The Little amp with the tone I love most wants to *ELECTROCUTE* me!

[Androgel]

From Andrew in Toronto - actually a pinch north of Toronto in Richmond Hill, but I CAN see the CN tower from Yonge St, where I live lol


Yes, ladies and gentleman, it is true.. I bought this little gem a few years ago at a garage sale.. there is no obvious brand on it, and to be honest, it looks home made.. This is a tube amp.. To describe its sound is as follows: like Buddha (butter! Lol) creamy tone when you want it, in your face acdc or Van halen when you want it, without touching a knob.. That's right - the way this works, is that if you play softly, as in, use pick and sting control, play *lightly* you get the sweetest clean tone, sounds beautiful.. But when you hit that string or chord like you mean it, you have got balls to the wall gain all the way - I'm talking back in black gain, then back to sweet clean tone if you want it to..

I loved it..

Until one day - ?

I went to the basement one morning, and unbeknown end to me, I wasn't wearing any shoes or socks.. 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.. It never occurred to me that this amp may have not been made properly.. Anyway.. I still love that thing, but I don't know what to do.. I called an electrical engineer amp guy, and he quoted me at over a thousand bucks just to look at it, and MAYBE be able to fix it "no promises"

Here are a few pictures, maybe someone can see something that's noticeable right away?

Any help would greatly be appreciated..

I have mild electronic experience.. I'm ok with a schematic and soldering iron, but not great, not do I trust myself with trouble shooting...

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 I came across this forum, and thought I'd make a post and see what happens..

Thanks, hopefully someone, or a few cool people can help me out - kind regards


Andrew from Toronto

[52 Bill]

...unbeknown end to me, I wasn't wearing any shoes or socks.

Did you file a police report? Were your shoes and socks ever found?

Welcome to the place.

Your amp is what is often referred to as a "Widow Maker". It is powered directly from the ac line and if plugged into a miswired outlet or if the internal ground cap fails, it could place a hazardous amount of voltage on the chassis, which as you have found can cause quite a shocking experience.

You need to add an ac isolation transformer and a 3-wire grounded cable to the amp to make it safe for use. My guess would be that the 3 tubes are a 50C5. a 35W4 and a 12AX7.

The amp looks like there has been a bunch of work done on it before, so I would also suggest that the amp be gone through to see that there is no other problems with the way that the amp has been wired.

Again, welcome to the place.

[DrGonz78]

I called an electrical engineer amp guy, and he quoted me at over a thousand bucks just to look at it, and MAYBE be able to fix it "no promises"

Definitely don't ever take the amp to whoever this "Guy" is or was...That is just nuts!

[Mick Bailey]

+1 on the above. You have a number of issues - isolation from the mains, grounding, and quality/integrity of the build. Even if isolated you may have some other shock hazard.

The first think I would do is to secure the design before making any changes. Draw up a schematic and write on the component values. That way you've got a record of an amp you really like. If you publish a rough sketch here we can help you fine-tune it. You then need to decide if you're comfortable with any recommendations, or prefer to find someone who will charge you a realistic and fair price to sort it out.

The guy who quoted over a thousand Bucks to fix it is entitled to charge what he likes. That's his offer, but it's ridiculous. It's what I call a 'F*ck Off' price.

It isn't difficult to put right.

[Jazz P Bass]

Quote"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.. "

Yup.

You need an "isolation transformer" BEFORE you attempt to add a 3 wire cord.

https://lectrolab.wordpress.com/lect...ls/widowmaker/

[Androgel]

Firstly, YOWZA! Wow I'm almost as shocked now as I was by my amp with the amount of replies and people who cared enough to notice lol thank you, this is a great forum for sure! I can see myself hopefully becoming a regular user and hopefully learn a few things.. Right now, my. Win interests are tube amplification, and diy synth stuff - I have a lot of ideas on easy things to make that don't need an engineering degree, that can make cool sounds, for example (before getting back to my amp) - I have a Hammond spinette tone box (with all of the pickups and sine wave generating gears and whatnot) - someone gave me a Siemens salesman unit for a motor control system, it's in a suitcase type setup, with a really nice motor in the case connected to a chassis, with its driveshaft (or whatever it's called) connected to a torque device, so you can turn a wheel and add torque, and it's all digital.. There is also a transmitter and receiver, where you can input rpms, as slow as 0.1 and as fast as several thousand I believe.. I was thinking of taking it out of the case, and connecting it to the Hammond, where the Hammond ac motor would normally be connected, at a continuous rpm (which is what keeps the organ perfectly in tune) so I can change the rpm on the fly.. There are no keys, but I was thinking about connecting the output wire from each pickup to a switch or two, one a temporary button switch (so notes/solos can be played) , the other a switch that stays on (for interesting chords) and a volume pot, maybe one for each pickup as well, and a master, possibly even pan pots, it could get complicated I guess.. But the basics of it are that the motor can change the rpm quickly, and make interesting sounds likely not heard before..

I also have a handful of other ideas related to using various types of wound magnetic pickups and basic electronic circuits not involving much voltage (other than the small amount generated by the pickup itself, the microphonic voltage?)

I really am thinking about taking a course or two as well, I know I really sound green here.. I've stopped myself twice from using the word "thingy" rofl

Ok back to the amp

Thanks for the replies!

I have no idea where to start, how would someone recommend that I go about making a diagram? I can solder, and follow a few steps above basic schematics (if that makes sense) - I guess what I mean is that I'm a step up from knowing nothing at all, but way below any of you in terms of knowledge of electronics.. I do know now that this amp can kill me, which is a shame, and why I'm not going to plug it in until this is resolved.. Actually, I was wondering: if I made some type of fuse for the cord, like, maybe made something that would make the cord connected to two strips of aluminum cut extremely thin, barely enough to even work (I'm not going to do this, I'm just curious about if this is even possible) - would something like that act as a fuse? Where if a large current went through it, enough to kill, it would melt the aluminum first? Is that something that would work? Or would a backwards fuse like that not work and kill me anyway? I'm thinking that if enough current went through it, it would heat it up and break the connection, preventing prolonged exposure.. ? Maybe the person would get a nice shock, but not fatal..? No idea! Lol


Is there anyone willing to help me make a schematic here? I am willing to take this amp apart and photograph or video record it, but not unless someone could help me put it on paper so I could rebuild it.. That would be the first step I guess.. Then, anyone who is up for it, could contribute any ideas towards fixing this little beautiful bugger, hey that's what I'll call it: the BB ..or maybe the killer beauty lol.. The tone really is saweeet! ...is there any safe way to use it in its current state? I do have a circuit breaking wall plug - if I plugged it into that, and wore rubber boots, would it be safe to use for a few mins just for the purpose of recording a short video to show everyone what it sounds like and why I'm even bothering with it?

Lastly,

Does anyone know of a source where I can buy original old stock components to fix this with? I'm guessing it was made in the 60's? (Someone reading this could probably guess a more accurate date by looking at the components) - I did put a different speaker in it, I think I put a speaker from an organ in it, I tried a few different speakers and left the one I liked best..


Anyway,
Thanks again for noticing me (eyore reference heh)

All the best to you all, and hope to hear from anyone who has any ideas.. Appologies if I'm all over the place regarding subject matter, that's just how I am..

Was diagnosed with ADHD (attention deficit hyperactive disorder), Tourette's (involuntary ticks, although I still have them, I can control them for the most part, and OCD (obsessive compulsive disorder- for about 2 years in my late 20's-early 30's, I was collecting Hammond organs.. I filled the garage, basement, and almost the house with them, until they had an intervention lol, you would be surprised by what you can get for free on Craigslist or other similar sites)


That's a little about me, I hope we will all have cool, interesting, informative, and entertaining interactions.. If there are any rules that I should know please do tell,

Thanks, all the best,

Andrew

Ps. I apologize in advance for any strange autocorrect happenings, my iPad does this a lot

[52 Bill]

From the photos that you have posted, your amp may have been produced by PEPCO in Canada. I guess that they were sold under many brand names, but the circuits are very similar.

The model that seems to match yours is an 801. If you search you may find a schematic for the 801 and you may be able to use that as a starting point for drawing yours.

Search PEPCO amps and you'll find there is a lot of great info out there. See if yours looks like it was made by them.

AND:
Don't even think about creating some sort of fuse yourself. There is a way to modify this amp to make it safe to use, and that is not it.

[nickb]

Pepco 801 "Lark" Schematic

[olddawg]

As said before. Series filament. No power transformer. You need an isolation transformer. Not expensive. Not much to this amp. Honestly though... Under best conditions with modern ground equipment, I usually use a wireless because I sing. Even if a venue that has brand new stage outlets, it doesn't mean they are wired right or even have a ground at all. Especially in old buildings. Zap!

[tubeswell]

(Power) Transformerless amps are illegal now in most places I'm aware of.

You're lucky you're still alive. If I was you, I'd go to the doc and get my ticker checked-out after that.

[rjb]

(Power) Transformerless amps are illegal now in most places I'm aware of.

I noticed the date on the schematic: Rev 1.1 5/7/2009.
Were these killer amps still made that recently, or is the schematic someone's unofficial version?
/

[J M Fahey]

Not even looking at it, it's obviously a redraw, nothing like that has or could or should have been produced in the last 30 or 40 years, at least.

Not any sense anyway, even if legal; no power transformer means **CHEAP** and SS will always beat it in any concept.

EDIT: the schematic is obviously computer drawn, but main point it's WRONG and has a DEADLY error: it shows a 150 ohms 5W resistor joining chassis ground and semi-floating input ground , bypassed by a .047uF cap,;proper value is anything between 68k and 150k (which probably was the misread original one) and its purpose is to limit current if you plug it "upside down" to tingling but not deadly 1 or 2 mA.

[tubeswell]

I noticed the date on the schematic: Rev 1.1 5/7/2009.
Were these killer amps still made that recently, or is the schematic someone's unofficial version?
/

Are you joking with me?

[Enzo]

Nobody has made an amp based on 35W4 and 50C5 in decades. It is a redraw.

[J M Fahey]

act as a fuse? Where if a large current went through it, enough to kill, it would melt the aluminum first? Is that something that would work? Or would a backwards fuse like that not work and kill me anyway? I'm thinking that if enough current went through it, it would heat it up and break the connection, preventing prolonged exposure.. ? Maybe the person would get a nice shock, but not fatal..?

That amp needs at least a 250mA fuse.

20 to 30mA will either stop your heart or cause fibrillation (it beating at 100Hz , all 4 "pumps" at once, not in proper sequence and pumping no blood, pick one, both DEADLY .

In fact, most Death Certificates state "cardiopulmonary arrest" as Cause of Death, go figure.
https://en.wikipedia.org/wiki/Cardiac_arrest

Cardiac arrest is synonymous with clinical death.

Not news, these are experiments showing what happens when animals (from rabbits to large dogs) were subject to 50V and 100V for 2 seconds; with 50 V the heart has a large contraction but resumes pumping afterwards; with 100V it fully stops.

Many will say "but I touched 120V , even 220V an here I am"

Fact is they made *poor contact* with mains voltage, were on a wooden floor, a carpet, or were wearing rubber shoes, or just "brushed" against the electrified point with an elbow or something (happened to me) , but if they had been grabbing a metallic object and contracting hand muscles wouldn't let them go ... you'd be reading about them in papers, with a cross (or any religious symbol or a black strip) by their name.

This experiment is from 1898!!!!!!
Not exactly News .... but is as true today as way back then: