Disadvantages !

[Electric Al]

Other than the obvious , what are the disadvantages of an older guitar amp ,

that has the neutral grounded to the chassis ?

When I got this amp , it had a two wire power cord with a non polarized cord end.

I replaced the cord end with a polarized one .

Like I said , what are the disadvantages ?

 

[Enzo]

Why would it have disadvantages? If you installed a grounded power cord, that much is up to date. other than that, it either sounds pleasing to you or it doesn't. That is what I ask of an amp, new or old.

Tubes wear out, but they do that on new amps too. Caps have age, so 40 year old electrolytics are probably due for a change.

 

[rayma]

Other than the obvious , what are the disadvantages of an older guitar amp,
that has the neutral grounded to the chassis ?

Do you mean there is no AC line isolation transformer?
If so, I'd install one immediately before using it further.

 

[Thomasha]

Wait, are you saying you just replaced the cord end, or are you using a 3 prong cord?

And when you say the neutral is grounded to the chassis are you really saying the ground is grounded to chassis (3 prong cord) or are you really saying that the neutral aka the return of the hot wire?

I'm guessing it already has a transformer. Couldn't it be dangerous to ground the neutral to the chassis, where you plug your guitar in? In case it goes bad you will be the neutral right? (considering the 2 prong cord, and neutral as the return of the hot wire, and not the ground).

 

[jeff5may]

There are many disadvantages to having a piece of equipment that has a two-pronged, non-polarized plug, which has one wire attached to the chassis. For one, your chances of being connected to the power wire through the guitar strings and bridge are 50 / 50. Many artists were shocked through the lips by singing into a metal microphone, or by grabbing a mic stand with a free hand, in the past. If another piece of equipment was connected directly (effects loop, house drop, etc.) the lights would dim in certain circumstances. Usually, at least one piece of equipment would let out magic smoke before a fuse or circuit breaker cut the power.

Many of these older rigs were built that way, and must be rewired to ensure safe operation. In every piece of equipment, the power transformer primary winding should not be directly connected to the chassis. The chassis should be solidly connected to the ground prong of the power cord for safety.

 

[JMFahey]

Other than the obvious , what are the disadvantages of an older guitar amp ,

that has the neutral grounded to the chassis ?

When I got this amp , it had a two wire power cord with a non polarized cord end.

STOP!!!
Do not plug that amp again until you answer 2 questions:
IF it had only a 2 wire cord AND IF one one of the wires was directly connected to chassis, THEN that amp is a deathtrap.

Why?

Because NO amplifier grounds one power wire IF it has a power transformer. Period.

So IF it was, you are confirming it does NOT have a power transformer and so has a LIVE chassis, very dangerous/deadly and absolutely forbidden today.

So please:
* tell us brand and model, "old amp " covers way too much ground.
* try to post a couple pictures, one inside the chassis, other outside, we want to see and count transformers present.

Please do.
Thanks.

 

[Electric Al]

 

[Enzo]

OK, so it is a real basic small solid state amp with a power transformer. Your three wire cord will be fine, no hot chassis to contend with.

As to advantages, I am back wher I started, it sounds good or not TO YOU. There isn't much you can do to this. Different speakers would have the largest effect on sound. The amp is too simple to have many opportunities to tune the circuit.

 

[rayma]

what are the disadvantages of an older guitar amp , that has the neutral grounded to the chassis ?

From the circuit photo, significant ground loop hum would be expected, due to the various commons
being connected directly to the chassis. Careful and neat work, though.

 

[Electric Al]

Thanks guys, I don't think I will sell it , probably just use it myself once in a while !

 

[JMFahey]

Glad to see from your pictures that it is indeed a SS amp *with* a power transformer.
Lots of people were alarmed around here when we heard the brand, because Paul/Pep/Pepco amps surface regularly at pawnshops and such and are well known "widowmakers" ... literally.
Just read about them here:
Pepco Paul Combo - Anyone have a schematic or more info?

Now I'm not yet 100% at ease: I see a 117V primary power transformer, and a somewhat fumbled primary wiring, plus you said that one mains wire was connected to chassis or ground.

Can you please follow each mains wire through fuse and (pot mounted) power switch and confirm or deny that?

Any mains wire, even if Neutral, must *only* connect to transformer primary, power switch, fuse, and Neon Power light ... and *nothing* else.

Please turn amp on, unplug it from mains, and check that you do NOT have continuity from any mains plug leg to chassis.

Sorry for insisting but the picture does not show all, there's some wire hidden by parts, also some black tape.

Thanks.

If in doubt, why did you say there was a chassis connection?
Can you please show it?

Besides safety, I see just one power transistor.
If so, it's Class A and needs an output transformer, where is it?
Probably on the other side of the chassis, I don't see collector connections either.
That's why I also asked for a picture showing the other side of the chassis

 

[JMFahey]

Can't edit the above post, so here's a new one:

Look what the cat brought!!!!
Just yesterday, *another* deadly Paul/Pep/Pepco amp showed up!! (Told you they were popular):
The Little amp with the tone I love most wants to *ELECTROCUTE* me!
[IMGDEAD]http://music-electronics-forum.com/attachments/38363d1458957158-image.jpeg[/IMGDEAD]
[IMGDEAD]http://music-electronics-forum.com/attachments/38365d1458957190-image.jpeg[/IMGDEAD]

I plugged in and after a few minutes I noticed something different.. My wrists were feeling an uncomfortable 'scratching' feeling.. Not quite electric, but I'm sure it was caused by electricity.. But not enough to make it feel like a shock, not just yet... Until I got THE FREEKING SHOCK OF MY LIFE! I QUICKLY UNPLUGGED, And while shaking, I dare not touch the amp, I went to the wall panel and flipped the breaker.

I tried to change the power cable with a grounded one, and I soldered the ground wire to the chassis, the only thing this did was start to make the chassis warm.. I thought "ok, now I'm going to either make this thing explode, it'll REALlY electrocute me, or I'm going to start a fire, so YOU are going in the closet until I can fix you

So please check what's asked in the earlier post

 

[Electric Al]

I see golf clubs in the background !

If I had golf clubs , I would be tempted to introduce them to this piece of S*it .

It might be fun !!!

 

[jeff5may]

The real question here is this: would it sound better being pummeled by a fine iron or wood than operating? Only you can answer that question.

 

[Electric Al]

I am going to pull it apart one more time , and try to draw out a schematic !

If it turns out , I will post the schematic and try and get some more info .

I am a bit of a Pack Rat , and I hate throwing anything away ,
in case I might need it some day !

 

[Electric Al]

Took it apart , realized it is not worth reviving , as it has been Mickey Moused !

Saved as many parts as possible !

No need for the GOLF CLUBS !!! LOL !

GONE !

 

[jasse]

I think it's obvious a shitty amp based on the fact that's a toilet paper roll in there.
(Ducks and runs for cover)

On topic: what does it means when something has been Mickey Moused ???

 

[JMFahey]

When something has been "repaired"/modded by an incredibly incompetent "tech" .

 

[Electric Al]

Right On ! Bro .

 

[Thomasha]

Looked like a nice housing for a low wattage tube amp though.