G
Guest
Guest
I just finished wiring up Fabios BA283 output stage only boards and have a few questions
This is my first hit at debugging audio signals - PSUs no problem - this a bit out of my depth
Here is the schem and layout
http://www.groupdiy.com/index.php?topic=5335&postdays=0&postorder=asc&highlight=ba283&start=0
I have it on t bench (well a desk) and am feeding it 24v from a homemade Bench PSU
I am feeding a 1v sign wave from a signal generator and measuring the 1v sign wave on a scope
I am using the second probe on the scope to poke at the various bits of cricuit to see what comes out (before I plug it in)
The scope shows absolutely fine up to a point
then I start seeing a small square wave (the gate of the transistors?)
And just before the feed to the transformers there is a quick wiggly shallow line vibrating like mad
The output from the transformer is roughly the same
The scope shows a sine wave from R14 all the way to the beginning of R15
There is no sine wave after the R15 (in fact not at all after lower leg of R15) - signal tester proves there is a connection though
I jumpered RGx and put a switch at Gain to Rg
RV1 has no effect on anything on the scope
Just out of interest - do both bolt holes on the T03 need to be attached to the circuti or do I isolate one (?) - there are solder rings for both on the board
Anything else I need to check?
This is my first hit at debugging audio signals - PSUs no problem - this a bit out of my depth
Here is the schem and layout
http://www.groupdiy.com/index.php?topic=5335&postdays=0&postorder=asc&highlight=ba283&start=0
I have it on t bench (well a desk) and am feeding it 24v from a homemade Bench PSU
I am feeding a 1v sign wave from a signal generator and measuring the 1v sign wave on a scope
I am using the second probe on the scope to poke at the various bits of cricuit to see what comes out (before I plug it in)
The scope shows absolutely fine up to a point
then I start seeing a small square wave (the gate of the transistors?)
And just before the feed to the transformers there is a quick wiggly shallow line vibrating like mad
The output from the transformer is roughly the same
The scope shows a sine wave from R14 all the way to the beginning of R15
There is no sine wave after the R15 (in fact not at all after lower leg of R15) - signal tester proves there is a connection though
I jumpered RGx and put a switch at Gain to Rg
RV1 has no effect on anything on the scope
Just out of interest - do both bolt holes on the T03 need to be attached to the circuti or do I isolate one (?) - there are solder rings for both on the board
Anything else I need to check?