Trouble finding replacement part for power relay

shortbus

Joined Sep 30, 2009
10,045
You are absolutely sure the relay is faulty? If you have a good ohmmeter you may want to isolate the relay and measure the coil resistance. Coil resistances are listed in the relay data sheet. Since these controller units allow the vacuum to run a short time after power is removed from the load I am guessing there are some other electronics involved.
Being he is using this with a miter saw, couldn't it be that the relay contacts are burned out? Usually with a miter saw they are on and off more than, say a table saw or jointer. So the relay contacts see more use over time.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
I contacted the manufacturer and they mentioned the upgrade from 30A to 40A allows a higher HP vacuum to be used from 6 amps to 8 amps, respectively. They also mentioned about the start up surge current and how customers were experiencing problems prior to the upgrade to 40A. Can start up surge current hit or exceed levels at 30A or more and last for several seconds?
These explain some of the advantages to venting the relay. When sealed the contact life can be shortened.
Max.
 

Attachments

Reloadron

Joined Jan 15, 2015
7,501
Being he is using this with a miter saw, couldn't it be that the relay contacts are burned out? Usually with a miter saw they are on and off more than, say a table saw or jointer. So the relay contacts see more use over time.
A good possible. I wonder how well a SSR would work out? Unless cost was a factor at design time there are plenty of SSRs which should work. They come with a wide range of control voltages and current handling capability.

Ron
 

Thread Starter

Jolteon

Joined Feb 6, 2018
24
There are several ways round the picture size problem.
1 Take the picture with the camera a little further away from the board. Taking the picture from a greater distance would also avoid viewing the parts at the edge of the board at such a steep angle. You can then crop the image with software.
2 Change the resolution setting on your camera to a lower resolution.
I have just looked at the image information for the picture of the board and it is only about 87 K bytes so you don't have a problem
That is a very risky fault finding method fitting a suspect part in a good board. There are many situations where the faulty part could have destroyed components on the good board. We still need the information requested if we have any hope of working out what the relay coil rating is.
One other question. As you do not say what country you are in we don't know what your mains voltage is likely to be so what is you mains voltage ?

Les
I took the good working relay from my dad's friend switch box and replaced it onto the non-working board but you are right, it is bad practice and can destroy other components. I stated in the first post: "Which sites do you use to order parts in Canada besides digikey and mouser?". I live in Canada and the standard voltage is 120V. I will take the picture of the back and upload it shortly. Thanks for taking the time out answering my questions.
 

Thread Starter

Jolteon

Joined Feb 6, 2018
24
Typically the Inrush Current, Input Surge Current or also called the Switch On Surge Current can be as much as ten to twenty times the normal motor run current. This high current normally only last for about the first 1/2 cycle of the input current or on a 60 Hz system about 8.3 m/seconds. The subsequent peaks and valleys of the incoming waveform will drop off quickly. Fuses and circuit breakers take this into consideration when chosen for motor start circuits. So really only the first few cycles of the current only last well below one second. I base the line frequency on you being in Canada?

You are absolutely sure the relay is faulty? If you have a good ohmmeter you may want to isolate the relay and measure the coil resistance. Coil resistances are listed in the relay data sheet. Since these controller units allow the vacuum to run a short time after power is removed from the load I am guessing there are some other electronics involved.

Ron
Thanks for the information regarding inrush current. Yes, I live in Canada. I am positive the relay is faulty because I desoldered the relay from my dad's friend switch box (same model, in working order) and resoldered it onto my dad's switch box. When I plugged in hair dryers to test it, it worked and you can hear the relay clicking.

Maybe I'm doing it wrong but I tried testing the relay with my multimeter (ohms setting at 200) and the only reading I get is OL. I tested pins 2 with 3 and 1 with 4. Please correct me if I'm wrong. I was told by the employee at the local electronics store that one possible reason was a worn out relay from switching on and off repeatedly over time.
 

Thread Starter

Jolteon

Joined Feb 6, 2018
24
These explain some of the advantages to venting the relay. When sealed the contact life can be shortened.
Max.
Interesting, I'll definitely keep that in mind from now on and remove the vent pip with a sharp knife in the future. Can one use a drill bit to drill a hole instead? Thanks.
 

Thread Starter

Jolteon

Joined Feb 6, 2018
24
Being he is using this with a miter saw, couldn't it be that the relay contacts are burned out? Usually with a miter saw they are on and off more than, say a table saw or jointer. So the relay contacts see more use over time.
That appears to be the case and was also one possible reason that the employee at my local electronics store mentioned.
 

Thread Starter

Jolteon

Joined Feb 6, 2018
24
There are several ways round the picture size problem.
1 Take the picture with the camera a little further away from the board. Taking the picture from a greater distance would also avoid viewing the parts at the edge of the board at such a steep angle. You can then crop the image with software.
2 Change the resolution setting on your camera to a lower resolution.
I have just looked at the image information for the picture of the board and it is only about 87 K bytes so you don't have a problem
That is a very risky fault finding method fitting a suspect part in a good board. There are many situations where the faulty part could have destroyed components on the good board. We still need the information requested if we have any hope of working out what the relay coil rating is.
One other question. As you do not say what country you are in we don't know what your mains voltage is likely to be so what is you mains voltage ?

Les
The images are shown below:
PCB1.JPG PCB2.JPG PCB3.JPG PCB_back.JPG
Let me know if there's anything else you need or if any of the parts are illegible.
 

LesJones

Joined Jan 8, 2017
4,174
I have managed to trace part of the schematic but the picture of the etch side of the board is so poor that I cant follow the tracks on the left hand end of the board. (The mosfet end) The transformer is a current transformer whose secondary is rectified to drive the gate of the mosfet. My guess would be that the relay has a DC coil with a voltage rating to match the local mains supply voltage (Which we STILL have not been told.) We can confirm or disprove this guess when I have a good enough picture to trace the rest of the scjematic Can you take a better picture of the etch side of the board so that ALL OF THE TRACKS are visible. You could try illuminating it from different angles and with different light sources. You could also try taking a picture with it illuminated from underneath. I agree with SB in post #21 that the fault with the relay is more likely to be the contacts than the coil. CAN YOU MEASURE THE RESISTANCE OF THE COIL ?

Les.
 

Reloadron

Joined Jan 15, 2015
7,501
I am positive the relay is faulty because I desoldered the relay from my dad's friend switch box (same model, in working order) and resoldered it onto my dad's switch box. When I plugged in hair dryers to test it, it worked and you can hear the relay clicking.
Based on that I would say a bad relay with an open coil. Then too a relay with welded contacts won't necessarily click but the contacts normally weld closed. Anyway, since a replacement worked I would guess a faulty relay.

Now as to form, fit and function the ideal replacement would be another identical relay. However, with some ingenuity either a different mechanical relay or a solid state relay could likely be incorporated.

Ron
 

shortbus

Joined Sep 30, 2009
10,045
That appears to be the case and was also one possible reason that the employee at my local electronics store mentioned.
I don't use one, but most other guys I know that do wood working have the automatic vacuum hooked up with their table saw, jointer, etc. But they use the normal on/off switch on the vac when using the miter saw, and let it run until done cutting. My wood and metal shop is in a separate building from the house, so dust isn't a concern to me.
 

shortbus

Joined Sep 30, 2009
10,045
Based on that I would say a bad relay with an open coil. Then too a relay with welded contacts won't necessarily click but the contacts normally weld closed. Anyway, since a replacement worked I would guess a faulty relay.

Now as to form, fit and function the ideal replacement would be another identical relay. However, with some ingenuity either a different mechanical relay or a solid state relay could likely be incorporated.

Ron
But aren't most relays of a certain "type" or form factor interchangeable? Just made by different companies?
 

Reloadron

Joined Jan 15, 2015
7,501
But aren't most relays of a certain "type" or form factor interchangeable? Just made by different companies?
Yes, as to things like Contact Form , this link gives a good overview. Problems can arise when the actual pin out on for example, a board mounted relay are not the same. This leaves the end user crawling through endless data sheets looking at dimensions and what the actual pin out is. My reference to form when I mentioned form, fit and function was to finding a relay which would fit in the space provided. That or start getting creative. :)

I was surprised the system manufacturer did not simply have one off the shelf.

The existing relay appears to have a 110/120 VDC coil. If I could not find a suitable mechanical replacement I would likely just shove an SSR in and be happy. 90 to 240 VAC output SSRs are pretty common. I would settle for the common 3 - 32 Volt DC control voltage and simply divide the now incoming coil voltage to a usable control voltage. Not like the control voltage requires any current and a simple 4:1 or 5:1 divider should work fine. That's likely how I would try to go about it.

Ron
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
I have done a simple conversion in the past making my own SSR using a power Triac with zero-cross Opto (MOC3160 etc), I already had the parts so it was even cheaper.
Max.
 

GopherT

Joined Nov 23, 2012
8,009
Hi,
I'm having some trouble finding an exact replacement part for the following power relay:
FRA1TNA - E
DC 110V
40A 240VAC
View attachment 145289 View attachment 145288

The relay is from an iVAC Switch Box. The employee at my local electronics store mentioned that the following part can be substituted instead:
T9AS1D12-110 - Power Relay, SPST-NO, 110 VDC, 30 A

http://www.newark.com/te-connectivity/t9as1d12-110/power-relay-spst-no-110vdc-30a/dp/66F6696?ost=T9AS1D12-110&ddkey=http:en-US/Element14_US/search


I am a novice when it comes to electronics in general. The part has to be special ordered and the only difference I see is 30A instead of the original 40A.
My questions are:
1. What is the difference between the two and can the 30A power relay be used to replace the original 40A power relay?
2. What happens when you use a lower DC voltage instead of 110VDC?
3. Are there any safety hazards from using a lower amperage?
4. Which sites do you use to order parts in Canada besides digikey and mouser?

Contact Bailey

http://www.baileyproducts.com/files/86694322.pdf

Phone number is on the bottom of PDF
 

LesJones

Joined Jan 8, 2017
4,174
Hi Ron,
I think an SSR cold well be a good solution. From what I have traced of the schematic so far the secondary of the CT is half wave rectified then fed through a 100 ohm resistor and clamped with a 10 volt zener diode. The positive then goes via a 4.7 K resistor to a 10 uF capacitor with a 1 meg resistor in parallel with it. This connects to the gate of the mosfet. The negative of the capacitor is connected to the negative of the zener. I suspect it also connects to the source of the mosfet but can't confirm this due to the very poor quality picture of the etch side of the board. I think connecting the input of the SSR to the ends of the zener could work. The rest of the components would be redundant.
Have you spotted any infomation from the TS to say what his mains voltage is or what country he is in ?

Les
 
Top