Well I got lost somewhere but 
49V! The schematic I just looked at must have had about 100mA total coming out of it's CCS. 1/2 of that per side says those two 1500s should only have 37.5Volts on 'em... 37.5 * .05 = 1.875 Watts. Some potential for heat! But, you say 49 Volts! / 750 Ohms... you have 65mA+ in your circuit... Hmmm * 49Volts = 3.2 Watts. Deffinatly potential for heat...
Let me just say that when it comes to anything with power dissapated (that "potential for heat!") I ussually 3 to 5 times the rating, maybe more. Use a bigger part. Source resistors for instance. If you want them to maintain an accuratte value you have to control the temp a little. I use mills 12 Watt non inductive for a typical 1-2 Watt application and they still get to hot. Provide airflow, ventilation etc.
My Zen differential line stage usses Caddock TO-220 case 1Ks with 50V on them and 50mA through them, screwed to a heatsink though
I'll bet you want to know where the problem is coming from though... Need more voltages to figure that out... did you say it sounds fine???
49V! The schematic I just looked at must have had about 100mA total coming out of it's CCS. 1/2 of that per side says those two 1500s should only have 37.5Volts on 'em... 37.5 * .05 = 1.875 Watts. Some potential for heat! But, you say 49 Volts! / 750 Ohms... you have 65mA+ in your circuit... Hmmm * 49Volts = 3.2 Watts. Deffinatly potential for heat...Let me just say that when it comes to anything with power dissapated (that "potential for heat!") I ussually 3 to 5 times the rating, maybe more. Use a bigger part. Source resistors for instance. If you want them to maintain an accuratte value you have to control the temp a little. I use mills 12 Watt non inductive for a typical 1-2 Watt application and they still get to hot. Provide airflow, ventilation etc.
My Zen differential line stage usses Caddock TO-220 case 1Ks with 50V on them and 50mA through them, screwed to a heatsink though
I'll bet you want to know where the problem is coming from though... Need more voltages to figure that out... did you say it sounds fine???
Banned
Joined 2002
flg said:Well I got lost somewhere but
Let me just say that when it comes to anything with power dissapated (that "potential for heat!") I ussually 3 to 5 times the rating, maybe more. Use a bigger part. Source resistors for instance. If you want them to maintain an accuratte value you have to control the temp a little. I use mills 12 Watt non inductive for a typical 1-2 Watt application and they still get to hot. Provide airflow, ventilation etc.
My Zen differential line stage usses Caddock TO-220 case 1Ks with 50V on them and 50mA through them, screwed to a heatsink though
I'll bet you want to know where the problem is coming from though... Need more voltages to figure that out... did you say it sounds fine???
It was sounding perfectly, then i was smelling something as i was still monitoring this thing, and i noticed 2 resistors on one channel fell off then the other were really hot/ HOT! i'm thinking ill replace these resistors then elevate them more, According to the schematic all resistors are what they should be.
voltages
OK JL, you are going to have to post some more DC voltages, that one is too high.
I believe that the Twisted BOSOZ uses the following schematic (post
132 of the massive thread, but I have not read the whole thing).
Are you able to annotate the schematic with your DC voltages at each node?
Are your zener's the right voltage?
I don't get the joke but I hope all is swell with your good buddies (above).
OK JL, you are going to have to post some more DC voltages, that one is too high.
I believe that the Twisted BOSOZ uses the following schematic (post
132 of the massive thread, but I have not read the whole thing).
Are you able to annotate the schematic with your DC voltages at each node?
Are your zener's the right voltage?
I don't get the joke but I hope all is swell with your good buddies (above).
Banned
Joined 2002
Off topic:
Few guys who are asking trouble solutions often inform the
solution-providers of their quizzes, making the place loose
and enjoying leading the forum into a garbage bin, rather than
looking for real solutions. It could be my wrong impression . . .
Thanks for accepting the off topic.
Few guys who are asking trouble solutions often inform the
solution-providers of their quizzes, making the place loose
and enjoying leading the forum into a garbage bin, rather than
looking for real solutions. It could be my wrong impression . . .
Thanks for accepting the off topic.
If even one channel has equal 65mA+ in each side of the diff, it would have to be the CCS driving the higher current (and voltage) across those two 1500s. I suppose this would mean the cascode is barely working, depending on the levels involved. I'm thinking the voltage at the collector of Q2-3/1500x2 node should be more like 35V for proper operation....
So, what is the voltage across the 27 ohm source resistor of the CCS(QX?)???
DIY
So, what is the voltage across the 27 ohm source resistor of the CCS(QX?)???
DIY
Banned
Joined 2002
Re: Re: Re: voltages
I was simply asking him what ones are the important ones that he needs me to measure to help me.
I checked one channel and across the resistors that got hot was 49V.
I will have to solder the other channels resistors back on to measure that channels voltage across those resistors.
cviller said:
Seriously jase, there seems to be a nice person who wants to help you and you won't even make the effort to measure a few voltages? He even found the schematics for you - pls show a little gratitude instead of your usual selfishness...
I was simply asking him what ones are the important ones that he needs me to measure to help me.
I checked one channel and across the resistors that got hot was 49V.
I will have to solder the other channels resistors back on to measure that channels voltage across those resistors.
DigitalJunkie said:
ROTFL!
That's why we love ya Choky!
Without BBQ pics from Choky, this forum would be a boring place where we could only post pics of blown resistors. No meat, no fun!
Btw, I never liked speaker grills. Uhmm..now I see that they can have another application...moreover...put some red hot resistors under them and you can start BBQ-ing!
Back OT (On Topic)...It must be a short circuit somewhere....heheh
(I can't be so cruel)
Can it be that some trace under the PCB is getting a short to ground....(it happened to me once-the washer was slightly touching the + voltage trace and providing a short to ground. When PCB was removed, it worked fine, when mounted-pufffff.....(killed a fuse)...
(I can't be so cruel)
Can it be that some trace under the PCB is getting a short to ground....(it happened to me once-the washer was slightly touching the + voltage trace and providing a short to ground. When PCB was removed, it worked fine, when mounted-pufffff.....(killed a fuse)...
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