r8247

[taxi32]

hi all.

has any one had problems with there r8247

the problems im having is on one of my r8247 is when i connect points to the no:2 output

1,3,4, output stop working, disconnect no:2 and 1,3,4, start working again.

the other problem i have on my other r8247 is no:4 output switches one way but not the other.

does any one have repair knowledge on these.

[96RAF]

Try resetting them (if your controller is capable) by writing va.ue 8 to CV8 with the device connected to the controller Prog output.

[Chrissaf]

The number 4 port might be damaged or it may be mis-wired. Crossed solenoid wires can cause a point motor to only function in one direction only. See this previous explanation thread.

http://www.hornby.com/uk-en/forum/surface-point-motors/?p=1

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However, given the port 4 is not your only issue, it may be that you have a more seriously damaged R8247.

 

The number 2 port could possibly have a 'short circuit' output MOSFET semiconductor. Such that connecting a Solenoid Coil to port 2 causes the inbuilt CDU capacitors to immediately discharge and prevent any re-charge. This will have the effect of disabling the other ports on the R8247.

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If Rob's suggestion of using your Elite (Elite from your posting history) to write 8 to CV8 to reset the R8247 doesn't work. Then it does look like the R8247 is fatally damaged.

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Has the R8247 been exposed to any transient short circuits on the layout. For example a loco running against a point set the wrong way. Transient 'short circuits' on DCC tracks create very high ringing (oscillation) voltages up to 3 times the baseline track voltage [baseline is 28.8 volts peak to peak]. I know from my own personal experience that the Hornby R8247 is prone to damage by these short circuit induced ringing voltages.

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The R8247 can be protected from damage by fitting a 'snubber'. But you do need fully working R8247s to start with. A 'snubber' will not restore a R8247 that is already damaged.

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See this previous thread.

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Fitting a ‘snubber’ to protect a R8247

https://www.hornby.com/uk-en/forum/r8247-accessory-decoders-problems/?p=1

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Since fitting my own 'snubber' I have not had a single corrupted or damaged decoder issue.