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Unread 01-05-2014, 10:29 AM   #1 (permalink)
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Standy switch rating for JCA2112RC please explain

The standby switch in my Jet City JCA2112RC seems to have crapped out. It felt like it was stuck when I tried to turn it off, and didn't feel like the normal click. The amp gets no sound now no matter what (replaced all the tubes and kept trying, tested the speaker using another head).

The standby toggle is a DPDT being used as a DPST. One side of it will not turn on, but the other will (tested with the continuity function on my VOM).

So here's my question: can I use a Carling 0822R switch to replace it? I have one that came as the power toggle on my Fender Blues Jr (I replaced it with a BillM mod off-standby-on toggle switch; the original switch is a DPST that was used on the mains).

The Jet City switch has an odd amperage rating on it, not only because the numbers are so high, but also because the 250V figure is not double the 125V. It says "15A 125V, 20A 250V."

The Carling switch from the Fender (and all of the DPST standby toggle replacement switches at AntiqueElectronicSupply) is rated "3A 250VAC, 6A 125VAC."

The Jet City amp is the combo/reverb version of the JCA20. Solid state rectifier. Two heavy red wires coming off the PT go to this standby switch, two slightly thinner red wires go to the PCB so I assume this switch is before the rectifier.

So do I really need a switch that's rated (or labeled at least) for 20A 250V? Somehow the Carling 3A 250V, 6A 125V switch gives me more confidence.
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Unread 01-05-2014, 11:24 AM   #2 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

Yes, you need a properly rated switch.
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Unread 01-05-2014, 11:50 AM   #3 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

Nuts. I don't seem to see any available like that. Spade terminals preferably. I emailed Jet City customer service but I'm not sure what kind of repair network they have since these are manufactured overseas.

Thanks for the response, Micky; you're knowledge is well valued here.
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Unread 01-05-2014, 02:15 PM   #4 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

A Carlings 2GK51-73 DPST on-off, according to the Carlings data sheet, is rated for 10A 250VAC, 15A 125VAC - it's only $4.89 -- is that heavy enough??

I find it hard to believe that a $300.00 amp would need a $45.98 toggle switch (Honeywell 32NT91-2 or -8 rated at 20A 277VAC or 250VDC).

A Honeywell 12TS95-3 costs only $11.70 and is rated 10A 277VAC, 20A 125VAC per the Mauser listing, and the 12TS95-2 (DPST instead of DPDT) is only $9.80
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Unread 01-05-2014, 02:44 PM   #5 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

OK maybe it's academic. Jet City customer service just replied by email (on a Sunday afternoon) offering to mail me a replacement switch.

Thanks, though, Micky, you kept me from temporarily using the wrong switch.

And if anybody's listening, the Jet City amp was constructed by soldering the wires onto quick-connect (spade) terminals on the standby switch, instead of using crimp-spade connectors, with shrink-wrap over each connection. the mains power switch has a combination of quick-connect (with clear shrink-wrap) and soldered (black shrink-wrap) connections.
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Unread 01-05-2014, 02:51 PM   #6 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

Sorry I didn't get to this sooner. but glad you got it sorted.
This is the kind of thing people need to see, not only to prevent damage to their equipment but to prevent injury to themselves or others. Generally on most schematics, the hi-voltage or special order parts are noted, so that the exact replacement can be fitted. With a standby switch such as this, it is critical to replace with a same-rated component, especially when switching high voltage.

The other thing is, people shouldn't be afraid to contact the manufacturer. It generally works out well.
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Unread 01-05-2014, 03:54 PM   #7 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

Please, you don't owe any apologies for answering my question within an hour of starting the thread.

For the record Jet City's customer service has been exceptional, and they quickly answer any question I've emailed about my JCA2112RC or my Picovalve.
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Unread 01-06-2014, 09:06 PM   #8 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

Quote:
Originally Posted by BobV View Post
Please, you don't owe any apologies for answering my question within an hour of starting the thread.

For the record Jet City's customer service has been exceptional, and they quickly answer any question I've emailed about my JCA2112RC or my Picovalve.
I actually 2nd their customer service - they sent me a new switch within days after I emailed them a few years ago...I really liked my JCA20H...
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Unread 01-11-2014, 09:32 PM   #9 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

Replacement switch was a nice Carling 10A 250VAC toggle. Received it in the mail today and soldered it in with no problems.

For the record, a 5751 in V2 and 12AT7 in V4 (PI) put the distortion within a reasonable range of control.
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Unread 01-18-2014, 06:59 PM   #10 (permalink)
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Re: Standy switch rating for JCA2112RC please explain

Since intermittent problems are so hard to diagnose, I took apart the old standby switch. there were some loose shards of plastic floating around inside that must have jammed the metal contacts. The actuator broke just enough to shower pieces into the works, but not enough for it to come loose from the end of the toggle.

So I'm glad to know for sure that this switch was the problem. Mind you, it doesn't sound like a Marshall, but it's really not supposed to anyway.
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