Really!
That might just possibly maybe 😉 do odd things to start up of oscillators. It's all low power stuff, just give it full mains.
40w
I have tested all the power supply and all good and running straight of mains .
It seems to do a little more now ,but I need to test oscillator
I have tested all the power supply and all good and running straight of mains .
It seems to do a little more now ,but I need to test oscillator
If there’s no echo, a likely fault could be the foot switch or its socket
If that’s ok, do all the heads have sensible resistances?
By sensible, I mean not open circuit and not short circuit
Can you hear any tape hiss?
Brian
If that’s ok, do all the heads have sensible resistances?
By sensible, I mean not open circuit and not short circuit
Can you hear any tape hiss?
Brian
I have just connected the scope to the erase head and I get a sine wave at 48khz.
I just got a piece of recorded reel tape and tried moving it back and forth across the play heads whilst connected to the scope but got no waveform.
I just got a piece of recorded reel tape and tried moving it back and forth across the play heads whilst connected to the scope but got no waveform.
not a good way to assess things it doesn't take being off by much to get nothing.
does touching the connections on the playback heads produce any noise on the output.
the schematic states 40 khz bias,no?
does touching the connections on the playback heads produce any noise on the output.
the schematic states 40 khz bias,no?
What about the left hand 10k pot - the one next to the foot switch in the diagram?
Does it measure OK?
Does it measure OK?
^^^^^^^^ THAT!!!!
"Everything" has been tried and done EXCEPT the most important Troubleshooting tool: injecting signal and following it along the different paths. 😕
40kHz vs 48kHz bias makes no large difference. It has to be > twice audio band, yet low enough to pass stray reactances. ~~1MHz has been used on fancy audio.
Recording will work with no bias at all. Grossly distorted but recognizable.
It is hard to understand why touching the head wires does not make BIG buzz, yet sine injection gets sound.
Recording will work with no bias at all. Grossly distorted but recognizable.
It is hard to understand why touching the head wires does not make BIG buzz, yet sine injection gets sound.
To me, this is key and means that there is signal on the right hand of the two 10k pots. There is no signal on the left hand one, next to the foot switch on the schematic. Either all three heads are faulty or there’s a break in the circuit between the heads and the pot