Siemens
Siemens SIMATIC HMI Comfort Panel Repair (TP700–TP1200, KP Series) — Mail-In
Board-level repair for Siemens SIMATIC Comfort Panels (TP700/TP900/TP1200 and KP siblings). Dominant failures are power-supply capacitors and touch wear — both fully repairable with your project intact. Flat $499; 15" and larger from $599.
Coverage: SIMATIC Comfort Panels — TP700, TP900, TP1200, KP700–KP1200 (15"+ from $599)
✓Fixed — or it's free
Unrepairable units are refunded; evaluations cost $0
✓24-month warranty
Every repair covered, parts and labor
✓3–5 business days bench time
Rush (1–2 day) and emergency service available
✓Program preserved
Your application and settings stay in the unit
Symptoms this repair fixes
- ✓Dead unit / will not power on
- ✓Powers on then shuts down / restarts
- ✓Touch not responding or drifting
- ✓Dim or dark display
- ✓Boot stuck at Siemens loader
Honest limits
- ✕Destroyed LCD assemblies quoted first
What you get
- ▸Diagnostic + board-level repair
- ▸Power-supply repair with quality capacitor replacement
- ▸Touch digitizer and backlight repairs included
- ▸WinCC project and settings preserved
- ▸Full functional test incl. PROFINET comms
- ▸24-month warranty
Your program is safe
Your WinCC runtime project lives in the panel's internal flash / SD card and is preserved through power and touch repairs.
Typical article numbers
Part-number pages for this service
How Siemens Comfort Panel units actually fail
Most units we receive fail in one of a handful of well-understood ways. Here is what each fault looks like from the machine, what is happening electronically, and what we do about it at the bench.
Power supply capacitor failure
- What you see
- Panel will not power on, restarts on its own, or fails to boot when the cabinet is warm.
- Why it happens
- The internal supply runs continuously in an enclosed cabinet. Its electrolytic capacitors lose capacitance and gain ESR over years at temperature, so rails sag under the load of initialisation while still reading acceptable at idle.
- What we do
- The capacitor set is replaced, all rails verified under load with ripple checked, and the panel booted repeatedly from cold and warm.
Backlight and display faults
- What you see
- Dark or dim screen on a panel that is otherwise running normally.
- Why it happens
- Backlight assemblies and their drive circuitry degrade with running hours, and in a continuously operating panel that is a large number of hours.
- What we do
- Backlight and driver circuitry are repaired and brightness verified across the panel through a warm soak.
Touch controller and digitizer faults
- What you see
- Touch drifting off target, dead regions, or inputs registering without contact.
- Why it happens
- Both the touch surface and the controller that interprets it can fail. Localised dead areas point to the digitizer; whole-screen drift or phantom input more often points to the controller.
- What we do
- The fault is isolated to the correct component before replacement, then calibration is verified across the whole screen.
Storage and boot faults
- What you see
- Panel hangs during startup or reports an error instead of loading the project.
- Why it happens
- Boot faults arise from storage problems or from a supply that cannot hold its rails through startup. The two present almost identically and are routinely confused.
- What we do
- We establish which it is before replacing anything, repair the real cause, and confirm clean repeated boots.
What happens on the bench
The same sequence on every 5-stage repair, so nothing gets skipped because a fault looked obvious.
- 1
Intake and symptom replication
We log the unit against your RMA and power it on the bench to reproduce what you reported. A terminal that boots fine for us is worth knowing about early — intermittent faults are usually thermal or a marginal power rail, and both change what we test next.
- 2
Rail and power-supply measurement
The internal supply is measured under load, not just at idle. Aging electrolytic capacitors lose capacitance and gain equivalent series resistance, so a rail can read correct on a meter and still collapse the moment the backlight or processor draws current. Ripple is checked on a scope rather than assumed.
- 3
Display, backlight and touch isolation
A dark screen is separated into three different repairs: a failed backlight (image still faintly visible under a bright light), a failed inverter or LED driver, or a genuinely failed LCD. Touch faults are isolated to the digitizer, its flex tail, or the controller before anything is replaced.
- 4
Board-level repair
We replace the failed components — capacitors, backlight assembly, digitizer, driver circuitry — rather than swapping whole boards. Where capacitor aging is found on a supply, the set is replaced, because the ones that have not failed yet have lived the same thermal life as the one that did.
- 5
Functional test and burn-in
The terminal is booted repeatedly from cold, the touch grid is calibrated and checked corner to corner, communication ports are exercised, and the unit is left running to catch faults that only appear once it is warm.
Check these before you ship
Some of these will tell you the unit is fine and the fault is elsewhere. We would rather you find that out now than pay to ship a good unit.
- □Confirm the supply feeding the terminal is actually delivering its rated voltage under load — a failing panel supply mimics a dead HMI exactly.
- □Shine a bright light at an angle across a dark screen. If you can make out the application faintly, the LCD is alive and you have a backlight fault, which is a cheaper and faster repair.
- □If the unit boots but the touch is wrong only in one region, note where. Localized dead zones point at digitizer wear; whole-screen drift more often points at the controller.
- □Note the exact text of any boot or fatal error. The code narrows the fault far faster than "it will not start".
- □Back up your runtime application if you have a copy — we preserve what is on the unit, but a backup is cheap insurance on any repair.
Repair or replace?
Operator terminals are the clearest repair-over-replace case in a plant. Much of the installed base is discontinued with no drop-in successor, so replacing means specifying new hardware, re-developing or converting the application, re-testing it against live machinery, and retraining operators on a screen that behaves differently. The repaired terminal drops back into the same panel cutout running the same application. Even where a successor exists, the migration engineering usually costs several times the repair.
What to ship
- ▸The panel only
- ▸Symptom description with your RMA number
Full packing guidance: mail-in instructions.
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.
Frequently asked questions
Siemens cancelled part of the Comfort Panel range — what does that mean for me?
Siemens has issued cancellation notices covering the larger Comfort Panels, which pushes replacements toward lead time and migration projects. Repairing your existing panel keeps the exact validated hardware and project in service.
Is my WinCC project safe?
Yes — it is stored in flash / SD and untouched by the physical repair. If you have the TIA Portal source, keep it archived as normal practice, but the repair does not require it.
Fix it for $499
Buy the repair now, get your RMA instantly, and ship the unit today.
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