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 Post subject: Capacitor explosion
PostPosted: Sep Sun 10, 2017 3:40 pm 
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Joined: Jan Thu 24, 2013 11:50 pm
Posts: 2596
Location: Bristol, Rhode Island
Must have been a heck of a bang when the first filter cap (bottom center) on this Zenith 9S262 exploded. The chassis is literally covered with tar, paper and bits of aluminum. Fun!


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 3:52 pm 
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Joined: Jun Sun 03, 2012 12:40 am
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Location: Cromwell, Connecticut
What a mess! Hopefully the PT didn't get any damage.

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 4:17 pm 
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Joined: Nov Mon 05, 2007 11:08 pm
Posts: 2312
Location: Calgary Alberta
I had a Westinghouse that had the same problem . It was like this when I looked under the chassis.
Dan in Calgary


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 4:33 pm 
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Joined: Jan Thu 24, 2013 11:50 pm
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Location: Bristol, Rhode Island
Tbone wrote:
What a mess! Hopefully the PT didn't get any damage.

Resistance measurements check out fine. Haven't powered it up for more than a few minutes yet with rectifier pulled. Seems to be putting out correct voltages. We'll see what happens once I drop in the rectifier.


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 5:59 pm 
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Location: Maryland 20709, USA
That radio needs a whole lota work before power is applied.

Every one of those waxed paper caps must e replaced.

- Leigh

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 8:01 pm 
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Joined: Nov Mon 05, 2007 11:08 pm
Posts: 2312
Location: Calgary Alberta
Leigh, if you are referring to my Westinghouse.. I have replaced all the caps and it is working good now.
What had caused it was someone had hooked up a PM speaker to the radio and of course with no field
coil it exploded.
Dan in Calgary


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 8:32 pm 
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Location: SoCal, 91387
I think Leigh would be referring to Diverted's scan. I would add to verify the resistances of the Dog bones, as well.

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 9:54 pm 
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Joined: Jan Thu 24, 2013 11:50 pm
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Location: Bristol, Rhode Island
Leigh wrote:
That radio needs a whole lota work before power is applied.

Every one of those waxed paper caps must e replaced.

- Leigh

I'm aware of this. Thus why I said I had not yet powered it up with rectifier in circuit.


Last edited by Diverted on Sep Sun 10, 2017 9:56 pm, edited 1 time in total.

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 9:54 pm 
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Joined: Jan Thu 24, 2013 11:50 pm
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Location: Bristol, Rhode Island
fifties wrote:
I think Leigh would be referring to Diverted's scan. I would add to verify the resistances of the Dog bones, as well.

Most resistors were out of spec. Replaced 90 percent of them. All wax caps, two micas, candohm etc etc all replaced. Powered up the set and it plays well.


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 10:00 pm 
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Location: Maryland 20709, USA
Diverted wrote:
Leigh wrote:
That radio needs a whole lota work before power is applied.
Every one of those waxed paper caps must e replaced.
- Leigh
I'm aware of this.
Perhaps you are... perhaps not.

We have no way to assess the expertise of folks who ask questions.
The only information we have to go on is what you expressly provide.

And even that is not relevant to the folks who may retrieve this thread from the archive.

Often information and cautions are intended for other readers as well as the OP.

- Leigh

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 10:04 pm 
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Leigh wrote:
Diverted wrote:
Leigh wrote:
That radio needs a whole lota work before power is applied.
Every one of those waxed paper caps must e replaced.
- Leigh
I'm aware of this.
Perhaps you are... perhaps not.

We have no way to assess the expertise of folks who ask questions.

Kinda harsh on him, aren't you? The guy's been on the board for 4 years and has over 2500 posts, so it would be difficult to believe that he didn't know basic restoration procedures...

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Sun 10, 2017 10:15 pm 
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fifties wrote:
Leigh wrote:
Diverted wrote:
I'm aware of this.
Perhaps you are... perhaps not.
We have no way to assess the expertise of folks who ask questions.
Kinda harsh on him, aren't you? The guy's been on the board for 4 years and has over 2500 posts, so it would be difficult to believe that he didn't know basic restoration procedures...
Nope.

Our community includes collectors as well as restorers.
Some of them have never opened a radio.

Since you chose to delete the balance of my post, which is quite relevant, I'll repeat it:
Leigh wrote:
And even that is not relevant to the folks who may retrieve this thread from the archive.
Often information and cautions are intended for other readers as well as the OP.
- Leigh
- Leigh

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Mon 11, 2017 12:52 am 
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Joined: Jan Thu 24, 2013 11:50 pm
Posts: 2596
Location: Bristol, Rhode Island
Leigh wrote:
And even that is not relevant to the folks who may retrieve this thread from the archive.
Often information and cautions are intended for other readers as well as the OP.
- Leigh
- Leigh[/quote]
Good point. Plenty of folks out there who would just fire it up and hope for the best.


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Mon 11, 2017 3:39 am 
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Joined: Dec Sat 24, 2011 9:17 pm
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Location: Vancouver Island, Canada
Thanks for sharing your grief, and for being a good sport about it all.

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 Post subject: Re: Capacitor explosion
PostPosted: Sep Tue 12, 2017 12:20 am 
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Posts: 8817
Location: Victoria, Australia
One has to be impressed with the "Big bang" & smoke test method. Time and a gain I warn that this can happen when the over exuberant power an unknown set with out rudimentary checks. It is a fact of life that Ecaps left unused for long periods (like years) will loose polarity & can present as a short and go bang: Never should a set be powered with old Ecaps in it (that is all Ecaps). I have even seen oil filled small NP caps exploded.

I appreciate the effort taken in proving my comment in practice. (That's about the third one I have seen this year: Same cause & effect :mrgreen: )

Marc


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Wed 13, 2017 12:53 am 
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Joined: Jun Wed 08, 2011 2:33 am
Posts: 5919
Location: Ohio 45177
In high school electronics we had to assemble an AA5 radio chassis made for training purposes. I built it and was proud, for a short time. I had wired the tubular lytic backwards and it went off like that. So I had a real clenup job as after you built your radio and showed it worked, you had to unbuild it for next years students to start over.


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Wed 13, 2017 1:55 pm 
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The NZ one that I sorted out was the best powder coating job I had seen in ages. They destroyed, in spectacular fashion, an #80 as well...... Unimpressed: Collector, he was told never to power a set like that. However ........

Marc


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Wed 13, 2017 9:55 pm 
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Joined: Dec Mon 08, 2008 8:27 pm
Posts: 7918
Location: alameda,CA
I've blown up my fair share. The latest was a big Grundig that I wound up accidentally shorting out one of the leads going to B+. Sounded like firecrackers going off on the bench. It made a nasty stink too.


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Thu 14, 2017 4:47 pm 
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Posts: 17468
Location: Warner Robins, GA
I blew up one cap well it actually just vented. Had made a power supply for a field coil of 110Vdc and connected one cap to the wrong wire so that AC was applied to the cap. Plugged it in and in short order I saw white smoke or steam.

Did have a cap blow up on me.

Was using an Electronic Futures INC. Program control and trying to figure out why the neon audio level indicators were somewhat dim and was looking at the power supply board. Not 10 seconds after I slid the unit back in the cabinet I heard a slight thunk.

Opened it up to see a 150Vdc cap had lost its top and only some electrolyte had gotten on the board next to the power supply with the innards staying in the plastic shell. !0 seconds longer looking at that board and I'd have had a serious eye problem.

At the tech school during AC class my instructor at one point connected a small electrolytic cap to a variable 0-120Vac supply to show us what it would do. It as expected went bang.


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 Post subject: Re: Capacitor explosion
PostPosted: Sep Fri 15, 2017 4:27 am 
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Joined: Apr Thu 16, 2015 11:04 pm
Posts: 336
Location: Sacramento, California
When I was 17 or so I tried measuring the ohms of a wax paper cap in a Philco 38-12 that I owned. Next time I turned the radio on, my room filled with smoke. My mom told me to let "Don", the local go-to guy for fixing tube radios, handle it. The thing was, the cabinet was in awful shape and I really should have just pulled the tubes and trashed it. But Don got it working. I guess he needed the money. :roll: My high school had auto shop but had cut the electronics program ages ago to save money. Sacramento City College wouldn't let me in their electronics program until I passed intermediate algebra, which I couldn't do due to dyscalculia. Eventually I learned it off the net.


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