Fluke 8050A 220V mod - Page 1
Forum section: electronics / beginners

author: Neshco
author_rank: Contributor
timestamp: December 14, 2023, 01:16:22 pm
content: Got this beauty from USA (decent price on ebay) with idea to use converter 110->220 but would rather mod this and replace transformer inside the device if possible, or even better configure existing one if that is an option.I see that there is more than two pins out of the transformer on the primary side and just thinking that maybe there is a way that transformer is universal, just need to jump it properly. Is it possible or even better does someone have schematic of this device?I see on the second photo that there are 100V and 240V hole where the white wire is soldered in 120V, guess that is the "jumper" for the problem?

author: electr_peter
author_rank: Unknown
timestamp: December 14, 2023, 01:33:07 pm
content: Manual states transformer "Factory configured for customer specified voltage". Not sure if that implies transformer is configurableIt uses only 4W so you can use simple and cheap external transformer.

author: Neshco
author_rank: Contributor
timestamp: December 14, 2023, 01:36:14 pm
content: That is an option of course, just, there is high possibility that there is a jumping wire inside the device that can solve this problem without any hassle. Just want confirmation from someone who knows well this devices that I can just move white wire to the 240V.

author: tunk
author_rank: Super Contributor
timestamp: December 14, 2023, 02:32:44 pm
content: The schematics shows taps for 100, 120 and 240V, YMMV:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Fluke/8050A_sch.pdf

author: Neshco
author_rank: Contributor
timestamp: December 14, 2023, 03:09:39 pm
content: Thank you for schematic.Yes there is a tap, I see it, but moving it there did not worked.Removed transformer, and found that only 120V are populated, 100V and 220V are not. And there is also missing holders for F3 fuse. Guess there are many revisions of this one so...Look like I will need to improvise or use 120->220V converter.

author: Neshco
author_rank: Contributor
timestamp: December 14, 2023, 07:42:07 pm
content: I cant see voltages on the secondary side of the transformer, can someone who have this same model measure it for me?This one is without battery.

author: Neshco
author_rank: Contributor
timestamp: December 15, 2023, 08:11:46 am
content: So, just for case someone need it, transformer need to be replaced, taps are not populated and there are 3 different transformers, for 100, 120 and 240V.

author: BillyO
author_rank: Super Contributor
timestamp: December 15, 2023, 05:17:27 pm
content: Yes, there are 3 different transformers for the AC only model and they are likely about as available as a new Model 'T' Ford.The battery model (Option -01) can actually be configured for different voltages but you would likely need to source new batteries. Not as big a problem as finding a suitable transformer. OF course you can modify the battery model to be battery less, but that is not insignificant surgery.

author: Neshco
author_rank: Contributor
timestamp: December 15, 2023, 07:40:06 pm
content: This is battery less model actually.I decided to go with power transformer 110-220, if it not affect the mm itself somehow. Not sure but I will give it a try.And will continue to search for solution, maybe some custom built transformer. Just need to find what are the voltages on secondary side of the transformer and somehow I miss it.

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 16, 2023, 12:23:36 am
content: I have the same non battery version like you do. I measure the AC input to the rectifier bridge U29 and it's 31VAC with 123VAC at my outlet. So looks like it's a 4 to 1 step down transformer.

author: Neshco
author_rank: Contributor
timestamp: December 16, 2023, 12:59:08 am
content: Thank you for bothering to measure it, while you are there can you check point 10? Both 12-10 and 10-8?

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 16, 2023, 02:09:11 am
content: The #10 is center tap and thus it's 15.5 to either 8 or 12.

author: Neshco
author_rank: Contributor
timestamp: December 16, 2023, 09:44:05 am
content: In that case, guess this little guy can do the jobhttps://no.rs-online.com/web/p/toroidal-transformers/2239216

author: Kleinstein
author_rank: Super Contributor
timestamp: December 16, 2023, 10:04:02 am
content: To get some 13 V out after the rectifier and filter cap. the transformer should have a nominal votlage of some 10 V, maybe even only 9 V if lightly loaded only. Such voltages like 2x10 V (or 9, 11, 12 V) are common.The transformer should have good isolation and low coupling. So ideally this would be more like an EI type core with separate winding compartments.Toroidal transformers are nice otherwise, but the isolation / coupling is more a weak point.

author: Neshco
author_rank: Contributor
timestamp: December 16, 2023, 12:16:21 pm
content: Thank you.I understand BeBuLamar that 15,5V are measured right after transformer, so AC is that much, not a DC side after rectifier, regulator and capacitor. Or I get it wrong?

author: Neshco
author_rank: Contributor
timestamp: December 16, 2023, 03:04:01 pm
content: Guess something likethis onewould be fine? And it is cheaper as well.

author: bdunham7
author_rank: Super Contributor
timestamp: December 16, 2023, 03:38:48 pm
content: Quote from: Neshco on December 16, 2023, 03:04:01 pmYes, and I'd guess the 12-0-12V version would do. I just popped mine out and measured a bit, with 122.8VAC input, I get 26.7VAC at the bridge, 15.6VDC on the 13V circuit.

author: Neshco
author_rank: Contributor
timestamp: December 16, 2023, 04:13:28 pm
content: Quote from: bdunham7 on December 16, 2023, 03:38:48 pmHmm, that is at the 120V, here is 240, so, 12 or 15 is a question.And are you sure that it is 2x12 or 2x15 and not for example 8-0-4 or 9-0-6 or something crazy like that?Can you please confrm?

author: bdunham7
author_rank: Super Contributor
timestamp: December 16, 2023, 04:33:52 pm
content: When the meter is on, the voltages will not be perfectly balanced anywhere because the loads aren't matched. There will also be a fair amount of voltage drop from unloaded to loaded. With the power switch off, I get 15.8VAC on each half and 31.6VAC total, so perfectly even as expected. Your replacement transformer will be rated for 12VAC at full load and 220VAC input. I'm guessing you have more than 220VAC and you won't be fully loading the transformer, thus I think the 12-0-12 version is probably the right one. But you never know for sure, that's just an opinion based on the way thing I've seen these things work out in the past. Are you sure this transformer will mechanically fit in place?

author: Kleinstein
author_rank: Super Contributor
timestamp: December 16, 2023, 04:51:03 pm
content: It should definitely be a symetric transformer as only this way both half waves are used evenly. With imbalance the high voltage would be used more and with only one side one would still get a hal wave rectified signal.The small transformers have some 20-30% or so higher voltage when unloaded and chances one would have less than the nominal load anyway.Modern transformers are usually calculated for 2x115 or 230 V primary.If the voltage turns out to be a bit on the low side one could still increase the filter capacitors a bit and this way get more voltage from reduced ripple. The relevant voltage is usually more the min value and less ripple thus helps quite a bit, more than is visible at the average voltage.The mechanical side (does it fit and can be fixed) can be an important point and may determine the size.

author: Neshco
author_rank: Contributor
timestamp: December 16, 2023, 06:27:00 pm
content: First ss is my main voltage on all three phases. So it is there between 240 and 220 in average.Judging by this sketch from the Ali seller it will fit in. I have 4cm height clearance inside the box, from the pcb to the upper plastic of the case and case inside is wide enough thanks to battery compartments that are not in place. And those are 5W and peak consumption written on the device is 4W.So, it is fine, just to decide what is better, to go with the 12-0-12 or 15-0-15. That is only thing left to be determined.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 16, 2023, 07:13:54 pm
content: The 2x12 V voltage is high enough. With light load the voltage will be higher than normal and if really needed one can increase the filter capacitors (e.g. 470 µF instead of the relatively small 220 µF) to get away with less voltage. The question is more if 2x12 V is on the high side, so maybe 2 x 11 V if available.

author: bdunham7
author_rank: Super Contributor
timestamp: December 16, 2023, 07:21:00 pm
content: Quote from: Neshco on December 16, 2023, 06:27:00 pmOn mine, if I reduce the meter input voltage to 90V, but the +6 and -5V supplies are in regulation, there is about 18V at the bridge and ~10.6V on the 13V supply. The meter works, but I didn't test all of its functions or accuracy. At 105V, I get ~23VAC at the bridge and 13.2V on the 13V supply. Since all the power specs are met I would expect the meter to work properly at this level, but I didn't actually do a full test.The only thing you really don't know is how closely that transformer matches its specs. It says 5W, but transformers should be rated in VA. With an inefficient linear power supply like this, 4W would be bit more the 5VA.

author: Neshco
author_rank: Contributor
timestamp: December 16, 2023, 08:18:01 pm
content: Quote from: Kleinstein on December 16, 2023, 07:13:54 pmNo, there is only 9, 12, 15... I mean I can catch some other seller there, but it is Ali, you cant blindly trust to their specifications.Quote from: bdunham7 on December 16, 2023, 07:21:00 pmYou think this would not be powerful enough or...? Guess there can be fitted slightly stronger then this, but I am not sure if something like that is necessary, especially comparing to the one that is factory installed, it is really tiny in size compared to the Chinese one.I found on Ali sellers likethis onethat encapsulate it in resin just like original is encapsulated AND is 10VA and 40mm high, and it is possible to order custom voltage(s) which is great.Now just need to finally agree about the voltage if we now have 10VA (of course we dont know for sure, but there is a bonus to compensate), so, 11-0-11, 12-0-12, 15-0-15 or something else?

author: Kleinstein
author_rank: Super Contributor
timestamp: December 16, 2023, 10:43:25 pm
content: In the circuit diagram the +13 V voltage is used for the main amplifiers and for 2 V input, some 5 V drop at the FETs and some 2 V for the drain side resistors a voltage of 8 V should be sufficient for that circuit part to work. It is a bit strange that the plan also gives +13 v and -10 V from the same rectifier, just the other half.The filter capacitors are only 220 µF - this is normally only good for some 100 mA at best, especially if the raw votlage without regulation is also used.. So I would not expect the meter to take much power.The battery circuit looks like it would charge the battery with some 130 mA / 200 mA (if the regulator is a LM317). It is not so clear if the charge time is with the meter on or off, thus the 2 currents.This would mean cells of some 1.3 or 2 Ah, which would be sub C of C size about which would sound reasonable. For a 10 hour run time this would be some 130 or 250 mA at some 5 V (4 cells in series). So this would be some 0.6 or 1.2 W as power drawn from the batteries. This could much more reasonable. With a +-10 V supply this would be some 50 mA per side which about fits for 220 µF filter capacitor. This would still result in some 2 V of ripple, which is well on the high side to power parts of a sensitive circuit.So a 4 or 5 VA transformer should be OK, even 3.2 VA may work, but could be close as the transformer would provide a slightly higher voltage and because of filtering would need some 1.4 VA per watt.The question is if even a 9 V transformer may be enough, at least least with 220 V mains, maybe not all the way down to 200 V as the original fluke specs.The input power specs include the loss of the transformer, while the rating is for the output. The small transformers usually have a relatively poor efficiency, like mybe 70% if they were good.For getting tranformers there may be a better, more local source than Ali- express. They are just a bit heavy for shipping.A European alternative would be this:https://www.tme.eu/en/details/ts4_30/transformers-with-fastening/indel/ts-4-30/

author: Neshco
author_rank: Contributor
timestamp: December 17, 2023, 01:03:18 am
content: Quote from: Kleinstein on December 16, 2023, 10:43:25 pmThank you for this, just, pay attention that this is the model without batteries. Schematic cover both versions, guess you get battery one. Batteryless version have tap on the middle while Battery version does not, just two wires on the secondary side. Then, guess, this transformer would be fine? And thank you for the shop, didnt know that it is there, just to check if shipping prices are not kidney expensive.

author: Neshco
author_rank: Contributor
timestamp: January 10, 2024, 03:35:03 pm
content: Quote from: Kleinstein on December 16, 2023, 10:43:25 pmJust to confirm that this transformer is installed and work nice. Thank you Kleinstein!I have not tested it yet thoroughly because I plan to replace the electrolytic capacitors and clean it, but so far it look just fine. No obvious problems.Off topic:Mechanic switches was worked very poor on this device, often did not lock etc. I have clean it with the contact cleaner and now there is no any problem it switch nice and lock everytime, just clicking sound is somehow strong and sharp, not sure it is normal, there must be some kind of grease there.Is there some dielectric greasing spray that can be used here to get smooth movement and sound when switching, to grease it?