Oscilloscope crash course for audio / 1072 - I could use one

Jazz · Jan 18, 2007

Hello, pals. I thought I would fire up my old Teletronix 2215 60Mhz scope to take a look at my second 1272 clone that is not working. My experience with scopes was about twentyfive years ago with microprocessor boards when the CPU's used were Zilog Z-80 and apple 6502 and Intel 8080 ....so, a digital background.

I was wondering if anyone would care to tell me how to set the scope up for basic probing and looking around on this 1072 preamp.

Wait, still more :green:

A general plan of testing on this circuit would be helpful. I'm not a bad trouble shooter when I understand the theory behind the circuit. My knowledge of this circuit is limited.

Without knowing much about it..... this would be my current approach.

1) Double & triple check wiring, grounding, and solder splashes etc.

2) Hook up a mic, check output of the 31267 tranny.

3) View signals on preamp section of BA283

4) View signals on amp section of Ba283

5) Moving towards output transformer.

I've kept things simple.

Mic input wired only to input transformer at this time, dynamic mic, no phantom power.

I could swap stuff for days I'm sure.....but it is much more interesting to trouble shoot in a scientifc approach.

As usual, THANKS IN ADVANCE :thumb:

pucho812 · Jan 18, 2007

lucky for you Keef, SSLtech once posted a good tutorial on how to use one of them scope and the best part it was audio related. Do a search of the lab and one should fine it unless our crash yesterday too it out...

shortyboyboy · Jun 10, 2020

Whoooa! Any chance you could link us?? Thank you!!

pucho812 said:
lucky for you Keef, SSLtech once posted a good tutorial on how to use one of them scope and the best part it was audio related. Do a search of the lab and one should fine it unless our crash yesterday too it out...

ruffrecords · Jun 10, 2020

If you want to trouble shoot then as well as a scope you need a multi-meter and a signal source. Rather than connecting a mic to the input you should connect a 1KHz sine wave source. You scope will easily trigger on this and it is obvious if it is there or not or if the circuit is clipping. You need the multi-meter to check the dc voltages are about right.

Then divide and conquer. Start at the input and work you way through stage by stage.

Cheers

Ian