I have a friend that runs a photography class and uses these power supply timers dark room lighting. Apparently they’re quite important to him and he has had some failures of the power supplies. I’ve seen that many others have as well. It looks like the common part to fail is a little switching triac, a solid state relay.
He knows that I am into electronics and that I etch my own boards. he asked if I could build him some new boards for his power supplies using a different device since they are no longer available. You can get them from for China for fairly cheaply, but he knows other photographers that have gone this route and the devices from China are pretty poor I guess. So he was hoping I could redesign it. I see no reason to redesign it, just put in a suitable part. My thought is that they are failing because they use such a pathetically small heat sink for the device. I’m trying to figure out the exact load on these power supplies. I was hoping to get some of the lighting back to my house, but it would require removing the lighting from the dark rooms, which she was hoping not to do. Regardless, it is ready for 12 A at 250 Vac, I would think it would benefit from heat sink bigger than this.
At first, I was thinking a standard physical relay, but if the load was immediate, the arching on the contacts would not be great. so I’m back to a solid state. I’m thinking about just getting pretty much exact same device from a different company rated for either the same or more current and mounting it to an appropriate heat sink. There is plenty of room in the power supply case for a substantial heat sink. I don’t want to mount it to the case of the heat sink since it has line voltage, but it’s easy enough to isolate the heat sink from the rest of the chassis.
Similar to this
https://www.digikey.com/en/products...nduYfIIAt9b30ioSpvswMA3aq_YbhqdRoCQPsQAvD_BwE
But being $37 I was hoping to find something a bit less expensive. We were hoping to repair a total of 15 to 20 of these power supplies that are used between him and a couple of his other photography friends. so kind of just reaching out to see if maybe anybody is familiar with these types of devices and can point me in the right direction.
Thank you,
Dan
He knows that I am into electronics and that I etch my own boards. he asked if I could build him some new boards for his power supplies using a different device since they are no longer available. You can get them from for China for fairly cheaply, but he knows other photographers that have gone this route and the devices from China are pretty poor I guess. So he was hoping I could redesign it. I see no reason to redesign it, just put in a suitable part. My thought is that they are failing because they use such a pathetically small heat sink for the device. I’m trying to figure out the exact load on these power supplies. I was hoping to get some of the lighting back to my house, but it would require removing the lighting from the dark rooms, which she was hoping not to do. Regardless, it is ready for 12 A at 250 Vac, I would think it would benefit from heat sink bigger than this.
At first, I was thinking a standard physical relay, but if the load was immediate, the arching on the contacts would not be great. so I’m back to a solid state. I’m thinking about just getting pretty much exact same device from a different company rated for either the same or more current and mounting it to an appropriate heat sink. There is plenty of room in the power supply case for a substantial heat sink. I don’t want to mount it to the case of the heat sink since it has line voltage, but it’s easy enough to isolate the heat sink from the rest of the chassis.
Similar to this
https://www.digikey.com/en/products...nduYfIIAt9b30ioSpvswMA3aq_YbhqdRoCQPsQAvD_BwE
But being $37 I was hoping to find something a bit less expensive. We were hoping to repair a total of 15 to 20 of these power supplies that are used between him and a couple of his other photography friends. so kind of just reaching out to see if maybe anybody is familiar with these types of devices and can point me in the right direction.
Thank you,
Dan
How about this one at $15.08:
https://www.digikey.com/en/products/detail/bright-toward-industrial-co-ltd/TL216
https://www.digikey.com/en/products/detail/bright-toward-industrial-co-ltd/TL216
What is the failure mode of the device?
What is the load?
Most of these devices have a common package that has been used for years. They must be reliable.
They look like a Leggo brick with two fixing points.
That part looks like one of those mixed component circuits shoehorned into a power transistor package.
I would not use such a thing on more than a 100W lamp.
What is the load?
Most of these devices have a common package that has been used for years. They must be reliable.
They look like a Leggo brick with two fixing points.
That part looks like one of those mixed component circuits shoehorned into a power transistor package.
I would not use such a thing on more than a 100W lamp.
Much better!
No power getting the lamps, measured at the output of the power supply and nothing. I have confirmed it is the part that has failed and it would seem others that experienced the same failure.
As I mentioned in the first post, I am not too sure of the exact load right now. I’m hoping they can pull the lights from one of the dark rooms at the school. As I would like to see how hot this device gets in one of the working power supplies and measure the exact current going through the device. I can’t imagine anywhere near 12 A are going through it, that’s a lot of light. It’s clear that it’s meant to be mounted to a heat sink and I’m sure that rating is for adequate cooling.
What are the parts you’re speaking of, the ones that look like Legos?
Dan
The part in your photo does not look like it has been hot and also you say it has not gone short circuit.
I would guess without testing that the LED section is going open circuit.
Voltage spikes on the input would be the first thing I would be looking for.
I would fit a powerful zena diode at the input pins with a low value resistor in series to kill the spikes.
It is effectively an electronic circuit that has been designed by a chemist so things like spikes on signal lines are likely to get overlooked.
I would guess without testing that the LED section is going open circuit.
Voltage spikes on the input would be the first thing I would be looking for.
I would fit a powerful zena diode at the input pins with a low value resistor in series to kill the spikes.
It is effectively an electronic circuit that has been designed by a chemist so things like spikes on signal lines are likely to get overlooked.