My K8020 power supply line has tripped (230V / 50Hz). The unit was powerd on since 4h and waiting for an input signal from the DAC plugged in the CD input.
The preamp is brand new and has been operating well during 35-40 hours.
Now the fuse is burnt and it seems that there is a shortage between Phase and neutral at the Transformer input (45 Ohm). I’ve detected this typical smell of over heating and burnt coil coating… The transformer seems a bit blown at the top and the white side inscriptions have partly turned brown.
I checked the PSU wiring and found out that phase and neutral were inverted in the power plug on the wall.
There is no other evidence of anything wrong in the preamp (blown capacitor or burnt PCB track…).
The temperature of the casing above the transformer was around 45°C while operating
I am located in France.
My knowledge in electronic is very basic.
My questions :
Could the phase / Neutral inversion have caused this problem ?
how to ensure that the transformer is blown ?
What else could have burned and how to ensure this ?
Inverted phases cannot burn the transformer, the absolute phase of the supply is not important.
At this time, we cannot tell what might have caused this problem.
If the unit is still under warranty, please return the defective transformer for inspection/exchange to:
I’ll dispatch the transformer tomorrow.
The pin supporting face has blown up around the 18V secondary power supply pins . A thick black material effusion had stuck the transformer on the PCB but it seems OK.
Have you received the transformer ? Since I send it, I’ve carried out some more investigations :
I’ve checked connections on the PCB starting from the transformer. I found out that the 0V of the 2x18V coil is not grounded… I checked all ground connections and realised that most of them are not despite correctly linked together. The casing is correctly grounded but the pin #1 of SK7 header is not. So 10% of ground connections are correct and 90% are not correct but are correctly linked together… I can’t see any track on the PCB linking these two groups. I haven’t found any missing jumper or whatever. What do you think of that ?
Your transformer has been exchanged.
As we were unable to determine the cause of troubles, we have exchanged it under warranty conditions.
We suggest that you check your circuit carefully before mounting the transformer again.Check the ground layout carefully, starting from the 0 of the two 18V windings. Use a multimeter to measure continuity.
If you have any doubt, please return the complete amp for inspection/repair, as we cannot exchange the transformer a second time should it be defective due to the same problem.
Votre transfo à été envoyé le 31/8/12 par poste.
Nous regrettons que la poste ne permet pas de tracer votre colli.
En general, ça prend 2-3 semaines pour arriver, mais dans certaines cas, ça prend 4 semaines, selon la region en France.
Et merci ! Transfo reçu OK. J’en avais approvisionné un sans aucun soucis chez Reboul (de même qu’un potentiomètre Alps, pièce d’usure comme les lampes) . Après interconnexion de toute les masses comme évoqué précédemment (une liaison manquante sur le circuit imprimé), tout est rentré dans l’ordre. Plus aucun soucis depuis 8 mois, 2h de fonctionnement quodidien à 40%. Je suis complètement satisfait par la qualité ce kit, son rendu sonore, le service Velleman et la disponibilité des pièces de rechange. J’en retient de contrôler plus soigneusement ce qui peu l’être avant de mettre sous tension…