Whenever I try to turn on the power supply for the K4005b amplifier the fuses just blow after a second.
I am using a twin 32v AC supply with two 15A bridge rectifier diodes connected to create the -, Gnd and + voltage supplies.
Am I doing something wrong for this to happen?
Furthermore I connected the power transistors in wrongly the first time round and thus have replaced them.
I realise I am a novice and this is for my A Level project so any assistance would be greatly appriciated.
Dave
A couple of remarks:
Please check the supply requirements for your amp, depending on the speaker impedance.
http://www.velleman.eu/images/products/0/k4006_tabel.jpg
Anyway, 32VAC is too high (max. 30VAC)
Furthermore, we are puzzeled by the use of two bridge rectifiers ? Most likely, the power supply is not connected correctly.
Can you supply a link to a pic or drawing showing how you’ve hooked-up the amp ?
This is curious as the specifications there say below 30v but in my guidebook it says for 8 ohm + 35-40VDCand - 35-40VDC or for 4 ohm + 25-30 VDC and -25-30 VDC.
Essentially for the rectifier set up as the transformer has two 32V AC lines off it i have put one to rectifier but as the amplifier required +V, Gnd and -V connected the minus of one rectifier and the positive of the other to create a ground and then the positive terminal of one rectifier and the negative of the other being the positive and negative rails.
Sorry to be somewhat vague but they are currently connected up with croc clips for testing purposes so this is not really easy to show through imagery.
Power requirements in manual are DC, transformer table is AC !
Never ever connect the amp with crocodile clips ! A bad contact will ruin the amp, as one of the rails will fail and take out the transistors.
Sorry, your hook-up is unclear to us.
Check this manual for a hook-up example of the PSU
http://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k4006.pdf
We strongly suggest that you seek local assistance by someone with experience.
Hi, sorry its been a while but I have now purchased the correct transformer and power supply kit from yourselves (velleman) and it is all working now when turned on however i am only getting audio from the left speaker output and the other is providing 30v dc which has blown one of my test speakers, furthermore the larger of the two IC’s on the board TDA7250 is becoming increasingly hot.
I have conducted all the tests and the voltage on R40 and R28 are not as they should be.
Any assistance would be greatly appricated.
Regards
D Rossiter
Definately defective output transistors and possibly defective IC.
We’d recommend to replace them both.
