Indramat F8 fault — handling legacy Rexroth servos

Indramat is a legacy servo brand, now part of Bosch Rexroth — old European machines in Vietnam still run many Indramat drives (DKC, DDS series + MAC/MKD motors). When the drive shows an F8 fault group on its 7-segment display, the machine stops and technicians often struggle because documentation is hard to find.

Common cause groups (F8... faults)

1. Power / DC bus — voltage drop, lost phase, weak DC-bus capacitors after years.
2. Motor feedback — encoder/resolver fault, broken/noisy feedback cable, oxidized connector.
3. Overcurrent/overheat — mechanical jam, failed cooling fan, hot drive.
4. Parameters / firmware — lost parameters after a memory-battery swap, or a faulty firmware module.

How to check

1. Record the exact code Photo the 7-segment display + note model + firmware; consult the right series manual.
2. Check power Measure input voltage, phases; observe the DC bus; look for bulging caps, overheating signs.
3. Check feedback Inspect the encoder/resolver cable, connectors; swap/test cables; clean oxidized contacts.
4. Rule out mechanics Turn the shaft by hand (when safe) to check for jams; inspect the brake, load.
5. Parameters Check the memory battery/parameters; if lost, reload from backup (keep a parameter backup ready).
6. Source parts If hardware is dead: equivalent parts (Rexroth still supports some), or a salvaged drive.

When to call an expert

Few people still know legacy Indramat, and the docs are scattered. DeepDebug helps read the code correctly, localize power/feedback/mechanics, and source replacement parts — including advising an upgrade to a modern IndraDrive when needed.