Hi.
I'm new on this forum 🙂
My hifonics was damaged., repair is dificult.
My technical English is enought to write about damage,but i try.
When i set volume at radio at 50% was much disortion and green diode on amplifier was pulsing.
I put other amplifier to car and works ok.
But Hifonics was better 🙂
I open car amplifier, disconect DC unit from other elements.
Diagnose - low power from capacitors.
I change all in DC unit.
I check power transistors, replace new all capacitors.
Checked DC-DC unit (14V to ~30V) and its fault, it dont have current.(Voltage at working amplifier is 13-19~).
Should was be ~30-35V.
When i put "1A 12V bulb" to DC unit out then get down to 6V.
All capcitors is ok(new).
DC unit is based on KA7500B.
I need scheme for this model or any sugestion.
Greetings.
I'm new on this forum 🙂
My hifonics was damaged., repair is dificult.
My technical English is enought to write about damage,but i try.
When i set volume at radio at 50% was much disortion and green diode on amplifier was pulsing.
I put other amplifier to car and works ok.
But Hifonics was better 🙂
I open car amplifier, disconect DC unit from other elements.
Diagnose - low power from capacitors.
I change all in DC unit.
I check power transistors, replace new all capacitors.
Checked DC-DC unit (14V to ~30V) and its fault, it dont have current.(Voltage at working amplifier is 13-19~).
Should was be ~30-35V.
When i put "1A 12V bulb" to DC unit out then get down to 6V.
All capcitors is ok(new).
DC unit is based on KA7500B.
I need scheme for this model or any sugestion.
Greetings.
I found broken capacitor smd working in KA7500(TL494) he set frequency of dc unit.
I set it to 36kHz. (Resistor 3k and capcitor 1nF).
Now i connected to power supply ,set volume 50% and amplifier play and off and red diode protect was lighting.And dont play.
If i disconnect Remote and connect again,amplifer "play" at low volume only.
Should i change broken capacitor to other than 1nF?
Frequnecy is too low?
I set it to 36kHz. (Resistor 3k and capcitor 1nF).
Now i connected to power supply ,set volume 50% and amplifier play and off and red diode protect was lighting.And dont play.
If i disconnect Remote and connect again,amplifer "play" at low volume only.
Should i change broken capacitor to other than 1nF?
Frequnecy is too low?
If the frequency on pins 9 and 10 is 36k, it should be OK. If the oscillator frequency is 36k, it's too low. Mathematically, I think those values would produce an oscillator frequency of 366kHz which is too high.
Drive one channel at a time. Does the amp shut down when driving any individual channel to full power?
Drive one channel at a time. Does the amp shut down when driving any individual channel to full power?
I dont know what is frequency at output becose I don't have osciloscope.
Original was Rt 3kOhm and Ct was broken and i checked in other amplifier like Magnat 4 channel build too on Tl494 and when i calculate Fosc it was about 56khZ.
Then i try to recalculate to hifonics good frequency.
Fosc=1.1/Rt*Ct
= 1.1/0.01uF * 3k
=1.1/0.03= 36kHz - its ok?
Rt- pin 5
Ct - pin 6
And set Ct to 1nF to = 36kHz.
I checked to 1 channel connected to 12" subwoofer and protect was lighting.
Original was Rt 3kOhm and Ct was broken and i checked in other amplifier like Magnat 4 channel build too on Tl494 and when i calculate Fosc it was about 56khZ.
Then i try to recalculate to hifonics good frequency.
Fosc=1.1/Rt*Ct
= 1.1/0.01uF * 3k
=1.1/0.03= 36kHz - its ok?
Rt- pin 5
Ct - pin 6
And set Ct to 1nF to = 36kHz.
I checked to 1 channel connected to 12" subwoofer and protect was lighting.
WORKING !! 🙂 🙂 🙂
I set Rt=10k and C=1nF.( i found in google this value shout be 50kHz).
And working.
But tell me how to calculate this ?
Hz=1.1/Ct*Rt
1.1/0,000001*10000=110 ??? Where is the 50kHz 😀
Sory for post by post.
How is good frequency to this amplifier?
I set Rt=10k and C=1nF.( i found in google this value shout be 50kHz).
And working.
But tell me how to calculate this ?
Hz=1.1/Ct*Rt
1.1/0,000001*10000=110 ??? Where is the 50kHz 😀
Sory for post by post.
How is good frequency to this amplifier?
The 50kHz is the output frequency of the IC (pins 9 and 10), not the oscillator frequency. The oscillator frequency is 2x the output frequency.
That's a bit higher frequency than most amps use but it may be OK.
That's a bit higher frequency than most amps use but it may be OK.
Most amps operate at ~30-35kHz at the output (60-70kHz oscillator). I'd suggest that you set it to ~30kHz.
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