JMI AC30/6 NO SOUND

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Travis8
Posts: 51
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Re: JMI AC30/6 NO SOUND

Post by Travis8 »

Stevem wrote: Tue Aug 10, 2021 10:27 am On your 3rd output tube socket from the left it looks to me from your last photo that pin 3 is shorting to pin 2 .
I check It and there is not sorts

Violet to chasis and yellow to chasis around both 0.6 vdc
Last edited by Travis8 on Tue Aug 10, 2021 2:04 pm, edited 1 time in total.
pdf64
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Re: JMI AC30/6 NO SOUND

Post by pdf64 »

Travis8 wrote: Tue Aug 10, 2021 12:49 pm
Stevem wrote: Tue Aug 10, 2021 10:27 am On your 3rd output tube socket from the left it looks to me from your last photo that pin 3 is shorting to pin 2 .
I check It and there is not sorts

Violet to chasis and yellow to chasis around 0.6 vdc
Oh yes, it would be, so many posts!
Travis8 wrote: Mon Aug 09, 2021 5:07 pm Fuse it's okey, pin 8 of rectifier 0.640 vdc
It looks like your GZ34 rectifier may be bad.
Does it get hot?
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!
Travis8
Posts: 51
Joined: Sun Aug 08, 2021 8:47 am

Re: JMI AC30/6 NO SOUND

Post by Travis8 »

It's sovtek 5AR4 I turn on and wait some minutes.

It's light and It's hot
Travis8
Posts: 51
Joined: Sun Aug 08, 2021 8:47 am

Re: JMI AC30/6 NO SOUND

Post by Travis8 »

In summary:


Preamps valves:

Pin 1 to GND: around 0.685 VDC
Pin 6 to GND: around 0.740 VDC

Pin 9 to 4/5: 6.40 ACV

Rectifier:

Pin 8 to GND: 0.640 VDC

Pin 4 to GND: 282 ACV
Pin 6 to GND: 283 ACV

Pin 2 to Pin 8: 5.14 ACV

Choke/Big Cap to GND: around 0.6-0.7 VDC
pdf64
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Re: JMI AC30/6 NO SOUND

Post by pdf64 »

Either the HT fuse, the rectifier valve, or related connection, is bad.
3 1/2 pages to get here, yikes!
https://www.justgiving.com/page/5-in-5-for-charlie This is my step son and his family. He is running 5 marathons in 5 days to support the research into STXBP1, the genetic condition my grandson Charlie has. Please consider supporting him!
Travis8
Posts: 51
Joined: Sun Aug 08, 2021 8:47 am

Re: JMI AC30/6 NO SOUND

Post by Travis8 »

pdf64 wrote: Tue Aug 10, 2021 3:59 pm Either the HT fuse, the rectifier valve, or related connection, is bad.
3 1/2 pages to get here, yikes!
I try it with new fuse, maybe it´s rectifier valve.

How can I check it before buy one?
sluckey
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Re: JMI AC30/6 NO SOUND

Post by sluckey »

Travis8 wrote: Tue Aug 10, 2021 4:02 pm I try it with new fuse, maybe it´s rectifier valve.
How can I check it before buy one?
Take the fuse out. Measure the VDC on pin 8 of the rectifier tube.
Travis8
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Re: JMI AC30/6 NO SOUND

Post by Travis8 »

Around 90-100 mV without fuse
sluckey
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Re: JMI AC30/6 NO SOUND

Post by sluckey »

sluckey wrote: Tue Aug 10, 2021 4:13 pm
Travis8 wrote: Tue Aug 10, 2021 4:02 pm I try it with new fuse, maybe it´s rectifier valve.
How can I check it before buy one?
Take the fuse out. Measure the VDC on pin 8 of the rectifier tube.
Just to be crystal clear, I'm talking about taking out the HT fuse.
Travis8 wrote: Tue Aug 10, 2021 4:24 pm Around 90-100 mV without fuse
If you removed the HT fuse then that rectifier tube is dead.
Travis8
Posts: 51
Joined: Sun Aug 08, 2021 8:47 am

Re: JMI AC30/6 NO SOUND

Post by Travis8 »

sluckey wrote: Tue Aug 10, 2021 4:51 pm
sluckey wrote: Tue Aug 10, 2021 4:13 pm
Travis8 wrote: Tue Aug 10, 2021 4:02 pm I try it with new fuse, maybe it´s rectifier valve.
How can I check it before buy one?
Take the fuse out. Measure the VDC on pin 8 of the rectifier tube.
Just to be crystal clear, I'm talking about taking out the HT fuse.
Travis8 wrote: Tue Aug 10, 2021 4:24 pm Around 90-100 mV without fuse
If you removed the HT fuse then that rectifier tube is dead.
Yes, I remove the fuse and that was the VDC
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Travis8
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Re: JMI AC30/6 NO SOUND

Post by Travis8 »

sluckey wrote: Tue Aug 10, 2021 4:51 pm
sluckey wrote: Tue Aug 10, 2021 4:13 pm
Travis8 wrote: Tue Aug 10, 2021 4:02 pm I try it with new fuse, maybe it´s rectifier valve.
How can I check it before buy one?
Take the fuse out. Measure the VDC on pin 8 of the rectifier tube.
Just to be crystal clear, I'm talking about taking out the HT fuse.
Travis8 wrote: Tue Aug 10, 2021 4:24 pm Around 90-100 mV without fuse
If you removed the HT fuse then that rectifier tube is dead.
I'm going to buy new one (5AR4) and try It.
Travis8
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Joined: Sun Aug 08, 2021 8:47 am

Re: JMI AC30/6 NO SOUND

Post by Travis8 »

sluckey
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Re: JMI AC30/6 NO SOUND

Post by sluckey »

BUY A GZ34 TUBE!!!

And, you don't have to remove the entire fuse holder just to remove the fuse. That's kinda like removing the tube socket to remove a tube!
Travis8
Posts: 51
Joined: Sun Aug 08, 2021 8:47 am

Re: JMI AC30/6 NO SOUND

Post by Travis8 »

sluckey wrote: Tue Aug 10, 2021 5:19 pm BUY A GZ34 TUBE!!!

And, you don't have to remove the entire fuse holder just to remove the fuse. That's kinda like removing the tube socket to remove a tube!
I didn't remove the fuse holder, just the fuse! XD

Ok I will buy one 5AR4 like the ones it's bad
sluckey
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Re: JMI AC30/6 NO SOUND

Post by sluckey »

Travis8 wrote: Tue Aug 10, 2021 5:20 pm I didn't remove the fuse holder, just the fuse! XD
Phew! That's good. My mistake.
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