K4040 - power on problem

Kits Audio Hi Fi Projects
1

K4040

Just built and double checked all solder points, component polarities etc but no green light on power on.

When connected to power with switch in “off” position - LED2 glows solid red - 12V supply is correct.

When switched to “Fully On” (up) position relays RY3 and RY4 actuate immediately and Main power transformer is powered. 6.8VAC on grey and green (no load), 50VAC on yellow secondary and 300VAC on red secondary winding - all fine so far.

But HT voltage climbs very slowly to about 360VDC - never reaching 415VDC. RY5 does not actuate. LED1 flashes and LED2 blinks alternately red/green. Never reaches solid green.

The fault must be in the power supply stages but I can’t find it. Could it be a faulty transistor or diode? any help welcome thanks!

Steve

2

Hmm, I suppose I better send the PCB in for testing then!

Steve

3

Hard to troubleshoot from a distance.
Before sending in, can you post hi-res and sharp pictures of both solder- and component side of the turn-on delay section, so we can take a look.

4

OK, I’ve taken a few hi-res photos of the relevant areas and uploaded to:

http://www.sjbelectric.co.uk/Velleman/images

Note slight repair where copper lifted off board near switch but ohmeter test shows all seems well here.

Thanks, Steve

5

Any thoughts? - what’s the address to sent it to for checking / repair?

6

Difficult to say. A couple of solderings look rather poor.

Anyway, if you decide to send it in, please return it to:

Velleman Projects Repair Dept.
Legen Heirweg 33
9890 Gavere
Belgium.

Make sure to include a fault description.