[BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD

[prepanic]

I´m still biulding the Sta-Level, the most ist finished and i tried it yesterday.
The Resistor R3 in the Power Supply was cooking so i changed it with a 25 W / 1K Ohm Resistor.
The new Resistor is still very hot and also the Voltage Regulator for the Heater.

Is it normal?

All Voltages are ok.

B+ is 305 V
Bias is 96 V

Also the Voltages on the Mainboard looks good.

Any Ideas?

Best
Patrick

 

[bernbrue]

Hi Patrick,
Voltage regulator for heater needs to be mounted on chassis. Don't forget the isolation washer. For R3
I would also mount it on the chassis.
Best
Bernd

 

[groselicain]

Currently building mine and I had a couple of quick questions to see if anyone might have encountered a similar problem—I figure this might help diagnose it more quickly.

I followed the Monoklang's wiring diagram exactly, yet my V+ LED is not lighting up. Anyone else had this issue? Also, my Simpson meter is not lighting up, nor is my pilot light. Is the Pilot supposed to be an LED and not a Type 47 bulb?

Lastly, some of the voltages at the test points are a bit high, but I suspect that it may be connected to the V+.

I'll wait for your advice—thank you.

 

[prepanic]

Is it possible to let the LED and the both LED-Resistors for B+ and Heater out from the PSU-Board?

Best
Patrick

 

[bernbrue]

Hi,
Notification via email doesn't work, sorry.

@ prepanic: yes

V+ LED not lightening up = led  wrong orientation . It's optional anyway, you can leave it out.
But: do you get 5V from the psu? Measure, please.

Verify what kind of bulb/led is used in your Simpson meter/pilot light. Check the polarity.

As long as your voltages are in the 10% range there is no problem.
Cheers
Bernd

 

[groselicain]

@bernbrue

Even though the original LED was oriented correctly, I removed the V+ LED just to be sure and replaced with another. Still no light, but I noticed I get the smallest flickering on the filament of the T47 bulb in my pilot. Then I tried it without any LED and yielded the same result.

As I said before, the bulb in my pilot is a Type 47 bayonet bulb. The meter is a NOS Simpson 47 rated for 200ma DC, and I must confess I know nothing about these. Is there a chance that it doesn't have a backlight? I assumed the spade would at least jump as the unit powered, but there's nothing going on here.

Does that help you understand my problem better?

Thanks for your patience.

 

[bernbrue]

Hi,
You need to know wether your bulb needs 12V, 6V or whatever. Take out the bulb and try to identify what is written on the bulb. Have you measured your voltages with a multimeter? Please measure at all the test points provided on the main pcb.

Your meter is not suitable for this build. You need a 200 micro ampere or at least a 1 mA, not a 200 milliampere. Take any VU meter you've got and just test if the needle rises when powering on.
Cheers
Bernd

 

[groselicain]

Sorry Bernd, I really meant in the last post to write down what I was finding at the test points. I'll do so here:

A  81 V
B  10 mV
C  1.3 V
D  0.668 V
E  1.29 V
F  11 mV
G  80.6 V
H  128.6 V
I  188.1 V
J  3.1 mV
K  2.5 V
L  2.3 V
M  3 mV
N  199.6 V
O  321 V
P  15 mV
Q  2.5 mV
R  327 V
S  229 V
T  24.8 V

Looking at the pilot light bulb, which I assume is a 6.3V/150mA, I can't find any information that indicates anything to the contrary.

If I've left out any other pertinent information, just let me know. I'm very sorry for being a hassle—and I'm very thankful for your patience and help.

 

[bernbrue]

Hi,
Your voltages seem allright. At some test point they seem a bit high but within the acceptable range.

Please disconnect everything from the 5V rail and measure the output voltage. You can take out all the test LEDs with their corresponding resistors as well. They are optional and not necessarily needed.

Then connect your pilot lamp and see what's happening. In case both, the relays and the pilot lamp are powered from the 5V rail, I recommend to connect the pilot lamp to the 6,3V heater supply.

A picture could help.
Cheers
Bernd

 

[prepanic]

My finished Sta-Levels "PRO"

I made some modifications like a variable Threshold and a sidechainfilter.
Also i put the switch and the pot for the bias adjust on the back, so it is not nessacary to
open the chassis to calibrate.

 

[groselicain]

Bernd,

    Just reconnected the pilot to the 6.3V and it works now like a charm. I went ahead and ordered a couple of new 200μa meters. That was a stupid mistake on my part, I misread the parts list. I've also removed the V+ LED and resistor—I want to leave the LED on the B+, if for no other reason than to see that the capacitors have completely drained.

Now testing the V+, I'm getting a reading of around 12V.  Here's a picture:

I'm testing right from the terminal, so this should be what the relays are seeing. Is this too much? Should I be seeing a change when I adjust the V+ trim? It doesn't appear to be working. Maybe you'll see an error in my power supply. If I should post more pictures, just let me know. I apologize for my rat's nest of wiring.

Thanks again so much for your patience and help, Bernd.

Cody

 

[bernbrue]

Very nice units! Great work! I hope you like what they do!
Cheers
Bernd

 

[bernbrue]

Hi Cody,
What kind of power transformer do you use? The secondary of the transformer should deliver 300V, 9V and 5 VAC.  I'm a bit astonished that you've got 12V. So we need the specs of your power transformer.

Bernd

 

[groselicain]

Agreed on the transformer. It's the Don-Audio that was specified for the project.

 

[bernbrue]

and your LM350 regulator mounted to chassis  is in danger of causing a short because of the extremely bent pcb. Normally regulator and pcb are in a 90 degree angle.
Bernd

 

[bernbrue]

Ok, than I suppose that you connected the 9V secondary to the 5V rail of the psu and vice versa.
Bernd

 

[groselicain]

Bernd,

    I'll fix the PCB for the regulator now. I'll check the secondaries now and see if I that fixes things.

 

[bernbrue]

Take your time.
Bernd

 

[groselicain]

Well, I can say with a fair amount of certainty that it wasn't the secondaries being switched.

The jump to around 20V definitely reflects the additional voltage that's mysteriously appearing along the V+ PSU. I'm going to go through now and make sure it's not something I've done. Let me know if you come up with any other ideas.

Thanks so much, Bernd.

EDIT: I think I have an idea. At the last minute, I decided to change from the 24V relays to the 5V after seeing the pictures of others' builds. I never removed R8 after this, so the 3.9K resistor is still there. I'm removing it now.

SECOND EDIT: Never mind. Still hovering around 12V.

 

[bernbrue]

From your multimeter It looks as if you are measuring AC. We get DC there. Maybe I'm wrong.
Bernd