Hola,
In the "Checking and Testing" section: "Please connect always a power resistor or a cheap speaker..."
In the schematics: "All voltages measured at No-Load conditions"
Wich does I have to listen to?
A15MK2 question
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Hi,
No load condition means no AC signal at the input, because you are measuring the DC values...
But even if there's no signal at the input use a dummy load or speaker at the output for safety reasons
But you're right, these words are a source for misunderstanding.:)
Bernd
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hola Bernd & Co, nice to meet you again.
I've just finished the A15MKII assembly, its a more complicated project than BP1MK1, and the manual is not so complete.
Now I'm going to do the checking and I suppose I'll need your help.
Can I use a 4 Ohms speaker for the measurements?
Best regards
Guillermo -
Hi,
for measuring the DC values without signal you can use a 4 Ohm speaker plugged to the 8 Ohm output.
But if you want to use the amp with the 4 Ohm speaker you should wire the OT for 4 Ohm (lugs 3 + 16) to (another additional) output jack.
But the NFB connection hast to remain to the 8 Ohm output!
Bernd
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Hola,
the amp have three output jacks wired to the OT (4,8,16 ohms).
The feedback conection is in the 4 ohms output as in the diagram. -
Oh,
I refer to a schematic of the A15Mk2 revision 1.0 (date 28.02.2007). Maybe you've got a newer one...
Bernd
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Hola,
I´ve done the checking. All the voltages are in the 5% margin except: V4 pin 6, 164 V.
The heater voltage is 6.95
do you think it's allright?
Guillermo -
Hi,
if the other values around V4 are OK, you can't do anything except changing V4 or checking if R38 has the correct value of 82k (not 100k).
6,95 V heater voltage is at the upper limit - if you can rely on your voltmeter.
Do you have permanently high mains voltage (above 230 V)?
Then a 0,27 or 0,33 Ohm/2W resistor (or better two 0,15 Ohm/1W - one in each heater lead) would help...Bernd
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Hola,
R 38 is ok so I've changed V4 for V3 and now pin 6 V3 is 100v so the problem is the tube. I supose that is better to put this tube in other position than V4 because it is the phase splitter.
I'd like to have less gain in channel 2. Will I get it puting the "bad" tube as V3 or V2?
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