This is quite weird , I checked most of voltages in main amplifier and everything seems to be fine .
Voltage on 82R most of the time sits at 0.56V on both sides but sometimes there is inbalance around 0.1V , also voltage on minus side wasn't very steady varying 0.1-0.15V .
Voltage on 8R2 sometimes changing from 1.5V to 1.25V , I checked pre-regulator and pretty consistent between both boards .
Then I snipped Calvin buffers , same thing varying voltage on 8R2 everything else OK ,
Then I disconnected amplifier , voltage on 8R2 sits at 1.45-1.5V then suddenly dropping to 1.25V and back again like one of the trannies was conditionally conducting ,
Then out of nowhere leds on minus side went dead and voltage on 8R2 on the other side sits on 1.25V , I had to disconnect this board as heatsink started getting too hot .
I will pull all trannies and electrolytics and check them over also I will replace LED's and see what's happening
I checked for oscillations last night and seems to be fine
Voltage on 82R most of the time sits at 0.56V on both sides but sometimes there is inbalance around 0.1V , also voltage on minus side wasn't very steady varying 0.1-0.15V .
Voltage on 8R2 sometimes changing from 1.5V to 1.25V , I checked pre-regulator and pretty consistent between both boards .
Then I snipped Calvin buffers , same thing varying voltage on 8R2 everything else OK ,
Then I disconnected amplifier , voltage on 8R2 sits at 1.45-1.5V then suddenly dropping to 1.25V and back again like one of the trannies was conditionally conducting ,
Then out of nowhere leds on minus side went dead and voltage on 8R2 on the other side sits on 1.25V , I had to disconnect this board as heatsink started getting too hot .
I will pull all trannies and electrolytics and check them over also I will replace LED's and see what's happening
I checked for oscillations last night and seems to be fine
The regulator is fine as long as the heatsink is in place you can run without the back end connected.
Was it the first led in the string, if so that might point to a fault elsewhere. If middle of string then its just a duff led.
Which revision of the boards do you have? Do you have the 2.2n and 640pf caps fitted? Also maybe look at Werners shunt stability mod. Search my flickr albums for details, same user name as here. "Sq225917 paradise" as search query in Flickr should get you there.
Was it the first led in the string, if so that might point to a fault elsewhere. If middle of string then its just a duff led.
Which revision of the boards do you have? Do you have the 2.2n and 640pf caps fitted? Also maybe look at Werners shunt stability mod. Search my flickr albums for details, same user name as here. "Sq225917 paradise" as search query in Flickr should get you there.
Boards I have are the latest I think -R31b with above caps fitted , I also have 22uF caps on the input to regulator and 0.47uF fitted under the heatsink .
I haven't checked which LED as heatsink became boiling hot , it could be one of the transistors fitted to heatsink shorted when I tested , I'm not sure .
I think I will remove heatsink and replace all parts in the regulator just to be certain and probably will take less time than trying to find/isolate the problem .
I'm working in Dubai for the next few months at least
I started pulling some parts out of regulator ,
100uF cap at the end of the LED string measures ~500uF , it's quite good aluminum organic polymer cap marked 100uF also 2 LED's are dead but nothing seems to be bad on the side with weird voltage on 8R2 resistor , BC327 and 337 under heatsink are well matched within 3-4 hFe it is a good sign
Question , how to remove all solder especially from ground pins , suction pump don't seem to be very effective and I need to clean all power transistor holes unless there is another way of attaching them to heatsink after soldering ?
100uF cap at the end of the LED string measures ~500uF , it's quite good aluminum organic polymer cap marked 100uF also 2 LED's are dead but nothing seems to be bad on the side with weird voltage on 8R2 resistor , BC327 and 337 under heatsink are well matched within 3-4 hFe it is a good sign
Question , how to remove all solder especially from ground pins , suction pump don't seem to be very effective and I need to clean all power transistor holes unless there is another way of attaching them to heatsink after soldering ?
Pete, sounds like you have werners shunt mod already, you can rule out oscillation.
Two dead LEDs indicated an issue upstream. I've only ever seen two failure types on the shunt. One from reverse voltage on input, which blew the diodes. I assume we can rule that out. The other is from a short on the heatsink. That would be my money.
The 500uf value is odd, if the cap is still good the higher capacitance wont be an issue though. Do you have a higher esr cap fitted for the 25v 100uf part, that's needed for stability?
For cleaning holes I prefer to use a narrow plastic straw, put the tip of the iron on the pad with some flux and blow the solder through the holes. For the gnd vias do this on the side with the gnd plane.
Two dead LEDs indicated an issue upstream. I've only ever seen two failure types on the shunt. One from reverse voltage on input, which blew the diodes. I assume we can rule that out. The other is from a short on the heatsink. That would be my money.
The 500uf value is odd, if the cap is still good the higher capacitance wont be an issue though. Do you have a higher esr cap fitted for the 25v 100uf part, that's needed for stability?
For cleaning holes I prefer to use a narrow plastic straw, put the tip of the iron on the pad with some flux and blow the solder through the holes. For the gnd vias do this on the side with the gnd plane.
I pulled all parts from regulator , only 2 led’s and that capacitor are faulty .
I’ve been in touch with the guy who built it and should get all bits to replace whole part of the circuit , I will upgrade 100uF with higher rated .
This 10uF caps are standard Nichicon , I assume with usual ESR .
LED’s are probably my own doing when I checked voltages I flipped board upside down and most likely shorted something while measuring .
Still I’m not sure what caused that weird behaviour on 8R2 ,
That 100uF measures different every time , something in between 400-500uF .
I looked at your Flickr account , nice builds SQ, how many Paradises have you built ?
I’ve been in touch with the guy who built it and should get all bits to replace whole part of the circuit , I will upgrade 100uF with higher rated .
This 10uF caps are standard Nichicon , I assume with usual ESR .
LED’s are probably my own doing when I checked voltages I flipped board upside down and most likely shorted something while measuring .
Still I’m not sure what caused that weird behaviour on 8R2 ,
That 100uF measures different every time , something in between 400-500uF .
I looked at your Flickr account , nice builds SQ, how many Paradises have you built ?
Electrolytics that read that high are probably leaking badly and completely shot. The oxide film has degraded to be much thinner which is the cause of the capacitance rise, the variation in reading is the random changes in leakage I guess. Its likely to be either old, a badcap or abused (reversed?). Its definitely not "still good"
I've built 31 of them, mine's five years old now, never seen a bad cap in the shunt. Never had one back with an in use failure.
I guess it depends on the cap, I suspect the original group buy nichicon caps are safely overated by the manufacturer.
I know of one Paradise with at least 5000 hours on the clock since it was built. So can only suspect a bad cap, or none bom choice.
I have spares of those 10 and 100uf nichicons if you need some. Just checked I have four of each value.
I guess it depends on the cap, I suspect the original group buy nichicon caps are safely overated by the manufacturer.
I know of one Paradise with at least 5000 hours on the clock since it was built. So can only suspect a bad cap, or none bom choice.
I have spares of those 10 and 100uf nichicons if you need some. Just checked I have four of each value.
Oh it came out bit wrong as my comment to the diagram wasn't included somehow ,
what I was trying to say is that rating of that cap might've been overlooked and in most cases would work (other 3 caps in this location work fine) but after some time this might cause a problem ,
Thanks for the offer but guy I bought it from is sending me all parts to replace whole regulator , is better to be safe than sorry .
You clearly are the "high scorer" here ;-)
just wondering, with 31 built, there must be at least one mono system out there?
Hi,
one for everyone ... just none fore me... not even a buffer
jauu
Calvin
(lol)
Cry baby
