Peranders... I seem to have a problem with my SST03.
K1 activates, K2 doesn't. Voltage across D4 = 0V (so that's where the problem is).
Q3 base voltage = 40mv (relative to gnd)
Q3 emitter = 25V
Q3 source = gnd
Can you confirm the correct Q3 base voltage?
thanks!
Voltage over R10?
Voltage across R10 is 31.1VDC
Good.
Q1, base down to ground? Voltage.
Q1, emitter down to ground? Voltage.
Q2, base down to ground? Voltage.
Q2, emitter down to ground? Voltage.
Q1 base to gnd = 24.2V
Q1 emitter to gnd = 24.4V
Q2 base to gnd = 25 mV
Q2 emitter to gnd = 24.9 V
Q2 is broken I should think. Which type of transistor do you use? BC???
bc547c...
I have actually replaced Q2 already before, but this didnt fix it.... I will try another one.
You could test the transistor with a diode test. Plus on bas and then check the base-colletor and base-emitter.
D4 is turned right?
Just put in another bc547 as Q2... no success.
Q4 is correct position...
I also switched the 2 ralays to the K1 and K2 positions... seems that both relays are still functioning.
I don't really understand... K2 has 25V on pin 1 and pin 8... shouldn't it activate then?
Is Q3 base at 0 V and also the collector?
Q3 base is 60 mV, Q3 emitter is 0V
And the Q3 collector 24 volts or so?
Are your really sure that you have BC5_47, not 57?
Yes and yes...
I have tested the board with and without transformer to it (transformer without load)
R12, R13 values?
R12 = 22K
R13 = 2.2K
D4 is really OK and turned right?
As you see you have some problem around Q1 and Q2.
You should have 0.6-0.65 V base-emitter Q1.
Du you still have 24 volts at R12 and 0 V at R13? You should have 2 x 0.65 V.
I am looking at the traces on the board... they don't seem to correspond to the BC547 datasheet..... (e.g. Q1 emitter)..
I know that's very unlikely as the board has been tested and used..so maybe I am going crazy here...
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDIQFjAA&url=http%3A%2F%2Fwww.datasheetcatalog.org%2Fdatasheet%2Fphilips%2FBC546_547_3.pdf&ei=b6aJT7uEItL58QOEsbjdCQ&usg=AFQjCNG0b4yJnAnVzq1AWxZKbR5tV9Al2w&sig2=JVaa6wmgXJQIBaOrwzF_7Q
Pins down flat side to you from left, C B E
Seems opposite from datasheet, no? :?
Check if it's top view or bottom view.
I another datasheet it was more clear... it seems right on that one indeed. I have in the meantime taken a whole new pack of bc547c's and put them in. Still the same problem.
Quote from: peranders on April 14, 2012, 04:44:17 PM
D4 is really OK and turned right?
As you see you have some problem around Q1 and Q2.
You should have 0.6-0.65 V base-emitter Q1.
Du you still have 24 volts at R12 and 0 V at R13? You should have 2 x 0.65 V.
D4 is put in according to the silkscreen. Have used a second one to verify... still same problem.
Q1 base - emitter = 0.4V and (thermally) drifting downwards
Is the Q1 emitter at 24 V?
Q1 emitter = 0V (compared to gnd)... actually 40mv (0.04V)
And Q1 base 24 volts?
Q1 base = -0.5V vs gnd
Notice that you can't have less than zero. Check in the schematics for the electronics ground. Are you using a separate power supply or do use the mains voltage?
I double checked and confirm my earlier readings. I am taking gnd at DZ1.
Using direct mains input
I'l loosing track here. Can you measure once again please.
R10 and all transistors.
I will post the schematic with all the voltages later... this should help I hope to identify the problem...
Hi Peranders.
I have written down all voltages, and identified the fault. Voltage between D2 and D3 was 32V (good), voltage between D3 and Q1 was -0.4V. Hence I guessed there was something wrong with the caps. So I removed C4 and C5 and it worked.
Unfortunately, I am not sure if I am where I want to be.... I get a blown fuse now upon startup with transformer and PSU.... :?
Do you get a delay now? Have you replaced the caps which must be made of polyester?
I think it is delayed (I hear c-click I think). The caps I had in were 1uF 63V WIMA....
Quote from: Maarten Stevens on April 16, 2012, 10:09:38 PM
I get a blown fuse now upon startup with transformer and PSU.... :?
What kind of fuse, rating? Fast, slow?
Transformer size?
Hei Per Anders,
I was using a 1.25 slowblow, which blew all the time. I have now replaced for a 2A and it works now. The transformer is 400VA.
I am still running without C4 and C5 positions filled, what is the impact of that? How can I insert a suitable cap here?
Also I see sometimes a little spark around the relays... this doesnt seem to affect it though, as no fuse is blown, and the psu starts up normally. What can this be?
Thanks,
Maarten
The 1 uF caps are there for creating a delay - a soft start.
I have replaced with another 1uF 63V WIMA... then K2 doesn't activate again!
So: it only works with C4 and C5 empty, but I do see a spark then inside K2 relay (and of course there is no softstart then...)
what is the required rating of the caps in C4 and C5?
63 V, polyester is enough. I must say you have a mysterious error.
I haven now also tried a 250V MKT in that position... still doesnt work. As the designer of the circuit... what could be the culprit?
When the cap is inserted how many volts across it do you get? When you test this do you have a 24 volts power supply or do you use the mains voltage?