Stage Line 500W amp repair project

[bikemech]

The box only has 1 BNC input for the 1 probe, and 1 audio jack as the output to the soundcard/laptop,
I do have meter leads with crock clips and do have a BNC to crock clip lead

 

[bikemech]

The probes i have are said to 100Mhz , does this mean that it there capable limit?, i think i had my sig gen much higher than that

 

[bertus]

Hello,

Your signal generator can generate signals upto 500 kHz.
The 100 MHz probe will have no problems.
The soundcard scope can handle signals upto 20 kHz.

Bertus

 

[WHONOES]

O.K. You should still be able to carry out the battery check I suggested. You can, as you suggested, measure the output at the headphone jack using your DMM.

 

[bikemech]

At 1:1
I get 1.402vdc
That is with the positave probe on the base of the audio jack and the negative probe on the second connection point along, the BNC to crock clips have red and black clips, i set red to + and black to --,
I am wondering if i have the connectiong reversed to the phono jack

 

[bikemech]

I currently have it wired, green to pin 3, and yellow to pin 4,
See second diagram below

 

[WHONOES]

What does the battery measure on its own?

 

[bikemech]

What does the battery measure on its own?

1.41vdc

 

[WHONOES]

Ok. That's all reasonable. Your box seems to be working.
Have you tried it with you virtual scope recently?

 

[bikemech]

I think i see the issue here, with another set of headphones the computer sees the mic and lets me select it, with the lead i have cut up it does not!,
Is it possible it has something to do with the small board the MIC is attached to on the headphone lead ?

 

[bikemech]

 

[bertus]

Hello,

Could it be that 3 and 4 are exchanged?
When you measure the speaker between 1 and 4, 4 is the ground.
When you measure a high value between 1 and 4, 3 is the ground.

Bertus

 

[WHONOES]

Can you determine the maker of the sound card in your computer. If so we may be able to get some info on it and see where the hiatus is.

 

[bikemech]

I have just tried reversing the wires, that didnt work either, possibly as i am using a laptop and not a desktop with dedicated MIC input, i dont think i am going to be able to get this to work with what i have,

I could try one of these,
https://www.ebay.co.uk/itm/USB-PC-L...-/253113597748?_trksid=p2349624.m46890.l49292

However i think i am going to order a cheap scope and keep this project going on the side

 

[bikemech]

Not sure how good this cheap stuff is going to be, but its a start

 

[bikemech]

So how do i use this equipment?

 

[WHONOES]

Do you have any info on the devices you have bought?

 

[WHONOES]

Do you have any info on your units?

 

[bikemech]

This is the scope and sig gen, both were ebay purchases

https://www.ebay.co.uk/itm/With-Cas...-/303827383640?_trksid=p2349624.m46890.l49292

https://www.ebay.co.uk/itm/2021-DDS...-/353319828971?_trksid=p2349624.m46890.l49292

 

[bertus]

Hello,

As for the scope, have a look at the attached document.

Bertus