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Amp Catastrophies

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Anonymous
May 22, 2004 7:22:04 PM

Archived from groups: rec.audio.tech (More info?)

Hi Group,

After spending hours rebuilding a SS guitar amp, (thanks to all who helped
with IC data etc,) I got it up and running.

I had to replace a couple IC's and most of the output components.

As I like to keep detailed records on stuff I have repaired, I was taking
voltage and scope measurements with signal applied, and making notes on the
print.

As I was making my final measurements with the scope probe,,,, I slipped and
shorted B to C on the driver transistor.

This took out most of the components in the output,,

At least when you do stupid stuff like this with Toob stuff you are rewarded
with a shower of sparks!!

Anyone have any boneheaded maneuvers they would like to share?

Vin Collins
Loser of the Day

More about : amp catastrophies

Anonymous
May 22, 2004 7:22:05 PM

Archived from groups: rec.audio.tech (More info?)

In article <weKrc.3573$yc4.2438@nwrdny02.gnilink.net>,
"JVC" <spambegone@spam.com> wrote:

> Hi Group,
>
> After spending hours rebuilding a SS guitar amp, (thanks to all who helped
> with IC data etc,) I got it up and running.
>
> I had to replace a couple IC's and most of the output components.
>
> As I like to keep detailed records on stuff I have repaired, I was taking
> voltage and scope measurements with signal applied, and making notes on the
> print.
>
> As I was making my final measurements with the scope probe,,,, I slipped and
> shorted B to C on the driver transistor.
>
> This took out most of the components in the output,,
>
> At least when you do stupid stuff like this with Toob stuff you are rewarded
> with a shower of sparks!!
>
> Anyone have any boneheaded maneuvers they would like to share?
>
> Vin Collins
> Loser of the Day

Try shorting the gate of a TO-220 MOSFET that's driving an inductor. It
sprays plasma-heated silver with explosive force. The result either
looks very cool or really stings, depending on how close you are.
Anonymous
May 22, 2004 8:18:36 PM

Archived from groups: rec.audio.tech (More info?)

Hey JVC,

We all do them. I was troubleshooting the middle board of
a 3-tier wire-wrap board-based unit back in the 80s. These
boards were full of digital ICs and we had an 80-amp power
supply for the box. I rested my hand on the top board as I
was doing some probing when my watch got quite warm! (Thanks
for the series resistance of it!).

I am also reminded of college (DeVry) when the whole class had to
build a power supply. The last couple of weeks in the lab
when everyone was completing their construction and powering
it on for the first time yielded several explosions as the
caps that were installed backwards blew.

--RY

"JVC" <spambegone@spam.com> writes:

> Hi Group,
>
> After spending hours rebuilding a SS guitar amp, (thanks to all who helped
> with IC data etc,) I got it up and running.
>
> I had to replace a couple IC's and most of the output components.
>
> As I like to keep detailed records on stuff I have repaired, I was taking
> voltage and scope measurements with signal applied, and making notes on the
> print.
>
> As I was making my final measurements with the scope probe,,,, I slipped and
> shorted B to C on the driver transistor.
>
> This took out most of the components in the output,,
>
> At least when you do stupid stuff like this with Toob stuff you are rewarded
> with a shower of sparks!!
>
> Anyone have any boneheaded maneuvers they would like to share?
>
> Vin Collins
> Loser of the Day
>
>

--
% Randy Yates % "Midnight, on the water...
%% Fuquay-Varina, NC % I saw... the ocean's daughter."
%%% 919-577-9882 % 'Can't Get It Out Of My Head'
%%%% <yates@ieee.org> % *El Dorado*, Electric Light Orchestra
http://home.earthlink.net/~yatescr
Related resources
Can't find your answer ? Ask !
Anonymous
May 22, 2004 9:34:31 PM

Archived from groups: rec.audio.tech (More info?)

Not audio but it is electronics.

In High School, Physics, we set about building an RC plane and the
Electronics (Heathkit) as an overal examination of flight, aircraft
construction, radio Transmission, servo control, etc...

In our class was a chap we called Tiny (He was quite all) We should have
called him Twitchy. Tiny had a twitch, every once in a while, his whole body
would twitch and whatever he was working on would gte messed up, usually
quite badly. Fro some odd reason, the teacher gave Tiny the job of
assembling the Servo Motor Control boards, which were quite small and
required a good degree of precision to solder properly. Well the end of the
year arrived and we had 4 dead Servo's and 1 partially operational Servo and
an RC plane that never flew, due to lack of control electronics. The damage
to the servo boards was so severe, that Heathkit even refused to consider
replacing them at all.

On another occasion, Tiny brought a Tube Amp in to class to attempt repair.
Probbaly just a bad tube, but after hooking up an Audio Oscillator a load
and an Oscilloscope, one Twitch and that was the end of the Amp, blown caps,
Scope and Oscillator.

I heard years later that Tiny went on to work in the Train industry, so I
don't know how many engines he ruined, or maybe they were not as severly
affected by his twitch.

At my first employ, fresh from DeVry, I was set to work alongside another
person for training. We were working at GTE, in 1976 and it was a waterfall
experience. The year I started there, the telephony industry was going
through a major upheavel. At that time, almost all CO (Central Office) gear
was electromechanical for all the major communication pathways. We built
large PCB (Printed Circuit Boards) with 20 and upwards of 40 multicontact
relays on each. This was just past the build of the last Strowger Two Motion
Switch. Anyhow, this guy is showing me how to remove a defective relay from
a PCB and he carefully unsolders all the pins, wiggles them all to break the
solder connection and then turnes the PCB over to pull the relay. It didn't
want to come out of the board, so he pops the plastic cover off the relay
and then places a large screwdriver under the relay and with much physical
work and loud grunting, he removes a relay from the PCB, trailing a
collection of PCB traces stil soldered to all it's pins. Obviously, he had
puled the wrong relay. I was amazed at the mans strength though.

My most recent experience is mechanical. I acquired a Realistic DX-160
shortwave and in the course of cleaning it up, I decided to remove all the
control knobs. Well, the former owner had used glue to secure the knobs on
the shafts. I roke a shaft right off trying to pull the knob, the brass
broke, before the plastic knob gave out. I fashioned a tube with some thin
brass folil and applied heat and solder to the parts and reattached the
broken pieces. It's not perfect, but it works. I suppose I shoul dhave
realized something was amiss and looked for a different solution, rather
than force to remove the knob.

rtt
Anonymous
May 22, 2004 10:19:47 PM

Archived from groups: rec.audio.tech (More info?)

Kevin McMurtrie wrote:

> Try shorting the gate of a TO-220 MOSFET that's driving an inductor.
> It sprays plasma-heated silver with explosive force. The result
> either looks very cool or really stings, depending on how close you
> are.

I spent a summer before grad school working on a prototype electric-powered
delivery truck. It was powered by over a dozen of the largest golf cart
batteries anybody made at the time. There were three battery boxes, each of
which weighed something like a ton. The battteries in each box were
connected in series so there was about 80 volts across each string. In
paralell and fresh, they could deliver over 1,000 amps into a 72 volt DC
motor via a SCR controller, for something like a minute. The contacts were
at one end of the box, and to my chagrin I found that it was possible to
short them out. They were hooked in series for charging with a
transformerless battery charger operating off of a 240 volt three-phase
power line.

I had this little accident where I dropped a screw driver with a foot-long
blade that could have doubled for a small crowbar. In one blue flash the
screwdriver lost about half its length, and I was covered with many spatters
of steel and copper. The good news is that I had safety glasses on and had
turned away before actual contact was made. So, I was neither blinded nor
did I need to visit a hospital.

My tempered glass safety glasses had spatters of copper and steel melted
into them to the extent that they had to be replaced. My face and forearms
had little b-b sized chunks of copper and steel seared into them. But, in a
week or two they mostly all fell out on their own. My clothes were
perferated and had to be scrapped.

The lesson was that batteries generally don't have effective power-off
switches on them.
Anonymous
May 22, 2004 11:51:15 PM

Archived from groups: rec.audio.tech (More info?)

"JVC" <spambegone@spam.com> wrote in message
news:weKrc.3573$yc4.2438@nwrdny02.gnilink.net...
> Hi Group,
>
> After spending hours rebuilding a SS guitar amp, (thanks to all who helped
> with IC data etc,) I got it up and running.
>
> I had to replace a couple IC's and most of the output components.
>
> As I like to keep detailed records on stuff I have repaired, I was taking
> voltage and scope measurements with signal applied, and making notes on
the
> print.
>
> As I was making my final measurements with the scope probe,,,, I slipped
and
> shorted B to C on the driver transistor.
>
> This took out most of the components in the output,,
>
> At least when you do stupid stuff like this with Toob stuff you are
rewarded
> with a shower of sparks!!
>
> Anyone have any boneheaded maneuvers they would like to share?
>
> Vin Collins
> Loser of the Day

In the late '70s, I worked as a contract engineer for a number of broadcast
stations. One night I was doing transmitter maintenance on a 100-kilowatt FM
station in a large transmitter complex at the top of a ski area near Boise
ID. It was about 3:00AM, and I had just finished replacing the main power
amplifier tube, and a bunch of other general maintenance. Working on
high-power transmitters is always cause for a bit of nervousness, and this
particular transmitter was more glitchy than others I've worked on.

Anyway, I got everything finished, so I secured the doors on the
refrigerator-sized cabinet, powered it up, and started tuning it up. I just
about had it back up to full power when -- BANG!! -- it sounded like a
shotgun going off inside the transmitter as it immediately dropped off the
air. I had a mental picture of some critical, expensive, hard-to-get
high-voltage component completely fried, and my client off the air for a
week while we wait for parts. I powered the whole thing down, and went
around back and cautiously opened the cabinet to survey the damage.

The 3/4-horse cooling fan was still coasting to a stop. Inside, the air was
filled with some kind of fuzz or something. What the...??? I couldn't think
of any component that would throw fuzz everywhere when it exploded. Then my
eye fell on an insulated stand-off mounted on the floor of the cabinet,
where the main high-voltage power supply lines entered the box. There, I saw
the skeleton of a mouse, with its back feet on the metal cabinet floor, and
it's nose about a centimeter from the high-voltage terminal. His last act
must have been a curious sniff of the 10KV power supply line. I probably
wouldn't have noticed him climb in there.

Anyway, I gently lifted the bone-dry skeleton out of the cabinet and
restarted the transmitter, which ran just fine. So it wasn't a catastrophe
for me, but the mouse probably had a different perspective, if he ever got a
chance to think about it. It also explained a few other dry mouse skeletons
I found in the building when I first started working there.
Anonymous
May 23, 2004 3:20:00 AM

Archived from groups: rec.audio.tech (More info?)

In <weKrc.3573$yc4.2438@nwrdny02.gnilink.net>, on 05/22/04
at 03:22 PM, "JVC" <spambegone@spam.com> said:

[ ... ]

>Anyone have any boneheaded maneuvers they would like to share?

While working as a technician I was assigned to terminate a 50
conductor cable. I was pleased when I got through the very boring task
without melting or shorting anything. Just as I was about to pat myself
on the back, I noticed the connector cover was still on the bench.

Carefully, I unsoldered all 50 pins and started over. Amazingly I
managed to replace all 50 conductors without melting or shorting
anything. I was very pleased. Unfortunately, the cover was still on the
bench!

-sigh-

Carefully, I unsoldered all 50 pins and started over. Amazingly I had
managed to replace all 50 conductors without melting or shorting
anything. I was very pleased.

This time I got it right.

(no I couldn't slide the cover from the other end because it had
already been terminated).

-----------------------------------------------------------
spam: uce@ftc.gov
wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------
Anonymous
May 23, 2004 5:52:07 AM

Archived from groups: rec.audio.tech (More info?)

In article <zOydnei11PCVTzLdRVn-hg@comcast.com>,
"Arny Krueger" <arnyk@hotpop.com> wrote:

> Kevin McMurtrie wrote:
>
> > Try shorting the gate of a TO-220 MOSFET that's driving an inductor.
> > It sprays plasma-heated silver with explosive force. The result
> > either looks very cool or really stings, depending on how close you
> > are.
>
> I spent a summer before grad school working on a prototype electric-powered
> delivery truck. It was powered by over a dozen of the largest golf cart
> batteries anybody made at the time. There were three battery boxes, each of
> which weighed something like a ton. The battteries in each box were
> connected in series so there was about 80 volts across each string. In
> paralell and fresh, they could deliver over 1,000 amps into a 72 volt DC
> motor via a SCR controller, for something like a minute. The contacts were
> at one end of the box, and to my chagrin I found that it was possible to
> short them out. They were hooked in series for charging with a
> transformerless battery charger operating off of a 240 volt three-phase
> power line.
>
> I had this little accident where I dropped a screw driver with a foot-long
> blade that could have doubled for a small crowbar. In one blue flash the
> screwdriver lost about half its length, and I was covered with many spatters
> of steel and copper. The good news is that I had safety glasses on and had
> turned away before actual contact was made. So, I was neither blinded nor
> did I need to visit a hospital.
>
> My tempered glass safety glasses had spatters of copper and steel melted
> into them to the extent that they had to be replaced. My face and forearms
> had little b-b sized chunks of copper and steel seared into them. But, in a
> week or two they mostly all fell out on their own. My clothes were
> perferated and had to be scrapped.
>
> The lesson was that batteries generally don't have effective power-off
> switches on them.

Ouch!

That reminds me of when I first tried melting a carbon rod. It
sputtered, causing little fireballs of molten carbon to burn through
everything they touched down to the concrete floor. I looked down and
saw one ball drop through a can of paint thinner! Luckily the can had
been sealed long enough to have run out of oxygen.
Anonymous
May 23, 2004 8:57:58 AM

Archived from groups: rec.audio.tech (More info?)

"JVC" <spambegone@spam.com> wrote in message
news:weKrc.3573$yc4.2438@nwrdny02.gnilink.net...
> Hi Group,
>
> After spending hours rebuilding a SS guitar amp, (thanks to all who helped
> with IC data etc,) I got it up and running.
>
> I had to replace a couple IC's and most of the output components.
>
> As I like to keep detailed records on stuff I have repaired, I was taking
> voltage and scope measurements with signal applied, and making notes on
the
> print.
>
> As I was making my final measurements with the scope probe,,,, I slipped
and
> shorted B to C on the driver transistor.
>
> This took out most of the components in the output,,
>
> At least when you do stupid stuff like this with Toob stuff you are
rewarded
> with a shower of sparks!!
>
> Anyone have any boneheaded maneuvers they would like to share?

**I was working on a big, tubed push pull power amp. It employed anode caps.
My arm was 'round the back, performing a measurement and someone entered the
workshop. In my surprise, I brushed my arm against the anode cap on one
output tube. The amp ended up on the concrete floor.


--
Trevor Wilson
www.rageaudio.com.au
Anonymous
May 23, 2004 5:33:31 PM

Archived from groups: rec.audio.tech (More info?)

Trevor Wilson wrote:

>
> **I was working on a big, tubed push pull power amp. It employed anode caps.
> My arm was 'round the back, performing a measurement and someone entered the
> workshop. In my surprise, I brushed my arm against the anode cap on one
> output tube. The amp ended up on the concrete floor.
>

My stepfather had a Phase Linear 400 make it's infamous POP and
it took out the the 16 ohm drivers in two Electrovice Patricians, one
400 and a IV both original from the early 50's.


--
Check out the gaming & computer forums at the [SS] clan site.
http://www.shamikaserver.com
Anonymous
May 24, 2004 3:05:11 PM

Archived from groups: rec.audio.tech (More info?)

In article <weKrc.3573$yc4.2438@nwrdny02.gnilink.net>,
JVC <spambegone@spam.com> wrote:
>Anyone have any boneheaded maneuvers they would like to share?

I was working on my tube audio bench supply and managed to put my hand on
both the grounded chasis and rectifier diodes. > 450V DC hurts and leaves
a blister.

--
<a href="http://www.poohsticks.org/drew/">Home Page</a>
Life is a terminal sexually transmitted disease.
Anonymous
May 25, 2004 9:07:43 AM

Archived from groups: rec.audio.tech (More info?)

drew@revolt.poohsticks.org (Drew Eckhardt) wrote in
news:70at8c.fgt.ln@revolt.poohsticks.org:

> In article <weKrc.3573$yc4.2438@nwrdny02.gnilink.net>,
> JVC <spambegone@spam.com> wrote:
>>Anyone have any boneheaded maneuvers they would like to share?
>
> I was working on my tube audio bench supply and managed to put my hand on
> both the grounded chasis and rectifier diodes. > 450V DC hurts and leaves
> a blister.
>

You haven't experienced anything until you get across 1350VDC with current at
about an amp. I can tell you that you don't feel very good for quite a
while.

r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
May 25, 2004 11:27:06 AM

Archived from groups: rec.audio.tech (More info?)

Rich.Andrews wrote:
> drew@revolt.poohsticks.org (Drew Eckhardt) wrote in
> news:70at8c.fgt.ln@revolt.poohsticks.org:
>
>> In article <weKrc.3573$yc4.2438@nwrdny02.gnilink.net>,
>> JVC <spambegone@spam.com> wrote:
>>> Anyone have any boneheaded maneuvers they would like to share?
>>
>> I was working on my tube audio bench supply and managed to put my
>> hand on both the grounded chasis and rectifier diodes. > 450V DC
>> hurts and leaves a blister.
>>
>
> You haven't experienced anything until you get across 1350VDC with
> current at about an amp. I can tell you that you don't feel very
> good for quite a while.

Rumor was that an unfortunate Raytheon engineer got sloppy with some
measurement taps he had put HV cables for the > 10 KV ampere-level DC power
supplies for some CW Radars I used to work with. He never felt anything
again.
Anonymous
May 25, 2004 1:25:24 PM

Archived from groups: rec.audio.tech (More info?)

In my early chemistry days I made the experiment where you extract
hydrogen and oxygen from water using a battery connected to carbon
rods, which are placed inside of inverted test tubes. Not satisfied
with 3VDC, I plugged the rig up into 120VAC. It took less than a
second for the H tube to fill, and before the O tube filled, the whole
thing blew-up sending shards of glass everywhere. MORE POWER. I knew
the science world was for me!
Anonymous
May 26, 2004 2:38:59 AM

Archived from groups: rec.audio.tech (More info?)

I've heard of Radar Tech's in Soviet Block countries being cooked alive by
improper service management practises.

One guy I worked with from Slovakia said he spent a week sitting next to the
microwave generator at one site and then decided that defecting was safer
than working there.

I can believe this stuff, I've seen Submarine Reactor cores just turfed out
onto the land in the Baltic Sea area. Still cooking and no thing to keep
people back but a rusted fence.

rtt



"sodderboy" <miked@wrmusic.com> wrote in message
news:b62893ab.0405250825.21ef3503@posting.google.com...
> In my early chemistry days I made the experiment where you extract
> hydrogen and oxygen from water using a battery connected to carbon
> rods, which are placed inside of inverted test tubes. Not satisfied
> with 3VDC, I plugged the rig up into 120VAC. It took less than a
> second for the H tube to fill, and before the O tube filled, the whole
> thing blew-up sending shards of glass everywhere. MORE POWER. I knew
> the science world was for me!
Anonymous
May 26, 2004 3:35:01 AM

Archived from groups: rec.audio.tech (More info?)

"Rich.Andrews" <spmaway@ylhoo.com> writes:
> [...]
> You haven't experienced anything until you get across 1350VDC with current at
> about an amp.

Oh yeah - I'm just DYING to do that...
--
% Randy Yates % "Watching all the days go by...
%% Fuquay-Varina, NC % Who are you and who am I?"
%%% 919-577-9882 % 'Mission (A World Record)',
%%%% <yates@ieee.org> % *A New World Record*, ELO
http://home.earthlink.net/~yatescr
Anonymous
May 26, 2004 11:57:06 AM

Archived from groups: rec.audio.tech (More info?)

Randy Yates <yates@ieee.org> wrote in news:lljg2i0a.fsf@ieee.org:

> "Rich.Andrews" <spmaway@ylhoo.com> writes:
>> [...]
>> You haven't experienced anything until you get across 1350VDC with
>> current at about an amp.
>
> Oh yeah - I'm just DYING to do that...

If the current had passed across my chest, I would likely not be here now.
As it was, it passed from my right hand to my right foot. Still was a
nasty experience. The burns were quite deep and took a long time to heal.
Surprisinly they were quite small in diameter.

r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
!