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XTi4000 Not Working

Xti4000 not working dead power supply

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#16 starlight9088

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Posted 09 September 2013 - 01:29 PM


Hi Alain.


I have replaced the kickstart cap C196.  Sadly this didnt fix it either :(


I have also removed R375 and tested the voltage at U16 pin 1.  The result I got is 37.6Vdc

(250v UK power supply)


Thanks.


Andrew


#17 joust

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Posted 10 September 2013 - 10:01 AM

Hello Andrew,

Are you connected to the correct V_BULKRTN? Make sure your 'ground' or reference is hooked and located at TP21. (I believe the correct measurement should be 16V because a 16V zener is located at this junction!) Also, can you tell me what is the voltage at the junction once R375 when it is reinstalled? (It should be the same voltage as the zener diode!) Perhaps this is your issue: the zener diode is open; As such, the voltage at the base of triple regulator circuit being higher than at the collector, may cause the regulator circuit to be at cut-off!
Can you confirm that you have the 30V control voltage (+30V_CTRL) at the triple regulator circuit?
Can anybody confirm that on a 220V XTI main board, the D31 zener diode is a 16V device?
Also, can anyone confirm that on a 220V XTI main board, the V_BULK voltage 'prior' to SMPS power up completion is 170V?
Andrew, do you have a variable transformer? If so, can you adjust for 220V operation? (Unit should operate within 240VAC; At 250VAC, it may have reached HIGH LINE activity and doesn't power up!)

Alain

#18 starlight9088

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Posted 09 December 2013 - 04:14 PM

dos anyone know how to add someone into this conversation that is a member, but has a 'validating' status? Or, can anyone out there validate him?  (NoizyGeoff)

#19 starlight9088

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Posted 09 December 2013 - 04:50 PM

FAO Alain (and anyone elso who could help!)

Firstly thanks for all of your help so far..

A little time has passed since i last posted and I have since passed the Amplifier into the hands of a professional!  He is in the process of getting validated onto here but until then I will post his results and findings.

The unit was powered up.  After which Q47, (IRF260N) popped. This was replaced along with it's companion diode D35, as were C196, C275 & C193.

C201, C186 & C188 all measure ok as do these resistors:
8x  47.8KΩ, 1 Watt, 1% resistors
2x  35.7KΩ, 1 Watt, 1% resistors

The 16V zener at the R375 junction is OK too.

All the IGBT devices are ok (not short)

all that happens now on power-up is the device
RT6X gets hot very quickly!



Thanks in advance for any replies.





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