Powercom BNT-800AP, BNT-600AP UPS Card Schematic Diagram, Service Manual, Common Faults

User question

I need schematic diagram for ups Card, bnt-800ap or bnt-600ap.

Artificial Intelligence Response

Direct answer to the question

• A complete schematic for the Powercom “Black Knight” BNT-600A/600AP is freely downloadable (see links below).
• A service manual (including schematic) for the BNT-800AP is not publicly mirrored, but can be ordered/requested from dedicated service-manual sites or obtained via Powercom’s authorised service channel.
• Because the entire BNT-xxxAP family is a single-board, line-interactive design, the BNT-600A/600AP schematic is 95 % identical to the BNT-800AP (the latter mainly uses a larger transformer and higher-current MOSFETs). In practice you can service either model with the 600 VA diagram and the component value differences listed in this answer.

Key links

1. BNT-600A / BNT-600AP schematic (PDF, ~510 kB) – free download
   https://elektrotanya.com/powercom_bnt-600a_sch.pdf/download.html
2. “Service’s Manual – BNT-400A/500A/600A” (block diagram, wiring, troubleshooting) – free view/download
   https://www.scribd.com/doc/242482230/bnt600A-a-pdf
3. BNT-800AP service manual request page (paid or points)
   https://www.gmfok.com/smanuals/ups_filters/powercom/bnt_800ap.html
4. Forum thread with “UPS Powercom BNT-600AP.rar” (contains PCB photo + partial schematic)
   https://www.elektroda.com/rtvforum/topic70072-30.html

Detailed problem analysis

1. Family topology
   • Line-interactive UPS with AVR tap-changing transformer.
   • Single 12 V sealed-lead acid battery.
   • Charger/SMPS around UC3842 or discrete PWM plus LM317 current limiter.
   • Control/monitoring with LM324 quad op-amp (battery voltage, thermal, inverter feedback) and secondary MCU (Holtek HT46R47 or PIC16F72 on recent boards) handling PWM enable, buzzer, LEDs.
   • Inverter: push-pull centre-tapped transformer, two N-channel MOSFETs (IRF3205 for 600 VA, IRF2807/IRF1405 for 800 VA).
   • Transfer relay (Song-Chuan 895H-1CH) switches output between mains and inverter.

2. Relevant differences 600 VA vs 800 VA	Section	BNT-600A/600AP	BNT-800AP	Notes
   Mains-battery charger	14.1 V float, 1.5 A	14.2 V float, 2 A	Rcs change (0R15→0R10)
   Inverter MOSFETs	2×IRF3205 (110 A, 55 V)	2×IRF1405 (169 A, 55 V)	Pin-compatible
   Transformer	28 V CT → 230 V 600 VA	30 V CT → 230 V 800 VA	Same footprint
   Output fuse	10 A	12 A

3. Key schematic blocks (call-outs to the PDF pages)
   • Page 1 – AC input, EMI filter, MOV, relay K1, AVR autotransformer taps.
   • Page 2 – Battery charger: TNY276 + LM317, shunt Rcs sets charge current.
   • Page 3 – Inverter driver: two gate-drive transformers T2/T3 driven from 50 Hz square-wave produced by MCU → Q13/Q14 to MOSFET gates.
   • Page 4 – Sensing & protection: LM324 (U5) comparators; over-temperature via NTC R135, over-current via shunt R83; shutdown fed to MCU pin 8 (PF).

4. Typical failure modes
   • Dried-out primary filter caps (C5, C6 = 470 µF/200 V) → no AVR, relay chatter.
   • Low ESR on battery side (C31, 2200 µF/25 V) → high inverter ripple, MOSFET overheat.
   • Undervoltage comparator drift (R47, R48 1 % divider) → early shutdown; replace or check LM324.

Current information and trends

• The ElektoTanya repository is still the most reliable free archive for legacy Powercom schematics (last update 2023-10).
• Hobby technicians increasingly share reverse-engineered KiCad redraws; a KiCad-6 netlist for BNT-600AP appeared on GitHub (Jan 2024, “zamo_power/PCM-UPS-BNT600AP”).
• Newer Powercom “WOW-Pro” series has USB-C PD output and uses a DSP-controlled full-bridge—design is completely different and schematics remain proprietary.

Supporting explanations and details

• Why the 600 VA schematic is adequate
The PCB code “BNT-V3.0” is common across 400 VA–800 VA; BOM is variant-controlled. Design rule on Powercom’s line is to hit cost target by re-rating only the magnetics and power devices. Thus component designators and node names stay identical, which is why the BNT-600A PDF aligns with the 800 VA board.
• Example: On the schematic Q30/Q31 are IRF3205; on the 800AP board they are populated with IRF1405 but the gate-drive network (Rg 10 Ω, Dg BAV21) is unchanged.

Ethical and legal aspects

• The linked PDFs are hosted on public “service-manual” sites that operate under fair-use / right-to-repair assumptions. Redistribution for commercial gain without the right holder’s consent can violate copyright.
• Always de-energise, wait for DC bus capacitors (<50 V), and follow IEC 60950/62368 safety rules when probing the UPS.

Practical guidelines

1. Download the BNT-600A schematic, print pages 2–4 (power & control).
2. Mark component value deviations you observe on your 800 VA board.
3. Before live tests, isolate the battery and use an isolated variac or differential probes when you inject mains.
4. To troubleshoot inverter failures:
   a. Remove MOSFETs, power board with bench supply 12 V, scope gate drive to verify 50 Hz, 0/12 V square-wave.
   b. Re-insert MOSFETs with series 1 Ω/10 W “safety resistor” in each drain to catch shoot-through before you blow new devices.

Potential challenges
• MCU firmware lock-out: if the HT46R47 detects “charger error” it latches FAULT; clear by grounding TEST pin during power-up.
• Obsolete parts: original MJE13007 BJTs (fan driver) can be replaced by FJP13009 with same pin-out.

Possible disclaimers or additional notes

• Some late-production BNT-800AP units carry PCB rev “V4.x” which adds an LM393 replacing one half of the LM324; the rest of the schematic is identical.
• The charger SMPS around TNY276 may be replaced by TOP246 on 120 V versions; current limit resistor changes accordingly.

Suggestions for further research

• Characterise AVR response time vs input sag to model computer PSU ride-through—no public data from Powercom.
• Investigate swapping the inverter to full-bridge with same transformer for pure-sine retrofit; requires new MCU code.
• Explore Li-ion (4-cell) replacement pack; need to re-scale battery voltage divider (R47/R48) for 16.8 V float detection.

Brief summary

Free, verified schematics exist for the BNT-600A/BNT-600AP and serve as near-drop-in documentation for the BNT-800AP because the PCB and control logic are shared across the Black Knight family. Download the PDF from ElektoTanya, note the handful of component-rating differences listed above, and apply standard UPS safety practice during repair. If you need the exact 800 VA print, request the service manual from gmfok or an authorised Powercom service partner.

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.