OKTAVA MKL5000 / Electro Harmonix EH-TM Schematic
- Thread starter cmuller0420
- Start date
Help Support GroupDIY Audio Forum:
in the context of this thread it makes sense to correct the information for different reasons:
- just for sake of correctness of the schematic values provided and drawn by a member
- some people were also questioning the value of these resistors in different posts in this thread, as they were not sure about it, so now we know
- it might help some less experienced member in the future, to troubleshoot the mic and not get stuck when he can't find the 1G resistors in the circuit
- Also if there's any problem with those resistors or the mic, a member doesn't need to stress out if he doesn't have a 1G resistor at hand. 1G resistors are very expensive
- it's just information being added to a thread that might be helpful in the future for someone else, makes sense to add new info to it. This thread was useful to me even 10 years after it was posted, and it's still being useful as I still was not able to fix the mysterious Low-end Hum in my mic
Thanks mate
- just for sake of correctness of the schematic values provided and drawn by a member
- some people were also questioning the value of these resistors in different posts in this thread, as they were not sure about it, so now we know
- it might help some less experienced member in the future, to troubleshoot the mic and not get stuck when he can't find the 1G resistors in the circuit
- Also if there's any problem with those resistors or the mic, a member doesn't need to stress out if he doesn't have a 1G resistor at hand. 1G resistors are very expensive
- it's just information being added to a thread that might be helpful in the future for someone else, makes sense to add new info to it. This thread was useful to me even 10 years after it was posted, and it's still being useful as I still was not able to fix the mysterious Low-end Hum in my mic
Thanks mate
Not necessarily
Sure, not quite the 2 cents a more usual value would cost, but sub 1eu is still towards the affordable end, I'd say.https://www.mouser.fi/ProductDetail...=sGAEpiMZZMtlubZbdhIBIFho3SHfDXSt5nRQ4pdsqnc=
I made up my own test similar to above by Khron to measure the continuity of a 3GΩ resistor in an AKG C12VR. I lifted one end out of circuit and tacked a much lower value resistor in series with it. I worked out that I needed to read in the region of a few millivolts as my meter has a very high resistance in the DC millivolts range, so that went across the series low value R (I think I used 10MΩ and then 3MΩ just to have comparison readings) I then put 25V across the lot and read off the mV from the meter, worked out the current flowing through the circuit and from that the value of the resistance of the whole, subtracting the series resistor value from the total. The meter resistance in parallel with the low R became sort of negligible but to confirm I did also recalculate after measuring the mV meter resistance with another meter - not much difference, I also measured the resistance of the two low value series R’s to get a more accurate read result. The resistance on both sets of calculations was 2.97GΩ
Not necessarily
https://www.mouser.fi/ProductDetail...=sGAEpiMZZMtlubZbdhIBIFho3SHfDXSt5nRQ4pdsqnc=
Wow that's cheap,
I remember some years ago I needed 1G resistors to modify an MK-219 and I paid a lot, I remember at the time it was the cheapest my supplier had, can't remember if it was Farnell or Mouser.
Thanks for the link,
now I'm going to go back continuing to troubleshoot my MKL-5000.
Bought a couple of extra 6AK5 tubes to try out, I don't think the Low-End hum I'm having is from the present tube, but well it doesn't hurt to try out with a different tube.
Otherwise I'm a bit on a dead end here, as I already did all the mods to the PSU and the Mic that were suggested to reduce noise in the various MKL2500 and MKL5000 threads
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Is the mic supply ground at the same location as the ground of the equipment the mic is feeding? Had problems before with ground loops where the mic power supply has its power earth connected to equipment looping via the main switchboard creating a hum loop, or long mains earth distance between source and target compared to short audio earth (or vice-versa) Didn’t affect all - just some mics. One was an old Telefunken.
Air conditioning and refrigeration equipment on the same phase as audio can cause problems. Also in commercial environments where they split power take-offs for wall sockets between phases on different walls for load balancing and causes crazy hum. This has caused grief for me in clubs where the stage power or the front of house power is on the same circuit as bar fridges and the like, or front of house is on a different phase to stage power.
The problem is really in the MKL-5000 microphone itself
Meter check earth continuity all the way to the mesh I presume?
Edit: if the 1G resistor to ground is open this could cause an issue.
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