Oscilloscope and DMM Suggestions !

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JMPGuitars
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Re: Oscilloscope and DMM Suggestions !

Post by JMPGuitars »

Here's another interesting bit. In troubleshooting my amp that had a bad OT, I also tried out a Snubber. After replacing the OT, I scoped the power tube grids (no snubber). Take a look:
SDS00001.png

Then I added the snubber back in, and measured again, everything else the same as the first test:
SDS00002.png

All the knobs were at 50% for both tests. When they say "smooth out your sound" it looks like it's actually true.

Thanks,
Josh
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Re: Oscilloscope and DMM Suggestions !

Post by JMPGuitars »

I figured out a stupid trick that works really well when some caps are harder to tell the difference which side is which...

I turned on a power strip, and kept my bare foot a couple inches from it.

Here's a capacitor without the power strip on:
SDS00007.png
Flipped:
SDS00008.png

Here's that same capacitor with the power strip on:
SDS00005.png
Flipped:
SDS00006.png

That silly trick made testing this pile of caps for my upcoming Tremolo TMB build go much faster:
cap-foils.jpg

I assume this works because the whole point is for us to be an antenna, and this way the antenna has a stronger signal to work with.

Thanks,
Josh
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Re: Oscilloscope and DMM Suggestions !

Post by crgfrench »

I see the difference without the power strip. The results look backwards with it on?
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Re: Oscilloscope and DMM Suggestions !

Post by JMPGuitars »

crgfrench wrote:
Fri 05/29/20 7:56 pm
I see the difference without the power strip. The results look backwards with it on?
For that cap, yes, it was plenty obvious without the power strip. I'm too lazy to go backwards and retest a cap I already marked. ;)

Good eye. Going back to my laziness, they're out of order because I didn't bother to reconnect the sides in the same order (tested the same side with and without the power strip, then switched). One side is obviously correct, and one isn't.
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Re: Oscilloscope and DMM Suggestions !

Post by crgfrench »

JMPGuitars wrote:
Wed 09/19/18 9:34 am
Check out this cute adapter:

_JMP3402.jpg

_JMP3400.jpg

Pretty handy when measuring from a parallel output.
Where can I find those? Just ordered the Siglent SDS1052DL+
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Re: Oscilloscope and DMM Suggestions !

Post by JMPGuitars »

crgfrench wrote:
Fri 06/12/20 8:28 am
Where can I find those? Just ordered the Siglent SDS1052DL+
These are the ones I have: https://www.amazon.com/gp/product/B06Y1HDSCS
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Re: Oscilloscope and DMM Suggestions !

Post by crgfrench »

Siglent 1052 nice addition to my bench!
20200615_121757.jpg
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Re: Oscilloscope and DMM Suggestions !

Post by JMPGuitars »

crgfrench wrote:
Mon 06/15/20 10:58 pm
Siglent 1052 nice addition to my bench!
Very nice! Question: why do you still have a bulb tester, if you have a variac?
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Re: Oscilloscope and DMM Suggestions !

Post by crgfrench »

I use them both for startup, and I made the bulb limiter before I bought the variac. Truly appreciated your earlier advice about the scope, finally decided on 50MHz 2 channel as it's overkill for tube amp building, really 20MHz is more than enough... I do love that web control on yours but I def don't need 4 channels and couldn't justify paying twice as much to get the web control version.
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Re: Oscilloscope and DMM Suggestions !

Post by JMPGuitars »

crgfrench wrote:
Tue 06/16/20 1:44 pm
I use them both for startup, and I made the bulb limiter before I bought the variac. Truly appreciated your earlier advice about the scope, finally decided on 50MHz 2 channel as it's overkill for tube amp building, really 20MHz is more than enough... I do love that web control on yours but I def don't need 4 channels and couldn't justify paying twice as much to get the web control version.
No problem. Not that you need it, but I believe there's at least a bandwidth hack for your scope.

I also made a bulb limiter before I got a variac. But it lives in the basement now since it's redundant, and bench real estate is highly competitive. ;)
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