Substitute parting for Punch150

[chipper]

I have a 1st series Punch 150 here, i'm trying to find parts to sub the ones that are no good and are very hard to find (i found D40D8 and the others for $7 a peice but i'm not willing to fork out that much cash) So i'm wondering if i can use a transistor with similar specs but in a different case package (TO-220) for the drivers for 2N6488 and 6491. Also for the power supply i can't locate RFP18N10 anywhere so what would be good cheap alternatives for those? I've already replaced a few shorted MPSA56's. I put in two IRF540 fets that i had sitting around in the power supply and the amp turned i only did it for 5 seconds just to see what happens. So please LMK what can i do. Thanks!

[Perry Babin]

The MPSW42 and MPSW92 could be used for the drivers.

The IRF3415 will replace the 18n10.

This isn't a first generation 150. It's at least the second and possibly the third gen amp. The first generation amp had the metal heatsink on the top of the transformer.

[chipper]

I'm not sure either what model, generation it is but i was told it was a first punch 150. Anyway i need a couple potentiometers thats bass & treble. I ordered IRF3205's and went to radioshack and bought a pack of 47 ohm resistors. Someone on this forum was asking $25 for both treble & bass controls.... Is that a good price? Considering that the fact that they are no longer made. I saw this Punch 45 board on the bay that had what i needed on it for $35.....Is that worth it? And are they same values? I also need the emitter resistors for the outputs.

Also.... The soldering connections for the transistors are not there i was thinking of getting some wire and soldering them on the back to the transistor legs. Would that be safe?? I think this amp is still able to live and play again.....

[Perry Babin]

If it's the right pots, that's a good deal, considering that they're virtually impossible to find.

The problem with having the P45 board is that you won't be able to resist trying to repair it also.

Wiring the connections is OK. The old amps had very poor quality boards and the traces were easily damaged.

Is this the amp with two toroids in the power supply (assuming so if you were asking about the 18N10)? If so and you need photos of the board (to rewire missing traces), let me know.

[chipper]

Then i may probably buy that Punch 45 circuit board, then huh? Yes your right about the older boards. The solder pads for the transistors fell off now there nothing to attach the transistor to.

And yes this the one with two toroids in it (may i ask? Why two transformers?)

And BTW do you know where can i find those exact emitter resistors at? Or are those extinct also?

[Perry Babin]

I don't know why they used two transformers (although I don't know if the second one is technically a transformer). Sometimes, I think engineers do things on a bet.

I don't know about the exact resistors but the following should be close if you're looking for resistors that look the same. Confirm measurements before buying.
Digi-Key - 23JR10E-ND (Manufacturer - 23JR10E)

[chipper]

What are the two components near RFP18N10? They are TO-220 package parts.

Perfect! I needed some of those resistors. But yes i will check the measurements.

[Perry Babin]

18v regulators (7818 and 7918, 7818 closest to the 18N10s).