Old Peavey bass amp

[Sock Puppet]

On todays menu was a 1978 Peavey 400B series III.

A couple of output transistors are dead, one missing but looking inside I can go no further because of a couple of vapourised components.

Anyone have a schematic they would share?

Cheers,

S.

[drewl]

I'll try to attatch the schem.

[drewl]

sorry, that was a 300...lets try again

[Sock Puppet]

Thanks Drewl you're a star.

A small child had found this in his mother's loft and carried it over a mile to the shop wanting my mate to sell it.

He (breathlessly) said if it doesn't work to put it in the bin!

As it's in very good condition I'll fix it for him with the kudos points he earned for the laugh.

Cheers,

S.

[Sock Puppet]

Looking through some photos, I have a different revision of the the board, the components in the photo I posted aren't shown, it doesn't have the fuses etc.

This is a 400B/G module unfortunately.

Hopefully the 400BH schematic isn't too different.

S.

[drewl]

here...it's prolly very similiar

[Sock Puppet]

That's it, right down to the 99009015 legend on the board.

I owe you a pint.

S.

[Enzo]

The house numbered output xstrs - SJ6357 - are in fact MJ15003.

The predrivers - 5331, 5332:
SJE5331 = MJE243
SJE5332 = MJE253
(Verify the leads pinout the same)

These are factory part IDs.

If the predrivers are damaged, check the 47 ohm resistors for open. And of course check all the cement power resistors.

[Ryan's Guitar Repair]

Drewl, I have a Peavey Series 300 on the bench at the moment in need of pots. The vintage pots are obviously way before my time (even at age 49) because I've never seen any with such wide terminals before. Just curious if you might have any information about them? Clarostats maybe?
P.S. I am new to the forum, if I hijacked here it was unintentional.

[Enzo]

Hi Ryan
You can't really hijack a thread dead for 14 years. But in general we like to start new threads for new repairs. For example, this thread was about a blown up 400BG module.

What numbers are on the pots? Part numbers have format like 71190053 numbers like 1377942 are date codes. 137 means CTS made it, and the rest means 42nd week of 1979