Kenwood L09M Repair, Refurbish, Upgrades, Questions.
- Thread starter blfttieq
- Start date
Too bad about the dents, but those are still droolworthy.
blfttieq
New Member
got her plugged in and ran a bit no smoke no sparks
fan now runs totally silent on low and hope it does not ever need the higher setting.
Set bias to 33 mv, set dc offset to .001
I've learned this
I Love these amps
Using my thermal gun I can see the heatsink get hotter in one spot as I adjust bias up, then it will slowly start to stabilize a more even temp. This is not the long term full heat up Ive seen you guys discuss just a pre observation.
In the beginning before doing all this I had some noise. What I found funkyed up was the protection circuit area. But I still have a hunch that i may have a dying output transistor and now Im guessing it could be Q6
That thermal gun does not lie its very useful. That area just under the Power Amp "A" board is consistently warmer not crazy warm but it has my interest. 1 failing transistor might just sound like what I was experiencing. Im going to drive it on low power into some subs and monitor that heat sink.
Ok off to hookup and listen on low power.
Oh and I will be ordering some better pots for the bias adjust and the rough offset. The bias setting is just not a good feeling precision adventure at all.
fan now runs totally silent on low and hope it does not ever need the higher setting.
Set bias to 33 mv, set dc offset to .001
I've learned this
I Love these amps
Using my thermal gun I can see the heatsink get hotter in one spot as I adjust bias up, then it will slowly start to stabilize a more even temp. This is not the long term full heat up Ive seen you guys discuss just a pre observation.
In the beginning before doing all this I had some noise. What I found funkyed up was the protection circuit area. But I still have a hunch that i may have a dying output transistor and now Im guessing it could be Q6
That thermal gun does not lie its very useful. That area just under the Power Amp "A" board is consistently warmer not crazy warm but it has my interest. 1 failing transistor might just sound like what I was experiencing. Im going to drive it on low power into some subs and monitor that heat sink.
Ok off to hookup and listen on low power.
Oh and I will be ordering some better pots for the bias adjust and the rough offset. The bias setting is just not a good feeling precision adventure at all.
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blfttieq
New Member
She is running with almost no hum now. It does not noticeably sound better than before having issues, but I was happy with it before. No smoke no sparks protection working. DC offset at zero to .001 and a greenish meter glow that shows the meter without distracting from the tv.
blfttieq
New Member
I have the amp working well but learned a few things.
Thermal gun, the issue is Qe8 running hot. That heat was being sucked into the cooling tunnel at the joint between shield and heat sink. So the Sanken are good to go. Repairing the protection circuit got rid of the worst sound I was hearing. The electrolytics helped the noise floor making that inaudible. There are some things to rebuild with regard to the bias circuit. Need to replace 2sa964a?? It has some carbon resistors all around that are hooked to the supply. I'll now be taking a close look at hand matching some and checking for failures.
My last bit of hum is not from the L09M or the eq feed into it. It's from the pioneer vsx-d850s. I have that apart now and making a lyric list. I can see the main caps have just started to swell, one more so.
Thermal gun, the issue is Qe8 running hot. That heat was being sucked into the cooling tunnel at the joint between shield and heat sink. So the Sanken are good to go. Repairing the protection circuit got rid of the worst sound I was hearing. The electrolytics helped the noise floor making that inaudible. There are some things to rebuild with regard to the bias circuit. Need to replace 2sa964a?? It has some carbon resistors all around that are hooked to the supply. I'll now be taking a close look at hand matching some and checking for failures.
My last bit of hum is not from the L09M or the eq feed into it. It's from the pioneer vsx-d850s. I have that apart now and making a lyric list. I can see the main caps have just started to swell, one more so.
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Locomotive
New Member
How are these main caps compared to the originals? Are they the exact same sizes in diameter and height? Have you removed the hum? I have 4 of these amps in my system and they're all stock. They sound fantastic and I'm not too concerned that the caps are old, but I won't be closed minded about it. I'd like to rebuild one and compare the sound next to each other. If I find a significant difference in sound with the rebuilt unit sounding much better I'll rebuild the others. Not sure about this, just a gut feeling, but I have a hunch rebuilding them might (just might) degrade the original sound of my stock L-09Ms. Of course I'll monitor the caps etc. for swelling & leaking. Rebuilding them just might make them sound exactly the same for all I know, but I also realize rebuilding them will give some piece of mind that they won't let the smoke out any time soon after rebuilding. I have found out over several years when using the KENWOOD L-Series that the sound is SIGNIFICANTLY better when using the matching L-07T, L-07CII, L-07M's, L-09M's and using the special one way interconnect OEM KENWOOD cables supplied with the L-07C's & L-07CII's. My speakers are just KENWOOD MV-5's, MV-7's & MV-9's but they sound great to me with those amps & some 10 gauge stranded copper wires. I can't emphasize enough how big of a difference in sound between the special factory KENWOOD interconnect cables & any regular interconnect cables used with the aforementioned KENWOOD L-Series components. I was shocked at how marked a difference they made! Those cables are very rare though. I luckily found a pair on eBay a couple years ago from a seller in England & snatched them up quickly. All you AK'ers running anything but those special KENWOOD interconnect cables on your KENWOOD L-series components, pre-amps & amps I feel for you, you just don't realize how much of a difference they are until you hear it for yourselves. THE DIFFERENCE IS HUGE! Now if I can just find a reasonably priced L-07D to complete my KENWOOD L-Series system, then I'll be happy
blfttieq
New Member
Sorry just got round to checking on this post. I can say nothing about high frequency since I have just this one and use it for sub amp. But My hum is completely gone. The dynamics from the sub and the tightness with the rest of the system is improved after listening to it a lot now. I can not see any way that replacing electrolytics would hurt your sound, if anything it will improve the image. If your amp is original it can have some nasty pots on the bias board and those are not that precise. I improved that area and replaced every electrolytic on that board.How are these main caps compared to the originals? Are they the exact same sizes in diameter and height? Have you removed the hum? I have 4 of these amps in my system and they're all stock. They sound fantastic and I'm not too concerned that the caps are old, but I won't be closed minded about it. I'd like to rebuild one and compare the sound next to each other. If I find a significant difference in sound with the rebuilt unit sounding much better I'll rebuild the others. Not sure about this, just a gut feeling, but I have a hunch rebuilding them might (just might) degrade the original sound of my stock L-09Ms. Of course I'll monitor the caps etc. for swelling & leaking. Rebuilding them just might make them sound exactly the same for all I know, but I also realize rebuilding them will give some piece of mind that they won't let the smoke out any time soon after rebuilding. I have found out over several years when using the KENWOOD L-Series that the sound is SIGNIFICANTLY better when using the matching L-07T, L-07CII, L-07M's, L-09M's and using the special one way interconnect OEM KENWOOD cables supplied with the L-07C's & L-07CII's. My speakers are just KENWOOD MV-5's, MV-7's & MV-9's but they sound great to me with those amps & some 10 gauge stranded copper wires. I can't emphasize enough how big of a difference in sound between the special factory KENWOOD interconnect cables & any regular interconnect cables used with the aforementioned KENWOOD L-Series components. I was shocked at how marked a difference they made! Those cables are very rare though. I luckily found a pair on eBay a couple years ago from a seller in England & snatched them up quickly. All you AK'ers running anything but those special KENWOOD interconnect cables on your KENWOOD L-series components, pre-amps & amps I feel for you, you just don't realize how much of a difference they are until you hear it for yourselves. THE DIFFERENCE IS HUGE! Now if I can just find a reasonably priced L-07D to complete my KENWOOD L-Series system, then I'll be happy
You would not know part numbers for the above
