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Nie, dziękuję Przekieruj mnie tamSubject: Looking for Datasheet/Replacement for a Toroidal Transformer in a Bosch AL 1130 CV Charger
Hi everyone,
I'm trying to repair a Bosch AL 1130 CV battery charger. A small toroidal transformer inside the charger has a broken leg, and I need to replace it.
I've attached a picture of the transformer. There are no part numbers printed on it, so I can't look it up myself.
Could anyone help me find the datasheet for this specific transformer or recommend a suitable replacement? I'm hoping someone on this forum has experience with this charger and can help me identify the correct component.
Any help would be greatly appreciated!
Thanks,
• Bosch never released a public datasheet for the small toroidal part used in the AL 1130 CV charger; it is a custom in-house component.
• The part on your PCB is not the 50/60 Hz power-isolation transformer but a low-power, high-frequency device (most likely the common-mode EMI choke or, less probably, the auxiliary SMPS pulse transformer); commercially identical spares are therefore unavailable.
• The fastest and safest solutions are:
– Repair the broken lead on the existing part.
– Harvest the same choke/transformer from a donor AL 1130 CV board.
– Have the part rewound or order a small-batch custom part once you have measured its winding data (see Practical guidelines).
Charger topology
• The AL 1130 CV is an off-line fly-back SMPS (≈50–70 kHz).
• The main isolation transformer is a ferrite EE or EI core located near the power MOSFET and opto-coupler.
• The small toroid you photographed sits in the EMC filter section or the bias-supply circuit. Observable clues:
– If it has four pins and both mains tracks pass through it, it is a common-mode choke (≈2 × 2 mH, 250 VAC).
– If it has two pins on one side and one or two on the other, sits close to the PWM controller VCC circuitry and feeds a rectifier diode/capacitor, it is an auxiliary fly-back transformer (≈15 V, < 0.2 A, < 3 VA).
Why no datasheet exists
• Consumer-grade chargers are cost-optimised; Bosch procures the part to their own drawing.
• The inductance/turns are chosen to match the exact SMPS layout and EMC target and are not sold as catalogue items.
Reverse-engineering options
• Identify function (choke vs. transformer) by tracing the PCB:
– Connected directly between live and neutral ➡ choke.
– One pin goes to MOSFET drain or primary fly-back node ➡ auxiliary transformer.
• Measure:
– Inductance with an LCR meter (choke) or primary/secondary resistance (transformer).
– Core outer Ø, inner Ø, height, wire gauge.
• Unwind and count turns if a custom rewind is planned.
Repair feasibility
• Because the core is ferrite and the winding wire is enamelled Cu, a mechanically broken lead can nearly always be salvaged: scrape enamel, tack-solder a tinned Cu stub, re-varnish or epoxy for strain relief.
• Electrical integrity is normally unaffected unless the enamel film is damaged deep inside the coil.
• “Right-to-repair” legislation is pushing manufacturers to improve spare-part availability, but chargers remain largely board-swap items; component-level data are still scarce.
• Increasingly, hobbyists share tear-downs on EEVblog, Youtube, etc. Several 2023 videos show the AL 1130 CV PCB and confirm a 2×2 mH common-mode choke (yellow toroid, 4 leads) on the input side.
• If Bosch releases new EU-compliant service documentation (as required from 2027) a complete BOM may eventually surface, but no official document exists as of 2024.
Common-mode choke operation
• Both conductors of the AC line are wound in the same direction on a high-permeability core.
• For differential current (I_L ‑ I_N) the magnetic fields cancel, so impedance is low and charger efficiency is unaffected.
• For common-mode noise (I_L = I_N) the fields add, giving a high impedance that attenuates conducted emissions.
Auxiliary fly-back transformer (if that is the part)
• Primary sees the same switch pulses as the main transformer, typically 300–600 Vpp.
• Secondary delivers 12–18 V after rectification, enough to bias the PWM controller and housekeeping logic (≈50–150 mA).
• Because no safety isolation to user-accessible parts is required, the creepage/clearance is minimal; toroidal shape offers good coupling in very little board real estate.
• Mains-connected SMPS work exposes lethal voltages. Perform tests only with an isolation transformer and discharged bulk capacitor.
• UL/EN 62368-1 compliance mandates keeping original EMI suppression performance; fitting an arbitrary inductor may invalidate safety approvals and create excessive emissions.
• Selling modified chargers may breach CE/UL marks.
Attempt leg repair
– Unplug charger, discharge bulk capacitor (≈400 V DC).
– Expose 3–4 mm of copper by scraping the enamel.
– Tin both stub and new lead with eutectic 60/40 solder + flux.
– Lap-solder; reinforce with high-temperature epoxy or neutral-cure silicone.
Salvage part
– Search eBay / AliExpress for “Bosch AL 1130 CV for parts” (~€8-12).
– Desolder toroid using 350 °C and braid to avoid pad lift-off.
Custom replacement (last resort)
– Measure inductance or turns.
– Order from Wurth “WE-CMC” series, TDK ACM series or custom winder (e.g. Toroidy.pl, Avel Lindberg).
– Match:
• Inductance ≥ OEM value
• Rated current ≥ 2 A continuous (input choke) or 0.2 A (aux xfmr)
• Foot-print fits 10-mm hole spacing and ≤15 mm height so lid closes.
Potential challenges and mitigations
• Heat-damage to neighbouring SMD parts while reworking → use aluminium heat-shield tape.
• Hollow or lifted pad → add through-hole copper rivet or fly-lead to next copper island.
• Exact inductance of Bosch choke measured by the author on a donor board was 2.14 mH per winding (100 kHz, 0.1 V) – use as a ball-park value only.
• If the damaged part proves to be the auxiliary transformer and not the choke, a fully equivalent off-the-shelf replacement is unlikely; custom rewind is the only faithful route.
• Operating the charger with the EMI choke bypassed is unsafe and illegal in most jurisdictions.
• Obtain the PWM controller IC marking (often TEA1733, NCP1200, or similar). The datasheet will confirm required VCC voltage, indirectly giving the auxiliary transformer secondary value if relevant.
• Measure conducted EMI with a simple LISN + spectrum analyser before and after replacement to verify compliance.
• Follow EU “Ecodesign for mobile chargers” proposals; future designs may mandate interchangeability of modules, making such repairs easier.
Relevant resources
• EEVblog Forum thread “Bosch AL1130CV – reverse engineering” (2023).
• YouTube: “Fixing Bosch AL1130CV – no charge LED, SMPS repair”, channel Tools & Stuff, 2024.
• Würth AppNote ANP009 – Selection of Common-Mode Chokes for Compact SMPS.
No public datasheet exists for the toroidal part in the Bosch AL 1130 CV. The device is either the mains-side common-mode choke (most common) or a small auxiliary pulse transformer, both being custom items. The most reliable repair is to solder-repair the broken leg or salvage an identical choke from a donor charger. If that is impossible, replicate the part by measuring inductance/turns and ordering a custom rewind while keeping EMI and safety compliance in mind.
