Author Topic: 8656B only fan running  (Read 819 times)

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Offline Daxxin

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8656B only fan running
« on: November 19, 2017, 09:48:52 am »
cannot hear the relay switch , looking around this circuit i found CR17 (1N4150) open , since the panel is totally off , can be this the cause of trouble?
just finish to replace it with 1N4148 ..

 

Offline VK5RC

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Re: 8656B only fan running
« Reply #1 on: November 19, 2017, 10:10:24 am »
Isn't it there to stop "back emf' from the relay when it de-energizes, if you measured it in circuit and it's open , isn't the relay coil also open?
Whoah! Watch where that landed we might need it later.
 

Offline Messtechniker

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Re: 8656B only fan running
« Reply #2 on: November 19, 2017, 10:17:56 am »
To start with, the reverse voltage spec of 50 V for the 1N4150/1N4148
seems to me a bit low for this application. I'd use a jelly bean 1N1007
with a reverse voltage spec of 1000 V here. But that will not solve the
problem you have.
Agilent 34465A, Hameg HMO1022, R&S HMC 8043, Voltcraft VC 940 and M-Audio Audiophile 192
 

Offline Daxxin

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Re: 8656B only fan running
« Reply #3 on: November 19, 2017, 10:36:22 am »
Relay is working , desoldered  and tested all contacts with external psu , just replaced with 1N4007 , outside from the circuit cr17 was open
anyway the problem remain , measuring TP about 5V+ rail too weird dont have voltage at the input of regulator , the link is realized with wires and connectors and tested
it was OK , the relay i tested before it was working und UNREGULATED +5V is present , what you think if i connect with crocodiles jumper?

 

Offline Daxxin

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Re: 8656B only fan running
« Reply #4 on: November 19, 2017, 10:55:37 am »
With the jumper its working even no output but now dispay is ok ..meaning the relay is gone died  |O , what trouble if i short the traces under the pcb relay contact? ..really not worth 60 euro relay
« Last Edit: November 20, 2017, 07:18:30 pm by Daxxin »
 

Offline Daxxin

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Re: 8656B only fan running
« Reply #5 on: November 22, 2017, 06:55:58 pm »
This step attenuator was reworked by someone i dont know what they did but this pin marked wirh arrow remained unconnected
do you have schematic or detailed pic to fix?

 


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