FCUPS power supply DIY Hifi Supply Lux91 R6/R17 values

kehall

Member
2020-02-22 12:01 pm
Hi, I have on repair a couple of Lux91 monoblock amps - the problem has been fixed (dead heater voltage regulator), but I like to go the extra mile.

There's a couple of resistors on the FCUPS board, both seem a bit underrated as get exceedingly hot and have effectively gone very crispy and darkened and crumbling the surface paint away, so I can't easily tell what the exact value of these are but it looked to be 150K and 100K for R6 and R17 respectively - now when I took them out they measured 156K and 106K.

Anyone know what the exact values ought to be? Please see attached images (not sure if forum supports inline images - couldn't find the option)

Our mains voltage here in the UK is often well over 250V so we do find extra heat in things but these are very toasty indeed. There's about 470-500V drop across these resistors so they look a bit small for almost 3W of dissipation.

Any help welcome - I have tried diyhifisupply directly but get no response.

Thanks in advance

Keith
 

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kehall

Member
2020-02-22 12:01 pm
For what it's worth if anyone else is in the same position, I replaced these with 150K 3W and 100K 7W (5W probably would have been better physical size wise, but it's what was available as struggled to find a reasonable supply of these values in 5W form rated to 750V).

Much better heat dissipation now on R17 down from 162degC to around 100C and 129C on R6. :)

The excessive heat I think permanently increased the resistance of the older components, the other monoblock measured 164K and 108K.

Still no idea where schematics or service data can get obtained though, I get no answer from diyhifisupply :confused:
 

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