SSR01 12V with 15 volts out

[peranders]

Hi P-A

I've built 2 SSR01s and unfortunately neither of them work.  I've checked my build against the photos on your site, double checked the placement and values and checked for dry joints.

With 14.8v from my supply I get 11.96 out.  If I increase Vi, Vo also increases about 3 volts above Vi.  The LED H1 doesn't light, it is in correctly.

I've measured some voltages in circuit with a 120R on the load.

Vi  is 14.8

Vo is 11.96

Pre reg out is 13.1

Q1e is 12.6

Q1b is 11.8

reg nfb is 12.55

LM317 Vo is 13.1

AD825 pin 2 is 6V, 3 is 9.9V, 7 is 11.57V, 6 is 11.9V

R8/R11 is 6V

Vref FB is 1.8V

Vref is 9.9V

If I increase Vi, then Vref and VrefFB both increase.

The only difference I can see is that you are using BC556C, I'm using BC556B.

J1 and J2 are both shorted.

Any ideas?

[peranders]

For proper function you must have 5 volts more in than you have out. For 15 V out you'll need 20 V in. If you remove the LM317 you will gain 2.5 volts.

[peranders]

Kevin:

Hi

thanks for responding.  I can't get 5V above Vout.  I need 12V regulated, but with a Vin of 18V Vout is 15V.  Vout isn't clamping.

I find something that I don't understand.  DZ1 connection to Q1c is12.6V, ZD1 to Q3e is 6.7V, but if I put the DVM directly across ZD1 I only get 1.3v, where is the other 5V?

[peranders]

How much is the AC voltage?

[peranders]

Kevin:

I'm feeding it from a variable bench power supply.  AC is negligible.

[peranders]

How much voltage will you have in the finished installation?

You can also remove the series resistors you have in the smoothing section. (EDIT: Thought for a second that it was about the SSR03)

[peranders]

Kevin:

I'm building the SSR01 12V version.  I will be feeding it with a smoothed DC from a 15Vac transformer, so feed voltage will be about 20VDC.  It's going to supply the 12V to a DIY DDAC.

[peranders]

Have you used the 12 V BOM?

Pin 3 of the AD825 shall have 6 V. You have 9.9 Volts. Do you use LM431 or LM329?

[peranders]

Kevin:

Yes I have used the 12V BoM.

LM431.  Vref is 9.9V.  R13 is 2k2, R14 is 3K3 and R15 47K.  With my meter I measure across R14/R15 and get about 3k0 in circuit.  R16 is 2k2 which gives me 1.8v on pin 1 of LM431.  I have checked voltages on the pins of LM431 and found them to be as above.  I reference voltages to X8 ground.

It looks like R13 has about 1mA through it, R16 has about 0.9mA through it, so LM431 is not passing any current of note?  Input voltage set at 15V.

[peranders]

2.500 Volts across R14?

The LM431 fitted within the fat outline?

http://sjostromaudio.com/hifi_pics/hifi_100pr/ssr01r0_12V_LM431.jpg

[peranders]

Kevin:

R14 has 8.1v across it.

LM431 fitted as per this photo  http://sjostromaudio.com/hifi_pics/hifi_100pr/ssr01r0_12V_LM431.jpgI replaced the LM431 in  case of problem.  No difference to voltages.

[peranders]

Are J1 and J2 connected? Tin blob on the solder side?

Voltage drop across R16?

[peranders]

Kevin:

J1 and J2 are connected with a tin blob.

R16 has 1.8V, so about 0.9mA.  There is a drop across R14 of 8v so approx 3mA through there.  Which would suggest about 2mA going through the LM431 ref to ground.  It doesn't seem right.

AGND and GND are connected with a resistance of 0.2 ohm between X6 and X7 according to my meter.

[peranders]

Can you by accident have reversed the polarity? This will lead to instant destruction of Q3 and in some cases N1/N2.

The LM431 seems fishy but you could do a test to see if the opamp is alive. Short the Vref across A and C. Zero volt at pin 3 and more at pin 2 shall lead to low voltage at pin 6 and the output voltage should be approx. the DZ1 value, 6-8 volts. Check also if the base-emitter voltage of Q3 is 0.65-0.70 volts.

[Kev]

Well I got it sorted.
I had a spare 12v board and enough bits to build another regulator.  This worked fine with 12.1V out and stable.
The 5V board I found the problem.  When I built the board I followed the BoM, this says "'Zener diode, 6.8V, 500 mW, DO35 or a LED" so as I have lots of zeners I used that.  When I fault found the board I noticed that the output was too high, so I swapped for a LED and all is fine at 4.98V.

Now I have a better understanding of how this works I'll fault find the faulty 12V regulator later on.  At the moment there's too much building to do

regards
Kev