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Charging Circuits and Power-Path Repair

Behind every pack the chapter has handled sits the silicon that manages it, and this section opens that territory: the charging chain from port to pack, the profile that governs every honest charge, and the board-level bench where the chain's failures get repaired. The chain reads in links — the port and its negotiated contract, the input protection that takes the first insult, the charge IC that runs the whole show, the power path that feeds the system while the pack charges, and the fuel gauge watching from the side — and every charging complaint in the queue is one link failing, with the section's splits naming which. The profile is the IC's constitution: a gentle pre-charge for cells resting low, the constant-current bulk that does most of the work, the constant-voltage approach as the limit nears, termination at the taper — and temperature gating over all of it, pausing or slowing charge on purpose when the pack runs too cold or too hot, which is why half the profile's 'faults' are the profile working. The power path explains the queue's two most confusing intakes in one diagram: the device that runs plugged in but dies the moment the cable leaves has a healthy charge side and a pack-side problem — the pack, its FETs, its gauge; the device that runs happily on battery but will not charge has a healthy pack and a charge-side problem — port, contract, input stage, or the IC itself. The bench works by the volume's accumulated law: the USB-C chapter's evidence chain runs first — contract on the meter, rails measured at the IC's own nodes against the diagram, the thermistor line checked because a missing or wrong sensor quietly caps every charge — and the silicon is accused last, repaired under the rework bench's full discipline, with the conversion to board-level or replacement quoted at the evidence. The Switch chapter did this for one family; this section makes it a bench for all of them.

AdvancedMedium Risk23 min read

What You Will Learn

  • You will learn the charging chain — port and contract, input protection, charge IC, power path, fuel gauge — and how every complaint maps to one link.
  • You will learn the charge profile — pre-charge, constant current, constant voltage, termination — and the temperature gating that pauses charging on purpose.
  • You will learn the two splits the power path explains — runs-plugged-dies-unplugged as pack-side, runs-on-battery-won't-charge as charge-side.
  • You will learn the evidence at the IC — rails measured at its nodes against the diagram, the thermistor line checked — before any silicon is accused.
  • You will learn the repair tier — reflow and replacement under the rework law, and the honest conversion when the board says so.

What You Will Be Able To Do

  • You will be able to trace the charging chain on any family's board diagram.
  • You will be able to read a live charge session and name the profile's phases as they pass.
  • You will be able to run the two splits and route every complaint to its side of the power path.
  • You will be able to measure the evidence at the charge IC — rails and thermistor line — before accusing silicon.
  • You will be able to repair the chain under the rework law and convert honestly when the evidence orders it.

Required Tools

  • The PD-aware power meter and multimeter — the evidence chain's instruments
  • Board diagrams and schematics for the families served — rails are measured against maps, not memory
  • Fine probes and grabber clips for the charge IC's nodes
  • The rework bench's full kit — preheat, hot air, magnification — for repairs the evidence orders
  • The fireproof container and the foundations' gates — packs stay under the law at this bench too

When NOT to Attempt This

Do not attempt this section if any of the following apply to you:

  • You are not comfortable working with small surface-mount components.
  • You have not completed the prerequisite sections for this skill.
  • You do not have the required tools in working condition.

Section Overview

Behind every pack sits the silicon that manages it, and this bench repairs the chain the chapter has so far only fed (board-level-charging-repair-the-m92t36-and-bq24193). The chain reads in links. Port and contract, input protection, the charge IC running the show, the power path feeding the system while the pack charges, the fuel gauge watching — every complaint is one link failing (usb-power-delivery-diagnostics-and-charging-fault-isolation). The profile governs every honest charge. The charge profile — pre-charge, constant current, constant voltage, termination — with temperature gating pausing charge on purpose, which is why half its reported faults are the profile working (battery-diagnostics-health-measurement-and-capacity-testing). The splits route the queue. Runs plugged in but dies unplugged: pack side. Runs on battery but will not charge: charge side. Slow everywhere on an honest charger: profile territory, thermistor line first. The bench works by accumulated law. Evidence at the IC's nodes against the diagram, silicon accused last, repairs under the rework discipline, conversions quoted at the evidence (usb-c-port-replacement-and-board-level-rework). The chain, the profile, the splits, the evidence, the law — the charging bench entire.

Why This Matters

This is the bench where the chapter's verdicts meet the volume's board-level craft, and it inherits the stakes of both (board-level-charging-repair-the-m92t36-and-bq24193). This matters because the splits are free and decisive: one question — does it run unplugged? — divides every charging complaint into pack side and charge side before a single probe lands, and benches that skip it diagnose both sides at once, badly (usb-power-delivery-diagnostics-and-charging-fault-isolation). This matters because the profile's features masquerade as faults: the charge that slows near full is the constant-voltage taper doing its job, the pause in a hot car is temperature gating protecting the cell — and the bench that cannot name the profile's phases sells repairs against physics working correctly (battery-diagnostics-health-measurement-and-capacity-testing). It matters because the thermistor line is the quiet saboteur: a bargain replacement pack missing its sensor — or carrying the wrong value — leaves the charge IC blind to temperature, and a blind IC charges slowly, strangely, or not at all: the swap looked perfect and the chain broke anyway. It matters because the evidence is cheap and the silicon is not: rails at the IC's nodes cost minutes against the diagram, and the reflow they prevent — or justify — is an hour under the rework law (usb-c-port-replacement-and-board-level-rework). And it matters because this bench closes the chapter's loop: packs verified, verdicts measured, swaps proven — and now the circuits behind them repaired, so the whole battery system leaves the shop honest. Split first, name the profile, check the sensor, measure before accusing — and the chain's failures become the queue's most systematic repairs.

Required Prerequisites

  • Gel flux, braid, and low-melt assist for IC-scale rework — to run repairs the evidence orders under the rework law (usb-c-port-replacement-and-board-level-rework)
  • Kapton and foil shielding — to keep the air's spill off the battery bay and the neighbors (board-level-charging-repair-the-m92t36-and-bq24193)
  • Replacement charge ICs staged for the families served, sourced like packs — verified, not assumed — to never strand a stripped site (battery-diagnostics-health-measurement-and-capacity-testing)
  • A printed splits card at the intake counter — to route every charging complaint with one question (usb-power-delivery-diagnostics-and-charging-fault-isolation)
  • Donor boards with accessible charge ICs and diagrams — to trace chains and measure rails where mistakes are free (board-level-charging-repair-the-m92t36-and-bq24193)
  • A PD-aware power meter and a device that charges — to watch a live profile pass through its phases (usb-power-delivery-diagnostics-and-charging-fault-isolation)
  • Two donors with opposite splits — one pack-side, one charge-side, real or staged — to feel the one-question routing work (battery-diagnostics-health-measurement-and-capacity-testing)
  • An aftermarket pack with a missing or wrong thermistor, kept as a teaching part — to see the quiet saboteur on a meter
  • The rework bench's full kit — to practice the repair tier under its own law (usb-c-port-replacement-and-board-level-rework)

Real-World Applications

The charging bench turns the queue's most tangled complaints into routed, measured repairs. A technician taking a tablet that runs perfectly on its charger but dies the instant the cable leaves asks the split's one question and routes pack-side in ten seconds — the pack, its FETs, its gauge — and finds the swap-verified pack healthy but its connector's sense line bent, a five-minute fix a both-sides diagnosis would have circled for an hour (battery-diagnostics-health-measurement-and-capacity-testing). A bench facing an e-reader that charges at a trickle since a bargain pack swap checks the thermistor line against the diagram and finds a fixed resistor faking the wrong temperature where the family expects a live sensor — the charge IC, reading a cold pack that is not, holding reduced current forever, where a sensor missing outright would usually read out-of-range and refuse to charge at all — and the honest fix is a proper pack, not a board repair (usb-power-delivery-diagnostics-and-charging-fault-isolation). A counter fielding a laptop that stops charging every sunny afternoon in a sunroom office names temperature gating as the feature it is — the profile pausing to protect a warm pack — and sells a stand and an explanation instead of a teardown (board-level-charging-repair-the-m92t36-and-bq24193). And a bench whose evidence convicts a media player's charge IC — contract honest, rails dead at the IC's output with input present — runs the repair under the rework law end to end: battery out, preheat, the IC reflowed then replaced, the gate before power, the profile watched on the meter at the close (usb-c-port-replacement-and-board-level-rework). The failures this prevents: an hour circling both sides of a split one question answers, a board repair sold against a missing thermistor, a teardown quoted against temperature gating working, and a charge IC replaced on a hunch the rails would have acquitted.

Common Challenges

  • The chain is invisible and the symptom is global. Won't charge names no link — the difficulty is the discipline of the splits and the diagram, because the chain only localizes for benches that ask it to (board-level-charging-repair-the-m92t36-and-bq24193).
  • The profile's features file as faults. Slowing near full, pausing in heat, trickling into a low cell — all correct behavior — the difficulty is knowing the profile well enough to defend it at the counter (battery-diagnostics-health-measurement-and-capacity-testing).
  • The thermistor hides in the pack. The board is healthy, the charger is honest, and the sensor the IC needs left with the old battery — the difficulty is remembering the chain crosses the connector: pack-side parts serve charge-side functions (usb-power-delivery-diagnostics-and-charging-fault-isolation).

Safety Notes

Risk Level: Medium. Board-level work beside live packs — the rework law and the foundations' gates both apply, whole, at the same bench.

Professional Tips Before Starting

  • Print the splits question where intake can see it. Does it run unplugged? — one question routes the whole queue, and the counter can ask it (usb-power-delivery-diagnostics-and-charging-fault-isolation).
  • Learn each family's charge-IC nodes before the fault arrives. Input, system, battery, thermistor — labeled on the shop's diagrams — evidence is fast exactly where the map already exists (board-level-charging-repair-the-m92t36-and-bq24193).
  • Keep the teaching pack with the missing thermistor. Show, don't argue — the trickle-forever demonstration closes the aftermarket conversation in one meter reading (battery-diagnostics-health-measurement-and-capacity-testing).

The Charging Bench — The Chain, The Profile, The Splits, The Law

Recap and Frame

The chapter fed the chain — verified packs, measured verdicts, proven swaps — and this bench finally repairs it (battery-diagnostics-health-measurement-and-capacity-testing). The Switch section built the precedent. One family's charging chain — its port controller and its charge IC — diagnosed and repaired end to end, with the discipline this section now generalizes (board-level-charging-repair-the-m92t36-and-bq24193). The USB-C chapter built the upstream. Contract proven, cable proven, channel traced — the cases arriving here come with the accessory half already exonerated and numbers attached (usb-power-delivery-diagnostics-and-charging-fault-isolation). The rework bench built the law. Footprint read, removal law, alignment, the gate — every physical repair this section orders runs under that discipline unchanged (usb-c-port-replacement-and-board-level-rework). What is new is the system view. The chain as links, the profile as constitution, the power path as the splitter — the map that turns 'won't charge' into a named link and a measured accusation. And the chapter's last section waits past this one: emergencies and end-of-life — the bench this one exists to keep rare. Hold the frame — precedent generalized, upstream inherited, law borrowed whole — and the chain's failures become systematic.

Every charging complaint is one link failing, and the chain must be seen before it can be split (board-level-charging-repair-the-m92t36-and-bq24193). The port and its contract open the chain. The negotiated input the USB-C chapter owns — proven upstream, so this bench receives voltage as a fact, not a question (usb-power-delivery-diagnostics-and-charging-fault-isolation). Input protection takes the first insult. Over-voltage clamps and input FETs standing between the connector and everything expensive — the parts that die protecting, and the first suspects when input voltage arrives and nothing past them sees it. The charge IC runs the show. One controller taking the input, running the profile, steering the power path, watching the thermistor — the chain's brain, and the last link accused because it is the hardest repaired (usb-c-port-replacement-and-board-level-rework). The power path steers the energy. System fed while the pack charges, pack carrying the system when the input leaves — the switching that makes a device usable while charging, and the splitter every diagnosis leans on. And the fuel gauge watches from the side. The bookkeeper from the diagnostics bench — part of the chain's data, not its muscle, though on families where the gauge commands the pack's protection FETs its verdicts can open the pack's own path, still pack-side territory — audited exactly as that section taught (battery-diagnostics-health-measurement-and-capacity-testing). Contract, protection, brain, path, bookkeeper — the chain entire. Five links, one map — and the diagram is the bench's copy of it.

The Profile — Charging's Constitution

The charge IC runs every session by the same constitution, and the bench that knows it stops selling repairs against physics working (battery-diagnostics-health-measurement-and-capacity-testing). Pre-charge is the gentle open. A cell resting low takes a fraction of the full current until it climbs back to the bulk range — the trickle that looks like a fault and is the IC being careful within the margin the foundations described (board-level-charging-repair-the-m92t36-and-bq24193). Constant current does the work. The bulk of the session at the design's full rate — the steep, satisfying part of the curve the customer thinks of as charging. Constant voltage is the careful approach. As the cell nears its limit the IC holds voltage and lets current taper — the slowing-near-full that files as a complaint and is the chemistry being respected (usb-power-delivery-diagnostics-and-charging-fault-isolation). Termination ends it honestly. At the taper's floor the session ends — topping off later if the design does — because holding a full cell at its limit is the storage stress the foundations priced. And temperature gates the whole run. The thermistor's reading pauses or slows charging when the pack runs too cold or too hot — protection, not malfunction — the sunny-afternoon pause and the winter-garage refusal both the profile working (usb-c-port-replacement-and-board-level-rework). Gentle open, bulk work, careful approach, honest end, temperature over all — the profile entire. Half the profile's reported faults are the profile doing its job; the bench's first skill is telling which half.

The Splits — The Power Path as Diagnostician

The power path's switching is the queue's free diagnostician, and one question runs it (usb-power-delivery-diagnostics-and-charging-fault-isolation). Runs plugged in, dies unplugged: pack side. The charge side proved itself by running the system — input, protection, IC, path all working — so the fault lives past the path: the pack, its FETs, its gauge, its connector's sense lines — the diagnostics bench's territory with the swap bench behind it (battery-diagnostics-health-measurement-and-capacity-testing). Runs on battery, will not charge: charge side. The pack proved itself by carrying the system, so the fault lives upstream — port and contract first per the USB-C ladder, then input protection, then the IC — the board territory this section repairs (board-level-charging-repair-the-m92t36-and-bq24193). One pack-side exception stays in reserve. Protection FETs gate charge and discharge separately, and a pack whose charge FET latched off will pour for hours and still refuse the charger — so a board that measures clean sends the ladder back across the connector. Slow everywhere on an honest charger: profile territory. The thermistor line first — a missing or wrong sensor leaves the IC blind and blind ICs charge scared — then genuine gating conditions, then policy before any part is blamed. Dead both ways: the chain's shared spine. Power path or system rail territory — the deep end, entered with the diagram and the rework law, and only after the cheap check this route hides: some families cannot run packless or on a deeply flat cell at all, so a known-good pack rules the pack out before the diagram opens (usb-c-port-replacement-and-board-level-rework). One question, four routes — the splits entire. The power path answers before any probe lands; the bench's job is to ask.

The Evidence and the Law — Measured Accusations, Disciplined Repairs

The splits name the side; the evidence names the part; the law repairs it (usb-c-port-replacement-and-board-level-rework). The rails testify at the IC's own nodes. Input voltage arriving, system output present, battery node behaving — measured with clips against the diagram, because the controller's verdict is the difference between what enters and what leaves it — with one guard on the arithmetic: input present and output dead convicts only after the output rail itself checks clean to ground, board cold, because a controller folding back into a shorted rail is protecting its load, not failing (board-level-charging-repair-the-m92t36-and-bq24193). The thermistor line testifies early. The sensor's resistance where the diagram expects it — present, plausible, tracking warmth — because the blind-IC story is cheaper to check than any theory it mimics. The gauge's testimony gets its audit. The bookkeeper's claims against the measured truth, exactly as the diagnostics bench taught — a chain complaint wearing a ledger costume is common enough to check (battery-diagnostics-health-measurement-and-capacity-testing). The accusation lands last and repairs under the law. An IC convicted by its rails reflows or replaces under the rework bench's whole discipline — battery out, preheat, alignment, magnification, the shorts check, first power through the meter with the profile watched as it climbs (usb-power-delivery-diagnostics-and-charging-fault-isolation). And the conversion stays honest. Liquid history at the IC's neighborhood, pads that lift, corrosion under the shield — the job converts to board-level or replacement at the evidence, quoted with the photograph, exactly as the volume has priced honesty all along. Rails, sensor, ledger, lawful repair, honest conversion — the evidence bench entire. Silicon is accused by arithmetic — what went in minus what came out — and repaired by law, never by hunch.

Common Mistakes

  • Diagnosing both sides at once. Probing the board while suspecting the pack — the split's one question routes first, and everything after works one side (usb-power-delivery-diagnostics-and-charging-fault-isolation).
  • Selling repairs against the profile. The taper near full quoted as a fading battery, the hot-car pause as a failing IC — the constitution is named at the counter, not discovered after the invoice (battery-diagnostics-health-measurement-and-capacity-testing).
  • Forgetting the chain crosses the connector. The board exonerated while the missing thermistor rode out the door in the old pack — pack-side parts serve charge-side functions; the sensor line is checked early (board-level-charging-repair-the-m92t36-and-bq24193).
  • Accusing the IC by elimination instead of arithmetic. Everything else seemed fine, so the brain must be bad — the rails at its own nodes convict or acquit; nothing else does (usb-c-port-replacement-and-board-level-rework).
  • Repairing outside the law. A quick IC reflow with the battery still connected — this bench borrows every rule it touches, and the battery leaves before the heat arrives.

Troubleshooting Guidance

The charging bench troubleshoots by the splits and then the chain: side, link, node. If it runs plugged in and dies unplugged: pack side — the pack's numbers, its FETs, its connector's sense lines — the diagnostics and swap benches own it from here (battery-diagnostics-health-measurement-and-capacity-testing). If it runs on battery and will not charge: charge side — the contract first per the USB-C ladder, then input protection's continuity, then the IC's rails against the diagram (usb-power-delivery-diagnostics-and-charging-fault-isolation). If it charges slowly everywhere on an honest charger: the thermistor line before anything — missing or wrong sensors leave the IC blind, and blind ICs charge scared — then genuine temperature, then policy (board-level-charging-repair-the-m92t36-and-bq24193). If it is dead both ways: the shared spine — power path and system rails with the diagram open, the deep end entered deliberately, and only after a known-good pack has ruled the pack out on families that cannot run without one. If the IC's input is present and its output is dead: the output rail checks clean to ground first — a controller folding back into a short is innocent — and only then has the arithmetic convicted: the repair runs under the rework law, gate and all (usb-c-port-replacement-and-board-level-rework). If the evidence finds liquid or lifted pads at the IC's neighborhood: the conversion conversation, at the photograph, before the attempt. The throughline: the split names the side, the diagram names the node, the arithmetic names the part — and the law repairs what the evidence convicted.

Verification & Testing Methods

Confirm the charging bench end to end before the queue tests it:

  • [ ] I can trace the charging chain — contract, protection, charge IC, path, gauge — on any served family's diagram.
  • [ ] I can watch a live session and name the charge profile's phases as they pass — pre-charge, bulk, taper, termination, and the temperature gating over all of it.
  • [ ] I run the power path's split at intake — does it run unplugged? — and work one side only from that answer.
  • [ ] I measure before accusing — rails at the IC's nodes against the diagram, the thermistor line early, the gauge audited — and let arithmetic convict.
  • [ ] I repair under the borrowed laws whole — battery out before heat, clips before probes, the gate before power, the profile watched at the close — and convert honestly at the evidence.

Then try the practice exercises below — diagram, meter, and donor-board work; scenarios differ from the quiz.

Practice Exercises

  1. Map the chain on a real diagram (6 minutes, board diagram or schematic, desk). On a served family's diagram, trace and label the five links — connector and contract entry, input protection, the charge IC with its input, system, battery, and thermistor nodes, the power path's routing, the gauge's position — and mark where each of the splits' four routes would send your probes first (board-level-charging-repair-the-m92t36-and-bq24193).
  2. Watch a profile live (7 minutes, PD-aware meter, a device with a partly drained pack). Charge the device through the meter and log the session as phases — the current's behavior at the start, through the bulk, into the taper — annotating where pre-charge, constant current, and constant voltage each showed themselves, and write one line on what a temperature pause would have looked like and why it would be the profile working (usb-power-delivery-diagnostics-and-charging-fault-isolation).
  3. Run the splits and the evidence (7 minutes, two donors with opposite behaviors, multimeter with clips). Ask each donor the one question — does it run unplugged? — route each to its side, then take the routed measurements: pack-side numbers on one per the diagnostics bench, and on the other the charge-side ladder — input at the protection stage, then the IC's input, system, and battery nodes against the diagram, with the thermistor line checked where the family expects it (battery-diagnostics-health-measurement-and-capacity-testing).
  4. Write the splits card and the conviction line (5 minutes, desk). Draft the intake card — the one question at the top, the four routes below it, the profile's honest features listed so the counter can name them — and finish with the conviction rule written plainly — the IC is accused by the arithmetic at its own nodes only after the output rail checks clean to ground — followed by the repair's order of operations written from memory: battery out, preheat, reflow or replace, shorts check cold, first power watched, profile read at the close — with the job converting at the evidence of liquid or lifted pads, photographed first (usb-c-port-replacement-and-board-level-rework).

These core steps — the chain map, the live profile, the routed splits, and the conviction card — are tested in the Chapter Quiz at the end of this chapter, where a score of 80% is required to continue.

Key Takeaways

  • The chain reads in five links — contract, protection, the charge IC, the path, the gauge — and every charging complaint is one link failing, named by the splits before any probe lands (board-level-charging-repair-the-m92t36-and-bq24193).
  • The charge profile is the IC's constitution — pre-charge, bulk, taper, termination, temperature gating over all — and half its reported faults are the profile working: the bench's first skill is telling which half (battery-diagnostics-health-measurement-and-capacity-testing).
  • The power path is the queue's free diagnostician: runs-plugged-dies-unplugged routes pack-side, runs-on-battery-won't-charge routes charge-side, and one intake question runs the whole split (usb-power-delivery-diagnostics-and-charging-fault-isolation).
  • The thermistor line is the quiet saboteur — a missing or wrong sensor in a bargain pack leaves the IC blind, and blind ICs charge scared — checked early because it is cheaper than every theory it mimics.
  • Silicon is accused by arithmetic — what enters the IC minus what leaves it, with the output rail checked clean to ground first because a controller folding back into a short is protecting its load — and repaired under the rework law whole, with the conversion quoted at the evidence, photographed first (usb-c-port-replacement-and-board-level-rework).

Skills Learned

  • You can now trace the charging chain on any family's board diagram.
  • You can now read a live charge session and name the profile's phases as they pass.
  • You can now run the two splits and route every complaint to its side of the power path.
  • You can now measure the evidence at the charge IC — rails and thermistor line — before accusing silicon.
  • You can now repair the chain under the rework law and convert honestly when the evidence orders it.

Glossary Additions

  • charge IC — the controller at the center of a device's charging chain: it takes the negotiated input, runs the charge profile against the pack's chemistry, steers the power path between system and battery, and watches the thermistor for the temperature gating that pauses charging on purpose. The chain's brain and its last-accused link — convicted only by arithmetic at its own nodes — input present, output dead, and the output rail itself checked clean to ground first, because a controller folding back into a shorted rail is protecting its load — measured with clips against the diagram — because it is the hardest link to repair: reflow and replacement run under the rework bench's whole law, battery out before heat, the gate before first power, and the profile watched on the meter at the close.
  • power path — the switching a charging chain uses to feed the system and the pack independently: the device runs from the charger's input while the pack charges behind it, and the pack carries the system the moment the input leaves. The path is the queue's free diagnostician — a device that runs plugged in but dies unplugged has proven its whole charge side and routed the fault past the path to the pack, its FETs, and its gauge; one that runs on battery but will not charge has proven the pack and routed the fault upstream to port, protection, or the charge IC — one intake question, does it run unplugged, runs the entire split before a probe lands.
  • charge profile — the constitution every honest charge session follows: a gentle pre-charge for cells resting low, the constant-current bulk that does most of the work, the constant-voltage approach that tapers current as the cell nears its limit, and termination at the taper's floor — with temperature gating over the whole run, pausing or slowing charge when the thermistor reads too cold or too hot. The profile explains the queue's favorite non-faults — the slowdown near full is the taper respecting chemistry, the hot-afternoon pause is protection working — and its genuine failures usually enter through the sensor: a missing or wrong thermistor leaves the charge IC blind, and blind ICs charge slowly, strangely, or not at all.

Suggested Next Sections

Must read next:

  • Battery Emergencies, Swollen Packs, and Safe Disposal — Section 8.5 closes the chapter and the volume's territory: the swollen pack handled and converted without drama, the venting cell met with evacuation instead of heroics, the thermal event survived by the preparation this chapter staged, and every retired cell leaving through the disposal stream taped — the section the rest of the chapter exists to keep rare.

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