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Onkyo TK-2500 MKII Light Help

T

TheNickSmith

New Member
Hello fellow audio goobers and nerds out there I need help with my receiver. I got this thing around a year and a half ago at goodwill for 20 dollars and it worked well except for the burnt out lights and dirty pots with i cleaned. I didn't bother fixing the lights because my setup wasn't ready for it. Anyways now I'm here replacing the bulbs and all of them work except for the 3 "Locked", "Tuned", and "Stereo". I thought that they were just burnt out and only needed replacing, but after checking that the polarity was right they seem to not be working properly. The Stereo light doesn't come on at all and the Locked and Tuned lights are always on but slightly get brighter or dim depending on what the signal is like. It seems to be that the Locked light will get dimmer when the signal is Locked and the Tuned light will get brighter when the station is Tuned. Kind of confusing because I would think the Locked would get brighter. But when its switched over to phono or tape the two lights are always on. I measured around 16v going to the lights and close to none on the Stereo Light. Does anybody know how to fix this or can help me in the right direction?

Here i have a video in a google slide.
VIDEO LINK
 
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I have yet to come across a problem such as the one you are describing here but I read here and on other boards in which the "locked, tuned, and stereo" bulbs are not the same as the dial lights. Dial lights are usually 6.3 or 8 volt bulbs. The other bulbs are usually in the circuit in where if something goes wrong, they just won't light up at all or act weird even though the bulbs themselves are not burned out.

Someone else will probably come along and be able to tell you for sure what you would need to do or what to check.
 
I would think they should either be on or off, so the fluctuations you see in intensity could be due to dirty contacts, maybe? Lots of that model for sale, with picture showing all three lights working, or none with tuner deliberately adjusted out of range high.

Does the Lock function work?, same for Stereo, does it pull in a stereo signal? Assume Tuning meter works. Have you tried tracing the circuits from the sources to the lights to see if there are any moving parts or contacts?
 
Sandman1221 said:
I would think they should either be on or off, so the fluctuations you see in intensity could be due to dirty contacts, maybe? Lots of that model for sale, with picture showing all three lights working, or none with tuner deliberately adjusted out of range high.

Does the Lock function work?, same for Stereo, does it pull in a stereo signal? Assume Tuning meter works. Have you tried tracing the circuits from the sources to the lights to see if there are any moving parts or contacts?
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The lock function does work with a stereo signal. I don’t really know where it would have any moving parts for something related to this.
 
I worked on a TX-2500 Mk II in the past that had a similar problem with the lamps but unfortunately don't remember what I did to fix it other than doing something with a resistor.
The service manual describes how the circuits function. I can load a couple pics I saved from when I was troubleshooting.
Screenshot (1464).png

Screenshot (1465).png
 
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I seem to remember something like the collector of Q110 voltage as being high. Check that.

Here's what the voltages at the lamps should be.

The pic I had posted was from the T-4 so I deleted it. Here's the correct one from the linked service manual below.

Screenshot (466).jpg
 
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TheNickSmith said:
The lock function does work with a stereo signal. I don’t really know where it would have any moving parts for something related to this.
Click to expand...
Well in order to get a stereo signal, you have to adjust the tuning knob. I remember a youtube video of a guy fixing a lock problem on a receiver, he just used a cleaner on the contact surfaces.
 
Are you using L.E.D. bulbs? I had an issue with a 4500 mk II where it really only worked correctly with incandescent lamps.
 
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kwayde said:
https://elektrotanya.com/onkyo_tx-2500mkii-sm-receiver.pdf/download.html#dl
Click to expand...
I have some more updates about the receiver that i found.
1. The voltages of the Locked light when the station is not tuned in is around 3V but when its tuned in is 1.5V
2. The voltages of the Tuned light when the station is not tuned in is around 4V when tuned in is around 14V
3. I found the Base and Collector pin on the Q110 Transistor is shorted. And when the Emitter and Collector pin is shorted the stereo light works properly as it should And the Locked light voltage shoots up to 14V.

I am starting to thing this transistor will need replacing but I'm not sure if it will fix all the issues.
 
Q109 affects both Q110 and Q111.
Check voltages at all three xstrs to see where they compare to listed voltages, tuned and untuned.
If Q109 is off then the others could be too.
 
kwayde said:
Q109 affects both Q110 and Q111.
Check voltages at all three xstrs to see where they compare to listed voltages, tuned and untuned.
If Q109 is off then the others could be too.
Click to expand...
When Untuned all the pins read just about 0V when locked into a station the Collector pin reads 16V.
 
Another update... I replace Q110 with a C1815 But not the "Y" kind as it was the only one i could find in a stack of my 2000s receivers. Once i put it in the Stereo light works perfectly and when a station is locked all the lights grow bright as they should. But still when its not locked into a station there still is around 4V going to the Tuned light and 3V going to the locked light causing them to be dim but still on. Does anybody know what could cause this?

EDIT:
I measured the voltage to ground coming from the T/L.PL pin and its 19V. The voltage coming from the FM tuner board on the locked pin is 17V and the tuned pin is 15V. Could the voltage difference cause the dimness and how could i fix it?
 
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TheNickSmith said:
To add on i tested it and it has around a 570 hFE rating.
Click to expand...
I pull countless 2sc458's out and they test good but they make a shot noise, static. These transistors made it to that Top Ten List because they constantly fail.

I replace any I see that are on that list.

Could it be your problem? I don't know, but since it's on the list and affects both Q110 & Q111 its should be replaced.
 
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kwayde said:
I pull countless 2sc458's out and they test good but they make a shot noise, static. These transistors made it to that Top Ten List because they constantly fail.

I replace any I see that are on that list.

Could it be your problem? I don't know, but since it's on the list and affects both Q110 & Q111 its should be replaced.
Click to expand...
Alright thanks. Ill have to order some replacements. I'm still going to work on this voltage difference for now. I see that the KSC1845 is a newer 2SC1312 is that correct?
 
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