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Heineken's Garage

Radio Head Unit - Cassette Belt Replacement

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Introduction
Beside ageing capacitors, the NSX's Radio Head Unit suffers from another well known issue in the world of cassette drives: Lengthened capstan drive belts. Typical life time of the belt is estimated to be around 20 years but might vary based on storage conditions and usage.

Diagnostic
First indications of a failing belt are functions related to reverse operation acting strangely. Typical observations are auto-reversing instead of rewinding when using skip track, repeat or similar functions but fast-forward still works fine. Background of this behaviour is that the belt's looses its grip when reversing, causing the tape to stop moving and the radio to assume that the end of the cassette is reached - initiating auto-reverse.
At a later point the cassette deck stops working completely.

Preparation
A suitable replacement belt has a length of ~408 mm equivalent to a diameter of 130 mm. It's a square cut belt with a height of >1.0 mm (probably 1.2 - 1.5). It can be sourced from CSI Elektronik in a 1.0 mm version that works fine but the same length at a height of 1.2 would be even better.
Above dimensions are based on the observation that the worn-out belt had a diameter of 135 mm and 5-10 % is a typical figure for wear up to the point of failure.

After obtaining a suitable replacement belt, removal of the radio from the centre console is the next step, followed by opening the top of the head unit. Two screws at the back of the radio need to be unscrewed before the metal cover can be removed. As the metal lid is locked into the front cover, carefully lift up the back first, then detach it from the front. The cassette module is held by four screws on each corner and can be lifted straight-up after they are removed.

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the module secured in the housing ..
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.. and after removal
Repair
Looking at the bottom of the cassette module, two screws are holding a metal cover with the belt underneath. To detach the cover, remove the screws, slightly lift it up (don't damage the ribbon cable) and slide it a few millimetres towards the top. This releases it from the two bottom tabs and allows it to be removed.

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cover attached ..
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.. and removed
Installing the new belt can be a little tricky as its not allowed to be twisted on its path around the rollers. Once done, it's the reverse of removal to install everything back together. Ensure to test all functions of the tape deck before considering it a successful repair.
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