francisdemarte
500+ Head-Fier
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Just logged in to check and its good to see this thread is still going strong after all these years!
Report to the seller and request for replacement. All assembled boards are supposed to be tested before shipped out.
A thinkable failure reason to try first is if it´s dirt or oxide at either the phono jack or the socket, you can just clean the connectors metal surface with some alcohol (Isopronanol or similar).Hi I just bought a lehmann clone / lovely cube equivalent (board assembled) from eBay. I am currently having an issue where if I plugged my headphone all the way into either of the front 2 headphone jacks, only the right channel works. If I plug it almost in, then both channel works fine but lacks the same sound quality as if I plugged it all the way in (even though it is only 1 channel when all the way in, I can tell the difference). I tried the output at the back and only the left channel works.
Any help would be much appreciated, I can replace components if need be. Thanks.
A thinkable failure reason to try first is if it´s dirt or oxide at either the phono jack or the socket, you can just clean the connectors metal surface with some alcohol (Isopronanol or similar).
If that will not solve it, you can try this step: As I´ve had a similar problem with mine; there was silence at one channel when touching the headphone cables 6,35 mm (1/4 inch) jack, and it was the phono jacks three metal connectors pressing not firm enough. The solution was to open up the enclosures lid and simply pushing gentle at all the three metal connectors at the female phone socket with a plastic tool.
The last step you can try, if the problem still are there; visually check/measure all solderings to be sure they are good and measure all resistors they have correct values.
Have a Merry Christmas everbody!
So Assuming you have had a chance to read through the full thread - as much as it is very long, you need to be prepared to open the case- and if you are- when you do and turn the amplifier on- check that BOTh internal LEDs are on. that would establish that at least to a point you have the power going to both channels. There is no standard published troubleshooting method so first things first - before you get to unscrewing and removing the board to check for cold solder joints or checking for shorts or pressing and squeezing, first vicula inspection that at least you have the voltages in check the internal LEDs. They SHOULD be on, even if you have removed the OpAmp from the socket. In fact witht he AMPunplugged from Power, you could remove the OpAmp, and the 2 LEDs should be on. if they are on, then you can start looking for other things.
I think earlier in this thread -and i don;t know the post there was a diagram with voltages that can be checked. Do You have at least a universl meter? they are not expensive and are necessary for any kind of troubleshooting.
Also - be mindful that the primary of the transfomer is at Grid (High) voltage, and if the safety case grounding is not properly done it can be lethal. even if grounded properly, I would feel a more comfortable with an ELCB protected power point or at least extension cable.
Or it could be the connectors? I have this problem if I use my TRRS earphones due to the microphone need extra terminal on the jack. Do you have a different headphone with a 1/4" termination? Are you using an adapter for mini to 1/4" jack? Does the line out only one channel happens all the time or only when you plug in a headphone?
I am with Penmraker on this one- Considering LEDs are on - cheap phones WITHOUT a microphone would do fine to test.
Ok, So I Don;t know how to link directly to a post - but post 389 by Flukell has the voltages as measured on a Lehman amplifier with the diagram for one channel. I'd say if you also measure those voltages on the working channel you will have direct reference from you r version of the board as well as component. but they are a good reference and start. at least it will point you to which area to focus on.
See if this link works well:
https://www.head-fi.org/threads/the...ehmann-black-cube-linear-clone.501046/page-26
If not you will have to search for Post 389
As I already stated in my earlier post, I have experienced problem with my 6,35 mm socket - and the solution was to carefully bend the three connectors down with no headphone jack inserted.Thank you for finding the post. I just checked and all the voltages is ok.
As I already stated in my earlier post, I have experienced problem with my 6,35 mm socket - and the solution was to carefully bend the three connectors down with no headphone jack inserted.
To verify this is case also for you, please try to cut the cable on a old/damaged headphones or use a upgrade cable with no headphones to it.
Insert the jack into the amp´s socket, and with power turned OFF, open the enclosures lid and measure each at a time of the three connectors at the socket and the other end of the cable. You should have no more than a few Ohms. With the probes still left, gently push the jack in all directions and see if the resistans are changing. Repeat this for all three connectors. As you are aware your right channel are working fine, you can use that as a guideline (right channel using the middle connector and the inner (tip at the jack) are for the left channel and the connector closest to the inserting hole/nearest eclosure are ground).
If the inner connector measure different to the other, then you can try to do like me and carefully push it gently downwards.