my taste. If I would build something that has such heat development, I would at least add a heat sink. Even if this was only small or thin. Does anyone have such an amp and can confirm that the heat generation is common?
@petehall347
I may have missed something,...Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
After the arrival of the spare parts, I immediately set to work. I replaced the two transistors and the resistor. After 1 minute with electricity, the amplifier could now be switched on again. So I started to measure the idle current. It was noticeable that some deviated nevertheless already clearly from the target (up to +10mV). I readjusted everything appropriately then. The primary (large) heat sink is no longer hot after 5 minutes. The final sound check is still pending. However, I noticed that there is a noticeable heat radiation...Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
Have checked the potentiometers again individually, but they all seem to be okay. A short circuit at the output is excluded at least on the speaker side. Now I have to wait until the spare parts arrive, then I'll get back to you.Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
That was my guess too, but I wasn't sure. Thank you for the certainty. However, I still have the question of how the defect occurred. Material fatigue? All other channels have no deviations or obvious defects. Do you think there is another potential defect that can be deduced?Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
This is the current status of my measurements. The two marked in red are the ones that need to be replaced. Now I looked on Digikey but found replacements with different values for the transistor.
2SC2412 (a) [url]https://www.digikey.com/en/products/detail/rohm-semiconductor/2SC2412KT146R/650455[/url]
2SC2412 (b) [url]https://www.digikey.com/en/products/detail/rohm-semiconductor/2SC2412KT146Q/650454[/url]
The difference here is "DC Current Gain" with once 120 at 1mA, 6V and once with 180...Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
Thanks for now, I will then measure further tomorrow (it's already late). Can you deduce what could have caused it? The procedure for setting the idle current is described in the service manual as in the attachment. If I understood correctly, I should set/measure in series to a 100 Ω resistor the mentioned voltages at the mentioned time. The measuring points for e.g. the left and right channel are shown in the circuit diagram above....Last edited by roman-hartwig; 04-14-2023, 06:51 PM.Leave a comment:
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Re: Onkyo TX-NR828 - Repair assistance wanted
Sorry, I made a typo when writing down the types. Of course, the correct ones are installed:
Toshiba TTA0001 => 2S[B]A[/B]1962OTU-ND
Toshiba TTC0001 => 2SC5242OTU-ND
Without really having a concrete idea, I have already started to measure the left channel. Currently Q5410 and R5470 are striking and show too high values / results. Am I on the right track with this?Re: Onkyo TX-NR828 - Repair assistance wanted
Sorry, I made a typo when writing down the types. Of course, the correctLeave a comment:
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Onkyo TX-NR828 - Repair assistance wanted
Object: Onkyo TX-NR828
Problem: Overheating / Burned off
Service manual: available
Runs all the years without problems, day on day off. Then all of a sudden with a bang and a small flash one of the final transistors burned out. This is the left front channel. Since the original Toshiba were no longer available, I replaced them all with the equivalent:
Toshiba TTA0001 => 2SC1962
Toshiba TTC0001 => 2SC5242
This also included replacing the thermal paste and the very own insulators with pads (1.3W/mk).
After I... -
Re: New Members - please post your introductions here
Hi all, have read quite a bit here and there on the forum and thought it was about time to be a part of it too. I am currently struggling with my Onkyo.
About me:
- ozilliscope
- multimeter
- De-, soldering station
- knowledge of Ohm's law
Thanks to all who share their knowledge here.Leave a comment:
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