The only place I found any IRF230's in stock they are $13.49 a piece, any better sources out there? I need 4 for a Megabass head.
Quote from: markorock37 on March 09, 2012, 02:38:52 PM
The only place I found any IRF230's in stock they are $13.49 a piece, any better sources out there? I need 4 for a Megabass head.
I found some on eBay for $10/each (http://www.ebay.com/itm/IRF230-Manu-IR-Encapsulation-TO-3-N-CHANNEL-POWER-MOSFETS-/110836857263?pt=LH_DefaultDomain_0&hash=item19ce6439af), but it might make sense to try and find a reasonable substitute instead.
Do you have a MegaBass schematic?
Does it only use them or there are more output devices?
Personally, if I had it on my bench, I would replace them with much more powerful IRFP250.
Yes, bending the legs carefully (and opening the pad holes a little) you can mount plastic TO218 or TO247 plastic transistors in heatsinks and PCBs meant for TO3s.
I do it all the time. (such as today).
Tomorrow I will post a picture if you need it.
Anyway would like to see your schematic first to be sure.
Couldn't find a schematic for this anywhere. I think this amp was plugged into the wrong ohm cab. I tested all the IRF230's and they all failed. There are also 4 3 legged transistors (one next to each IRF230) that have the middle legs snipped off. I tested those in circuit they conduct one way only so I assume those are good.
I never mounted a transistor like that, a pic would be great.
Found IRF250's at $6.50 ea, will those work?
*If* they are true, yes.
If you found them in EBay from a Hong Kong supplier they are probably fake.
Post some pictures: the Power PCB, both sides, and a heatsink closeup, to see how they are nounted.
What codes do the "small transistors" have?
EDIT: is it a Peavey Megabass, a Mega Bass guitar or Bass amplifier or a Megabass car amplifier?
Very different animals.
Also search and build a Lamp Bulb current limiter, to plug your amplifier into until fully repaired.
(http://i1092.photobucket.com/albums/i414/markorock37/025.jpg)
(http://i1092.photobucket.com/albums/i414/markorock37/024.jpg)
(http://i1092.photobucket.com/albums/i414/markorock37/027.jpg)
Here ya go, its a Peavey Megabass. Already have a limiter. IRF230's were soldered in through a heatsink, even the screws were soldered in to the board.
Also have quite a few MJI5003's still not sure if those would work - 140V 250W.
IRF230's are 200V 75W. I didn't notice it until now, 2 of the 4 transistors in there were RFM10P15's and not IRF230's.
I have quite a few MJI15004's too.
Dear markorock.
IRF230 are N channel MosFets ; RFM10P15 P channel Mosfets, those "3 legged transistors" are RUR820 ultrafast diodes.
You will definitely need the schematic, this is a *complex* beast.
Write Peavey including serial number and model, they will send it to you.
I'll also give you a Peavey phone number to speed things up.
Their attention to customers is excellent.
Your MJ15xxx are bipolar transistors, not what's used here.
We can't advance further without the schematic.
PS: I found Peavey sells the MOSFETS needed ... for a whopping U$16 the N's and US30 the P's. Ugh !!
Contact them anyway and ask for the schematis.
Just put a request in for a schematic with Gene over at Peavey. I'll get it posted later tonight when I get out of work.
Peavey are great guys.
Yeah, I've dealt with them a few times and its always pleasant. I let my customer know his parts are $$$ he's on the fence with getting it repaired because he can get another one for $150. He's thinking about it and will let me know. I'd like to get some progress on it in the next day or so and see if I can't get it buttoned up quickly. BBL
*IF* he's going to drop it at the next garbage dump, offer him to do that, and keep it.
Not "to repair and sell it" but to gut it and have a nice rack chassis, a beefy power transformer and a couple big filter capacitors, plus assorted useful hardware.
You can put any 200+200W amp kit there and use it for PA or annoy the neighbours with some choice Death Metal.
Or go wild and add a simple tube preamp for your own use.
Like on a broken car, parts are often worth more than the car itself.
Yep definitely thought about taking it off his hands! But heres the schematic. I have a PDF file too.
(http://i1092.photobucket.com/albums/i414/markorock37/Megabasspowerboard.jpg)
(http://i1092.photobucket.com/albums/i414/markorock37/Megabasspowerboardlayout.jpg)
Thanks.
Please post the PDF too, this jpg is somewhat fuzzy.
A Digital amp. :-\
Beyond my knowledge. :'(
*Maybe* only problem is dead output transistors, and replacing them is all you need ... but if not, you've spent a lot of money for nothing.
Tough decision.
Here's the PDF. It took me a minute just to find the power amp page..so I see where your coming from..lol.
*Very* interesting amplifier, thanks for posting.
They turned an industial motor controller into an audio amp. Cool .
Searched for the datasheet, no mention of this use, so I guess only Peavey(who invented it) understands it.
*If* I had it on my bench, and thanks to it having separate boards for everything, I would pull the digital power amp out, keep everything else and mount one of my own 300W boards, which would be happy with those +/-60V.
Analog classic board, of course.
But that's me, of course. ;)
We opted to let it die in peace. The nice thing is its modular so the power amp can be switched out very easily should he find another one. Not worth trying to fix when another can be had for about the same price. I'll offer to waive his bench fee and add $20 to keep it for parts :)
I would ;)
Beautiful chassis and PSU to build some monster.
If the preamp still works (I guess it does) it's the icing on the cake.
If not, you strip it completely (except PSU) and build there some beefy power amp driven by a Sansamp Classic pedal clone.
Or a simple FET Randall "Preamp from Hell". Dimebag would love it.
Think about a killer guitar amp. :dbtu: