JTA2405-2 replacement? - Page 1
Forum section: electronics / projects

author: somlioy
author_rank: Regular Contributor
timestamp: December 13, 2013, 07:48:01 am
content: Hi. Does anyone know a replacement for JTA2405-2? This is a triac with ttl level input. Cant find this particular ic anywhere

author: minime72706
author_rank: Frequent Contributor
timestamp: December 13, 2013, 05:30:06 pm
content: I've not looked for a direct replacement yet, but after looking at a datasheet, I see this easily being replaced by common components if that seems potentially practical for this application. You would need an optotriac (MOC series?) and a suitable BTA-series TRIAC. The optotriac should be a random-phase device and it appears that the device you'd be replacing has no built-in snubber. I don't think a BTA device with a built-in snubber will cause any problems, but it depends on your load.Do you know what kind of load the TRIAC would be switching? Do you see any decent-sized resistors or capacitors near it on the PCB?I just now learned that the standard MOC3023 is not suitable for 220VAC+ mains, but I found the MOC3051 for this purpose. It is a random-phase optotriac and can be driven by TTL logic via a resistor to limit LED current. As for the TRIAC itself, I'd recomment a BTA08-600B.BTA series TRIACs claim to have internal isolation, but I've never understood the nature of it and always use an optotriac to drive one. If someone else wants to reassure you and I about the isolation, there is a logic-level version you might use standalone: BTA08-600SW or BTA08-600TW.This is just an option - later when I'm at my desktop I might try to help you in a more meaningful way.EDIT: Just a clarification as to why I came up with this recommendation ... The device you're trying to replace is an excessively-beefy (physically) TRIAC with built in opto-isolated driver. From a procurement point of view, it may be easier to go my route if you can "safely" mount the new parts.

author: somlioy
author_rank: Regular Contributor
timestamp: December 13, 2013, 08:51:06 pm
content: Thanks for your response.The load is a solenoid at 80VA at 110V iirc.I dont have the machine available right now, so cant check for any resistors or capacitors.The device I'm replacing is connected to the rest of the circuit with spade crimp Connectors, and the Device is mounted to a heatsink inside the controllbox.I agree it might be easier to just make a replacement With common Components. Will check out those Devices.

author: minime72706
author_rank: Frequent Contributor
timestamp: December 14, 2013, 02:31:32 am
content: Quote from: somlioy on December 13, 2013, 08:51:06 pmA solenoid, huh? No wonder they use a random-phase device! When you fix it, check the output going to the solenoid with a scope and look for enormous and narrow transients on the sine wave.I'm proud to see you use 'VA' rather than 'Watts' for some reason, even if it was marked or advertised as such.

author: minime72706
author_rank: Frequent Contributor
timestamp: December 14, 2013, 09:06:32 pm
content: I found the 120VAC version of the device you're looking for on ebay via item number 400343867764. This doesn't really help you, but shows that they do appear. I still do suggest you make your own module.

author: minime72706
author_rank: Frequent Contributor
timestamp: December 14, 2013, 09:35:46 pm
content: I did some more reading about the commonly available devices and I believe what you want includes:MOC3052 optoisolated TRIAC driver with random-phase turn-on and 240VAC operationBTA08-600SW power TRIAC with logic-level 10mA triggeringThe logic-level TRIAC would be similar to your old part and also puts less strain on the optoisolated TRIAC drive with a trigger current of only 10mA.There is the "BTA08-600TW" which only needs 5mA but I fear noise immunity might be an issue. 10mA seems good enough.

author: somlioy
author_rank: Regular Contributor
timestamp: December 16, 2013, 09:44:05 pm
content: Checked today if there are any big caps or resistors near the triac and these two are in series with the load/triac.Also, why should I look for transients?

author: minime72706
author_rank: Frequent Contributor
timestamp: December 17, 2013, 01:54:59 am
content: If you see big narrow spikes on the AC waveform, it means that the TRIAC and the load are not playing nicely. It may not even be a practical issue, but it's worth checking out since it can be improved.

author: minime72706
author_rank: Frequent Contributor
timestamp: December 17, 2013, 01:59:34 am
content: Assuming you mean that the R/C is in parallel with the load, it is indeed a snubber. It does not look like much effort was put into the choice of components, but usually anything is better than nothing. It sure looks like a snubber.

author: somlioy
author_rank: Regular Contributor
timestamp: December 17, 2013, 12:12:30 pm
content: Err ye, the cap and resistor in series, but in paralell with the load.This is a very old industrial machine at the local school.http://www.cvosupply.com/upload/images/Document/%E0%B9%80%E0%B8%84%E0%B8%A3%E0%B8%B7%E0%B9%88%E0%B8%AD%E0%B8%87%E0%B8%95%E0%B8%B1%E0%B8%94%E0%B9%81%E0%B8%81%E0%B9%8A%E0%B8%AA/koike/Koike%20IK-600C.pdf

author: minime72706
author_rank: Frequent Contributor
timestamp: December 18, 2013, 12:45:44 am
content: Quote from: somlioy on December 17, 2013, 12:12:30 pmThe choice of R and C looks as arbitrary as anything, but you may as well leave it intact when and if you decide to take my advice on replacing that AC switch module with an optotriac and power triac.

author: somlioy
author_rank: Regular Contributor
timestamp: January 09, 2014, 04:10:56 pm
content: Just to report back, finally got time to build the replacement circuit with a MOC3052 and a BTA08-600SW. Worked a threat! Thanks alot