Fixing a laboratory waterbath

[vrasp]

Re: Fixing a laboratory waterbath

I have a hakko soldering station I use at 300°C. I melt enough solder to allow the whole tip of the wire to be fully "submerged" in solder (but not too much either). The solder stays on the pad but sometimes, when i move the board around to put everything back together, a wire will pop off while the solder stays on the pad. I ve been leaving the iron a bit longer and it seems more steady now.

Any idea about the specs of the relay switch?

Thank you!

[sam_sam_sam]

Re: Fixing a laboratory waterbath

Continuing the waterbath saga.

I was able to resolve the issues I had. Everything worked fine until it didn't anymore. The problem is that I replaced the long pins with wires and I think there is a lot of strain on the solder joints. I keep having issues with wires popping off the solder joint and causing shorts as it touches other parts. Especially when I run the waterbath at high temperatures for long periods of time. I might not have the best soldering skills. There is also not much space so the wires end up being bent and twisted when I out everything back together. I m going to add solder to the weakest joints and add hot glue to all of them. If you have suggestions for this plz let me know.

The last time it happened it shorted something on the power supply card and the relay switch is now grounded. That short blew a trace so it probably killed the few components on the line. I think the wire that popped touched ground and a pin from the relay switch at the same time.

I m going to replace the relay switch and the other components around it. My problem is the same as the very first issue I had when starting to fix this waterbath: there is no info on the relay. I dont know what the specs are and so dont know what to replace it with. All I know is that the relay is connected to a 0.68 uF 250v capacitor getting 120v from the wall, and a 800v 15 amps triac. I believe I need a non latching relay since it has to turn off when power is off (for safety).

The relay is on the bottom left of the photo attached.

How can I figure out what relay to buy for this context?

Thank you!

Do you have a temperature controlled soldering station
If you do then turn the heat up until you have it where when you can put iron on the terminal and it melts the solder with in a few second not the trace pad you want to heat this last

Because it sounds like you are not getting the terminal connection hot enough

[vrasp]

Re: Fixing a laboratory waterbath

Continuing the waterbath saga.

I was able to resolve the issues I had. Everything worked fine until it didn't anymore. The problem is that I replaced the long pins with wires and I think there is a lot of strain on the solder joints. I keep having issues with wires popping off the solder joint and causing shorts as it touches other parts. Especially when I run the waterbath at high temperatures for long periods of time. I might not have the best soldering skills. There is also not much space so the wires end up being bent and twisted when I out everything back together. I m going to add solder to the weakest joints and add hot glue to all of them. If you have suggestions for this plz let me know.

The last time it happened it shorted something on the power supply card and the relay switch is now grounded. That short blew a trace so it probably killed the few components on the line. I think the wire that popped touched ground and a pin from the relay switch at the same time.

I m going to replace the relay switch and the other components around it. My problem is the same as the very first issue I had when starting to fix this waterbath: there is no info on the relay. I dont know what the specs are and so dont know what to replace it with. All I know is that the relay is connected to a 0.68 uF 250v capacitor getting 120v from the wall, and a 800v 15 amps triac. I believe I need a non latching relay since it has to turn off when power is off (for safety).

The relay is on the bottom left of the photo attached.

How can I figure out what relay to buy for this context?

Thank you!

[vrasp]

Re: Fixing a laboratory waterbath

I redid those solder joints today.

I m still stuck on the same problem. The trace of Vcc of LM324 goes to the metal corner of the board. I cant figure out why.

[vrasp]

Re: Fixing a laboratory waterbath

this needs looking at .

Thanks. I did check those connections and they are isolated from adjacent ones. I will still redo them.

The waterbath is in the lab so that's where I work on it now when I have time during the week. It's good that it works because if that display issue can't be fixed it can still be used at a set constant temperature which is likely how it would have been used anyways. I just need to put a temperature probe in there and find the right temperature with the potentiometer knob. However, it would still be nicer with a display.

I m thinking of a way I could see if that solder in my previous post is a through-hole or just on the surface. There is a solder pad on the other side of the board on that same spot which I thought meant it's a through-hole. Why would they run that line all the way to that same spot if it's not a through hole? But then if it is a though-hole, it means Vcc it connected to ground... and that wouldnt make sense.

[petehall347]

Re: Fixing a laboratory waterbath

this needs looking at .

[vrasp]

Re: Fixing a laboratory waterbath

Sorry but this is really bugging me. Is this pin circled on the picture a through hole? If it is then Vcc is directly connected to ground.

[vrasp]

Re: Fixing a laboratory waterbath

you forgot to solder this ..

I m gonna add some solder on that. Do you see that the Vcc seems to be connected to ground or is it just me?

[petehall347]

Re: Fixing a laboratory waterbath

you forgot to solder this ..

[vrasp]

Re: Fixing a laboratory waterbath

I fully disconnected the display board and the short is still there.

I noticed that Vcc of LM324 and OP07CP are also on this line and so there are shorted as well.

Now this is the part that I don't understand. It looks as though they are all purposely grounded. If you look at the board on the attachment of this post, I drew a red line over the circuit I m talking about. This line ends up on the bottom right corner where it is grounded (I desoldered the capacitor there so we can see the line). I must be wrong as it wouldn't make sense. But do you see this as well?

[vrasp]

Re: Fixing a laboratory waterbath

There is continuity between the output of the zener and ground. Now I have to find why that is.

[vrasp]

Re: Fixing a laboratory waterbath

There is continuity from the output of the zener all the way to the v+ of ICL. The input of the zener has 6.2v and 0v on the output

[petehall347]

Re: Fixing a laboratory waterbath

zener appears fine ,
bridging resistors can also make bad things happen .. in fact bridging anything can ..just don't do it . test the suspects properly .

[vrasp]

Re: Fixing a laboratory waterbath

My next step is to double check for continuity and if there is continuity, check each component on this line to make sure it s doing its job.

[vrasp]

Re: Fixing a laboratory waterbath

never just bridge components if you don't know what they are .
that zener is there for good reason . and most likely should read 6.2v right across it .

My bad. I first thought it was a tiny resistance and thought it wouldnt cause any issues.

Yes, it read 6.2v on one pin but not on its pin going to the display. Do you think the zener is the issue?

[petehall347]

Re: Fixing a laboratory waterbath

never just bridge components if you don't know what they are .
that zener is there for good reason . and most likely should read 6.2v right across it .

[vrasp]

Re: Fixing a laboratory waterbath

I think the line has continuity though. I have to double check.

I injected 5v by using one if the LED power lines and connecting it directly to v+ of ICL. The display turns on, its dim, but it turns on. I dont know how much power it draws. I guess I could put my ammeter in there too.

My assumption was that the component I showed in the previous picture was broken. I put a wire instead to see what would happen but still 0v. However when nothing is connected, one pin has 6v. Wouldnt that mean that something is shirrer to ground?

I was going to check the other components on this line. This is the line.

The black lines mean there is a component on the other side.

[petehall347]

Re: Fixing a laboratory waterbath

component looks like a 6.2v zener 500mw

[eccerr0r]

Re: Fixing a laboratory waterbath

If you inject 5V and it turns on, and it's not drawing a lot of power, this line doesn't sound shorted, it sounds open, and isn't that connector a previous point of weakness?

[vrasp]

Re: Fixing a laboratory waterbath

The ICL7107SCPL is nothing more that a voltage meter module you need to look at the data sheet for voltage in for the meter module to work and make sure you have voltage at these points that pins V+ which pin1 and V- pin26 ground pin is 21

Here is the data sheet website link

https://cdn.badcaps-static.com/pdfs/...7791fce5e7.pdf



You have to have a 5+ ground 5- for a power supply unless this unit has a negative power supply regulator ic chip

I hope this helps you

Thank you. I did check pin 1 earlier today and it had 0v. Injecting 5v turned on the display. I checked what the v+ is connected to and found a component that had 6v on its first pin but 0v on the other pin going to the ICL chip.

This is the component. It says 825 then A below it.

I think something is shorted to ground somewhere on this line.