Bottlehead Forum
Bottlehead Kits => Eros Phono => Topic started by: Suger on June 28, 2022, 10:30:47 AM
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Hello again,
So, now, I'm failing the shunt test. When I plug and touch the first MJE5731A, there is some initial high voltage, but it drains very fast to 0. And if I go to the second, I get a null reading. On the plus side, the leds do turn red. Just posting a couple of pictures in case there is something obvious, before going back to inspect the wiring. As usual, all hints are welcome.
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Rc on the board should be a 220 ohm carbon film resistor, but it looks like you have 220K resistors there instead.
Are the 431 regulators in the correct spots? (and not installed in place of Q1)
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Indeed, 220K instead of 220, well spotted (on another hand, I can confirm that the 431 are where they should)
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You might want to check where you put the 220 ohm resistors in lieu of the 220k
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If solder doesn't flow through the hole on the PC board to the other side, the joint may not be good. This is not at all an issue on the LEDs since they take so little heat to solder, but I can see other joints where it looks to be more of an issue. It's also worth mentioning that soldering the board from both sides can end up making other problems, so just apply the heat you need on the bottom side until you see the solder sink a bit, then you should be good.
To continue debugging your issue, seeing the build underneath the board could also be helpful.
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@Thermioniclife: I checked, but I hadn't (the two "extra" 220k came in later.
@PB: swapping the 220K for 220s in Rc (and reheating a couple of solders whilst I was at it) solved the problem.
Many thanks both for your help.