Bottlehead Forum

Bottlehead Kits => Stereomour II => Topic started by: Jackholden789 on April 02, 2024, 01:51:02 PM

Title: Voltage Check Issue [resolved]
Post by: Jackholden789 on April 02, 2024, 01:51:02 PM

I just completed my Stereomour II build and terminals 4 and 17 both are reading 27 mVDC in the voltage check. All other voltages and all resistances were good. I can’t seem to figure out where the issue is coming from, any ideas? Pictures below. Thank you very much.

Title: Re: Voltage Check Issue
Post by: hmbscott on April 02, 2024, 03:30:27 PM

Terminals 4 and 17 are both supposed to be pulled to ground by the 249K ohm resistor connecting them to 5 and 16 respectively. So a bad connection at either end of each resistor could interrupt that, but surprising that both would be affected the same way.

Now if the 2A3 tubes were both plugged in rotated in the same wrong way, you might have built voltage dividers across the tube heater filament, which could explain it. Check to make sure the 2A3's are plugged in with the correct orientation.

Title: Re: Voltage Check Issue
Post by: Paul Joppa on April 02, 2024, 03:43:48 PM

Are you sure that's not 27mV? If T4 and T17 are not close to zero, the 2A3 voltages would also be off.

Title: Re: Voltage Check Issue
Post by: Jackholden789 on April 03, 2024, 03:23:49 AM

Quote from: Paul Joppa on April 02, 2024, 03:43:48 PM

Are you sure that's not 27mV? If T4 and T17 are not close to zero, the 2A3 voltages would also be off.

Ah, yes - mV. 

Title: Re: Voltage Check Issue
Post by: Jackholden789 on April 03, 2024, 04:34:43 AM

Quote from: hmbscott on April 02, 2024, 03:30:27 PM

Terminals 4 and 17 are both supposed to be pulled to ground by the 249K ohm resistor connecting them to 5 and 16 respectively. So a bad connection at either end of each resistor could interrupt that, but surprising that both would be affected the same way.

Now if the 2A3 tubes were both plugged in rotated in the same wrong way, you might have built voltage dividers across the tube heater filament, which could explain it. Check to make sure the 2A3's are plugged in with the correct orientation.

Thank you - both 2a3 tubes are plugged in with the large prongs in the back (into the large holes).  I initially reflowed the solder connections on the terminals, but will try again and keep tinkering.  Odd that it is the same issue on both sides.

Title: Re: Voltage Check Issue
Post by: Paul Joppa on April 03, 2024, 04:48:25 AM

27mV is 0.027volts, and adequately close to zero. It indicates a grid current of around 0.0000001 amperes, which is no problem.

Title: Re: Voltage Check Issue
Post by: Jackholden789 on April 03, 2024, 04:50:17 AM

Quote from: Paul Joppa on April 03, 2024, 04:48:25 AM

27mV is 0.027volts, and adequately close to zero. It indicates a grid current of around 0.0000001 amperes, which is no problem.

Oh awesome.  Thank you very much!