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[markorock37]

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.

[joecool85]

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, but it might make sense to try and find a reasonable substitute instead.

[J M Fahey]

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.

[markorock37]

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.

[markorock37]

I never mounted a transistor like that, a pic would be great.

[markorock37]

Found IRF250's at $6.50 ea, will those work?

[J M Fahey]

*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.

[markorock37]

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.

[markorock37]

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.

[markorock37]

I have quite a few MJI15004's too.

[J M Fahey]

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.

[markorock37]

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.

[J M Fahey]

Peavey are great guys.

[markorock37]

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

[J M Fahey]

*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.