Onkyo TX-NR828 - Repair assistance wanted

[petehall347]

Re: Onkyo TX-NR828 - Repair assistance wanted

that's odd as they all appear to be drawing about the same current .

[roman-hartwig]

Re: Onkyo TX-NR828 - Repair assistance wanted

and they also all get equally warm.

[petehall347]

Re: Onkyo TX-NR828 - Repair assistance wanted

oh i thought you said they are warmer .
i have realised when they aren't on heat sinks they are drivers and your schematic is missing the outputs i did think it odd the resistors being 2.2 ohms but confused me again seeing the zobel networks . i dont know the class of this amp but its not what i am used to seeing .. anyway the outputs likely have low value emitter resistors so measure voltages across them if so .

[roman-hartwig]

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 as it should be.

So only the final question remains, why do the drivers get so warm and is this "by design" or a bad sign?

[petehall347]

Re: Onkyo TX-NR828 - Repair assistance wanted

probably by design .. you could look up the transistor datasheets and see how hot they can go to safely .

[roman-hartwig]

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.

[jons]

Re: Onkyo TX-NR828 - Repair assistance wanted

They all get equally warm, you don't want to leave your finger on them - so warm. There is no difference between the channels.

That is something above 60 degrees, for transistors with upper working t at 150°C it's nothing. I once had some Rotel with completely burned off painting on output transistor emiter resistors, all measured perfectly ok. Just replaced 2W original ones with oversized 5w for peace of mind but that amp went bloody hot no matter idle or full throtle, that was by design.

[roman-hartwig]

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.

[petehall347]

Re: Onkyo TX-NR828 - Repair assistance wanted

well done .