Hi, I think I messed up but cant understand why.
I made a dual mono LM3886 and proceded to integrate some old stuff I found in the basement. This was an ESP P05 rev B powersupply and P06 rev A phono stage. Everything worked as it should.
After that I thought that I should add a bluetooth receiver and purchased a CRS8645 module running on a 12vdc supply. Since I notices the aux pin on the psu I wanted to use that one to drive the module, but since it seems to be unregulated a bought a pre made regulator board consisting of a 12v regulator and some caps.
I connected the regulators dc-in to the aux pin on the psu and the ground to the gnd on the psu. Next the dc-out on the regulator to the bt modules dc-in and the regulators ground to the bt module ground and started everything up. The modules LED started to flash and the R10 on the psu went up in smoke.
What did I do wrong now???
I made a dual mono LM3886 and proceded to integrate some old stuff I found in the basement. This was an ESP P05 rev B powersupply and P06 rev A phono stage. Everything worked as it should.
After that I thought that I should add a bluetooth receiver and purchased a CRS8645 module running on a 12vdc supply. Since I notices the aux pin on the psu I wanted to use that one to drive the module, but since it seems to be unregulated a bought a pre made regulator board consisting of a 12v regulator and some caps.
I connected the regulators dc-in to the aux pin on the psu and the ground to the gnd on the psu. Next the dc-out on the regulator to the bt modules dc-in and the regulators ground to the bt module ground and started everything up. The modules LED started to flash and the R10 on the psu went up in smoke.
What did I do wrong now???
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Are you sure that the CRS8645 module can cope with 12VDC supply? To me it seems a 5VDC max supply. The chip itself can tolerate only 3.3VDC.
I also can not see where R10 resistor is!?
Regards,
Oleg
I also can not see where R10 resistor is!?
Regards,
Oleg
Well, the add said that it can take both 5v from usb and 12v from a car.
The r10 is the brned resistor on the psu.
The r10 is the brned resistor on the psu.
I see now. The resistor which is burned is R2 and is in the negative supply rail forming CRC filter, which makes it even more suspicious. AUX supply is on the positive rail. Are you sure you wired everything correctly?
Well, i'm looking at it now and I can't see any errors.
Everything works fine intill I added the bt module and regulator board. To low load perhaps?
Since BT module is attached to the AUX supply which sits on the positive supply rail I do not see how it can burn the negative supply resistor.
R2 is on the negative side and aux is positive.
Link to regulator description.
http://www.audiowind.com/pdf/A-230FIXED.pdf
Link to psu board, mine is revB
Power Supply for Preamps
I proceded to test the bt module with a 12v battery and it worked as it should. I also connected the regulator board to two 9v batteries and the voltage was lowered from 18vdc to 12vdc with a 3k3 resistor as dummy load.
Some more tests. I replaced the burned resistor with a R10 0.3w and tried the psu with only the phono stage and the resistor went up in smoke.
Replaced it again and started up only the psu with a 3k3 resistor as dummy load and the psu gave +-15vdc.
So it must med the phono stage.
This is strange since I tested the phono and psu before i hooked up the bt and regulator.
As we speak, signal input is connected to RCA sockets, input ground to RCA socket ground lug (these in turn to volume pot ground and power amp input ground). Signal output to volume pot (by input selector) and on to poweramp input.
Output ground are not connected.
When the resistors burned no sources or speakers where connected.
Replaced it again and started up only the psu with a 3k3 resistor as dummy load and the psu gave +-15vdc.
So it must med the phono stage.
This is strange since I tested the phono and psu before i hooked up the bt and regulator.
As we speak, signal input is connected to RCA sockets, input ground to RCA socket ground lug (these in turn to volume pot ground and power amp input ground). Signal output to volume pot (by input selector) and on to poweramp input.
Output ground are not connected.
When the resistors burned no sources or speakers where connected.
And the final test.
Bt module and regulator connected to aux works (phono not connected).
So something happened to the phono stage.
Bt module and regulator connected to aux works (phono not connected).
So something happened to the phono stage.
In my first post I didnt know its designation so I used its value.
So R2 has a value of 10ohms.
Original Power rating was 1 or 2W
To burn 1 Watt 10 Ohm resistor it should pass significantly more than 330mA. The regs can tolerate up to 1.5A so they will not burn. You should look at your phono and try to figure out what can cause such a high current draw.
Yesterday I dug deep in the used parts bin and found a single OP-amp, as luck would have it it was an opa2134. This OP had the same number on the top as one of the installed OPs, so I replaced the odd one with this new one only to have a pair with matched numbers, not very scientific but I had to try something while waiting for the post to deliver som ne5532s.
To my surprise it acually worked, at least without anything connected. Nothing started to smoke or catch fire. So today I'll try everything out again. With a litte luck it might just be the one OP that went bad for some reason.
To my surprise it acually worked, at least without anything connected. Nothing started to smoke or catch fire. So today I'll try everything out again. With a litte luck it might just be the one OP that went bad for some reason.
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