First Build Problems

Zacwah · 7231

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Offline Zacwah

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Reply #15 on: August 15, 2012, 11:24:41 PM
Ok so i installed the LEDS and sanded underneath the screws. The LEDS lit up but there was no sound.
When i unplugged everything i got a zap from the Right RCA jack ( Plate is still Live (im waiting about 15 minutes after powerdown before i do anything.))
So i decided to do OHM test. Ohm's are fine apart from T7, T9, B3 and B6 i don't get a reading from them if i ground off terminal 12, But i do if i ground of the chassis earth (Sometimes).
I plugged it back in and noticed the LEDS didnt come on. Then they flashed then came back on and stayed on about 2 minutes after power up. I took the voltages and everything was live. 170-220v

I'm getting a reading from T11 and T17? Surely that can't be normal with the Fiber shoulder washers?





Headphones: AKG 702

Headphone Amps/Dacs: Schiit Valhalla, Bottlehead Crack (ordered)

Sources: Schiit Bifrost, Yamaha P-750 (Refurb Project), Sony PS-J20


Offline Grainger49

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Reply #16 on: August 16, 2012, 02:04:22 AM
Getting a zap from the RCAs is wrong.  This indicated that there is voltage where it should not be. The RCAs should have no internally generated voltage.  It receives a very small, and unnoticeable AC voltage from the source.

Where else were you touching when you received the shock?



Offline Zacwah

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Reply #17 on: August 16, 2012, 08:36:16 AM
Pretty sure i was tightening up the fastener on the RCA so that and the centre pin of the RCA.


Headphones: AKG 702

Headphone Amps/Dacs: Schiit Valhalla, Bottlehead Crack (ordered)

Sources: Schiit Bifrost, Yamaha P-750 (Refurb Project), Sony PS-J20


Offline Grainger49

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Reply #18 on: August 16, 2012, 10:55:28 AM
If you were tightening the RCA jack with one hand where was your other hand, holding the chassis?  Was it plugged in and on?  I'm trying to get a handle on this.



Offline Zacwah

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Reply #19 on: August 16, 2012, 11:13:36 AM
Unsure on my other hand.
Waited 10-15 mins after power down to touch it.
Before I get a zap the plate reads 190v. And after I get the zap the plate is 0v
But when I get 190v off the plate the RCA jacks read negative 160v.

Will be away over the weekend so when I get back I will go over the manual and check all wires and connections.

Headphones: AKG 702

Headphone Amps/Dacs: Schiit Valhalla, Bottlehead Crack (ordered)

Sources: Schiit Bifrost, Yamaha P-750 (Refurb Project), Sony PS-J20


Offline Grainger49

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Reply #20 on: August 16, 2012, 11:45:42 AM
Ok, look at the manual page 30.  There is a 270k ohm resistor from T12U to T13U.  This should remove the voltage in less than one minute when the amp is turned off.  It isn't working/wired/soldered correctly.  

Still, there is no reason that voltage should appear on the RCA jacks.  
« Last Edit: August 16, 2012, 12:43:50 PM by Grainger49 »