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Author Topic: Spider III 75w died  (Read 3720 times)

malabarspyder

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Spider III 75w died
« on: February 06, 2010, 03:38:25 PM »

Amp is totally dead no display no hum no nothing.   :P

Transformer primary has 125v on the outside connectors. Center connector seems to be open. Reads 0v to either outside terminal. Which seems a little odd.

Transformer secondaries are all 0v.   :trouble

The transformer itself says On-Tech 1X-7640-02H0

I googled that and found nothing.

Any idears?

Thanks guys!
 ::)


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J M Fahey

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Re: Spider III 75w died
« Reply #1 on: February 06, 2010, 06:26:00 PM »

Hi Malabar.
Your transformer seems to be open, maybe a small hidden fuse in the winding.
With the amp disconnected from mains (double check that) measure resistance across all windings.
Draw a simple schematic showing them and the resistance measurements.
Thanks.
PD: I seem to recall that somebody had a problem similar to yours, slit open the outer insulation paper and found, skin-deep, an open thermal fuse, but i'm not quite sure.
Measure yours and we'll see.
In the worst case, you can find a new replacement transformer at a reasonable price.
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malabarspyder

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Re: Spider III 75w died
« Reply #2 on: February 07, 2010, 10:49:01 PM »

Hi Malabar.
Your transformer seems to be open, maybe a small hidden fuse in the winding.
With the amp disconnected from mains (double check that) measure resistance across all windings.
Draw a simple schematic showing them and the resistance measurements.
Thanks.
PD: I seem to recall that somebody had a problem similar to yours, slit open the outer insulation paper and found, skin-deep, an open thermal fuse, but i'm not quite sure.
Measure yours and we'll see.
In the worst case, you can find a new replacement transformer at a reasonable price.

Thank You for the reply, I will do some homework and send details. The Xformer plastic is melted on the secondary side- very suspicious.  But Ill slit the paper and see whats under it..

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J M Fahey

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Re: Spider III 75w died
« Reply #3 on: February 09, 2010, 10:27:51 AM »

Even before slitting anything, what are the winding resistance measurements?
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malabarspyder

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Re: Spider III 75w died
« Reply #4 on: February 09, 2010, 05:33:49 PM »

Even before slitting anything, what are the winding resistance measurements?

I looked closer and the plastic is badly melted so even IF there is a fuse- I wanna replace this xformer. I did find an authorized service center I can buy one at - for $40. Which seems about twice what a chinese low-current xformer SHOULD cost but I'll gladly pay if I can get this thing rockin
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malabarspyder

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Re: Spider III 75w died
« Reply #5 on: February 10, 2010, 12:19:32 PM »

Even before slitting anything, what are the winding resistance measurements?

I looked closer and the plastic is badly melted so even IF there is a fuse- I wanna replace this xformer. I did find an authorized service center I can buy one at - for $40. Which seems about twice what a chinese low-current xformer SHOULD cost but I'll gladly pay if I can get this thing rockin

Im seeing about 4 ohm on 2 of the primary side- but the two outer wires (which is where I measure 110vac) are totally OPEN. So one of the wires on the primary is open to the other 2.

On the secondaries Im seeing various values- without a schematic its hard to know whats what. But its like 0.6, 0.9, 1.5 for example
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J M Fahey

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Re: Spider III 75w died
« Reply #6 on: February 10, 2010, 05:34:16 PM »

Ok, those are consistent measurements. In an SS transformer, the thinnest wires are the primary ones, and on a very severe overload can act as fuses.
Of course the transformer gets open and unusable.
Even if the secondary didn't actually melt (good or your home would be in fire) it overheated so much as to melt plastic *and* compromise the enamel's integrity, so even if it had continuity on the primary, I would not use it.
If yiu can get a direct replacement for $40, good.
If not, I think somebody had the same problem here and posted some supplier.
There is also a member of this forum, I just don't remember his name now, who usually has various transformer, good quality, interesting price.
Search for it or maybe somebody with his brain less damaged than mine does remember better.
I seem to remember that your amp had a chipamp output.
Good because it simplifies service.
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malabarspyder

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Re: Spider III 75w died
« Reply #7 on: February 11, 2010, 02:04:08 PM »

Ok, those are consistent measurements. In an SS transformer, the thinnest wires are the primary ones, and on a very severe overload can act as fuses.
Of course the transformer gets open and unusable.
Even if the secondary didn't actually melt (good or your home would be in fire) it overheated so much as to melt plastic *and* compromise the enamel's integrity, so even if it had continuity on the primary, I would not use it.
If yiu can get a direct replacement for $40, good.
If not, I think somebody had the same problem here and posted some supplier.
There is also a member of this forum, I just don't remember his name now, who usually has various transformer, good quality, interesting price.
Search for it or maybe somebody with his brain less damaged than mine does remember better.
I seem to remember that your amp had a chipamp output.
Good because it simplifies service.

Thank You sir- placed order today, I will post results. Which hopefully will be POSITIVE!
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schaltung

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Re: Spider III 75w died
« Reply #8 on: March 17, 2010, 08:58:56 PM »

Hi,

Where did you order the transformer from? What are the specs of the transformer anyway?

I have a very similar case to yours on my Spider iii 75w.

I shut down the amp after I smelled burned metal. After I opened it, I sensed the same smell on the transformer.... and the wires seem shiny near the transformer, which i think is a sign of overheating.

40 bucks seems reasonable for retail
cheers
4
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