rowemeister said:I have a 3020SE its in my dining room. Great amp! May mod mine
It's well worth doing. I can dig out my Farnell order and let you know exactly what I used if you're interested?
The caps are not a high enough voltageMy KI runs at 44V.
I'm quite happy about this - the Kenwood is far too nice to start amputating such things...
The heatsink in the Kenny is plenty large. I've never felt mine get even remotely warm - the two smaller ones on the NEC chipamps are always warm to the touch.
If you do decide to mod the 3020SE, all I'll say is that the traces and pads on the underside of the power-amp PCB aren't as good as I've seen on other amplifiers. I killed two pads whilst removing the old capacitors, and had to make new traces using cat5e network cable
.It's a pain to remove the PCB, too - literally have to strip down the entire amplifier. Undoing the bolts holding the transistors to the heatsink was 'entertaining' - I seem to remember that a screwdriver wouldn't reach 2/3 of them, and that they used a really oddball size. I ended up using a miniature imperial spanner - 13/64?
Both my relays needed cleaning, as I had volume drop-outs when on low power - this was the main reason for removing the PCB. I ordered the capacitors as it seemed to make sense whilst the amplifier was in pieces - I ended up bypassing the relays, because neither of them worked again after I'd 'worked' my magic. Bank on replacing them if you have any similar problems.
I wouldn't mind finding a faulty amplifier, to turn into a Gainclone. If either of you happen to break them...
--Rich
Rich - A parts list is always welcome
Cool stuff. I have the service manual somewhere in my loft from the days when I used to repair these amps. I forgot how nice they were inside.
Yes the pcb pads are not the greatest but ok for the given £200 price when new.
Thanks Jim for the email with all the pics in it
Can I also see two silmics next to the res caps?
Brent
Cool stuff. I have the service manual somewhere in my loft from the days when I used to repair these amps. I forgot how nice they were inside.
Yes the pcb pads are not the greatest but ok for the given £200 price when new.
Thanks Jim for the email with all the pics in it
Can I also see two silmics next to the res caps?
Brent
Yep. 50v 470uF Silmics.
Eagle eye Brent strikes again! I guess when you've been in the game as long as you have they are quite distinctive.
Caps round the regs are Elna bog standard like the CD63. 2x 50v 220uF, 2x 25v 220uF, and 4x 100v 0.1uF.
Class A amp pale blue Rubycon 50v 100uF and Elna 50v 10uF. Would Silver Mica benefit where the brown blobs are?
That big fat tranny weighs a ton. Label on the side says BANDO LO7-0889 15-BE11-RIB. Big metal shield over it and chunky copper shield round the winding.
More food for thought and the offers of the Farnell list (Rich) and manual (Brent) both very much appreciated.
Not sure how all this is going to go down with my lovely wife - I've been modding my CD63 Ki for months now and just done the last of the BlackGates in my PM66KI.
Amp was sounding lurvely after the previous Blackgates and silver micas settled down
Player has had a bit of a torrid time, managed to fry something on my CD63Ki,
servo problem of some sort but think it might have been the tranny. (Dont think you must have seen my post about voltages at the time Brent after your pointers.)
Out of embarrassment I bought a CD63SE with a laser problem off eBay and have been using its board and tranny attached in the KI case. If I ever get to the bottom of the correct voltages from the KI toroid I might put it all to rights and have a spare board.
Problem is I only have a couple of (late) nights a week to play when my wife is on her night shifts at the local hospital, so everything seems to have taken forever and she doesn't quite believe it will all work when I've finished "tinkering". Blooming cheek!!!
Leave you guys to think now. Thanks for the emails Brent.
Cheers
Jim
Eagle eye Brent strikes again! I guess when you've been in the game as long as you have they are quite distinctive.
Caps round the regs are Elna bog standard like the CD63. 2x 50v 220uF, 2x 25v 220uF, and 4x 100v 0.1uF.
Class A amp pale blue Rubycon 50v 100uF and Elna 50v 10uF. Would Silver Mica benefit where the brown blobs are?
That big fat tranny weighs a ton. Label on the side says BANDO LO7-0889 15-BE11-RIB. Big metal shield over it and chunky copper shield round the winding.
More food for thought and the offers of the Farnell list (Rich) and manual (Brent) both very much appreciated.
Not sure how all this is going to go down with my lovely wife - I've been modding my CD63 Ki for months now and just done the last of the BlackGates in my PM66KI.
Amp was sounding lurvely after the previous Blackgates and silver micas settled down
Player has had a bit of a torrid time, managed to fry something on my CD63Ki,
servo problem of some sort but think it might have been the tranny. (Dont think you must have seen my post about voltages at the time Brent after your pointers.)Out of embarrassment I bought a CD63SE with a laser problem off eBay and have been using its board and tranny attached in the KI case. If I ever get to the bottom of the correct voltages from the KI toroid I might put it all to rights and have a spare board.
Problem is I only have a couple of (late) nights a week to play when my wife is on her night shifts at the local hospital, so everything seems to have taken forever and she doesn't quite believe it will all work when I've finished "tinkering". Blooming cheek!!!
Leave you guys to think now. Thanks for the emails Brent.
Cheers
Jim
Hi Brent,
Many thanks for your reply.
Only one channel on my PM44 blew but I didn't measure the idle current on the good channel before I started messing around with it. Besides, the amp the fairly old so it might have drifted from the original setting anyway.
Following your advice I have now set set the voltage on both channels of my PM44 to 14mV.
Since you suggest setting the voltage to the same value as the PM66 then am I correct in assuming that the typo in the PM66 manual is with the value of the resistors rather than idle current? The best way to check this of course would be to read the value printed on the resistor itself...if it's not too much trouble.
Thanks again,
Victor
Many thanks for your reply.
Only one channel on my PM44 blew but I didn't measure the idle current on the good channel before I started messing around with it.
Besides, the amp the fairly old so it might have drifted from the original setting anyway.Following your advice I have now set set the voltage on both channels of my PM44 to 14mV.
Since you suggest setting the voltage to the same value as the PM66 then am I correct in assuming that the typo in the PM66 manual is with the value of the resistors rather than idle current? The best way to check this of course would be to read the value printed on the resistor itself...if it's not too much trouble.
Thanks again,
Victor
Hello again. Thanks for all your advice in the past Brent, you've been a great help. After breaking my amp ages ago, I decided to shelf it and build my lm3886 based amp. Now I have decided to fix my pm66. I have tried to find the transistors Brent told me to change, but cannot find exact replacements for Q755 through to Q760.
Any ideas anyone?
Thanks, Lee.
Any ideas anyone?
Thanks, Lee.
Victor
The typo in the 66 manual is with the current. It should say 70mA rather than 39mA. The 66 uses 0.1 ohm output resistor packages where yours uses the 0.18.
Of course the current is across the two resistors in each package. IE 0.1+0.1 = 0.2 ohm in 66 and 0.18+0.18 = 0.36 ohm in 44.
So using ohms law 14mV / 0.2 ohm = 70mA in 66
14mV / 0.36 = 39mA in 44
I would be tempted to run your idle at 25mV as this would be 70mA as in the 66. Run it and see if it gets too hot.
What output transistors does the 44 use?
Brent
The typo in the 66 manual is with the current. It should say 70mA rather than 39mA. The 66 uses 0.1 ohm output resistor packages where yours uses the 0.18.
Of course the current is across the two resistors in each package. IE 0.1+0.1 = 0.2 ohm in 66 and 0.18+0.18 = 0.36 ohm in 44.
So using ohms law 14mV / 0.2 ohm = 70mA in 66
14mV / 0.36 = 39mA in 44
I would be tempted to run your idle at 25mV as this would be 70mA as in the 66. Run it and see if it gets too hot.
What output transistors does the 44 use?
Brent
Hi Brent,
The output transistors on my PM44 are the same as on the PM66- 2SC3182 and 2SA1265.
At 14mv they are quite cool to touch. I'll try winding the voltage up to 25mV but I'm a bit worried about shortening their life or even worse. How hot do your's get? Does increasing the current really improve the sound?
Thanks again!
Victor
The output transistors on my PM44 are the same as on the PM66- 2SC3182 and 2SA1265.
At 14mv they are quite cool to touch. I'll try winding the voltage up to 25mV but I'm a bit worried about shortening their life or even worse. How hot do your's get? Does increasing the current really improve the sound?
Thanks again!
Victor
It does make a difference.
Don't forget yours is running @ 39mV as standard where the 66 is running 70mV.
Maybe you should replace the 0.18 res with the 0.1 ohm type.
I run mine at 100mA and yes its warmer but not silly.
Its only idle current. What it does though is mean the output stage is switched on more. So the transistor has to switch on much less during the music when the current is demanded. Now that surley means less stress on the transistors.
Brent
Don't forget yours is running @ 39mV as standard where the 66 is running 70mV.
Maybe you should replace the 0.18 res with the 0.1 ohm type.
I run mine at 100mA and yes its warmer but not silly.
Its only idle current. What it does though is mean the output stage is switched on more. So the transistor has to switch on much less during the music when the current is demanded. Now that surley means less stress on the transistors.
Brent
Hi again. Thought i'd post an update on my pm66ki....
I replaced all transistors as recommended by Brent. Set trim pots to centre, volume to 0 and balance to centre.
Switched on and nothing went bang.
Unfortunately nothing went click either. The power led's on, but there's no-one home. Any ideas chaps?
Lee.
I replaced all transistors as recommended by Brent. Set trim pots to centre, volume to 0 and balance to centre.
Switched on and nothing went bang.
Unfortunately nothing went click either. The power led's on, but there's no-one home. Any ideas chaps?
Lee.
Finally got round to trying to fix my 66KI, I have now replaced R802 and removed Q764, Q762 and Q752 (Q764 burst in to flame last time i powered on).
I tried powering on again and was rewarded with the relay clicking in and getting sound from the left channel. However, I discovered that on the right channel R764, Q760 and Q756 get very hot within seconds of powering on. I don' really dare to try to test with a voltmeter because I think one of the above components will burst in to flame if I keep the amp powered on long enough to test.
Any ideas on what would cause this problem anyone? My guess was that I need to look at C802 to see if the insulation has broken down and it is conducting?
Neil
I tried powering on again and was rewarded with the relay clicking in and getting sound from the left channel. However, I discovered that on the right channel R764, Q760 and Q756 get very hot within seconds of powering on. I don' really dare to try to test with a voltmeter because I think one of the above components will burst in to flame if I keep the amp powered on long enough to test.
Any ideas on what would cause this problem anyone? My guess was that I need to look at C802 to see if the insulation has broken down and it is conducting?
Neil
Hi Brent,
Thanks for the quick reply.
No I haven't rebuilt the right channel at all yet, but I wasn't expecting to find anything getting hot on that channel with the output removed. Having another look at the schematics, I believe I can test for the voltage across the power caps if I am quick to prove if they are ok without blowing anything else. If they are ok, then I will assume that one or more of the transistors is knackered. I don't know if I will be able to test the transistors effectively so will probably replace all the ones you suggest and hope there are no other problems.
I'll post the results.
Neil
Thanks for the quick reply.
No I haven't rebuilt the right channel at all yet, but I wasn't expecting to find anything getting hot on that channel with the output removed. Having another look at the schematics, I believe I can test for the voltage across the power caps if I am quick to prove if they are ok without blowing anything else. If they are ok, then I will assume that one or more of the transistors is knackered. I don't know if I will be able to test the transistors effectively so will probably replace all the ones you suggest and hope there are no other problems.
I'll post the results.
Neil
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