Roender'S FC-100 - Group Buy

[odie1427]

Hello guys,

Is there anymore FC-100 PCB left. please spare me for 2 Nos.

Thanks,
odie

 

[meldano]

RMI-FC100, a single stage audio power amplifier

 

[Rudi_Ratlos]

Gentlemen, I have 1 pair of FC-100 PCBs and 1 pair of LT3062-FrontEnd-PSU - PCBs left (see image).
Give me a PM if you like to have them.

Best regards - Rudi_Ratlos

 

[Nisbeth]

Interested, PM sent

 

[Rudi_Ratlos]

Nisbeth, thank you for your quick answer.

Since you live within the European tax-union, shipping will not cost too much.
I will give you the price of the PCBs incl. shipping via PM.

Moreover: I will give you the documentation, the BoM (I even have a complete (more or less) "shopping cart" for the FC-100 components,
saved at "www.reichelt.de", drill-master, ...

We can talk about hard to get components, matching, ..., if you like.

Best regards - Rudi

 

[Studley]

@Rudi_Ratlos: Do you have any boards left?

 

[meanman1964]

The FC 100 uses 3 pair of thermaltrack trannies , is it possible to use only 2 pair ?

 

[archidea1]

Does anyone have a copy of the FC-100 builder's manual pdf?
I need to check the bias as
I have some issues with the amplifier.
It seems the bias is rising slowly with temperature and becoming unstable.
The 4A (F2) fuse keeps blowing if the amp gets hot.

 

[patriz]

usually it is a termaltrack mismatch

 

[archidea1]

Patriz, do you mean the issue described by Rudi in his builder's manual?
He solved the problem by disabling ThermalTrak diode and bypassing it with a BAT42 Schottky diode.
I'm not sure which diode should be bypassed. Rudi bypassed the second (Q2 transistor).

Also, in the datasheet of the BAT42 I can see the max forward voltage is 400-650 mV. Should it be lower @ 0.2-0.3 V?

 

[patriz]

I installed the Bat42 diode but it didn't solve the problem. I bought another set of TT I installed the TT in a non definitive way until I found the right combination. Now is working without the Bat42. I bypassed the diode that gave me the best matching. It could be T2 I don't remember

 

[archidea1]

I tested the amp again and when I power it on the voltage drop across each of the 2 emitter resistors is 38mV and then slowly doping down. After a few minutes it is 36mV and continue to drop 0.01 mV per second (from 36mV to 35.4mV in a minute).
Is this normal?
Rudi suggested checking and adjusting the bias after 15-30 minutes. Does it mean I should adjust to get 36-38mV when the amp is hot?
Once the amp is cooled down and powered back on the voltage is something about 44mV.

 

[patriz]

Yes I think is normal, don't expect to have the exactly same voltages on all Re