[jdkJake]

BTW, I took another look at the underside photos.

From the photo, it looks as if something is protruding from one of the unused holes of CA3R.

Can you check and verify that please?

 

[Nomnomnom]

Jake, just double checked all unused holes in Wima cap locations and they are all free of obstruction...

 

[jdkJake]

Ahhhhh got your edited pic. Was I just shorting it by connecting those points in the first pic?
 
Anyways, I'm hoping this is good news but I got 34.5V utilizing both of the rectifier locations and GND.

Well, that is actually a good sign. You may indeed have a blow regulator. Can you verify the correct value parts are populated in RR1, RR2! DR2 and DR3?

 

[tomb]

Quote:

Ahhhhh got your edited pic. Was I just shorting it by connecting those points in the first pic?
 
Anyways, I'm hoping this is good news but I got 34.5V utilizing both of the rectifier locations and GND.

Ahh!  Well, that is good news ... of a sort.  That's about what you should get after rectifying 26.5VAC.  I'd say it's definite that your LM317 is blown.
 
EDIT: No, you weren't shorting anything by measuring the first points I posted - they were the same voltage!
 
 

 

[jdkJake]

Quote:

Ahhhhh got your edited pic. Was I just shorting it by connecting those points in the first pic?
 
Anyways, I'm hoping this is good news but I got 34.5V utilizing both of the rectifier locations and GND.

Ahh!  Well, that is good news ... of a sort.  That's about what you should get after rectifying 26.5VAC.  I'd say it's definite that your LM317 is blown.
 
 

So the question remains, what caused it to blow? TomB, ever hear of that type of failure and what the ultimate cause turned out to be?

 

[Nomnomnom]

I do believe they are the correct values but just in case here's a couple thousand words worth of pics

 

[beerguy0]

Quote:

So the question remains, what caused it to blow? TomB, ever hear of that type of failure and what the ultimate cause turned out to be?

The OP stated that he placed his DMM in current mode across the LM317, and saw smoke. In current mode, the DMM is basically a short circuit, so he shorted the LM 317 output. Voltage regulators are somewhat protected from abuse, but the fact that he saw smoke is a sign that something bad happened - in this instance, a blown regulator.
 
The easiest way to replace the regulator is to just cut the pins and use tweezers and a soldering iron to remove the leads from the thru holes. Clean the holes with solder wick, install the new regulator and you should be all set.

 

[Nomnomnom]

Blahhhhhh lol. That thing looks like it's going to be a royal PITA to remove. I'm guessing remove both caps that are in front of it for access, snip the legs, unbolt and remove the device then get those legs out of there? Then once again is that LM317 that I picked up from Rat Shack today going to be an acceptable replacement? Looks exactly the same and the part number is the same but I don't know if there is any quality issue...
 
I guess that is good-ish news being that at least a portion of the problem is solved. I'm guessing a little more testing may be necessary to figure out the initial cause? I haven't moved the power leads back over to the "fuse" pads just yet either. I know they're fairly cheap but blowing them every time I powered up was a little frustrating...
 

 

[Nomnomnom]

Ahhhh yes Beerguy but.... The fuse was blown during the initial power up, before I tested anything.
 
This was also when the two rectifiers (DR1A, DR1B) were reversed. Would it be a fairly safe assumption that the reversed rectifiers caused the initial blown fuse, then my hamfisted ma-NOOB-er with the DMM in current mode killed the LM317?

 

[jdkJake]

Ahhhh yes Beerguy but.... The fuse was blown during the initial power up, before I tested anything.
 
This was also when the two rectifiers (DR1A, DR1B) were reversed. Would it be a fairly safe assumption that the reversed rectifiers caused the initial blown fuse, then my hamfisted ma-NOOB-er with the DMM in current mode killed the LM317?

Sounds plausible.

Removing the 317 should be pretty easy as you do not have to save the part. You can pretty much go medieval on it. Slice the legs off and go.

Did you solder in the heat sink?

 

[Nomnomnom]

Ohhhhh yes I did. Seemed like the right thing to do what with those massive metal tabs that came down through the PCB. I pretty much assumed that beast wasn't meant to move so I acted accordingly and soldered the crap out of it. I think if I get those two caps out of the way, I'll have enough room to access the VREG

 

[beerguy0]

Quote:

Blahhhhhh lol. That thing looks like it's going to be a royal PITA to remove. I'm guessing remove both caps that are in front of it for access, snip the legs, unbolt and remove the device then get those legs out of there? Then once again is that LM317 that I picked up from Rat Shack today going to be an acceptable replacement? Looks exactly the same and the part number is the same but I don't know if there is any quality issue...
 
I guess that is good-ish news being that at least a portion of the problem is solved. I'm guessing a little more testing may be necessary to figure out the initial cause? I haven't moved the power leads back over to the "fuse" pads just yet either. I know they're fairly cheap but blowing them every time I powered up was a little frustrating...

The fuse protects the wall wart. The fuses may be a PITA to replace, but much cheaper than a new wall wart.
 
As far as the replacement LM317, any LM317 will work. No worries there.
 
Quote:

Ahhhh yes Beerguy but.... The fuse was blown during the initial power up, before I tested anything.
 
This was also when the two rectifiers (DR1A, DR1B) were reversed. Would it be a fairly safe assumption that the reversed rectifiers caused the initial blown fuse, then my hamfisted ma-NOOB-er with the DMM in current mode killed the LM317?

That's what I just said - the DMM in current mode killed the regulator. The fuse popping could have been from the backwards diodes. (Looking at the schematic, I'm almost sure that's what happened.)
 
 

 

[Nomnomnom]

Beerguy - I know I restated what you said but I wanted to include it in story board form from the initial cause (reversed rectifiers) to final diagnosis and get confirmation from you guys before I tear into it tomorrow. Man, I really want to start right now but duty calls rather early...
 
Thank all of you guys very much for helping me out. I'll post the results of the transplant over the next couple nights and hopefully get a chance to do the casework this coming weekend. With all that being said and done, I'll move some pics over to the thread that has living MOSFET MAXs lol.
 
Thanks again for your time and support,
 
-Chris 

 

[tomb]

Quote:

Beerguy - I know I restated what you said but I wanted to include it in story board form from the initial cause (reversed rectifiers) to final diagnosis and get confirmation from you guys before I tear into it tomorrow. Man, I really want to start right now but duty calls rather early...
 
Thank all of you guys very much for helping me out. I'll post the results of the transplant over the next couple nights and hopefully get a chance to do the casework this coming weekend. With all that being said and done, I'll move some pics over to the thread that has living MOSFET MAXs lol.
 
Thanks again for your time and support,
 
-Chris 

Just some advice on the LM317 - don't worry about the heat sink.  Simply remove the socket head screw, washer, etc.  Then turn the board over and make a blob with extra solder that covers all three pins at once.  If the LM317 doesn't just drop out, tie a string around it and pull while you have the solder blob melted.  Clean everything up with de-soldering braid.  (Add solder if needed to clear out a hole - it helps to melt everything through and through so the de-soldering braid can clear the hole.)
 
Alternatively, do what Jake said - but try using something like a dental pick to push the remaining leads out of the pads.  You can buy these at Harbor Freight for pretty cheap.  Or, simply use a spent lead - but make sure it's long enough that you grab it with pliers and pull it out of the hole (with the solder melted) after you've pushed out the cutoff LM317 pin (for each hole).
 
I think Beerguy summed it up - fuse blew from the backwards rectifiers.  Then the LM317 blew when you shorted it out with the DMM in current mode.  I doubt anything else is messed up, though, so if you get this fixed, you should be into music ... I hope.

 
 

 

[Nomnomnom]

Okay guys I was hoping my next reply would be a good one but here goes...
 
I replaced the LM317 (lot easier than I thought it would be), moved the leads back over to the "Fuse" pads, cleaned and dried the flux up, waited a bit, put a new 1amp slo-blo in, attached power and POP! I blew the fuse twice in a row. I'll heed the earlier warning and not bypass the fuse but once again, I'm open to suggestion so fire away guys...
 
-Chris