Re: 35v DC at speaker terminal!
nevermind its working again, it was the q507
onejay09
Senior Member
Last Activity: 02-25-2023, 08:24 AM
Joined: 11-16-2011
Location:
-
Re: 35v DC at speaker terminal!
put the new output transistors in and a new (q507) vbe in, turns on but no sound nothing!Leave a comment:
-
Re: 35v DC at speaker terminal!
its fine it turns on and runs, just waiting for new vbe and driver trans deliveryLeave a comment:
-
Re: 35v DC at speaker terminal!
just got the outputs today, what should i be checking before i put these in?
0.4 v dv at r519/r520.Last edited by onejay09; 08-28-2014, 09:17 AM.Leave a comment:
-
Re: 35v DC at speaker terminal!
ill check its impedance when i get home but it sounded ok, im wondering if the new outputs arent matched then could i increase the value of r524 and r525, if i understand right these are emmiter resistors? would it give some lee way if the power transistors are not matched up well, what would the side effects be if i increased the values?Last edited by onejay09; 08-27-2014, 04:56 PM.Leave a comment:
-
Re: 35v DC at speaker terminal!
i have recapped the board all except 1 or 2. the black stuff is glue, but yea one of the poly caps blew near there.Leave a comment:
-
Re: 35v DC at speaker terminal!
it ran great for about 1 minute.
well the black stuff where not charred to a crisp was more like tar and where it was hot it was more like burnt plastic.
after i blew the outputs i decided id pass the time by cleaning the board where i could, replaced all the jumpers that were brown and crispy, also pulled some bigger parts off to get the last of the RTV off. went over all the solders, made some traces bigger.
noted the resistors id like to replace..
just waiting for these partsLast edited by onejay09; 08-27-2014, 01:25 PM.Leave a comment:
-
Re: 35v DC at speaker terminal!
its an 8inch very heavy sub speaker! it seems fine.
im worried that something is a miss, if not the fact that the mica insulater slipped from behind the tip36c, why wouldnt this cause both to blow?
i have took them out and theyre both dead shortLeave a comment:
-
Re: 35v DC at speaker terminal!
the jumper went from + from rectifier to r512 and r503Leave a comment:
-
Re: 35v DC at speaker terminal!
ive got driver transistors being delivered as a complimentary pair so ill change those with the outputs, might start replacing the resistors that are like the jumper, corroded...Leave a comment:
-
Re: 35v DC at speaker terminal!
yes that is bolted down along with the outputs, its an mpsa13Leave a comment:
-
Re: 35v DC at speaker terminal!
is that q507?Leave a comment:
-
Re: 35v DC at speaker terminal!
yea it was a complete mess anywhere theres heat+black stuff, theres corrosion, i think it took me 2 days just to clean it off with a pinLast edited by onejay09; 08-27-2014, 05:29 AM.Leave a comment:
-
Re: 35v DC at speaker terminal!
well it worked, tested the sub and it sounds fine, but the mica film for the outputs slipped out and i blew the outputs.good job i ordered new ones yesterday, so ill get back on here when ive fitted the outputs, maybe tomorrow. ill let you know where the jumper went when i unscrew it all again.Leave a comment:
-
Re: 35v DC at speaker terminal!
so if this was making poor contact?Leave a comment:
-
Re: 35v DC at speaker terminal!
i was trying to clean the board and pushed a corroded jumper, its snapped at the base. if this does fix it im going to replace them all with new,
blame a shoddy repair the first time around as i got exited and left it in a poor state, this is what the black glue does to stuff...Last edited by onejay09; 08-27-2014, 04:06 AM.Leave a comment:
-
Re: 35v DC at speaker terminal!
cool, ive just found somethingLeave a comment:
-
Re: 35v DC at speaker terminal!
the bottom left corner on the schematic? theres an op-amp and where it says iso thats an led and photo resistor,
or photos from the prev repair?
the schematic on the right the relay. i think its a soft start protection? perhapsLeave a comment:
-
Re: 35v DC at speaker terminal!
I forgot to mention that it started intermittently, once hot it would do this buzzing, then i left it off overnight and it had gone, it started again when it got hot and got worse
ive ordered some parts, ill check all values of all parts inside the red box, thanks budmLeave a comment:
-
Re: 35v DC at speaker terminal!
so i know its unbalanced and i assume thats where its failing to operate correctly, would biasing help, eg: replacing a resistor with a pot and re biasing?Leave a comment:
No activity results to display
Leave a comment: