If the rumbling is a 60hz hum you should replace all e-caps in the 13V supplies in the preamp and power boards.
The Sunfire sub standby circuit mutes the output until input charges the standby cap, maybe a half second. The cap will not re-mute after the input is removed until the cap discharges, maybe 10 seconds.
jworthin
Member
Last Activity: 03-13-2024, 08:39 PM
Joined: 02-21-2017
Location: Minneapolis, MN
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Re: Need Schematic Sunfire True Subwoofer Junior
Old post but a common problem: The 13V supplies are usually the source of the (no input cables connected) hum problems. On the power board replace C45, C46, C40, C39, C38 and C37. On the input preamp board replace: C7, C15, C17, C31, C32, C41 and C42. Use low ESR and low ripple caps. This applies to 2700W plate amps that have serial numbers that do not start with '96' (the year of production).
BTW: C18 (100uF) on the preamp is the cap that goes bad in the sleep/wake circuit.Last edited by jworthin; 03-09-2021, 06:42 PM.Leave a comment:
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Re: Recapping Tektronix 2235 PSU
Thanks redwire for putting this recapping spreadsheet together and posting it. It was very helpful!Leave a comment:
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Re: ONkyo TX-NR626 Check SP Wire
The thing that keep perplexing me was every time I fixed it, it would work fine for a few hours or even a few days and then blow the channel.Leave a comment:
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Re: ONkyo TX-NR626 Check SP Wire
Update: After repairing the R channel several times I finally cut the PCB trace from the power transistor emitter resistors to the output relay and replaced it with a wire and the unit no longer blows the channel. Maybe when the receiver warmed up the PCB trace somehow shorted to ground. There were no obvious signs of a short though.Leave a comment:
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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).Leave a comment:
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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.
...Leave a comment:
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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:
Any suggestions would be greatly appreciated.Leave a comment:
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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.Leave a comment:
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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.Leave a comment:
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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)Leave a comment:
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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.Leave a comment:
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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...Leave a comment:
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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...Leave a comment:
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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...Leave a comment:
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Re: ONkyo TX-NR626 Check SP Wire
I received a 626 that was in VPROT. The R channel was blown. I noticed that channel had been serviced before. I replaced the bad channel power transistors and some small parts in it's driver. I set the idle current and it seemed to work fine for about 4 hours when it blew the same channel again. (VPROT) It is ‘repaired' now again but I am reluctant to run it for very long. The idle currents on all channels are normal and stay within service manual limits. But here's the odd part, when it is turned on it starts getting hot with no input, no volume,...Leave a comment:
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Re: Dead Aiwa AV-D50
I did look up the transistor pinout in two different references.
If the single pin is center top I measured from the lower right pin to GND.
Self taught beginner.
The legs of the current sensing resistor have 0.005V across them.Leave a comment:
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Re: Dead Aiwa AV-D50
I did another test replacing Q106 and removing Q105. My thinking was to disable the over current latch mechanism. However the result was nearly no conduction in Q108 and Q109 and so no voltage for the zener D101 network and so 0.0V bias for Q106.Leave a comment:
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Re: Dead Aiwa AV-D50
I rechecked the Q106 B-E junction and verified it is 4.5V.
I'm confused, this voltage seems to be supplied from the series parts R113, D101, and R114. Without the Q106 transistor (removed) to bias Q107 there is no reduction of the supply 25v so there is 25V across these three components. The zener(D101) is 10V leaving 15V through R114 + R113 = 690 ohms giving 22ma. This 22ma times R114 (220) yields 4.78V bias for Q106. This seems to be about what I am measuring (within 7%). Why can't the bias be more than 0.6~0.7V? Thanks again for helping and answering...Leave a comment:
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Re: Dead Aiwa AV-D50
GND to Base of Q106 is 4.505VDC
GND to Base of Q107 is 1.556VDC
Unit is not working yet.Leave a comment:
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