[Dr_C]

The next three posts provide a simple summary of repairs carried out to a bundle of fourteen faulty Scalextric C8515 digital decoders. 

These were a mix of rev F, rev G and rev H decoders.
Some had previously been upgraded (i.e. MOSFETs) and in addition some had been re-flashed with ICP v3.3.

Faults are typically known to be diode failures, MOSFET failures, and occasionally npn transistor failures - all typically related to excess current and/or voltage spikes.

REPAIR PROCEDURE
===============

The repair procedure was as follows (results will be shared in the next post).

Step 1
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Test diodes with a Digital meter (in diode test mode) and replace any that are faulty.

Step 2
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Remove both output MOSFETs and replace only the n-channel MOTOR drive MOSFET with a new one. An upgrade replacement AO3434 can be used.

Step 3
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If the decoder then functions, i.e. motor is controllable, then replace the p-channel MOSFET with an upgraded replacement AO3401.

Follow-on
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If the decoder then functions i.e. motor and brake are controllable the job is done. If not a more advanced diagnostic is required.

ICP
===
Where decoders are flashed with ICP v3.3 an upgrade to ICP v4.0.1 is recommended.

Note: ICP v3.3 was upgraded to ICP v4.0.1 on arrival of the ARC PRO to improve compatibility with this newer powerbase (upgrade features, improved lap counting on ID5 and ID6, more reliable on-track power-up & improved throttle profiles). Neither ICP v3.3 nor ICP v4.0.1 is recommended for use with braided tracks.