When inspecting an Antminer S19XP hashboard, understanding the voltage flow of its five key signals is critical: RST, RX, BI (BO), CLK, and TX. Each of these signals has a specific voltage range as it passes through the ASIC chips, and a failure in any one of them can prevent the entire hashboard from working.
For the Bitmain Antminer S19XP, the expected voltages are:
- RST: 1.2V
- RX: 1.2V
- TX: 1.2V
- CLK signal: 0.5–0.6V
- BI (BO): 0V
What Happens When CLK Voltage Is Off?
Today, let’s focus on the CLK signal. Sometimes during diagnostics, you might see the CLK voltage at 0V or even as high as 1.2V.
- If the CLK signal is reading 0V, it is most often due to dry soldering, meaning the CLK pin is not making solid contact with the hashboard.
- If the CLK voltage is 1.2V, this could indicate a short circuit (bridge) between the CLK pin and an adjacent pin, or it could also result from dry soldering.
Typically, when the CLK signal reads 0V or 1.2V, there is a bad ASIC chip somewhere, usually in the middle of the chain. However, if the first chip (chip #1) shows an abnormal CLK voltage (0V or 1.2V), then you should also suspect the crystal oscillator, which is responsible for generating the CLK signal.
Case Example
On one Antminer S19XP board, the first chip’s CLK signal was within range, but between the first and second chips, the CLK voltage showed 1.2V — which is much too high. After deeper inspection, I found the crystal oscillator voltage was abnormal. I replaced it with a new crystal oscillator, and after that, the CLK signal of the first chip stabilized back to 0.62V, which is considered normal.
How to Identify the Fault
It can be difficult to distinguish between a failing ASIC chip and a faulty crystal oscillator. As a simple rule:
- If the CLK voltage is normal at the first domain and first chip, then the crystal oscillator is usually working fine.
- If you see abnormal CLK voltage in the middle of the chip chain, it is most likely a chip issue, and replacing the bad chip will usually solve the problem.
By carefully checking these voltages on your Antminer S19XP, you can quickly identify whether a bad ASIC chip or a failed crystal oscillator is the cause of a CLK signal issue. Always be mindful to inspect solder joints and double-check with a tester to make your repairs reliable and efficient.