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Display Problem on Onkyo T65

M

Marantzypant

New Member
I've acquired an Onkyo TX-65 Receiver. All of the functions work on it, but when engaging Loudness, The Bass Expander, Auto Tuner on/off, or looking at the Signal meter, nothing lights up. Other parts of the same display panel work, such as the Phono/Tape/Aux/Vid Indicator, etc.

Another interesting thing is that when you power it up, the Tuner "Manual" light flicks on for a sec. But when you set it to auto or manual as I mentioned, it never lights. When I had it on the dim bulb tester, all of the indicators across the bottom of the panel worked ok. Not so much under full AC power.
Just thought I'd ask the community to see if anyone has dealt with that on this model. Thank You.

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I would start by checking the power supply. If you have a scope, see if there's any ripple. Next I would be looking for the crappy brown glue that becomes conductive and corrosive. If you don't find issues there, check for cold / cracked solder connections. That's a nice looking receive. I hope you can fix it!
 
redk9258 said:
I would start by checking the power supply. If you have a scope, see if there's any ripple. Next I would be looking for the crappy brown glue that becomes conductive and corrosive. If you don't find issues there, check for cold / cracked solder connections. That's a nice looking receive. I hope you can fix it!
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Thanks. I put it back on the Dim Bulb tester and all the display functions work when the receiver is operating at 85 V AC, so it seems like when it's given full power, something is pulling the voltage low on the display driver board. Maybe a bad cap, or bad transistor. More probing needed. I'm going to do that with the schematic later today. As you mentioned, this could also be a bad salder joint that goes open under full voltage.
 
12voltvids on YouTube repaired a JVc receiver that would only operate at a reduced voltage. I think it turned out to be a bad ground connection.
 
redk9258 said:
12voltvids on YouTube repaired a JVc receiver that would only operate at a reduced voltage. I think it turned out to be a bad ground connection.
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Thank You. Good thought. I will reseat the grounds. I did end up finding a Zener diode on the Display Driver board that had a 2.55 V forward voltage out of circuit, so I'm going to replace that regardless.
 
If anyone ever runs into this, in this case it was indeed the zener diode at position D955 on the display driver board. The diode had a 2.55 V forward voltage tested out of circuit, and it should have been 0.7 V and 1.0 V max. It was causing votage regulation problems and likely causing the IC to freak out. Once replaced, everything worked fine.
 
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