XXV Sampson power up issues

[Perry Babin]

The connections to the 494 aren't supposed to be to a particular pin, I assume.

The emitter outputs don't connect to the other EF pair. They drive their own individual groups of FETs.

What is it that you can't read about the diagram? Reading it is not complex. Understanding how a circuit functions can be more difficult. The connections, not so much.

 

[beatnbronco]

the connections to the 494 itself are important, not meant to specify to any individual pin and the emitter outputs were joined in the drawing just to simplify, it's not to say they actually join in the circuit

 

[beatnbronco]

i've got all of the supply drivers back in and connected i believe the way they should be, the amp powers up and output relays click

 

[Perry Babin]

Did you load the FET locations and confirm that all drive signals were good before installing the FETs? It's not a big deal if you didn't but it's a good/safe way to check the drive.

Are you 100% sure that the connections to those transistors are solid? You know that this amp is likely to take a beating from the bass.

 

[beatnbronco]

i checked voltage at each FET and they all were good and stopped there. Still need to check the signals, still need to install my scope software. It's a pc based scope so i'm not sure how reliable the readings will be. It's that or my dso nano v2 or v3

 

[Perry Babin]

Are the FETs in it yet?

To test the scope, probe one of the output terminals of the driver IC and post the image. Set the scope to 5v/div and 10ms.

 

[beatnbronco]

no FETs are in it yet. I was just about to take a pic and the scope died so it's charging now. Each center leg location for the FETs read the same so i'm hoping that's a good thing.

 

[Perry Babin]

Do you have a small capacitor to load the gates?

 

[beatnbronco]

I'm sure I do, but I do not know how to do that. I'm not sure if you can see this tiny square wave but it's there. I can try to get a closer pic if need be.

 

[Perry Babin]

If you have the tutorial, refer to TT9, item #23. If not, let me know and I'll explain here.

That's nothing. You couldn't get 5v+ on a meter from that. With the same ground, touch the probe to the B+ terminal of the amp and post a photo.

 

[beatnbronco]

ok, probe touching amp +, didn't move the ground. Not sure what i'm looking for here. I don't have the tutorial

 

[Perry Babin]

I think your probe is on 10x. Move it to 1x.

 

[beatnbronco]

you were right. New pics with prove set to 1x and probing driver IC and amp + terminal

 

[Perry Babin]

Adjust the trigger so the scope will lock on the waveform.

 

[beatnbronco]

I adjusted everything I could but couldn't get anything besides a flat signal, changing the time/div did nothing either, this is grounded on amp ground and probe to amp +. I tried both of my pocket scopes and got the same results. The switch on the probe set to x1. I've tried to send this all day but for some reason i couldn't reach the site

 

[beatnbronco]

one more thing, how do i know when dc coupling is set on this scope? There is no setting in the functions to activate it. It's a DSO v201 by Seeed Studio

 

[Perry Babin]

If you are on DC coupling, the trace will deflect up, off of the ground reference.

You are looking for a lock on the waveform, not on B+. Post a working link to the owner's manual for that scope and I'll try to find it.

The site has been down most of the day.

 

[beatnbronco]

this is the scope I have, only mine has white selection buttons. I had the one with the black selection buttons before and besides the button colors, functionality and design are exactly the same

 

[Perry Babin]

On page 8, if you set it to Threshol, does it give you a way to adjust the trigger level?

 

[beatnbronco]

Got the Hantek 6022BE running and updated. With 5v/div and 10ms this is what I get on amp pos and neg terminal. Scope and probe calibrated per manual instructions