Hakko 888 - replace transformer 110 to 220 volt - Page 1
Forum section: electronics / general

author: namlu
author_rank: Contributor
timestamp: August 15, 2014, 11:37:03 am
content: Hello.I want to buy US version and replace the transformer, like in this video:http://youtu.be/QK3pTam0GkkHere are 2 transformers I think of buying:http://www.ebay.co.uk/itm/290930357566http://www.ebay.co.uk/itm/360622925682One is 60VA, other is 80VADimensions: 60 is 85x34 mm, 80 is 87.5x39 mm1) I plan to buy the analog version if the 888, and not the digital like in the youtube video. Do they have the same transformer? Is it connected the same way in both devices?2) are these transformers ok in size?3) does it matter which one i buy, 60 or 80 VA? Are they both safe to use?4) If they Both safe, what would be the difference? Which one is recommended? Will it heat slower with the 60 VA? How much slower?5) am I the only one who think the analog version would be more convenient?Thank you.

author: nanofrog
author_rank: Super Contributor
timestamp: August 15, 2014, 11:45:44 pm
content: Thinking more along the lines of 120VA, as Watts /= VA.Take the following into account (rough calculations):1. FX-888/D is rated for 70W.2. Efficiency for a linear supply is about 60%.So 70W/0.60 ~= 117VA, so a 120VA transformer would be appropriate. Found the following listing on eBay:Toroidal Transformer 120VA 230V -> 2x12V / 1x24V ; Sedlbauer, RSO-861756. Physical dimensions are very similar (89mm diameter x48mm tall for 120VA vs. 85mmx34mm for the 60VA you linked).Take some measurements to see if it will fit, as they use an EI type (won't matter for this use if EI or toroid, just needs to have sufficient ratings and fit the available space). Just measure the existing transformer from corner to corner, as well as the height to see if a toroid will fit. Height is less of a concern than diameter in this case, given the Hakko's enclosure dimensions.Another alternative, is to find an appropriate step-down transformer (100W continuous rating would be sufficient, but if you mean to run other 120V gear, take that into consideration). Much easier to use, as it's just a matter of plugging the transformer into mains, and the 120V gear into the step-down transformer outputs. Won't even need to change any plugs.Needs to be an actual transformer, not a wall wort looking thing that's using a circuit instead of copper + iron (transformer = true sine wave output; wall wort versions tend to have an approximated sine wave output rather than a true sine wave). Avoids problems this way.Example:300W Step Down Transformer(smallest appropriate type that would work for the lowest cost I could find on eBay).Based on the two links I provided, the Step-Down is not only less expensive, but it could be more useful as well (i.e. ~ 200 - 230W available for another bit of 120V gear).A few GBP more perhaps could provide you with a larger unit (especially if you find a nice one used), that saves you more money down the road if/when you come across a US model for the right price to your door (assumes it doesn't have a switchable/convertible supply via internal wiring already, as some do).

author: nanofrog
author_rank: Super Contributor
timestamp: August 15, 2014, 11:55:00 pm
content: Few larger step-down units currently listed on eBay.co.uk (used; some, if not all are local pickup, but well worth a drive if there aren't many bids and it's not too far to get it at the right price):UK/US HEAVY DUTY STEP DOWN TRANSFORMER1.5KVA, Stepdown Transformer 240VAC to 110VAC, KD-1500MEE-113 1500W Step Up / Down Voltage Converter Transformer500W Step up, step down transformer1000W Step up, step down transformer

author: VK5RC
author_rank: Unknown
timestamp: August 16, 2014, 06:27:23 am
content: +1 for getting a step down transformer, you can get some really good 'wrong voltage' bargains! :-)

author: namlu
author_rank: Contributor
timestamp: August 16, 2014, 09:29:43 am
content: I don't have enough desk space for a step down transformer. I will probably go for replacing the transformer inside the hakko station.The transformer in the video is 60VA. Does it mean it heats raise slower? Is it a safety hazard?I also noticed in the video that there is not fuse after the transformer swap. Why is that? Is it safe? Is it possible to keep the fuse small pcb?

author: nanofrog
author_rank: Super Contributor
timestamp: August 16, 2014, 09:57:50 am
content: Quote from: namlu on August 16, 2014, 09:29:43 amWhy not place it on a shelf or the floor?Simple solution that preserves not only desk space, but the previously listed benefits.Regarding the video, the 60VA transformer they used will heat up if it's loaded past it's nominal ratings for an extended period of time (should have a thermal fuse to shut it down when it's too hot to prevent a fire <installed during it's manufacture>). As per a missing line fuse, the little board on top of the original transformer likely didn't fit. Even if it did, the fuse on it wasn't the correct rating with the new transformer (double the voltage, so the fuse needs to be half the current of the original). Should be a slo-blow type.Your choice as to which way to go, but swapping the transformer isn't a necessity. So much nicer and easier to be able to use other gear with a step down, and only need plug stuff in.

author: namlu
author_rank: Contributor
timestamp: August 16, 2014, 02:18:28 pm
content: Hi. Thank you. Last question. Does it matter which polarity I connect the net transformer inside the station (to main voltage and to the circuit)? Does AC have plus and minus poles?

author: nanofrog
author_rank: Super Contributor
timestamp: August 16, 2014, 07:00:57 pm
content: Quote from: namlu on August 16, 2014, 02:18:28 pmPolarity is always present, and in the case of DC, it's always the same direction. For AC however, the polarity alternates 50 - 60 times per second, which means the direction of the current changes back and forth.In the case of domestic wiring, AC has aLinewire (can think of it as +, sometimes called the "hot" wire) and aNeutralwire (can think of it as -). Transformers usually denote the Line side by a dot on the schematic for both sides (input side is calledprimary, and the output side is called thesecondary). This is important so you get the current direction of the input side to match the output side.Wiki'sPolarity (mutual inductance)has a bit more detail, and some other relevant links you might find of interest on the bottom of the page (source for the image).

author: IanB
author_rank: Super Contributor
timestamp: August 16, 2014, 08:49:55 pm
content: Quote from: namlu on August 16, 2014, 02:18:28 pmIt generally won't matter which way round you connect the wires to the transformer.

author: ssrobzoom
author_rank: Newbie
timestamp: March 11, 2016, 09:07:13 pm
content: Do you still have the orginial 120volt transformer that came out of the Hakko Fx-888D