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Old 05-31-2018, 04:59 PM   #61
jworthin
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Default Re: ONkyo TX-NR626 Check SP Wire

I replaced all transistors and all electrolytics in the R driver. I have triple checked the SMD and discrete resistors as well.

Idle voltages stay within service manual tolerances even as it heats up!
The voltages across the plus and minus sides of the driver match the L and C channels.

I have even tried reducing all channel idle voltages to 1mv and it still overheats and drops the B voltages in half (you can hear the drop-down voltage relay click in). How can the power transistors get so hot when the idle voltages/currents are so low??

When the B voltages drop in half the unit temp drops to room temp (75F) in a couple minutes.

The heat sink gets so hot (135F) you cannot leave your finger on it. And this is with no input, no volume, and no speaker load.

Thanks.
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Old 05-31-2018, 05:55 PM   #62
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Default Re: ONkyo TX-NR626 Check SP Wire

Every channel is that hot, or only the R.
The 626, has a fan?
If I remember correctly, at 60C the fan should kick in.
You are using a 100 Ohm resistor on each lead, when measuring the idle current?
I have never replaced all the capacitors, usually only one is blowing, or none.
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Old 06-01-2018, 04:34 AM   #63
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Default Re: ONkyo TX-NR626 Check SP Wire

Did you check the main board resistors near the final transistors as well ? There are at least two there known to go open, one being the dual package emitter resistor.
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Old 06-01-2018, 12:11 PM   #64
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Default Re: ONkyo TX-NR626 Check SP Wire

tibimakai:
All channels were hot.
The unit did not arrive with a fan but researching further looks like this model should have one. I have ordered a replacement.
I did not have the 100 Ohms resistors installed correctly. Fixing them and resetting the idle current seems to have fixed the overheating and voltage drop back. Thanks!

Could overheating cause the shorting of power transistors before the immediate thermal protect shutdown could protect the unit at 100F?

mmartell:
I checked the two base 0.22 Ohm resistors and the 5W ceramic double 0.22 Ohm resistor.
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Old 06-01-2018, 01:02 PM   #65
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Default Re: ONkyo TX-NR626 Check SP Wire

You are talking about, the 100 Ohm resistors, in the measuring leads?
I'm not familiar, with that voltage drop thing. Why would that happen at all?
The receiver did not show any message, that is in protection mode?
If it was overheating, it should have shown something.
mmartell, was referring to other resistors as well.
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Old 06-01-2018, 02:33 PM   #66
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Default Re: ONkyo TX-NR626 Check SP Wire

Yes, I incorrectly connected the resistors in the measuring leads.

The schematic shows the drop-down relays are MPU controlled by SEC1H on pin 128. This appears to switch between the +-S1L and +-S1H voltages. It certainly let the amplifier cool down when it switched low. I could hear the click but there was no change in the display. The first time I 'fixed' it, it died after 4 hrs resulting in a reported VPROT fault. (from overheating???)

Warning: I'm strictly an amateur here so I could easily be mistaken about anything I report.

Again, thanks for your help. It is greatly appreciated.
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Old 06-01-2018, 04:53 PM   #67
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Default Re: ONkyo TX-NR626 Check SP Wire

In the 626 diagnostics menu there is a "confirmation of output sensor and thermal sensor" test. It reports the voltage of the VOLH port, the temp sensor, fan speed, and the amplifier power supply voltage condition (High-B or Low-B). The implication is the Low-B may be used for overtemp situations.
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Old 06-01-2018, 05:18 PM   #68
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Default Re: ONkyo TX-NR626 Check SP Wire

I know, there is a way to check the receiver's temperature, with a combination of button presses.
Per artois7. on page #3:
"From memory, I think if you hold down display and the power button, release display and press the tone button, you should get an internal temperature reading. My 609 reads around 23 degrees on first power on and will idle somewhere mid 30s-40s ish (and it's got no ventilation around it..!)"
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Old 06-02-2018, 09:22 AM   #69
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Default Re: ONkyo TX-NR626 Check SP Wire

Temperature and output voltage can be confirmed the following operation when the unit is powered on.

[DISPLAY] + [ON/STANDBY] * 2 → [TONE]

e.g. 001 042 F:x S:H

Displayed Fields:
(001)Voltage of VOLH port,
(042)Temperature of thermal sensor,
(x)FAN speed (x: Stop, L: Low speed H: High speed),
(H)Amplifier power Supply voltage condition (H : High-B L : Low-B)
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Old 06-02-2018, 11:24 AM   #70
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Default Re: ONkyo TX-NR626 Check SP Wire

My fan order on eBay fell through (seller lost the part). Anybody have a Onkyo TX-NR626 or 616 fan for sale? KF1225B1E-33ACD54RB or 4710KL-04W-B10-EA2. Thanks.
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Old 06-02-2018, 12:31 PM   #71
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Default Re: ONkyo TX-NR626 Check SP Wire

If you want to keep this receiver and not resell it, I would suggest to get a 120mm PC fan and mount it to the top case from inside.
When I had these older receivers, I have used a laptop cooler's internals, fan and fan controller. I have ran the USB cable to the TV. When the TV it was on, the fan it was on.
I have adjusted the fan controller to a speed, that the fan noisy did not bother me.
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Old 06-03-2018, 10:37 AM   #72
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Default Re: ONkyo TX-NR626 Check SP Wire

Found another fan assembly from an eBay seller by contacting everybody that is selling or has sold any NR626 parts. No need to reply to my previous post. Thanks.
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Old 06-19-2018, 10:10 AM   #73
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Default Re: ONkyo TX-NR626 Check SP Wire

Replacing the fan fixed the overheating nicely but the unit still failed (VPROT) after threes days running 6-8 hours a day. Failed parts are: Q6051, R6081, Q6061, and R6091 the R channel power transistors and their 0.22 ohm base resistors.
On the driver board R channel: R5351, R5471, Q5461 and Q5411 failed.

Service manual link:
https://elektrotanya.com/onkyo_tx-nr.../download.html

Any suggestions would be greatly appreciated.
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Old 07-11-2018, 01:06 PM   #74
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Default Re: ONkyo TX-NR626 Check SP Wire

I bought a working NR626 and swapped driver boards to try to solve this problem. The old driver board in the working NR626 works fine but the working driver board in the old chassis blew the same R channel components. With no input nor volume this second unit combination has 354mv on the R amp output (before it eventually blows). It also has 254mv voltage difference on the differential pair bases for the R channel while the L channel has only 8mv on the differential pair bases. It also drops to the low B voltages after about an hour.

I'm assuming the swap test points to the motherboard amp section. I believe I have double checked all those R channel components at least twice.

Please help...
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Old 07-11-2018, 01:27 PM   #75
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Default Re: ONkyo TX-NR626 Check SP Wire

The only thing I can say is, that you have missed some bad component(s).
There is no point, in buying other boards. You still have to find the bad part.
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Old 07-11-2018, 02:04 PM   #76
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Default Re: ONkyo TX-NR626 Check SP Wire

I was hoping the point of the other boards was to eliminate the driver board components as possible suspects, thereby narrowing the search for the bad part(s).
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