rewinding an input toroid?

marko · Post by **marko** » Wed Oct 24, 2007 9:23 am

is it an easy job or does it have to be spot on to work right? think the one in my m50 project need rewinding? the anodising has burnt off in places and will cause a short i think....

Post by **Francious70** » Wed Oct 24, 2007 9:43 am

Yea, that'll need to be redone.

Just ask the Doc about rewinding the torrid in his project MS1000TA.

Look here

http://www.soundbuggy.com/Eric/Car%20Au ... index.html

and here

http://www.soundbuggy.com/Eric/Car%20Au ... index.html

Post by **Eric D** » Thu Oct 25, 2007 1:54 pm

That input coil is a noise filter. It is designed to rid the amp of high frequency noise from your electrical system.

Even though that one looks bad, it is most likely still good. It is pretty hard to destroy these, unless they melt. I think you should just pull it out of the amp first, and check it for shorts.

If it is bad, just bypass it. Fix up the rest of the amp and give it a listen. If you hear an unacceptable level of noise, then worry about repairing or replacing the coil.

Otherwise, I think I have a spare M50 board I scam parts off of. I could probably hook you up with one of these if you need it.

marko · Post by **marko** » Thu Oct 25, 2007 9:27 pm

Eric D wrote:That input coil is a noise filter. It is designed to rid the amp of high frequency noise from your electrical system.

Even though that one looks bad, it is most likely still good. It is pretty hard to destroy these, unless they melt. I think you should just pull it out of the amp first, and check it for shorts.

If it is bad, just bypass it. Fix up the rest of the amp and give it a listen. If you hear an unacceptable level of noise, then worry about repairing or replacing the coil.

Otherwise, I think I have a spare M50 board I scam parts off of. I could probably hook you up with one of these if you need it.

sound great! didn't know you could by-pass these, some of the anodising has burnt off where the green and red wire meet, will this cause a short? i guess there's only one way to find out

ps- did you have to swap any other components in the rebuild other than caps? i need to change the diode that connects to the coil as this has cracked with heat from the damage!

1moreamp · Post by **1moreamp** » Thu Oct 25, 2007 9:41 pm

I would be surprised if Phil doesn't have a few laying around. They should not cost much if they do.

They also perform another function if not designed properly. They act like a current limit when they saturate, by choking the voltage flow off to the amp. no volts, no amps, No power. But I don't think PG intended this for these on their M amps. and Doc has you covered with the noise thing.
Any PG input coil would probably work from any 50 to 100 watt range amp.

Post by **Eric D** » Fri Oct 26, 2007 2:59 am

I am not certain, but I would guess it is nearly impossible to saturate these coils, or any similar coil.

They are not acting as a transformer. The red wire leads straight through, as does the green. They are operating in DC, in which a coil acts as a wire. And, since there is a direct wire connection from one end to the other of each lead, even once the iron core saturated, it will not likely limit the inflow of current. I would assume the wire gage itself would become the limiting factor, not the design of the coil.

All I had to replace on my M50 were the capacitors. I might have replaced the diode on mine as well, but I do not remember. I replaced all of the power supply MOSFETs as well, but that was not related to the fire in the amp.

The amp should work without the diode installed, and it is really just a reverse wiring protection item anyway. But, if you have one or can get one, there is no reason not to install it.

marko · Post by **marko** » Fri Oct 26, 2007 8:39 am

that diode is chared beyond recognition so no idea what spec it is, do i just get a similar sized one are they specific items?

Post by **Eric D** » Fri Oct 26, 2007 10:10 am

I think the diode is a 1N5401.

marko · Post by **marko** » Sat Oct 27, 2007 5:17 am

coming on nicely, soldered some brass on today as well an 3 new caps, not quite in the same league as eric's work but more than happy at this stage, put some power to the board too and got the red light then green light! looks promising!

just got to figure out that diode, it looks like it's just in series with that input coil?

marko · Post by **marko** » Sat Oct 27, 2007 8:05 am

damn! just about to fit the sink to the board and realised i'm missing loads of screws that hold the devices down

does anyone know what size they are? they don't appear to be metric.

1moreamp · Post by **1moreamp** » Sat Oct 27, 2007 8:09 am

If your referring to the fet mounting screws? I use a 4.5 MM tool to remove them with, and they use thru hole phenolic insulators. I have no other info, as I have been lucky enough not to loose any over the years...Hope this helps...C

marko · Post by **marko** » Sat Oct 27, 2007 8:14 am

this is the problem when your trying to scratch build an amp from several pieces, always a few screws missing!!

1moreamp · Post by **1moreamp** » Sat Oct 27, 2007 9:46 am

Do you have any of the other transistor mounting hardware ? It should all be the same thread >If my brain is working today

marko · Post by **marko** » Sat Oct 27, 2007 10:10 am

1moreamp wrote:Do you have any of the other transistor mounting hardware ? It should all be the same thread >If my brain is working today

there should be about 17, i only have 8!

when i originally bought my outlaw with a blown m50 side some of the screws were missing and the doner m50 i bought fixed that, now i have the doner case i'm fixing up with that australian board i got last week. so i'm missing about 10 screws and all 7 gold terminals too

1moreamp · Post by **1moreamp** » Sat Oct 27, 2007 1:22 pm

The gold terminal blocks will be the trick to find. I have some but they are for the ZX Ti line not the early M/MS series < big differences>.
I have a M-100 skeleton at the shop I will search and see whats availible just in case PG can't come to the rescue.

If you don't hear from me by Monday evening PM me...C

marko · Post by **marko** » Sat Oct 27, 2007 1:34 pm

the terminals are there just no screws in them! can just use regular screw-bolts till i can source some fancy gold plated ones..

1moreamp · Post by **1moreamp** » Sat Oct 27, 2007 9:31 pm

Send or [post a pic of your terminals I have NON gold plated stock that fits most of this stuff. If I can match you up I will need a mailing address to get these to you...C

marko · Post by **marko** » Sun Oct 28, 2007 3:31 am

here you go, just test fitted the board in the case and the 3rd cap is just a bit too tall!! no chance of a 4th cap, what is the max hight cap you can use in the 4th "spare" place before height becomes an issue?

the caps i bought were for my ms amps and just fit in!!

1moreamp · Post by **1moreamp** » Sun Oct 28, 2007 9:07 am

Oh you just need 4 screws for the speakers ?/ I thought you needed power screws

I can help you out on those, and I have shorter 6800uf caps also, or even shorter 4700uf caps, anything over the stock 2200uf is a improvement...LMK C

marko · Post by **marko** » Sun Oct 28, 2007 10:05 am

i need the power screws too, i didn't bother taking a pic of these because they look exactly the same size only there are 3! so 7 in total, think i'm ok with the cap size now, i screwed the heatsink in place and it lifted the top cover up a bit

it just sits on the lower cap, is this safe? would of been nice to put 4 caps in as it would of hidden most of the repaired area

as for caps i use nichicon 3300uf 25v 105o caps, i got a batch of 50 to do my projects, done one of my ms2125's and they seam ok.

just stuck on the fet screws now before i can test it properly....

1moreamp · Post by **1moreamp** » Sun Oct 28, 2007 6:06 pm

I got some 4700uf at 35 that are short enough to allow all 4 to be replace with plenty of clearance. The cap should not touch only because of thermal expansion issues the can is ground and so is the case so no biggy there at all.

marko · Post by **marko** » Sun Nov 04, 2007 6:18 am

here's my efforts on major board reconstruction, not bad for a 1st attempt, if it were a more valuable amp i would have spent a bit more time making it cleaner etc.. but was more of a project than anything!

Post by **Eric D** » Sun Nov 04, 2007 8:08 am

Good job marko!

That work is at least as good as any I have done. All my repairs still look pretty raw compared to the original board.

Now, does the amp work?

marko · Post by **marko** » Sun Nov 04, 2007 10:19 am

havn't put sound through it yet as i'm trying to source the 4.5mm screws that some monkey lost that hold the fets down, does power up with green light though so looks promising! havn't fitted a diode yet either!

1moreamp · Post by **1moreamp** » Sun Nov 04, 2007 10:38 am

Nice effort Marko ! Are those Nicichon Caps I see you using ? Good choice in my opinion. Keep up the good work my friend...