Hello,
I’ve just finished a K4700 kit in a Crown DC-300A mk1
PSU is symetrical : +60Vdc GND -60Vdc
Stereo : 150w / channel
Power on is fine : WAIT led on for 6sec and then dim.
During the DC tests : PA with V+ and V- both channels react ERROR+WAIT after 2-3seconds.
Is this time correct ? I thought the reaction was instantaneous.
Thanks for your help.
Astuck
Should be more or less instantanious, as far as we recall.
Can you provide LINKS to HI-RES and SHARP pics of your assembly (both SOLDER and COMPONENT side), so that we can take a look and maybe spot a problem?
Hi Vel417,
Here’s the link for the close-up : My K4700 kit
After second troubleshoot, capacitors, diodes, IC1 and transistors polarity/position are checked and OK.
Here are the parts as seen on my pcb : I replaced some original Jamicon caps for same value Panasonic caps.
C1-C6 = 1uF 50v Panasonic FC
C7-C10 = 100uF 25v Jamicon
C11 = 220uF 25v Panasonic FM
C12/C13 = 470uF 16v Jamicon
T1-T3 = BC547B
T4 = BC517
IC1 = LM324N
ZD1 = Zener 6V8
No R23-R26
I’ll do a resistor check.
Thanks for your help !
Astuck
Assembly looks OK as far as we can see.
Just thinking: Most likely you performed the test as explained in the manual. This test uses the internal power supply of the K4700, which is approx 9VDC.
Reaction time depends on caps charging. In the real world, input voltage will be 60VDC, so reaction time will be a lot faster.
Hi,
Thanks a lot for this quick answer 
The mains coming to the velleman transfo is 226vac,
IC1 pin 4 and test point V+ are +6,94vdc
IC1 pin 11 and TP V- are -6,90vdc
The K4700 MASS point is wired to the ground star point in the DC300,
I’ve tested the K4700 with and without MASS point wired to star ground.
After these tests, I put the IC1 LM324N out and put it back.
Now the response time is <0,5sec
It seems better.
By “Reaction time depends on caps charging”, can you specify which caps ? Thanks
Cheers
The caps that are put in anti-series to form a low-pass filter.
Thanks a lot for your answer !
So C1 to C4 and C7 to C10.
Cheers
