ok, thanks. but if I remember correctly I always had 5V between pin 2,3,4 & 5,6,7. I will check it again, if TH201 is replaced and there is still a problem.
A 5V 2A rated SMPS is needed.
BTW silly practice: 2 bridge rectifiers in parallel BD251 and BD252. First thing one normally learns not to do with rectifiers.
BTW silly practice: 2 bridge rectifiers in parallel BD251 and BD252. First thing one normally learns not to do with rectifiers.
Many thanks for your effort. I just did a last measurement for today.
At CN205
Device did not start until TH201 has been cooled.
Workflow: AC power plug unplugged for around a minute. TH201 cooled with the spray. Waited up to 10 seconds and plugged the AC again. Directly pressed the main switch. Device booted as normal after around 20 seconds.
At CN205
- Pin 9 & 10 (around 1V)
- Pin 2,3,4 & 5,6,7 (around 5V)
- Pin 15-19 & chassis ground (around 15V)
Device did not start until TH201 has been cooled.
Workflow: AC power plug unplugged for around a minute. TH201 cooled with the spray. Waited up to 10 seconds and plugged the AC again. Directly pressed the main switch. Device booted as normal after around 20 seconds.
If you will mount a new PSU: please connect the new 5V SMPS after LF201. Also leave fuse F201. Remove D202 ...205 and use the pads of D202...205 for the 230V AC connection of the new PSU. Use a jumper for TH201.
If you remove R235, C230 and D208 you can use the cathode pad for the new +5V and you'll have extra filtering plus overvoltage protection. Remove now superfluous parts.
At least that's how it looks optimal on paper as the new PSU will have a filter working both ways and it will be fused separately. I haven't touched any N-50.
If you remove R235, C230 and D208 you can use the cathode pad for the new +5V and you'll have extra filtering plus overvoltage protection. Remove now superfluous parts.
At least that's how it looks optimal on paper as the new PSU will have a filter working both ways and it will be fused separately. I haven't touched any N-50.
I think I will not mount any new PSU. If the NTC does not do the trick I will use the following workaround:
Power off AC completely via an external switch. Power on AC and directly push the main switch on the device. Most oft the time it fixed the starting problem at least what I experienced the last days. Where I used the device it was permanently connected to AC and for sure this leads to permanent power on TH201 and the switching IC201.
I do not use the N50 really often and I spend a lot of time and some money so far to get it repaired. I think I'm done and for sure I will report on replacement of TH201 next week 🙂
Power off AC completely via an external switch. Power on AC and directly push the main switch on the device. Most oft the time it fixed the starting problem at least what I experienced the last days. Where I used the device it was permanently connected to AC and for sure this leads to permanent power on TH201 and the switching IC201.
I do not use the N50 really often and I spend a lot of time and some money so far to get it repaired. I think I'm done and for sure I will report on replacement of TH201 next week 🙂
There's a mains filter and a fuse on a new SMPS - no need to double up by using 2 fuses and 2 filters... that's just silly.
If you ever decide to get an SMPS - just do it as per the photo I attached.
If you ever decide to get an SMPS - just do it as per the photo I attached.
If the NTC does not do the trick then you will have a failed/failing component in the device. Not a nice thing to have 😉
Not if one uses the sealed module type. No one knows if and what will be bought.
https://uk.rs-online.com/web/p/switching-power-supplies/2333523
That would mean no fuse with this one following your advice. It likely has an internal one but one usually prefers an external one with sealed/molded SMPS.
SMPS are famous for pollution. That extra input filter will partly prevent feedthrough of the SMPS to the transformer. The extra CLC at the output won’t hurt either.
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SMPS faultfinding is not easy... I hope you'll get it going, though.
Just another thought.... you could also use an external wall wart 5V power supply and then just feed a twisted pair through a hole somewhere on that N-50... to provide an external 5V _STB to CN205. That will also work. The unit will power up okay.
Just to let you know the TH201 didn't do the trick. At normal room temperature (today at around 25°) the device does not start. Also not if it has been AC disconnected for a while.😡
Stupid question: how is the status of the electrolytic caps, (Zener) diodes and KIA2431? All have been measured?
I mean, it are not a lot of parts and the fault is intermittent. There must be some part misbehaving.
I mean, it are not a lot of parts and the fault is intermittent. There must be some part misbehaving.
IC202
Wait a minute, you wrote that you have:
Wait a minute, you wrote that you have:
- Pin 2,3,4 & 5,6,7 (around 5V)
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Sigh, basic schematic reading... Near the optocoupler.
1. It is important to know if you always have 5V at the pins otherwise you are looking in the wrong direction. Do you have 5V?
2. If so what happens with the relay?
3. Are you sure pin 1 of CN205 gets a voltage?
1. It is important to know if you always have 5V at the pins otherwise you are looking in the wrong direction. Do you have 5V?
2. If so what happens with the relay?
3. Are you sure pin 1 of CN205 gets a voltage?
Yes I think so. Therefore I still believe in IC201 (FM260N). There is something going on with this IC if the temp is higher than 20° (basement temp of my workshop).
I just checked again the voltages:
- 5V available
- relais always switches
- pin 1 3V
But device does not power on (now in the living room at 25°). If I go back downstars to 20° it boots up. It is really strange. No clue 🤔