Fixing a laboratory waterbath

[sam_sam_sam]

Re: Fixing a laboratory waterbath

I meant to have a fuse there for when I turn it on. Sounds good I ll do that. What do I risk using the 15A fuses? I already bought those.

Nothing until you try to test it with the heater element

[vrasp]

Re: Fixing a laboratory waterbath

You do not have to use a fuse to check it on ohms scale now if you are going to use the incandescent light bulb instead of the heater element yes I would agree with you to use a fuse before the triac input this would be advisable but use a 10 amp fuse not a 15 amp one

I meant to have a fuse there for when I turn it on. Sounds good I ll do that. What do I risk using the 15A fuses? I already bought those.

[sam_sam_sam]

Re: Fixing a laboratory waterbath

Alright then. That's the new plan haha

I had checked for continuity between the pins and the heatsink and there was none. However, I did not try with the voltmeter on the max Ohm setting. I ll do that this time and also have a fuse just in case. I ve gone through enough TRIACs.

You do not have to use a fuse to check it on ohms scale now if you are going to use the incandescent light bulb instead of the heater element yes I would agree with you to use a fuse before the triac input this would be advisable but use a 10 amp fuse not a 15 amp one

[vrasp]

Re: Fixing a laboratory waterbath

Vwrasp

WHY are trying to be dangerous in what you are talking about doing ( steps 4 and 5 and 6 )

All you need to do is put one led of volt meter to the heat sink and and check for resistance on the three pins on the highest setting if you have any kind of resistance you have an issue you which you need to fix

Then if this part is correct then undo the heater element wires and hook an incandescent light bulb and see if you are getting the signal to the transformer to turn ON the triac if not then you need figure out why this is not working correctly

Alright then. That's the new plan haha

I had checked for continuity between the pins and the heatsink and there was none. However, I did not try with the voltmeter on the max Ohm setting. I ll do that this time and also have a fuse just in case. I ve gone through enough TRIACs.

[sam_sam_sam]

Re: Fixing a laboratory waterbath

Vwrasp

WHY are trying to be dangerous in what you are talking about doing ( steps 4 and 5 and 6 )

All you need to do is put one led of volt meter to the heat sink and and check for resistance on the three pins on the highest setting if you have any kind of resistance you have an issue you which you need to fix

Then if this part is correct then undo the heater element wires and hook an incandescent light bulb and see if you are getting the signal to the transformer to turn ON the triac if not then you need figure out why this is not working correctly

[vrasp]

Re: Fixing a laboratory waterbath

Ok so this is my new plan:

1) Remove the transformer.
2) Connect a 0.1A fuse on GATE and 15A fuse on MT1.
3) Connect a 100w bulb instead of the heating element.
4) Turn on the waterbath. Without the transformer, the TRIAC should be OFF. If a fuse of GATE or MT1 blows, the TRIAC must be getting shorted on the heatsink.
5) Short MT1 and MT2 to light up the bulb. GATE should not be getting any current from MT1 so if the GATE fuse blows there is something wrong there. (is that a relevant test to do?)

6) If the bulb lights up and all the fuses are fine, connect the transformer back onto the PCB and turn on the waterbath. If the GATE fuse blows, there is a fault on the input side of the transformer, so that's coming from the control board. If everything is fine... well then everything should be fine.

[sam_sam_sam]

Re: Fixing a laboratory waterbath

There is an LM324 on the control board.

If this is the case I would buy a new one and see if it behaves differently or not
But make sure that you have the triac mount correctly as well

[vrasp]

Re: Fixing a laboratory waterbath

The description of the device will tell if it is a micro controller or not

Now it could be done with ic chip like a LM339 or something similar where you have a reference value and compare to the input value

V1 is controlled by something the question is what this is controlled by this is where you are going to have to trace where these connections go to it has to go to some type of ic chip to control the triac unless it to some type of resistance pot which I doubt very seriously that it was done this way

One note when you use a device that mount to a heat sink and the heat sink is mounted to the circuit board and has soldering joints that are connected to something else you need to make sure that the tab does have connection to the heat sink so you need use an ohm meter to check this

There is a difference between the two devices one has the metal mounting tab and the other one dose not and if you did not mount the device correctly this might explain why the new device failure happened

Now there are devices that have the metal tab that has no connection to the device but you must check them to be sure that this is the case the data sheet should tell you this information

The one thing that this data sheet does not tell you if the metal tab has a connection to the device so have to go with the assumption that it has a connection unless you have tested this with an ohm meter

There is an LM324 on the control board.

[sam_sam_sam]

Re: Fixing a laboratory waterbath

The description of the device will tell if it is a micro controller or not

Now it could be done with ic chip like a LM339 or something similar where you have a reference value and compare to the input value

V1 is controlled by something the question is what this is controlled by this is where you are going to have to trace where these connections go to it has to go to some type of ic chip to control the triac unless it to some type of resistance pot which I doubt very seriously that it was done this way

One note when you use a device that mount to a heat sink and the heat sink is mounted to the circuit board and has soldering joints that are connected to something else you need to make sure that the tab does NOT have connection to the heat sink so you need use an ohm meter to check this

There is a difference between the two devices one has the metal mounting tab and the other one dose not and if you did not mount the device correctly this might explain why the new device failure happened

Now there are devices that have the metal tab that has no connection to the device but you must check them to be sure that this is the case the data sheet should tell you this information

The one thing that this data sheet does not tell you if the metal tab has a connection to the device so have to go with the assumption that it has a connection unless you have tested this with an ohm meter

[vrasp]

Re: Fixing a laboratory waterbath

I think he does, https://www.badcaps.net/forum/attach...4&d=1626717671 but M4 is too big (should be M3 or #4), and the plastic shoulder washers for #6 screws seems rare.

Again something really wrong is here that's not being described. In the off state, according to the PCB, gate is shunted to MT1 through the diode/isolation transformer and therefore should be off. Unless MT2 reaches above the isolation voltage limit it won't heat up until it's forced to turn on. So therefore unless there's a wiring mistake somewhere, this makes no sense and not worth investigating further. Based on history, wiring mistakes are abound and has been extremely annoying to work through.

Could be a wiring mistake but then I think it would be on the control board. I double checked and the TRIAC was wired correctly. The last time the waterbath worked was when I used a NTE5671 TRIAC (800v 16A https://cdn.badcaps-static.com/pdfs/...779fb4dd7a.pdf). It does not have a metal plate. I dont know the material but I had installed it without a mica and it worked so it isn't conductive. The original TRIAC (so before the NTE5671) was a IT715 (800v 15A). IT715 seems to be equivalent to NTE56010.

I have not wired anything differently since then. The only difference is the TRIAC which is a NTE56010 (800v 15A https://cdn.badcaps-static.com/pdfs/...3966fef995.pdf).

Below is the schematic in the manual of the waterbath. I posted it earlier too. It's a general schematic for 220v and doesn't go into the details.

[vrasp]

Re: Fixing a laboratory waterbath

“ I dont know if there is a controller but there might be. Is it a chip? How do I find it?”
You just have to Google the part numbers to find what each part number

I know that but what do you call the controller? Is the transformer the controller?

[sam_sam_sam]

Re: Fixing a laboratory waterbath

“ I dont know if there is a controller but there might be. Is it a chip? How do I find it?”
You just have to Google the part numbers to find what each part number

[vrasp]

Re: Fixing a laboratory waterbath

Did it blow when the heater wasn't supposed to be on, or was the heater supposed to be on at that point?

This is specifically to trigger the heater right? How is the chiller supposed to be turned on?

It blew when the heater was on. The heater turns on with the waterbath because the set temperature is above the water temperature. If I want to turn it off I have to set the temperature to below the water temp.

The chiller is turned on with another switch. There is no PCB for that. The switch just closes the circuit to the compressor and it stays on as long as the switch is activated. So one could turn on the heating and cooling at the same time if they wanted to.

your triac should have one of these in the hole ...

Yes I have those. They're supplied with the TRIAC. It s the screw I m unsure of. Although I think it was small enough.

[eccerr0r]

Re: Fixing a laboratory waterbath

I think he does, https://www.badcaps.net/forum/attach...4&d=1626717671 but M4 is too big (should be M3 or #4), and the plastic shoulder washers for #6 screws seems rare.

Again something really wrong is here that's not being described. In the off state, according to the PCB, gate is shunted to MT1 through the diode/isolation transformer and therefore should be off. Unless MT2 reaches above the isolation voltage limit it won't heat up until it's forced to turn on. So therefore unless there's a wiring mistake somewhere, this makes no sense and not worth investigating further. Based on history, wiring mistakes are abound and has been extremely annoying to work through.

[petehall347]

Re: Fixing a laboratory waterbath

your triac should have one of these in the hole ...

[eccerr0r]

Re: Fixing a laboratory waterbath

Did it blow when the heater wasn't supposed to be on, or was the heater supposed to be on at that point?

This is specifically to trigger the heater right? How is the chiller supposed to be turned on?

[vrasp]

Re: Fixing a laboratory waterbath

i suppose you could replace the heating element with a bulb .

I ll do that too!

^ this

and again how do you know it blew or not, it would need to get hot to blow. It was rated for 15A after all, which would be in the range of tripping upstream fuses, wires, etc.

The key thing is that when it's out of circuit, MT1 and MT2 should not conduct in either direction when gate is disconnected. Now some conductivity between G ant MT1 is expected as there's a diode region there.

Then the other thing is if you're connecting the gate to the wrong terminal. Hooking gate between what would be MT1 and MT2 would instantly fry it...

It blew when I went from plugging with the bulbs to without them, thinking it was working fine. The bulbs were bright but I thought this to be normal as there is up to 15A pulled to the heating element. When I say I blew it I mean it actually went and is physically damaged. I m pretty sure they re soldered to the right terminals but I ll double check. One thing I can think of is that I dont know the exact size of the screw I used to mount it. It was definitely quite smaller than the TRIAC hole and fit the washer. There was also no continuity with the screw or heatsink. This time I m gonna get an M4 just to make sure.

There is no upstream fuse. Just the lab circuit breaker.

When I troubleshoot my battery spot welders that uses a triac ( that uses a high current transformer) and want to test the controller function I will use an incandescent light bulb so I do not trip the breaker because some of these controllers have issues with the programming

These battery spot welder machines controller are suppose to control the current going to the transformer but when the controller has issues it will one of two things one turn the transformer fully ON and fry the triac and trip the breaker to the hole house or does not power the transformer at all

I have a feeling that your controller is one that is suppose to control the current as well and if this is the case it might not be doing this and just turning it fully ON which might be a problem

My suggestion would be try programming the controller with an incandescent light bulbs so you can see if the controller is working correctly and you can heat up the sensor to pretend that it has reached the set point then let it cool down and do this several times this would allow you to see if the triac is functioning correctly or not

And when you test it with the heater element you really need to have an amp probe on the heater element to make sure that you are over current-ing the triac you should be unless you have an issue with the controller

I dont know if there is a controller but there might be. Is it a chip? How do I find it?

I might have to get a better multimeter or an amp probe. Mine only goes up to 10A.

Thanks guys!

[eccerr0r]

Re: Fixing a laboratory waterbath

And that's why I'd suspect that the TRIAC should be fine as is controlling a shorted heating element, even... and it should end up throwing a breaker before it "instantly fries the TRIAC". With the past history of this thread, I'd highly consider the possibility of the miswiring of the TRIAC when soldering it, causing it to blow. Again connecting the gate terminal and MT1 (the diode drop) across mains voltage will instantly fry the TRIAC. Other miswirings would just cause issues in it turning on or it being always turned on.

Seems as typical for all these three terminal devices that aren't high powered RF devices, when facing the TO-220/TO-247 the left pin is the high impedance input (gate for TRIAC, base for BJT, gate for MOSFET), center pin (and thus metal tab) is the "output" (MT2 for TRIAC, collector for BJT, drain for MOSFET) and the right pin the low impedance common input (MT1 for TRIAC, emitter for BJT, source for MOSFET).

Oddly enough SCRs seems to not follow this pattern - more like diodes ... and again RF transistors where the center pin is typically emitter/source...

[sam_sam_sam]

Re: Fixing a laboratory waterbath

When I troubleshoot my battery spot welders that uses a triac ( that uses a high current transformer) and want to test the controller function I will use an incandescent light bulb so I do not trip the breaker because some of these controllers have issues with the programming

These battery spot welder machines controller are suppose to control the current going to the transformer but when the controller has issues it will one of two things one turn the transformer fully ON and fry the triac and trip the breaker to the hole house or does not power the transformer at all

I have a feeling that your controller is one that is suppose to control the current as well and if this is the case it might not be doing this and just turning it fully ON which might be a problem

My suggestion would be try programming the controller with an incandescent light bulbs so you can see if the controller is working correctly and you can heat up the sensor to pretend that it has reached the set point then let it cool down and do this several times this would allow you to see if the triac is functioning correctly or not

And when you test it with the heater element you really need to have an amp probe on the heater element to make sure that you are over current-ing the triac you should be unless you have an issue with the controller

[eccerr0r]

Re: Fixing a laboratory waterbath

^ this

and again how do you know it blew or not, it would need to get hot to blow. It was rated for 15A after all, which would be in the range of tripping upstream fuses, wires, etc.

The key thing is that when it's out of circuit, MT1 and MT2 should not conduct in either direction when gate is disconnected. Now some conductivity between G ant MT1 is expected as there's a diode region there.

Then the other thing is if you're connecting the gate to the wrong terminal. Hooking gate between what would be MT1 and MT2 would instantly fry it...