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February 18, 2019, 02:25:24 am

Recent Posts

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1
General Discussion / Re: Full preamp - what features?
« Last post by Kermit on Yesterday at 06:03:43 pm »
Does anyone use balance controls?  I’ve had a couple amps with them and never used them.  Was looking at some tube amps by other mfrs, and was surprised to see balance knobs.

What’s the use case?
2
Smash / Re: Smash build with a few wonky resistance measurements
« Last post by Paul Birkeland on Yesterday at 03:49:10 pm »
Pull it back off an check again.

I'll reiterate that the solder tab, screws, and L-bracket touch the chassis, and terminal 6 touches the chassis, ergo the solder tab should show 0 ohms.  Do the L-brackets themselves show 0 ohms?  What is the DC resistance between the L-200 metal tab and the chassis when it's mounted?

3
Crack / Re: How hot does the Crack get?
« Last post by Paul Birkeland on Yesterday at 03:47:50 pm »
I don't think you'll have any problems, provided you use the rubber feet of course.
4
Crack / How hot does the Crack get?
« Last post by kill_surf_city on Yesterday at 03:26:08 pm »
I'm asking because I'm sealing the chassis I painted with semi-gloss Polycrylic. Does the Crack get hot enough to melt/damage this?
5
Smash / Re: Smash build with a few wonky resistance measurements
« Last post by FS on Yesterday at 11:52:09 am »
When I removed the PCB from the chassis, the mica insulator pad looked well positioned to prevent the L-200 touching the chassis. I have reinstalled this, with the mica covering the full length and width of the L-200 metal tab. The shoulder washer is properly set.
I still have the same issue. The screw and the nut show OL, the L-200 tab shows 360 Ohms. Shall I insulate the mica from the cassis with electrical tape underneath, and another piece of electrical tape over the shoulder washer?
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Smash / Re: Smash build with a few wonky resistance measurements
« Last post by Paul Birkeland on Yesterday at 11:09:56 am »
Yeah, so I'd review the mounting instructions for the heatsink mounting kit.  The metal tab of the L-200 was touching the chassis and causing these issues.  This can happen if the shoulder washer isn't properly installed onto the metal tab of the L200, or if the mica insulator is well out of position.
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Smash / Re: Smash build with a few wonky resistance measurements
« Last post by FS on Yesterday at 11:08:03 am »
I have unscrewed the PCB and the L-200 from the chassis. lifted them up to make sure there is no contact. I remeasured and got the following resistance values:
0 at terminal 25, OL at 26, OL at 27, 0 at 28, OL at 29, 0 at 30.
On the PCB, I got OL on the soldering tab, IN, GND, and OUT.
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Smash / Re: Smash build with a few wonky resistance measurements
« Last post by Paul Birkeland on Yesterday at 10:37:41 am »
Can you unscrew the PCB and the L-200 from the chassis plate, lift them off it, then remeasure?
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Smash / Re: Smash build with a few wonky resistance measurements
« Last post by FS on Yesterday at 09:57:18 am »
I am using 6U as the reference. Checking these measurements again, I get 360 Ohms at 26, A1, and C1, OL at 27, 360 at the "GND" of the PC board, OL at the "In" of the PCB.  And yes, I confirm that there is 360 Ohms between "GND" and "OUT" of the PCB.
6U shows as grounded - I measured 0 Ohms against other grounded terminals.
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Smash / Re: Smash build with a few wonky resistance measurements
« Last post by Paul Birkeland on Yesterday at 09:22:40 am »
Resistance reading at the "GND" pad show 360 Ohms on the black wire end, OL on the tab.
OL at the ground tab on the PC board?  The ground tab is grounded to the chassis.  If you see "OL" there, then your chassis isn't grounded. This is a contradiction since 6U touches the chassis and the grounding lug touches the chassis.  You are using 6U as your ground reference correct?

There is 360 ohms (approximately) of resistance between "OUT" and "GND" on the PC board, can you verify this measurement? 
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