I’ve had my Eros since 2017, and there’s always been a bit of background hum that worsens as I increase the volume. I’m listening through Crack and Mainline amps into multiple 250-300 ohm headphones.
I’ve neglected addressing the hum for a few years, so I’m a bit rusty. However, today I performed a resistance and voltage check, hoping to sort this out with some help. I can’t send the unit in for repair since I live in Denmark, and the cost of shipping would be significant.
Here’s what I’ve done so far:
Measured the resistance on the small brown resistors on the B board—all three show correct values, so I don’t think they’re mixed up.
Reflowed some suspicious solder joints, particularly at B3, B6, T10, and T15.
Tried a different 6922 tube, but there wasn’t much of a change.
Swapped the EF86 tubes, but that didn’t make a significant difference in the values either.
Below are my resistance measurements:
Terminal strips:| Terminal | Value |
| 1 | 0 |
| 2 | 85,3k |
| 3 | 0 |
| 4 | 74,8 |
| 5 | 0 |
| 6 | 465k |
| 7 | 465k |
| 8 | 0 |
| 9 | 46,4k |
| 10 | 46.5k |
| 11 | 0 |
| 12 | 74,8k |
| 13 | 0 |
| 14 | 85,3k |
| 15 | 0 |
| 16 | |
| 17 | |
| 18 | 0 |
| 19 | 46,8k |
| 20 | 0 |
| 21 | 0 |
| 22 | 0 |
| 23 | 0 |
| 24 | 0 |
| 25 | 0 |
| 26 | 0 |
| 27 | 46,9 |
| 28 | 0 |
| 29 | No connection |
| 30 | No connection |
| Input/Output | Channel | Specified Resistance | Measured Resistance |
| Input Jack | Left (black) | 47K ohms | 46,9k |
| Input Jack | Right (red) | 47K ohms | 46,8k |
| Output Jack | Left (black) | 470K ohms | 465k |
| Output Jack | Right (red) | 470K ohms | 465k |
Nine pin sockets :
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| A | 27k | 0 | * | * | 0 | 74.8k | 0 | * | 47.1k |
| B | 26.9k | 0 | * | * | 0.5 | 74.8k | 0 | * | 47.1k |
| C | 46.5 | 75k | * | infinity | 0 | 46.6 | 75k | * | 0 |
The voltage check seems a bit off:
| Socket Side | Kreg (VDC) | OB (VDC) | bA (VDC) | breg (VDC) | OA (VDC) | IA (VDC) |
| Socket A | 1.377 | 98.3 | 0 | 99.6 | 163.9 | 223 |
| Socket B | 0.616 | 66 | 0 | 70.7 | 206 | 224 |
I am having problems with posting pictures, I get the following Error 500.
I have uploaded some photos to imgur.
https://imgur.com/a/TGettrTPlease let me know if I should run additional tests or provide photos to help diagnose the issue. Any guidance would be greatly appreciated.
Thanks in advance for your help.
@forum moderators: I get the following error when I post .jpg pictures, you might be able to see more about it in your logs.
This page isn’t working right now
forum.bottlehead.com can't currently handle this request.
HTTP ERROR 500