Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: AyeVeeN on February 26, 2016, 08:28:40 AM
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To make it short, my terminal 13 starts at about OL to 8MOhms and then it slowly drops to 270kOhms. Drops by about .03 MOhm/s, getting slower as it gets closer to 270k.
Is this something to worry about? I thought it was normal initially so I proceeded to voltage checks and all the voltages checked out / were within tolerance. Most were about 10% above nominal. Turned it on and it also sounds good, though one issue I've encountered is that my pot has a left channel bias up until about 1 o'clock.
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If the filter caps are discharged they usually start very low and rise to 270K as the meter battery charges up the caps. If the caps have some charge on them the meter may read high because the caps are discharging across the 270K ohm resistor as you are measuring its resistance and interacting with the meter battery. Either way if it settles around 270K it is good.
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Alright I'll check tomorrow to be sure. Thanks!
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Alright so I tried it at the lab. After discharging and checking the resistance, the capacitors charge from 0k to 11k and then jumps to OL. Then it starts dropping from 110MOhms. Is this still alright? Whenever I try to check each individual capacitor after discharging, the same thing occurs.
Edit 1: After clipping the leads on and waiting, it drops from about 110MOhm to 5MOhm and then resets.
Edit 2: After testing a 3rd time, we left the alligator leads clipped to terminals 12 and 13 and then discharged the capacitors through terminal 20 and 21 using a 10kOhm resistor. Somehow it was actually successful this time and charged from 0 to ~263k (when we unplugged). Not sure what was done different though.
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Yeah you're fine, 270K in this case is not critical. The point is simply that caps charging and discharging will make different meters act different ways. You can move on to the next step.
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Alright thanks again!