Hi. I did play with it a lot. load or not, it dont change a thing in the fact that it dont want to power up logicaly is turned on off rapidly. There is not mucho components for the start up. They are all fine.
It is realy a bad design, just it. Since that now it works if i respect the power up procedure, i will add all the necessited electronic to make it work better. Simple mute relay and maybe a litle PIC like i did into the IR redesign, so it will check if this stupid thing have started its oscillation, i have figured that if i apply a short burst of anything like a sqare wave to it, it will go off of its lethargy (-vcc, hummmmmm).
Lets see hoe it realy plays, i still havent pluged it to my home stereo.
It is realy a bad design, just it. Since that now it works if i respect the power up procedure, i will add all the necessited electronic to make it work better. Simple mute relay and maybe a litle PIC like i did into the IR redesign, so it will check if this stupid thing have started its oscillation, i have figured that if i apply a short burst of anything like a sqare wave to it, it will go off of its lethargy (-vcc, hummmmmm).
Lets see hoe it realy plays, i still havent pluged it to my home stereo.
Another update...
D3 in the main board was misplaced with a bad component value, from factory !!
This part never been removed. It should be a 62v zener, it was a 14v zener...
it was simply over powering the sd circuit, making it act far shorter than it should, and not charging up the bootstrap cap enough...
That was some source of the poor start-up scheme...it controls the SD (shut down) upon start-up, and shut down too. what a difference. It is not perfect, but better.
D3 in the main board was misplaced with a bad component value, from factory !!
This part never been removed. It should be a 62v zener, it was a 14v zener...
it was simply over powering the sd circuit, making it act far shorter than it should, and not charging up the bootstrap cap enough...That was some source of the poor start-up scheme...it controls the SD (shut down) upon start-up, and shut down too. what a difference. It is not perfect, but better.
Ok, everyone, here is my latest update....
I replaced both schmitt inverters, and both mosfets. I did the diode/resistor swap on the main board, and kept everything else stock.
Guys,
IT WORKS! IT POUNDS! IT'S SWEET!
Hats off to all of you, for your contributions, inputs, and co-diagnostics!
WE DID IT!!!!!!
Thank you for all your help, and I am glad I was able to contribute to this forum, this problem, and help to find the solution that many, many people out there are searching for.
KUDOS!
Jeremy Boeck
Lead Electronics Technician
Schweighert Foods
Albert Lea
Minnesota
I replaced both schmitt inverters, and both mosfets. I did the diode/resistor swap on the main board, and kept everything else stock.
Guys,
IT WORKS! IT POUNDS! IT'S SWEET!
Hats off to all of you, for your contributions, inputs, and co-diagnostics!
WE DID IT!!!!!!
Thank you for all your help, and I am glad I was able to contribute to this forum, this problem, and help to find the solution that many, many people out there are searching for.
KUDOS!
Jeremy Boeck
Lead Electronics Technician
Schweighert Foods
Albert Lea
Minnesota
Hi, mine is working ok, after all the component replacements and fixes. Even the pcb is cheap, one trace was mysteriously cut and making the preamp work arraticaly (-vcc rail to one op amp, wheuu euuuu !!) looks like the cancer is into my unit.
I am now waiting for the main caps. I have found some that actualy fits the original footprint, but are 3300 uf rather than 2200 uf.
Unless than that, i am happy. I have added some protection components under the board, some 100nf caps and some zener diode to clamp anything bad.
I made it play on a dumy load at 100wrms for half an hour and my massive homemade heat sink barely gets hot. No fan required in mine.
One consideration about the free oscillating frequency, mine never oscillated at 100khz. I have replaced the cap that is on the op amp with a smaller value (47p) so now it runs at 85khz, it is still not within the 10% tolerance specified into the service manual, but it dont bother me that much, it is just a subwoofer amp.
the square wave looks good, not too much overshoot as one might expect from this poor design.
I am wondering whats the frequency of Jeremy's amp.
I am now waiting for the main caps. I have found some that actualy fits the original footprint, but are 3300 uf rather than 2200 uf.
Unless than that, i am happy. I have added some protection components under the board, some 100nf caps and some zener diode to clamp anything bad.
I made it play on a dumy load at 100wrms for half an hour and my massive homemade heat sink barely gets hot. No fan required in mine.
One consideration about the free oscillating frequency, mine never oscillated at 100khz. I have replaced the cap that is on the op amp with a smaller value (47p) so now it runs at 85khz, it is still not within the 10% tolerance specified into the service manual, but it dont bother me that much, it is just a subwoofer amp.
the square wave looks good, not too much overshoot as one might expect from this poor design.
I am wondering whats the frequency of Jeremy's amp.
Pat, you really should try Newark Electronics, www.newark.com . Might save you some $$$$. The newark part number for 2200uF 100V caps is 93b0190 and is 3.92 USD
Hi, thanks for the link. One concern is that we (astroflex inc.) buy trains of parts from digikey each day, so order is received next day early morning and shiping cost is minimum. I only have to send an e-mail to our purchase department...
And also note that it is not a 2200 uf but a 3300 uf, and that i am in canada so duty fees and taxes and exchange will bring up the prince.
thanks!
And also note that it is not a 2200 uf but a 3300 uf, and that i am in canada so duty fees and taxes and exchange will bring up the prince.
thanks!
pat allen said:no no, im upgrading them, they are originaly 2200 uf , i will install those 3300uf/100v, same footprint.
It is totaly out of logic and never been an option to downgrade them, it is already pumping a bit.
the price at newark for a 3300uf cap is close as the one at digikey, but usd.
Good idea, but, yours were already changed once weren't they? How small and inadequate were they originally any idea?
