Have a look here:
If the meter shows 140 mV, then the current through the capacitors is 14 nano Ampere, that's 0.000000014 Ampere, it is simply the leakage current you are measuring.
Ok Thanks...
I didn´t know this
I would like change the ceramics capacitors of the input and something else, nothing complicated.
Normaly there will by no problem in changing the type of capacitors.
Is there a way I could see the schematic ?
But I have no schematic to look at, is there any place I can see it ?
I believe you can, here it is thanks to Miles Campbell.
Attachments
I believe you can, here it is thanks to Miles Campbell.
Hi guys
Ok, it´s the schematic. Thanks Mkusan.
Well, I used a cap on the output because I measured the voltage between the Output pad and signal ground and the volt was around 500 mVolt.
Regards
Well, I used a cap on the output because I measured the voltage between the Output pad and signal ground and the volt was around 500 mVolt.
It should be possible to reduce the offset there by means of VR3/4
Ok, I see that the schematic is the same as used in the blue PCB. There is an error on it C23 and C24 shall have + to GND.
C23/24 see AC voltage so it don't matter. You should use non polarized audio cap (or two series cap) here.
I suppose that this pcb have some problem... I'm thinking buy the new version (blue PCB).
What do you think?
Regards
I believe, apart from the color of course, they are the same, so there is no point doing that.
There is a build guide with pictures made by Miles Campbell in this thread, did you have a look at it and measured various voltages on the PCB as advised.
It would be also helpful if you post pictures of your build (both sides of the PCB).
Hope you will sort it
Marko
Hm, really, sorry! I misunderstood the schematic... But I used 2 series caps here and the sound is clear, detailed.No, there is no AC voltage on C23/24. Standart elektrolytics are all right, but they shall be connected with + to GND.
According to simulation there is really about -1V. I will not take apart it now for a measurement...
The offset is almost the same at my both JLH amps. I built these according to Miles Campbell's build guide, except I used multiturn cermets and trimmed the offset.By the way, at startup I measure about 100 mV Offset, and after 5 min. the Offset is down to 5 mV and stays in that area.
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Tomorrow I will take some pictures of this PCB
By the pictures, I suppose that the components are the "best" quality on the blue PCB ¿?
Regards
No, I don't believe that better quality parts come with newer blue PCB kit,
e-bay sellers use what is available to them and cheapest at a given time.
Replacing input caps with something better like WIMA as oz7aff suggested is worth doing, C23/24 could probably benefit from better parts as well.
Regards
Marko
An externally hosted image should be here but it was not working when we last tested it.
Rear:
An externally hosted image should be here but it was not working when we last tested it.
And I don´t like this (around C32 and C26)
An externally hosted image should be here but it was not working when we last tested it.
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