Mx8000 power supply problems

[fxxrob]

The solution to power supply problem is simple. The five voltage regulators will fail. They consist of the following.
1-ml7812a from radio shack rs276-1771
3-lm350t from national semiconductor. The are aboout .90 each + shipping.
1 tl783c from texas instruments
they sent me one for free.

The only one that was bad in my power supply was the one for the +18vdc output. I changed all them anyway, I am sure another would have failed too. they are the only part that is bolted to the heat sink when open the top of the cabnet. The other parts seem to be bullit proof. instead of trying to de-solder the old regulators, I cut them out leaving plenty of leg length. Un-bolted the old ones in the exact same spot re-bolted the new ones with heat sink cream, and soldered thr new legs to the old ones. Make sure that you don't over heat them or they will be cashed right away. Clip an aligator clip between the solder gun and the body of the new part on each leg as you connect it. this will prevent them from getting fryed!

 

[cgrajko]

The solution to power supply problem is simple. The five voltage regulators will fail. They consist of the following.
1-ml7812a from radio shack rs276-1771
3-lm350t from national semiconductor. The are aboout .90 each + shipping.
1 tl783c from texas instruments
they sent me one for free.

The only one that was bad in my power supply was the one for the +18vdc output. I changed all them anyway, I am sure another would have failed too. they are the only part that is bolted to the heat sink when open the top of the cabnet. The other parts seem to be bullit proof. instead of trying to de-solder the old regulators, I cut them out leaving plenty of leg length. Un-bolted the old ones in the exact same spot re-bolted the new ones with heat sink cream, and soldered thr new legs to the old ones. Make sure that you don't over heat them or they will be cashed right away. Clip an aligator clip between the solder gun and the body of the new part on each leg as you connect it. this will prevent them from getting fryed!

Hey, I just picked up one of these mixers for $50 on Craigslist. When I first plugged it in and tested everything, all seemed to work fine, but then, every time I hooked up the meter bridge the -18vdc light would go out and all the signal/peak LEDs would come on. Now, it's gotten to the point to where it does that with the meter bridge unplugged and can't even use the board. I know the power supply connection to the board is good and can't find any other cause of the problem. In your opinion, do you think I just need to replace the lm350t voltage regulator for the -18v and that fix the problem?

Thanks

 

[eurodesk1]

The solution to power supply problem is simple. The five voltage regulators will fail. They consist of the following.
1-ml7812a from radio shack rs276-1771
3-lm350t from national semiconductor. The are aboout .90 each + shipping.
1 tl783c from texas instruments
they sent me one for free.

The only one that was bad in my power supply was the one for the +18vdc output. I changed all them anyway, I am sure another would have failed too. they are the only part that is bolted to the heat sink when open the top of the cabnet. The other parts seem to be bullit proof. instead of trying to de-solder the old regulators, I cut them out leaving plenty of leg length. Un-bolted the old ones in the exact same spot re-bolted the new ones with heat sink cream, and soldered thr new legs to the old ones. Make sure that you don't over heat them or they will be cashed right away. Clip an aligator clip between the solder gun and the body of the new part on each leg as you connect it. this will prevent them from getting fryed!

I replaced all regulators and no more lights but lost phantom power. Would
you know which regulator deals with phantom power it worked before
I replaced regulators? Thankds