This would be good for your amp if using 4 ohm speaker: http://www.antekinc.com/details.php?p=40
22-0-22 and 100VA

If using an 8 ohm speaker: http://www.antekinc.com/details.php?p=41
25-0-25, 100VA

Hi,
The supply voltage would depend on the speaker load. Less voltage for lower speaker impedance to keep the max current down (and heat dissipation).
You'll need a split supply (+/-) - easily as much as +/-28VDC for 4 ohms and up to +/-38VDC for 8 ohms.
Here's a handy design calculator for these chipamps: http://www.national.com/vcm/national3/en_US/products/audio/files/Overture_Design_Guide15.xls
Works with Excel.

I've used heatsink USA (barrredboss on Ebay) a couple times and his stuff is excellent and good value.
A great (cheap) source for heatsinks are old amps/receivers at Goodwill, thrift shops etc. They don't need to be working. These are also good for a wealth of screws, standoffs and other hard to get items - transformers too. Worthwhile grabbing a couple or more to scrap for parts.

The side heatsinks of this monster are from HeatsinkUSA:

It's likely that by plugging in the ext speaker, it switched off the int one. So, if the one that was inside the cab originally was 8 ohms, you should try to match this. Two 4 ohm speakers in series makes 8 ohms.
If in doubt, go higher with the impedance (for example: 16 ohms (two 8's in series) as opposed to 4 ohms (two 8's in parallel). Lower impedance draws more current from the amp and this can stress it.

Quote from: Enzo on March 22, 2011, 09:54:38 PM
The question then arises, are all your other parts also 10x overspec, or just the bridge?

Would a 1A bridge be 10x overspec for a 200mA supply? Equal to or less than the cost of 4-1N4004. 4 leads to solder, not 8. Higher peak current.
Like I said in my first post, I learned the hard way by nearly losing an expensive transformer through ignorance and trying to save a few cents. To me, it's easy - use a bridge and worry about other things.

It's 60 watts - good for most everything I do. Convenient and out of the way, it's always ready. It feeds an outlet on the front of the supply, top one is limited by the bulb, bottom one has unlimited mains voltage.

The spec to look at is Peak Forward Surge Current. 1N4004 has 30A, a 15A bridge will handle ~240A. Sounds excessive but if the power supply has a large capacitor bank to charge (or a fault somewhere), it can come in handy.
I don't fix things, I build them and for anything drawing more than a couple hundred mA, I'll use a bridge.

Quote from: guitarkitbuilder on March 16, 2011, 09:23:09 PM

Quote from: MJL21193 on March 11, 2011, 09:25:52 AM
I learned my lesson with diodes (had 1N5406's short and nearly smoked the transformer) - I only use bridge rectifiers now, for anything that draws serious current.
Might be worthwhile to replace those with a 15-25A bridge.

A bridge rectifier is four diodes in a pre-configured package, so it isn't inherently safer.  If you replace lower current diodes with a higher rated bridge rectifier, you might keep the diode/bridge from failing but you'll just be inviting some other problem, since something is still drawing too much current through the rectification circuit. 

Replacing the diodes with a bridge wasn't meant to be 'safer', it's not supposed to act like a fuse. A bridge will withstand a lot more instantaneous current than 4 diodes combined. It keeps on doing what it's meant to do - rectify AC. If there is trouble further down the line, having the rectify blow doesn't help.

Nice!
I built mine into my homemade lab supply. There is a plastic tube that channels the light to the front panel:

I learned my lesson with diodes (had 1N5406's short and nearly smoked the transformer) - I only use bridge rectifiers now, for anything that draws serious current.
Might be worthwhile to replace those with a 15-25A bridge.

To calculate the resistance the dropping resistor in a resistor/zener regulator, you need a rough idea of how much current the circuit will draw. Most opamp circuits, with no discrete devices will draw (much) less than 100mA. Ohms law comes to the rescue:
V=IR
V=15
I=.1
R=150 ohms (15/.1=150)

For the 7.5V, safe to say the circuit will draw half that 100mA, so:
V=7.5
I=.05
R=150 ohms.
A word about wattage (power). The resistor will get hot and need to be of a high enough wattage to avoid burning. Formula for calculatin wattage is P=IV(dropped)
I=.1
V=Vcc-15. If Vcc is 22 that's 7V
P=.7 watts - the resistor needs to be at a minimum .7 watts. Making it double that will give some margin, so 2 watts.
Hope this helps.
EDIT: Some silly mistakes I made

The switches themselves are easy, if they are the problem. I'm not sure what circuit they are using to switch between channels but it is probably very involved and not easily diagnosed.
Anyway, good luck

Hi,
It's most likely not a problem with the power switch. It may be a problem with either the switches or control circuit that selects the channel.
It would probably be a reasonable idea to locate qualified service and have them look at it. It may be something very simple.

Cool (hot!) amp in a heater!
I have my old Wonder Woman lunchbox - gee, where could I put the volume and tone controls? 
Great ideas men.

Quote from: joecool85 on March 03, 2011, 04:28:01 PM
Great work.  How'd you do the "Eminence Inside" plaque on the back of the enclosure?

Thanks again.
The plate came with the driver, and a pair of picks. I thought it would be a nice touch back there.