#1
Hello,

So this is my first post on this forum. I just wanna start by saying I only recently got into vintage fenders, and im HOOKED

I first got a 68 Pro, but it was too loud for my purposes. So I went huntin and found an awesome deluxe reverb.

Heres my first question - was $1300 an overpay? Its a 1968 drip edge Deluxe in near pristine condition, with a blackface circuit, a Weber Ferromax speaker, NOS tubes (mostly RCA and GE), a Mercury Magnetics power transformer ( I would also like to know more about this components overall role in the amp), with original output transformer, reverb tank, and everything else pretty much stock I think.

The problem I'm running into is it has a 2 prong power cable. Now, the guy I bought it from was an amp tech himself, and didn't seem too concerned about the 2 prong. I'm wondering if this might have been because he modified it somehow to make it more safe? I dont know if thats possible or anything, just a theory

I know this topic has been addressed a hundred times, but because a misunderstanding is potentially lethal, I would like to ask questions pertaining to my specific situation. Before you start saying "its soooo dangerous just go get a 3 prong mod and be done with it", trust me - I will get that done as soon as I possibly can. But, I have to record in the studio tomorrow and my band has a big show in a week that we need to practice for

So, my understanding of the two prong issue is that it stems from when the plug is plugged in backwards, and the polarity is reversed, causing the chassis/amp to conduct electricity in some way, potentially shocking someone (me) if they plug in a guitar and touch the strings. Is that correct?

Furthermore, if the above situation occurs, AND there is something wrong in the amp (filter caps or something?), or the amp is exposed to water, or the person is touching something wet or metallic, or if the person sings into a mic, the shock is potentially lethal. Is that correct?

If im understanding this correctly, all of the danger is completely avoided if the plug is plugged in properly, and thus has the correct polarity. Does that mean I am completely safe if I use a voltage tester to make sure the amp is NOT conducting electricity in any way? And if it is, I can just flip the plug (or the ground switch on the amp?) and everything is good?

Here are the specific situations I need to know about - if im safe, if im in danger, or if I can get by with certain precautions.

1.) Playing in the basement of my house, on a rug, with shoes, with the amp plugged into a surge protector, being very careful not to touch anything metal, and using a voltage tester to make sure the plug is polarized correctly. Playing only my guitar through the amp - no mic
2.) The same situation as above except in a studio, with the amp being mic'ed
3.) Practicing with a band, with mostly the same situation as 1.), except with me playing guitar AND singing into a microphone connected to a grounded PA, with other instruments being nearby (but not plugged into the same outlet) and a metal pole in the middle of the room?
4.) Playing a show, same situation as 3.) except in a completely unknown space

Sorry if the post is long/covers a lot of different things, but I wanted to be as thorough as I possibly can.

Please help!! You dont know how much it sucks to buy a deluxe reverb and not be able to play it for fear of your life! I HAVENT EVEN TESTED IT OUT YET ONCE!!!!
#2
1300 was a high price for that amp, as you were told in your last thread.

Two prong isn't the end of the world, that amp made it almost 50 years with two prongs and it hasn't killed anyone yet. Three prongs is best practice but you're not going to get murdered in your sleep by a two prong amp, especially if you're not contending with dodgy club/bar wiring. Your understanding is (mostly) correct, the issue is typically with reversed polarity, such that you might get lit up by a microphone or other piece of gear with a different ground reference. With a bit of precaution it's pretty easy to avoid those issues most of the time.

Your situations:
1. Wouldn't worry about it.
2. Same.
3 and 4 - this is exactly where you want a 3-prong. Easiest thing to do is to label the plug with a sharpie or something so you can just line up the correct orientation every time you plug in. Pull the chassis and find the ground wire from the power cord, then use your multimeter to figure out which prong of the cord that corresponds to (or even just test the chassis against the prongs - the neutral prong should have continuity with the chassis). Label that prong and then just make sure you plug it in so that prong gets grounded (larger slot/left side on most outlets). Keep in mind that this amp has a switch on the back labeled "ground" that switches which prong is used as neutral. After you do the test, be careful not to flip that switch. You'll want to have it disconnected when you get the 3-prong installed.
#3
Get the 3 prong soon as you can. Much safer. Roc covered the basics, it's the ground reversed situation that causes problems. Probably won't kill you, but it's not fun stepping up to the mic in the middle of a song and getting the crap knocked out of you. Been there done that. Lots of times. That's the first thing I did when I got my Super Reverb and Champ.

Yeah you paid too much for that amp. Good amp, but that's top dollar for a modified amp. That probably didn't need to be modified...The only mods really needed on older Fenders are the ones after about 1970 when CBS started changing the circuits and went to different transformers and rectifier tubes, (they ran out of existing parts) and started changing components in the circuits that made the bass way to loud and boomy and put some capacitors on the power tubes that robbed them of the really high highs that gave Fender that chimey sound they were famous for. $10 and a few minutes of soldering cured mine...(73 Super Reverb) Actually I think it was well under 10 bucks. I went ahead and replaced every capacitor in it, almost 40 years old, they were dying out.

But a 68 shouldn't need anything but a capacitor replacement, those were still built according to the Blackface circuits, they still had the parts sitting around, and just changed the faceplate when CBS took over. That's cosmetic. Otherwise it should have been the same as a 65 with a different look.

The power transformer just takes standard 110 volt outlet power and transforms it into the various voltages needed to run the amp. 6.3VDC for the heaters, anywhere from 300 to 450 or so for the tubes. Usually the only reason to replace a transformer is if the original was fried. One of the common reasons for that with older amps is when a capacitor fails in the wrong place and creates a short. That's why I replaced all of mine, I thought it already had a fried output transformer. Turned out it was a bad capacitor failing after it got heated up. I got lucky, it didn't kill a transformer. It was one of the larger caps, though, not an electrolytic that can dry out. The ones Fender used were cheap, I put in good Spragues.

Anyway if the transformer is all that has been replaced, then it might not be an outright mod, just a repair. It basically supplies the right voltages to the amp and tubes so it can run right, it can't work on straight 110-117 volts from the outlet. Mercury is the transformer brand, apparently a fairly well respected brand. Fender got them from the lowest bidder, then again in 1966-68 when that one was original, they were still pretty good even if you got the lowest priced ones, most were US made and good quality..Mine are both still holding up quite well only a couple of years younger than yours. They usually bought in bulk so they might be actually put in an amp after sitting on the warehouse shelf for 2 years. So your 68 could have had anything in it from 66 to 68 when it was built.
Hmmm...I wonder what this button does...
#4
Thanks a lot, both of you, youv bern a lot of help and very informative. I appreciate yall takin ur time to drop sone knowledge