MOSFET issue
In the world of crypto mining, uptime is everything. Every minute a machine is offline is money left on the table. Previously, I discussed common MOSFET issues specifically affecting the Antminer S19J Pro. Today, we are broadening that scope to look at a quick—albeit temporary—fix for older generation units, like the standard S19 series.
If you are running older Antminer models, you have likely encountered a hashboard that refuses to hash despite the ASIC chips appearing perfectly fine in diagnostic tests. Often, the culprit is a single, inexpensive component: the MOSFET.
This article will guide you through a fast antminer MOSFET repair technique that can get you back up and running in under five minutes when you don’t have spare parts on hand.
Understanding the Problem of MOSFET
On older Antminer hashboards, the MOSFET acts essentially as a digital switch or gate for the power supply. It manages the flow of electricity to the rest of the components.
Because these components handle significant current, they generate heat. Over time in a hot mining environment, they can degrade and fail. The most common symptom of a bad MOSFET is a hashboard that won’t power up its domains, even though the tester shows the chips are technically functional. Often, you can visually identify the failure; the component will look scorched, cracked, or visibly burnt from overheating.
The “Proper” Way vs. The “Fast” Way
If you have determined with certainty that the board issue is isolated solely to the MOSFET—meaning all other chips and LDOs are good—the gold standard repair is a direct replacement.
A new MOSFET is inexpensive, and for anyone with basic micro-soldering skills, it is not difficult to install. You can even buy dedicated repair kits for this exact purpose. If you have the parts and the time, always choose full replacement. It restores the board to factory specifications and retains necessary circuit protections.
However, miners don’t always have the luxury of waiting for parts to arrive. What if you are out of stock on replacements kits, but you need that S19 hashing right now?
There is an alternative way to perform an antminer MOSFET repair.
CRITICAL WARNING
Before proceeding, understand this: The following method is NOT a recommended long-term repair solution. It is a temporary bypass to get a miner running in an emergency.
The MOSFET serves a protective purpose. By bypassing it, you are removing that layer of protection. While it works, if another short circuit occurs elsewhere on the board later, you risk more severe damage to the hashboard. Use this fix only as a temporary measure until proper parts arrive.
The 5-Minute Emergency MOSFET Bridge Fix
Since a failed MOSFET is essentially a closed gate preventing power from flowing, the emergency fix involves manually forcing that gate open by creating a direct electrical bridge.
First of all, remove the heatsink:
Here is the process for this quick antminer MOSFET repair:
- Remove the Component: Using your hot air rework station, carefully remove the dead or burnt MOSFET from the hashboard pads. Clean the area with flux and braid to ensure a clean workspace.
- Identify the Pads: You will need to identify the input voltage pads (usually the larger pads coming from the power connector side) and the output pads going toward the ASIC domains.
- Create the Bridge: You need to create a solid electrical connection between the input and output pads.
- Do not use thin jumper wire, as the current is too high and will melt it.
- The best method is to use a small piece of thick copper bar or copper tape to bridge the gap.
- Alternatively, some technicians create a large, solid solder bridge across the necessary pads, though a copper interface is preferred for better current handling.
- Test: Once the bridge is solid and cooled, hook the hashboard up to your tester. It should now power up and initialize the chips, allowing it to hash again.
Conclusion
While the bridge method is a viable 5-minute fix to get an S19 back to hash, always remember it is a temporary patch. Treat it as a stop-gap measure. Get the proper replacement MOSFET ordered immediately and schedule the board for a correct repair as soon as possible to ensure the long-term safety of your equipment.