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Amp Camp Amp Kit V1.6
Amp Camp Amp Kit V1.6
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Old 14th January 2020, 01:14 AM   #631
Salas is offline Salas  Greece
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Amp Camp Amp Kit V1.6
Quote:
Originally Posted by Porter15 View Post
My high school son and I were congratulating each other on our pretty solder joints...then one of us soldered Q4 LK170 in “backward”—drain and gate reversed. After an ugly fix, I’m worried we fried the jfet.

Is there a way with a multimeter to see if the in situ, correctly oriented, but abused jfet Q4 is still alive? I would prefer to pause, get a replacement part, rather than finish the build to find one dead channel.

Please help as my kid is dying to hear Slipknot and The Offspring through a Pass circuit. On second thought...
Measure RDS. Its resistance between drain and source pins with power OFF. Circa 30 Ohm for a medium IDSS K170 is a healthy indication. Certainly not a short or an open indication or some kΩ for any IDSS. Compare with the K170 on the other channel.
No need to remove the part from the board in most cases for measuring that parameter.
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Old 14th January 2020, 06:45 AM   #632
RafaPolit is offline RafaPolit  Ecuador
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Quote:
Originally Posted by Porter15 View Post
My high school son and I were congratulating each other on our pretty solder joints...then one of us soldered Q4 LK170 in “backward”—drain and gate reversed. After an ugly fix, I’m worried we fried the jfet.

Is there a way with a multimeter to see if the in situ, correctly oriented, but abused jfet Q4 is still alive? I would prefer to pause, get a replacement part, rather than finish the build to find one dead channel.

Please help as my kid is dying to hear Slipknot and The Offspring through a Pass circuit. On second thought...
I did EXACTLY the same thing! Of course, not with a simple cap or replaceable part, with the unobtanium (then, now just pricey! ) part.

Luckily, it was perfect, no damage done even if the legs ended up crooked and the poor guy was heated severely during de-solerding.

I hope yours is as resilient as mine was!
Rafa.
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Old 14th January 2020, 07:23 AM   #633
Porter15 is offline Porter15  United States
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Salas and Rafa
Thank you for your helpful and encouraging replies. Salas, resistance measurement between drain and source in abused jfet approximately the same as jfet on other board: ~35 ohms. Thank you for your help—feel more confident we’ll have a working amp soon.
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Old 14th January 2020, 11:09 AM   #634
ZACC is offline ZACC  Sweden
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I'm doing a 4-way active build with Two (2 pcs) Firstwatt M2's. One on midbass (2 x 15") and one on midrange (2 x 8"). Sub (2 x 21") will be powered by a Crown XLS. As tweeter I will use Beyma TPL-150B.

Would a Amp Camp Amp be suitable for the TPL's? Total system sensitivity will be around 100dB so I guess the power of the ACA is enough.
The TPL also seems to be an easy load, see pic.




TPL impedance.PNG
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Old Today, 04:47 PM   #635
eyspot is online now eyspot  Germany
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Help! Suddenly no sound out of one Channel. All voltage Checks are OK. Items is also warming up. Any idea?
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