Bottlehead Forum
Bottlehead Kits => Mainline => Topic started by: jagmeetbatth on November 26, 2023, 03:31:37 PM
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hello
i am building amplifier using your kit and i am not getting leds on one of c4s board
the other board have leds light up
OB voltage with working c4s =around 220
OB voltage no leds c4s= 300 plus
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i am building amplifier using your kit and i am not getting leds on one of c4s board
Is this one of our kits? If so, which one?
If not, you'll have to describe what you're building to get an idea of what might be going on. Based on the limited information available in this post, the center joint of Q2 isn't always easily soldered, and this can create the issue you describe. Whatever you do, do not apply a ton of extra heat and solder to the LED solder pads themselves, as this can damage the LEDs.
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its one of your kit .someone gave it to me to build for them
in photo the one on left side c4 board doesnt light up led and voltage at OB is diffent(higher) than other board.
there is sound output but very quiet in headphones.
the right side c4 board two led light up
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OK, this is a Mainline kit, so I have moved your thread to that section of the forum.
Can you describe what's going on under the R4 resistors on the center C4S board?
On the center board, what are the Kreg and +reg voltages on each side?
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i just marked red r4 resister with marker as they were missing but later found and soldered.
voltrage A side +reg=306v
kREG 1.2v
B side +reg 218v
Kreg 4.18v
DC
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It would help to see the bottom of the high current C4S board on the problematic side.
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attached
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Pin 1 on the center 9 pin socket should have a connection.
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thank you done b1 to 16L
both boards light up on a side led and sound output is very very quiet
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thank you done b1 to 16L
both boards light up on a side led and sound output is very very quiet
You need to measure the voltages before using the amplifier.
You also need to set the bias before using the amplifier.
Failure to do this is using an amplifier that may not be working properly, and there can be some unfortunate consequences...
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adjusting the bias .
voltage is stuck at 215v on 30 and 20 pin
doesnt change anything when i adjust potentio
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The center C4S board has OA and OB pads, could you provide DC voltage measurements on each of them?
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ob 7.5v
oa 5.6v
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On the side where you were missing the red wire, a new 431 regulator will likely be required to get the regulated voltage to drop down.
Can you post a picture of the bottom of the center PC board up front?
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here?
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Can you let me know what soldering products were used on this? There seems to be a ton of flux all over everything and that's rather unusual. Also there appears to be two wires going to pin 1 of the 12AU7 socket, and I'm not sure why that is either.
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they wer both going to 19L i removed one now .too muct flux shouldnt be an issue.
any more areas i need to check .
still stuck at 215v on 20 and 30
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Does the voltage at the "O" terminals on the center board change if you attempt to adjust the trim pots either way?
Depending on the flux used, flux can indeed cause some substantial issues.
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yes it does change at oa and ob when i adjust trims
LM431? faulty
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If the LM431 is faulty, your Breg voltages would be incorrect, are those incorrect?
What voltage ranges are you able to get on the OA/OB terminals on the center board while rotating the trim pots?
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ob min 4.6v max 5.7
OA min 4.6v max 5.7
+reg 216v both A and B side (no change with potentio)
20L and 30L pin also 216v
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As best as I can tell, neither one of your 6C45P tubes is really drawing any current. This can happen if they aren't receiving heater voltages (if they aren't lighting up), from poor solder joints (especially the center leg of the MJE5731A on the B side of the C4S board in this case), or possibly having the R1 resistors on the high current C4S boards swapped.
The lower than expected Kreg voltages that you have tell us that the 12AU7 is tacking up the slack for the lack of current drawn by the 6C45P tubes, so it's unlikely that you have to be concerned with the A side of each high current C4S board, and likewise the outer portions of the center C4S board that hold the high voltage regulators seem to be operating happily.
It is incredibly common for builders to make mistakes on that center PC board, especially forgetting to fold over the trim pot leads to make it into a variable resistor, but I don't see any obvious errors on yours.
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i can see both tubes lights up when turned on.
i checked potentio have folded legs also same as in diagram.
there are 4 small leds on each board ony two on A side lights up
on the b side no led lights up
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Yes, the LEDs not lighting up are consistent with the 6C45 tubes not drawing any current.
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i got lm431 replaced didnt make any difference i double checked all wirings and solder joints everything looks ok.all tubes get warm middle one hotter than other two.still no leds lighting on B side of small boards
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Could you verify the resistor values connecting to pin 7 on each 6C45P socket?
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90ohm
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Could I see both sides of the 6-7-8 terminal strip?
I'm also still very curious about the soldering products used, as it looks like some of the nuts in the kit are already corroding, which is a bit odd.
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we are repair shop.
customer mentioned they have unfinished project from few years.we agreed to complete it for them.
rust is there maybe its old kit
we used same products we use to repair laptops.we do reball bga chips with this flux no issues so far
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some more
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more
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If the kit was really old before the HLMP-6000 diodes were installed, they are hygroscopic and can absorb enough moisture over time that damage can occur when soldering. It may be worth a shot to replace the LEDs on the B side of each C4S board just to rule that out. Also triple check that the R1 resistors on the high current C4S boards are the correct values.
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diode range on all 8 leds are same.
can you please mention on photo which r1 resister needed triple check?
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These.
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bside 50ohm
a side 37 measuring
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If you remove the 12AU7 and run the amp with just the 6C45PI tubes, do the OB voltages go up or down?
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with 12AU7 removed ob voltages stays 330v.
with 12AU7 installed i push power on OB on middle boards starts to rise from 3 to 5 volts and Ob on side two board starts to drop 330 to 245volts and stays at 245v
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Here are some circled cold solder joints on one of the boards in the amp. These kinds of soldering issues are a common cause for problems like this when building a kit.
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i think they are well soldered i checked the continuity.because pads are running underneath it.
anythinng else othher than drysolder joints or bad solodering products.
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As I mentioned before, the 6C45P tubes are refusing to draw current. I posted some situations that could occur to cause that to happen. Bad solder joints would be high on the list. I would expect that some of those joints that I circled are so poorly flowed that the flux is residing between the through hole and the component lead.
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I just saved myself $600 yesterday by reflowing about 20 solder pads that looked perfect in the fuel injection control module on my truck, rather than replacing it with new or rebuilt one. Went from no cold start to firing right up on the first try. A reflow very often solves the problem.
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ok will reflow all three boards
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reflowed all three boards.connected back again
no change.
what is supposed to bring down pin 20 and 30 to 145 .
is it something in circuit not working
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what is supposed to bring down pin 20 and 30 to 145 .
When the 6C45P tubes conduct, they will pull that voltage down. The high voltage at OA/OB on the center PC board and the high voltage on the OB terminals on the high current C4S boards tell us that the 6C45P tubes are unable to do so.
One thing that is common to both tubes is the ground connection from the attenuator to the ground bus line. It's certainly possible that the black wire leaving the attenuator isn't well soldered on one end.
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Since this kit uses the Teflon insulated wire it is also worth checking for breaks in the wire just inside the insulation where the wire might have been nicked when it was stripped. We see that issue every so often.
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i havetested connectectivity of all ground wires and to all point where they go.
i am 100% sure its not the issue with any dry joints
what are the chances of tubes being faulty.
is there any way to test
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The odds are very, very low that you received two dead 6C45P tubes. You could certainly purchase another pair to rule that out though.