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Old 16th April 2012, 06:46 AM   #1
jeff517 is offline jeff517  United States
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Question Don't know where to start...

Just finished putting together my first project. K16 LS kit from tube depot. It didn't catch on fire or anything when I plugged it in and turned it on. Great news for me.just doesn't make much noise (sound) Built it just how the instructions say. Sounds like headphones turned up full volume. Going over it everything looks the way it should. double triple checked... where dou you think I should start looking? not much I know but, I'm a newb.
K16LS w tone control
klipsch heresy speakers (efficient enough?)

just need a direction to start in.
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Old 16th April 2012, 12:38 PM   #2
DF96 is offline DF96  England
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Measure DC voltages. Compare with what they should be.
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Old 16th April 2012, 02:19 PM   #3
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Can you post a schematic? That will go a long way toward a solution......

Here are a couple of threads that might be of interest:

Review of New S-5 K-16LS Kit

Edcor OPT in S5 Electronics K-16LS kit?

EDIT: If this is the schematic, carefully measure your B+ voltages (DC voltage across C10 and C11) and the DC voltages across R12 and R25 to start.
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File Type: jpg k-16ls - schematic.jpg (89.3 KB, 267 views)

Last edited by boywonder; 16th April 2012 at 02:32 PM.
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Old 16th April 2012, 02:21 PM   #4
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Check your wiring again, make sure all the tubes have proper voltage, you might have one disconnected.
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Old 16th April 2012, 02:35 PM   #5
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check the hi-voltage first,it should be alround 220. then check the pin 5 and pin 6 of 6005. should be over 200v. then check pin 2, should be alround 18v(maybe?if it is running in classAB1)
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Old 16th April 2012, 02:37 PM   #6
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try check the pin 2 of 6005, should be around 18v
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Old 21st April 2012, 04:06 PM   #7
jeff517 is offline jeff517  United States
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Checked voltages at suggested points and they are C10 - 233 V, C11 - 228 V, C7 - 220V, R12 and 25 - 13V. On schematic C10 and 11 should be 250V. C7 250V also. R12 and 25 I don't know. When I touch the Volume pot I get lots of hum. Ground issue? Going to check all connections again. Third time. What do ya'll think?
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Old 21st April 2012, 04:10 PM   #8
jeff517 is offline jeff517  United States
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I'll check pins on 6005 next. Interesting... I'm not going to let this go.
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Old 21st April 2012, 04:33 PM   #9
Enzo is offline Enzo  United States
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If touching the volume control pins makes a lot of hum, that means everything AFTER the volume control is working. It amplifes the hum from your finger. The amplifier doesn;t know that it isn't music, it just amplifies what it gets. In fact, here in the shop when I need a quick go/no-go test signal, I usually do just that, touch the signal path with something to inject a hum signal.]

The problem with checking and checking and checking is that it LOOKS right to you as it sits. If you are overlooking some error or omission, you are likely looking at it the same way each time through. Others have sugested voltage readings, and that is good, because it doesn't matter why it got this way, good troubleshooting will find the problem. Then we can repair it or correct it, and perhaps do a forehead slap.

I once had a guy send me his build that wouldn;t work. He had done very nice work, it looked flawless. The problem was not readily apparent, but at one end of the part board, he had swapped places with a cap and a resistor. Didn;t look out of place, and they were neatly soldered in, but they were wrong. He had spent hours looking for that and was blind to it.

Your problem then could be some misplaced parts, or a missing connection, rather than a "bad" conection. I saw an amp once very neatly wired up, but one tube socket had all the wires off one pin clockwise. I guess if one is convinced that pin 1 is pin 2, then it is easy to think the next pin over is pin 3.

ANother common error is misreading resistor color codes. People install a 470 ohm resistor instead of a 470k resistor. And if you do that for a grid return resistor, well, you won;t get much sound output.

If the boywonder schematic is for your amp, and touching the volume control makes hum, that leaves precious little to be bad. An unconnected input cap, miswired jack.

Looking at that schematic, I see the input connections. In my experience, usually the ground connetion is drawn below the signal connection. This is drawn in reverse. If you soldered the input cap C1 to the ground terminal of the jack, no sound.

And both channels affected?
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Old 21st April 2012, 05:39 PM   #10
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Quote:
Originally Posted by jeff517 View Post
Checked voltages at suggested points and they are C10 - 233 V, C11 - 228 V, C7 - 220V, R12 and 25 - 13V. On schematic C10 and 11 should be 250V. C7 250V also. R12 and 25 I don't know. When I touch the Volume pot I get lots of hum. Ground issue? Going to check all connections again. Third time. What do ya'll think?
Jeff: The voltages at C10, C11 and C7 are reasonable. What are you getting across R12 and R25? That'll tell you how much current each tube is drawing.

The voltage drop across R3, R4, and R15, R16 would also be helpful.

Yes, your volume pot has a ground issue.....does the volume change when you turn the pot?

Last edited by boywonder; 21st April 2012 at 05:43 PM.
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