Hola amigo tengo una consulta técnica. Tengo un pl400 serie two y uno de los vumetros. Se ven los leds con menos intensidad luz no sabes que puede ser?
Hi Jorge, LED's are very sensitive for production differences. Second LED are like bulb lights sensitive for aging. The most PL's are almost 40 years oldn so LED are beginning to degradate. I suggest to change the LED with new LED BARS (RED are the best) and you will see that new LED's are more intensive. See on ebay on 10 segment LED Bargraph. Remember a PL uses 36 LED's and 4 x 10 is 40 LED's so you always have 4 unused, but if you start and end with 2 unused LED's it will fit. An example is ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Bcc-syPfrXk.html see on :40 how intens and accurate they work.
gracias Filip !!!! veo que son diferentes a los originales pero iluminan realmente muy bien, are la compra en ebay muchas gracias por la pronta respuesta, tengo una colección de Phase Linear mira mis videos. otra consulta tengo un Pl 400 con los transistores fpl909 hongkong y quería saber cual es la tensión de reposo Bias recomendable? saludos y muchas gracias Filip
Hi Jorge, These are older transistors. You must see that you have no distortion between 60 Hz and 20 kHz. This can be done by looking to the form of the sinus or a THD distortion meter (expensive). The higher the bias the better the THD but the warmer your amplifier get and the faster he will break. So look between 0,30 V and 0,60 V but for MJ15024/TP9054 it will be 0,35 V and for older like fpl909 it will be higher, I suggest stay under 0,60 V and go to 0,49 - 0,50V. If it is good on 0,35 V leave it this way - your amplifier will be more stable. Also play a while on 20 Watt average : normal is that when an amp gets warmer (40-45 °C) the bias will go lower. See that it stays above 0,20-0,25 V otherwise you have distortion. After 3-7 minutes it must go back to initial value : the thermal feedback transistor works fine (2N3402 with d-clip). But .. please do change the thermal feedback transistor (with d-clip on cooling plate) with a 2N3417 and do this ALWAYS even when the 2N3402 is good. This is the reason why the power transistors fail (thermal drift).
