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UNIC RV-2002 amplifier turns on but does not sound
37
hace 5 años
hace 5 años
Greetings YoReparo colleagues, I have an amplifier of the UNIC brand RV-2002 model, which turns on but does not give audio, when checking it immediately notice that 2 zener diodes were reheated, I decided to remove them to measure them and indeed one was bad, having the license plate illegible and finding nothing about this amplifier I decided to measure the voltage of the zener that is apparently good, 14.8v, so I decided to replace both with ones of the same voltage, but still no audio, when turning on the amplifier if the pop is heard in the horn, but there is no noise, attached some images, thanks
IMG1
IMG2
IMG3
335
hace 5 años
hace 5 años
These zener that you mention are perhaps the ones that regulate the symmetric voltage of the preamp stage, if so, you must measure in one of them positive voltage and in the other negative voltage if you do not have these 2 voltage the preamp stage will never work for you and If you already have these voltages that must be of the same value as the Zener Czechs, the preamps,
37
hace 5 años
Indeed, colleague, the problem is that it only measures + 0.6v and -0.6v, so I assume that you place the wrong zeners, is there any way to know what zeners are? the pcb as seen in the photos only says "dz601" and "dz602" on the license plate only 5 is readable because they are very overheated and cannot be seen anymore, and I could not find the schematic of this amplifier.
335
hace 5 años
It is assumed that the value of the zener already have it because you comment that one was good and that I mark you 14.8v
These zener if they are the ones that I tell you must be inverted from each other, that is, the one that regulates b + the anode is grounded and the one that regulates b- the cathode is grounded. Normally this power comes from the same symmetrical source of power and it is reduced by resistors of about 2 to 3w to feed the preamp stage and with the help of the zener the stability is maintained
I want you to confirm first whether or not it is the low voltage symmetric line
1.594
hace 5 años
Remove the audio output either integrated or transistors remove them and measure if the power supply does not arrive so go to the source of the voltage and track it to its arrival so you will see where the voltage is lost maybe it is some fuse resistance burned domes
37
hace 5 años
I confirm that if it is the symmetric line, the resistances are from 2w to 2k2 and in effect, the zener comes inverted to the other
37
hace 5 años
The resistors didn't work either, I changed them and the amplifier is already beautiful, thanks for your answers
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