Allen-Bradley · SLC 500Obsolete / discontinued
1746-P3 Repair
Allen-Bradley SLC 500 rack power supply, 24VDC input (1746-P3). Capacitor, input-stage, and fan failures repaired flat-price and load-tested.
Known failures on the 1746-P3
- ▸Dead rack / no output
- ▸Faults when warm
- ▸Output sag under load
Ship your unit to
USPS
Control Board Lab
PO Box 120241
Arlington, TX 76012
UPS / FedEx
Control Board Lab
1009 Oakwood Ln # 120241
Arlington, TX 76012
Write your RMA number on the outside of the box and include it on a note inside. Units over 50 lb (large VFDs, spindle drives, industrial PCs in enclosures) ship by freight — contact us before ordering and we will arrange dock-to-dock shipping.
Check these before you ship
Some of these will tell you the 1746-P3 is fine and the fault is elsewhere — worth ten minutes before you pay to ship it.
- □Measure the output under real load, not disconnected. A supply that reads correct at idle and sags in the rack is the single most common industrial power-supply fault, and it is invisible on a bench meter with nothing connected.
- □Check whether the rack is drawing more than the supply is rated for. Modules added over the years quietly push some racks past their original supply budget.
- □Look for the physical evidence: bulged or vented capacitor tops, heat discoloration, or a burnt smell. It is not a diagnosis on its own, but it tells us where to start.
- □Note whether it fails from cold, only when warm, or only under a particular machine state. Thermal-dependent failures point straight at capacitor and regulation problems.
Not your exact model?
Search the catalog or send us the number on your unit's label — we service far more than the catalog shows.
How the 1746-P3 differs from the rest of the SLC 500 range
These share an electronics platform and fail in the same ways, but they are not interchangeable — check the number on your unit's label against this list before you ship, and before you buy a replacement.
Why a 1746-P3 fails — and what we do about it
The SLC 500 shares its electronics across the family, so these are the faults we see on this part number again and again.
Output sag under load
- What you see
- The rack faults, resets, or behaves erratically, yet the supply measures correct when you meter it disconnected.
- Why it happens
- Aged electrolytic capacitors hold voltage fine with nothing connected but cannot supply current. The supply looks healthy on a bench meter and collapses the instant a populated rack draws from it.
- What we do
- Capacitors are replaced and every rail verified under genuine load with ripple measured — the only test that reproduces this fault.
Dead supply — no output
- What you see
- No output at all, sometimes with visible or audible evidence of failure.
- Why it happens
- Failure of the switching device, its controller, or the input section. Continuous operation at panel temperature is what wears these parts out.
- What we do
- The failed stage is repaired at board level and all rails verified under load before the unit ships.
Repair or replace a 1746-P3?
Power supplies are inexpensive relative to what they take down with them, and they fail in a way that is genuinely worth repairing: predictably, in the capacitors and switching section, with a well-understood fix and a long service life afterwards. The case for repair is strongest where the supply is discontinued, where it is an odd form factor that fits one specific rack, or where you want a maintained spare of a unit you already trust. A repaired and load-tested supply is a far better spare than an untested surplus one.
Full technical detail for this repair
The PLC Power Supply service page covers the complete bench sequence — how the unit is tested, what gets replaced and how it is proven before it ships back — along with the rest of the family we service.
PLC Power Supply Repair — full details →Frequently asked questions
Can the 1746-P3 be repaired?
Yes — dead rack / no output, faults when warm, output sag under load are the failures we commonly repair on the SLC 500 platform. The flat price is $349 including parts, testing, and the 24-month warranty.
How long does a 1746-P3 repair take?
Standard bench time is 3–5 business days once the unit arrives. Rush service (+$149) moves it to 1–2 business days, and emergency same/next-day attempts are available — contact us first.
How do I send it in?
Start the repair online to get an RMA number instantly, pack the unit well with the RMA on the box, and ship it to our Dallas–Fort Worth lab with any carrier. Full packing guidance is on the mail-in instructions page.
Machine down? Let's get it back up.
Start a repair online in two minutes, or send us the part number for a free technician review.
The Fixed-or-Free Guarantee: if we can't repair it, you don't pay for the repair.
Call (817) 799-7332 · 📱 Text us a photo of your unit · Email repairs@controlboardlab.com