How to test a Bi-Directional Triode Thyristor

In summary: If the fuse is not blown, I'd suspect something wrong on the other side of the transformer.The block diagram will be useful in tracking it down.
  • #106
Planobilly said:
The symbol for the triac did not look like anything I had seen before, nor have I find found one just like it elsewhere. Perhaps it is normal and just not known to me.
Meh,
i'd call it an Andy Warhol Edit oops make that Salvador Dali - triac.
 
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  • #107
Planobilly said:
Someone would need to put me up to speed on how DC could be used to control a transformer in the first place.
When you're ready to go there start a search on Magnetic Amplifier. Dont worry this isn't one.

Planobilly said:
I got the idea from some post that the triac (or what ever was controlling the triac) was not only controlling the timing of the AC but was controlling the voltage to the transformer. I have no idea how that could be possible.

When you chop out part of the wave you are controlling the voltage.
Shaded are is where conduction is going on
carver13.jpg

actually, conduction into the caps stops when they've charged , before zero crossing.
Mr Carver's artist was not an electronics guy.
Point is, when there's no conduction, before triac gets fired, there's no voltage applied to the transformer.
That is called "Phase Control ". Your SCR manual has a chapter on it.

Remember "average value" is the area under the curve ?
Firing triac earlier or later in the cycle varies the shaded area. So the average value of voltage is controlled.
This is just a lamp dimmer with electronically adjusted knob, the knob being current through the optocoupler.

Remember - Triac is a just a snap action switch , a very fast one like only a few microseconds to turn on .
Gate current turns it on.
Remove gate current and it stays turned on until current through it falls to almost zero. That happens at or near sinewave zero crossing.
 
  • #108
Thanks Jim,

I went to bed last night thinking about this. I then remembered what the phase angle could be so I now see how the voltage is reduced.

Thanks,

Billy
 
  • #109
Planobilly said:
I went to bed last night thinking about this.

Our mind settles a lot of things in our sleep. And in the shower, for me ...

Congratulations - we learn fastest by simultaneous doing & studying, don't we ?
 
  • #111
  • #112
You know you are dealing with a strange amp when Salvador Dali's name gets mixed up in the conversation...lol
 
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  • #113
TomG cleaned up the schematic.
He sent me a copy
But i don't know how to post it, it's a 3.2meg jpg.
Photobucket didn't work , shrunk it down to illegible.

old jim
 
  • #114
Hi Jim,

Perhaps there is no way to post such a large file here on the forum.

I also received a schematic from Mesa Boogie for the Nomad 45 guitar amp via email that I do not know how to post here. Actually there is no new information on the schematic except for a mod to the amp which we really don't need.

Still do not have the parts yet for the Carver or the Mesa. I guess if one had a 10,000 sq foot room filled with parts there would always be something missing...LOL

I did not grow up in this internet world so I am always having issues trying to post stuff. We all need a couple of nine year old kids to show us the way..!..LOL

Cheers,

Billy
 
  • #115
Jim, can your large image be cropped somewhat, and then uploaded? I think the upload limit is around 3 MB
 
  • #116
NascentOxygen said:
Jim, can your large image be cropped somewhat, and then uploaded? I think the upload limit is around 3 MB
Dang. I just logged into catch up on this thread and was going to suggest just that. You're putting out some fairly strong bran waves I guess. :bugeye:
 
  • #117
jim hardy said:
TomG cleaned up the schematic.
He sent me a copy
But i don't know how to post it, it's a 3.2meg jpg.
Photobucket didn't work , shrunk it down to illegible.

old jim

It's a PDF, using ZIP compression internally. I didn't use JPG because that loses details during compression.

I'll try some tight cropping and see what happens.
 
  • #118
Here it is cropped and resized to 50%
still about two screens wide
further reduction is too small to see

and it gets autoshrunk (by forum software i guess) to one screen wide , which is a good thing, keeps it from wrecking the thread - see feedback forums thread on that subject.Image removed to save disk space
 
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  • #119
Tom.G said:
It's a PDF, using ZIP compression internally. I didn't use JPG because that loses details during compression.

Yes i was able to "copy image" and paste into paint, save as jpg... Sorry for the mis-information.
 
  • #120
It might be better to leave it as a thumbnail, not display it inside the post, then readers (those who want to see the detail) can open the image in a separate browser tab and magnify it to heart's content.
 
  • #121
NascentOxygen said:
It might be better to leave it as a thumbnail, not display it inside the post, then readers (those who want to see the detail) can open the image in a separate browser tab and magnify it to heart's content.
What a good idea !
I'll remove that last post and try it.
Here's the cropped one, 2.96 mb. Thumbnail only.
Edit - removed unneeded image to save disk

I'll go remove that last one now, to save 3 megs of magnetized iron oxide .

Hmmmmm looks like it gets downsized to 960 pixels anyway
shrunk from 2.96 megs to 207.7K during "Upload"
 
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  • #122
That works well.

I can download the file and work with it as I like.

Thanks,

Billy
 
  • #123
Members who don't use a tablet could be forgiven for assuming that when using a tablet we can just keep spreading the image to magnify it almost without limit. Not so, at least not on my Android 4.4

Well before a small image like this schematic becomes readable, the PF page headers MENU, MY PF, INBOX, etc., enlarge and move down to cover over the viewing area!
:H:H:H

I must instead open the pic in its own browser window.
 
  • #124
Just to clarify the situation a bit:
NascentOxygen said:
It might be better to leave it as a thumbnail, not display it inside the post, then readers (those who want to see the detail) can open the image in a separate browser tab and magnify it to heart's content.
That would be fine, even tablets have PDF readers. HOWEVER I can't find a way to post the full size PDF. Compressing and zooming doesn't work because the readability/detail is lost in the compression, and zooming something that isn't there doesn't help.

The original page size of the image was roughly 8.5x11 but if the resolution is taken below about 360 DPI the small printing and details, like whether a transistor is NPN or PNP, are lost.

EDIT: You guys are fast! The time it took me to write this, there were four more posts.
 
  • #125
Tom.G said:
I can't find a way to post the full size PDF. Compressing and zooming doesn't work because the readability/detail is lost in the compression, and zooming something that isn't there doesn't help.
Correct, but you're running up against our 3MB attachment limit? If you need to make available a file larger than that limit, the only way is to store it on an outside host (of which there are many available for free) and to include the URL in your PF post.

The big drawback in using a hosting site is that at some future stage it's likely that either you or the host will drop the file, and then the PF thread of which it was an integral part becomes next to worthless.
 
  • #126
Planobilly said:
That works well.

I can download the file and work with it as I like.

Thanks,

Billy

It's not as clear as Tom G's rendition
i'll email that to you
 
  • #127
Thanks Jim

I assume there is some site somewhere that PDF's can be stored on that anyone can access. I am looking now.
 
  • #130
NascentOxygen said:
Correct, but you're running up against our 3MB attachment limit?
I must have missed the 3MB limit. All I saw was image limit of some pixel count. If your file size limit is 3MB I'll see what tricks I can figure out to get there.
 
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  • #132
If the upload is successful at 2.998MB, here is the enhanced Carver M1 schematic in PDF format.
 

Attachments

  • Carver M-1 Pg16 360dpi cropped.pdf
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  • #133
Tom.G said:
If the upload is successful at 2.998MB, here is the enhanced Carver M1 schematic in PDF format.

Works great - You 'da Man !
 
  • #134
  • #135
I guess the only thing remaining for this side issue is to get a link in or near the OP, rather than buried 7 pages deep.
 
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  • #136
Now if we could just get schematics that actually tell us what we want to know!...lol

I am off to bed.

Cheers,

Billy
 
  • #137
If only!

All my Wizard contacts have either died or left town.
 
  • #138
Tom.G said:
I guess the only thing remaining for this side issue is to get a link in or near the OP, rather than buried 7 pages deep.
I have added a link in the OP. Which old links/attachments should now be removed?
 
  • #139
i cleared out mine, hope i got 'em all.
 
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  • #140
I will be out till this afternoon.

Billy
 

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