cdam, I take it you're still having problems. Here's a shot in the dark...are your thermistors in contact with the screw or washer holding the transistors.
Hi,
After a long time I just yesterday had my full set of transistors and I plan to disassemble the left channel, test the components values, replace the active parts and burnt resistances and try it again. In the meantime I biased again the right channel, everything'a OK (-0,594 / 0,595V / 0,4 mV) but I haven't yet plugged in a pre and feed it with signal.
KevinHeem my thermistors are in contact with washers and upper body of mosfets. What is your suggestion?
One thing to say
Check and double check that the semiconducters are the correct location and orientation.
Check again that the pots are really at zero.
Use a bulb to limit current when testing.
Check and double check that the semiconducters are the correct location and orientation.
Check again that the pots are really at zero.
Use a bulb to limit current when testing.
When I built my F5 I was told the thermistors should not be in contact with the metal washer or screw (continuity with chassis), only the plastic case of the transistor.
I ground one side of the washer down to accomplish this.
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KH I thought the plastic coating of the thermistor is an electric insulator, however I'll follow your suggestion.
I am sure the coating around the Thermistor is electrically insulating.
If one wants to be sure then you could double insulate with a thin film of plastic like mylar or polyester. Then Thermally help heat conduction by using Thermal goop or heat conducting expoxy glue in the interface from Thermistor coating to plastic film.
For more speedy reaction time (less time lag) one NEEDS good thermal contact.
I am biasing up my BA3 FE and I am getting some measurements wrong.
I have about .75V on each mosfet.
I get no voltage reading across the 2 legs of R12.
I have an elma silmic on the C3 position but still I get DC offset on the output if I play with P1 and P2.
I don't have the electrolytic capacitors installed in the C1 and C2 positions as I have the regulator very close to the circuit, could this be the problem?
Should I jumper the capacitor pins?
Here is a pic:
I have about .75V on each mosfet.
I get no voltage reading across the 2 legs of R12.
I have an elma silmic on the C3 position but still I get DC offset on the output if I play with P1 and P2.
I don't have the electrolytic capacitors installed in the C1 and C2 positions as I have the regulator very close to the circuit, could this be the problem?
Should I jumper the capacitor pins?
Here is a pic:
An externally hosted image should be here but it was not working when we last tested it.
Hello Joca (tudo bem?)
You can try here, it's a good seller, or if you prefer like you said and try Mouser, check also RS where you can buy a 30m roll from Alpha wire. If all that fail you can try to find kimber kable speaker cable from 4TC up to 12TC, just 1m i'll give you plenty of wire to build a F5, just the silver plated is missing.
Good luck
Carlos Barata
You can try here, it's a good seller, or if you prefer like you said and try Mouser, check also RS where you can buy a 30m roll from Alpha wire. If all that fail you can try to find kimber kable speaker cable from 4TC up to 12TC, just 1m i'll give you plenty of wire to build a F5, just the silver plated is missing.
Good luck
Carlos Barata
Just one more thing...please.
What do you recomend for the input/output internal wire? and for the PSU wire?
thank you
i am at the RS store, the john's store and there a lot to choose from.
What do you recomend for the input/output internal wire? and for the PSU wire?
thank you
i am at the RS store, the john's store and there a lot to choose from.
Those capacitors have nothing to do with the PSU - they are part of the bias circuit.
Install the capacitors.
Install the capacitors.
Hi. I have a 240v single primary transformer. How do i connect the thermistors? i read that it must be in series. But i've also read that i need 2 thermistors instead of one. Do i need a ceramic cap like in the schematic? i'm a little confused here