New PassDIY Headphone Amp (now available)

[6L6]

stijn001 - It's a .33uF 630V, chosen for the following reasons; I had it, and I had only the one.

Wayne used a .1uF in one of his builds -

 

[Tix88]

I definitely have some faulty components, but I can not figure out which one. The part of the power supply seems ok, the output voltages from the regulators are constant at +/- 15v. I can not understand now why on pin 7 I have 2V Dc

 

[Tix88]

I measured the voltages on all the pins of the opamp


Pin1 214mV

pin2 -0.1mV

pin3 -0.2mV

pin4 -14.83V

pin5 -0.2mV

pin6 -0.7mV

pin7 3.7V

pin8 14.74v

 

[dabore84]

Turn the amp off and measure resistance between each pin on the opamp and the ground.

 

[wayne]

look at the other side of the 47 Ohm on pin 7 and see if it is higher or lower.

 

[RobLK]

If you add together the dc voltages on the mosfet gates the remainder should be what the output voltage is on pin 7. So if one gate is -2.5v and the other is 2.6v pin 7 should read 0.1 volts. So something is not right there, it should not have that much dc voltage on pin 7.

 

[AndrewT]

I measured the voltages on all the pins of the opamp


Pin1 214mV

pin2 -0.1mV

pin3 -0.2mV

pin4 -14.83V

pin5 -0.2mV

pin6 -0.7mV

pin7 3.7V

pin8 14.74v

Are you using a single opamp, or a dual opamp?

 

[Tix88]

Dual. Opa2132

 

[stijn001]

...

Hadn't seen that before, intresting, thanks.

 

[Tix88]

look at the other side of the 47 Ohm on pin 7 and see if it is higher or lower.

Today I made the measurements, now at the output of pin 7 I have 14.56V, after the r 17 = 47ohm I have 14.42V

 

[Tix88]

Turn the amp off and measure resistance between each pin on the opamp and the ground.

Should I take my first measurement or do I have to wait for the physiological charge of the capacitors?

 

[RobLK]

If you have 14.56v at pin 7 it could mean you have no negative supply at pin 4.

 

[Tix88]

If you have 14.56v at pin 7 it could mean you have no negative supply at pin 4.

Yes on pin 4 I have a -14.96v

 

[RobLK]

If you have a socket under the op amp you could easily try another op amp.

 

[Frazzled]

These build look beautiful. I'm looking forward to building one of my own, any updates on a BOM?

 

[6L6]

Here's the (very) rough list without any annotations - (This will be organized with notes and example parts in the official guide)

P-CAD Bill of Materials C:\...\Headphone1.pcb

======================================================================

Count ComponentName RefDes Value
------ --------------- --------------- ---------------

(2) .1UF C13, C23 .1uF



(1) .22/250V C20 .22/250V

(6) 1N4003 D1,D2, D3, D4, D7, D8 1N4004


(2) 1UF_PP C1 C5 1UF_PP


(2) 2SJ313HS Q2Q4 2SJ313


(2) 2SK2013HS Q1 Q3 2SK2013


(2) 4N35 OPTO 1 2 4N35


(6) 22UF/25V_ELNA C12 C17 C22 C25 C26 C27 22UF/25V


(1) 78XXAVID U3 7815


(1) 79XXAVID U2 7915


(2) 100PF C2 C7 100PF


(6)220UF/50V C3 C4 C8 C9 C10 C28 220UF/50V



(6) 3300UF/35V C6 C11 C14 C15 C18 C19 3300UF/35V


(1) ALPS_POT P1 RK27

(1) AMVECO_25VA TR1 Amveco 70053

(2) LED D5 D6 {RED}


(1) Socket 8 pin U1


(6) RESQ R1 R2 R7 R10 R12 R14 1K


(2) RESQ R39 R40 2.2K


(2) RESQ R4 R8 4.75K


(4) RESQ R16 R22 R29 R32 10ohm


(8) RESQ R6 R15 R23 R24 R25 R28 R33 R34 10K


(4) RESQ R17 R27 R35 R26 47 ohm


(2) RESQ R18 R30 100 ohm


(2) RESQ R3 R5 100K


(2) RESQ R9 R13 330 ohm


(4) RESQ R11 R19 R26 R31 499 ohm


(4) RES_HALF R20 R21 R37 R38 5.1ohm

 

[Frazzled]

Thank you. I'll start gathering parts now so I'm ready when the board is.

 

[dabore84]

Should I take my first measurement or do I have to wait for the physiological charge of the capacitors?

Completely off, just to check that everything is properly soldered and that you didn't shorty anything.

What op-amp are you using?

 

[Tix88]

yes completely off, When I go to measure on the pins of the opamp, the measure Increment is not stable, probably for the charge of the capacitors, I have to wait for the measure to stabilize, or do I take the first measure I do without waiting for it to stabilize?

 

[dabore84]

Just initial measurement. Its should be in high kOhm range for the input and the output pins of the opamp. The supply voltages for the opamp seem ok.