Hi Bill
No problem at all. I've used 22V toroids as well as is working very well. My A30 is now playing for over 2 years flawlessly.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=89939&highlight=
No problem at all. I've used 22V toroids as well as is working very well. My A30 is now playing for over 2 years flawlessly.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=89939&highlight=
Hi !
I'm building a standard Mini-A using BrianGT's boards (Amp+PSU) with a 2x12V toroid, hoping 15v at the rails. I need about 10W.
I was wondering about some questions :
1° - With 3K3 resistors as R1/R2, a strap is required for R3 and R12. Please confirm.
2° - Could the PSU board be fed with 2 Leds and a single 10K R ? Please confirm.
3° - I'm planning to use 2x(22000µF/10000µF/3K3/10000µF) in this order. I'm right or not ?
Would it be a better solution with 22000µF/22000µF/3K3/10000µF ?
Nice to read from the expert !
I'm building a standard Mini-A using BrianGT's boards (Amp+PSU) with a 2x12V toroid, hoping 15v at the rails. I need about 10W.
I was wondering about some questions :
1° - With 3K3 resistors as R1/R2, a strap is required for R3 and R12. Please confirm.
2° - Could the PSU board be fed with 2 Leds and a single 10K R ? Please confirm.
3° - I'm planning to use 2x(22000µF/10000µF/3K3/10000µF) in this order. I'm right or not ?
Would it be a better solution with 22000µF/22000µF/3K3/10000µF ?
Nice to read from the expert !
Need some help to trouble shoot a mini-A
It has been raining for the weekend. Dug around my tresaure box and found a Peter Daniel Aleph 30 board. I also located enough parts to build a pair mini-A. I had both channes soldered up last night but no dice - there was no current through the IRFP240, both!!! I must be making some really stupid mistake but can't fingure out.
Using Grey's mini-A parts numbering, I got:
1. 5V at the source resistor of Q2 (the CCS IRF9610). Appeared to be correct.
2. 4V at the drain of Q2, reference to ground. Appears to be OK.
3. Q4 (top ztx450), there is virtually no voltage across the emitter and the collector, but it is not shorted when measuring the resistance (very high). There should be 4-5 volts across it .....
4. Q5 (bottom ztx450), approx 3.6V between the emitter and collector, not quite 4-5 but is certainly better than 0.
5. At the first split second of start up, I could see almost 0.6V appeared across R18 and R19, but fell to zero very quickly.
Not sure what to look for next ... Any suggestion where to start the trouble shooting?
TIA!!
It has been raining for the weekend. Dug around my tresaure box and found a Peter Daniel Aleph 30 board. I also located enough parts to build a pair mini-A. I had both channes soldered up last night but no dice - there was no current through the IRFP240, both!!! I must be making some really stupid mistake but can't fingure out.
Using Grey's mini-A parts numbering, I got:
1. 5V at the source resistor of Q2 (the CCS IRF9610). Appeared to be correct.
2. 4V at the drain of Q2, reference to ground. Appears to be OK.
3. Q4 (top ztx450), there is virtually no voltage across the emitter and the collector, but it is not shorted when measuring the resistance (very high). There should be 4-5 volts across it .....
4. Q5 (bottom ztx450), approx 3.6V between the emitter and collector, not quite 4-5 but is certainly better than 0.
5. At the first split second of start up, I could see almost 0.6V appeared across R18 and R19, but fell to zero very quickly.
Not sure what to look for next ... Any suggestion where to start the trouble shooting?
TIA!!
Hi Choky,
My poor camera probably just as bad, but I couldn't find the better one that my wife uses. Here are a few to look at first, please let me know which ones you want more close up. The lightning was not good, but the flash would make it worse. Better than nothing and hope to get a jump start.
Some pics are here:
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-1.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-2.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-3.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-5.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-6.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-7.jpg
Thanks!!
My poor camera probably just as bad, but I couldn't find the better one that my wife uses. Here are a few to look at first, please let me know which ones you want more close up. The lightning was not good, but the flash would make it worse. Better than nothing and hope to get a jump start.
Some pics are here:
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-1.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-2.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-3.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-5.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-6.jpg
http://i257.photobucket.com/albums/hh207/fredvu/Mini-A/ma-7.jpg
Thanks!!
Yup yup, same issue on both channels. Ought to be some stupid mistake from me 
I read pretty much all the Aleph and Mini-A posts over again. Many said the IRF9610's are hot, but in my case, they are not, only slightly warm. Not sure this should be the case when the amp is idling. It is funny that most of initial issue of other builders had symptom of too hot, but mine is the opposite, LOL.
I read pretty much all the Aleph and Mini-A posts over again. Many said the IRF9610's are hot, but in my case, they are not, only slightly warm. Not sure this should be the case when the amp is idling. It is funny that most of initial issue of other builders had symptom of too hot, but mine is the opposite, LOL.
pchw said:Yup yup, same issue on both channels. Ought to be some stupid mistake from me
I read pretty much all the Aleph and Mini-A posts over again. Many said the IRF9610's are hot, but in my case, they are not, only slightly warm. Not sure this should be the case when the amp is idling. It is funny that most of initial issue of other builders had symptom of too hot, but mine is the opposite, LOL.
have you links for naked pcb pics ?
then make same plane pic of yours , so we can compare
MINI-A 3 WATTER QUESTION.
Have just finished perusing MINI-A threads in anticipation of restarting this project.Brian's blue boards are ready for stuffing with all parts on hand with the exception of .47 source and sense resistors.I have only eight on hand.I do have fifty .33 ohm 3 watters which ,of course ,will increase the bias. What should happen to R12 & R13 ?? Must they also increase ?? If so how much??
On Grey's schematic there are TWO sense resistors and Brian shows
FOUR(like a real Aleph) . Could I get away with two on Brian's board?? If so I would have enough .47 units. I did try to solve this through a search but was not successful.
What would you do???
Will use +-15volt rails.
Have just finished perusing MINI-A threads in anticipation of restarting this project.Brian's blue boards are ready for stuffing with all parts on hand with the exception of .47 source and sense resistors.I have only eight on hand.I do have fifty .33 ohm 3 watters which ,of course ,will increase the bias. What should happen to R12 & R13 ?? Must they also increase ?? If so how much??
On Grey's schematic there are TWO sense resistors and Brian shows
FOUR(like a real Aleph) . Could I get away with two on Brian's board?? If so I would have enough .47 units. I did try to solve this through a search but was not successful.
What would you do???
Will use +-15volt rails.
Hi Choky,
Here is the linkies of PD board layout:
http://www.diyaudio.com/forums/showthread.php?postid=608702#post608702
http://www.diyaudio.com/forums/showthread.php?postid=610533#post610533
http://www.diyaudio.com/forums/showthread.php?postid=610543#post610543
and here are the linkies to my doomed boards
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view¤t=ma-top-1.jpg
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view¤t=ma-bottom-1.jpg
Sadly to say, the wifey does have a better camera than the poor yours truely
Thanks!!
Here is the linkies of PD board layout:
http://www.diyaudio.com/forums/showthread.php?postid=608702#post608702
http://www.diyaudio.com/forums/showthread.php?postid=610533#post610533
http://www.diyaudio.com/forums/showthread.php?postid=610543#post610543
and here are the linkies to my doomed boards
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view¤t=ma-top-1.jpg
http://s257.photobucket.com/albums/hh207/fredvu/Mini-A/?action=view¤t=ma-bottom-1.jpg
Sadly to say, the wifey does have a better camera than the poor yours truely
Thanks!!
Re: Need some help to trouble shoot a mini-A
looking at all pics , everything looks OK , thinking about diodes , transistors etc ;
1. OK
2. who cares where is drain vs. ground ? at least for Q2 ?
3.yes - there must ve 4 to 5V
4. not enough for opening full throttle
5. irrelevant
look at enclosed schm
..... tweak value of R4 to have around 4V3 across R3
it's best to place ( maybe temporary , maybe for good ) pot instead of R4 ; say that R4 is series connected resistor of 150R and 100R pot
when you do that - measure again these values I sketched on schmtc , and write here ...... also check what's output offset
also - replace R11 with 100K pot ... it's for coarse Iq setting ; later you can replace it with fixed resistor
pchw said:
looking at all pics , everything looks OK , thinking about diodes , transistors etc ;
pchw said:
1. OK
2. who cares where is drain vs. ground ? at least for Q2 ?
3.yes - there must ve 4 to 5V
4. not enough for opening full throttle
5. irrelevant
look at enclosed schm
..... tweak value of R4 to have around 4V3 across R3
it's best to place ( maybe temporary , maybe for good ) pot instead of R4 ; say that R4 is series connected resistor of 150R and 100R pot
when you do that - measure again these values I sketched on schmtc , and write here ...... also check what's output offset
also - replace R11 with 100K pot ... it's for coarse Iq setting ; later you can replace it with fixed resistor
It was my stupid mistake, no less.
When I looked at Peter's board, I found Q4 (Peter's board parts number) was sensing the voltage of of Q11. I automatically thought Q5 was sensing Q8 for symmetrical reason. I should be using Q7!!!
I moved the FETS to Q7 position and added a 221R and 0.47R resistors then powered it up using a variac. Bingo, I am seeing voltage across the top and the bottom 0.47R resistors. The voltage was somewhat higher than I expected. I got over 0.5V when the B+ surpassed 9.5VDC. This means over one amp was passing through the FETS. Not sure it was too high or not and didn't want to push my luck. I then powered the board off. All in all, I am happy to make some progress.
Thank you so much for your guidance, Choky. You gave me the ideas what to look up.
When I looked at Peter's board, I found Q4 (Peter's board parts number) was sensing the voltage of of Q11. I automatically thought Q5 was sensing Q8 for symmetrical reason. I should be using Q7!!!
I moved the FETS to Q7 position and added a 221R and 0.47R resistors then powered it up using a variac. Bingo, I am seeing voltage across the top and the bottom 0.47R resistors. The voltage was somewhat higher than I expected. I got over 0.5V when the B+ surpassed 9.5VDC. This means over one amp was passing through the FETS. Not sure it was too high or not and didn't want to push my luck. I then powered the board off. All in all, I am happy to make some progress.
Thank you so much for your guidance, Choky. You gave me the ideas what to look up.
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