TENMA 72-10495 thoughts ??? - Page 1
Forum section: electronics / testgear

author: alin_im
author_rank: Regular Contributor
timestamp: June 08, 2015, 09:09:58 pm
content: Hey guys,Do you have any thoughts of this TENMA 72-10495 power supply??? Now I have 2x dual rail power supplies, build by me using lm317 and lm337 and i wanted to upgrade. Keep in mind that i am at the beginning of my career and I do not have to much to spend on the equipment. That catch my attention because it has a wide range a voltages and current and also has a very good price.http://cpc.farnell.com/tenma/72-10495/power-supply-2ch-30v-5a-adjustable/dp/IN06823

author: Maxlor
author_rank: Frequent Contributor
timestamp: June 08, 2015, 09:39:10 pm
content: This is a relabelled and paired up version of the Korad power supply. Search for Korad in this forum, and you'll find plenty of discussion of the merits and issues it has. The very short answer is: good value for money.

author: neslekkim
author_rank: Super Contributor
timestamp: June 08, 2015, 09:53:40 pm
content: I have one, bought from TopLoser, very good, couldn't measure any overshot or something like that.You should ask TopLoser if he have any around, he uses to sell these from time to time.

author: Pinkus
author_rank: Frequent Contributor
timestamp: June 09, 2015, 07:22:24 am
content: I am using two of them too. Nice, reliable devices. Only one things is nagging me always and every day: the automatic saving of set values to the active memory place. E.g. if you have 3,3 Volt and 500mA programmed to M1 and you would liketemporarilyset the voltage to 2,9 Volt: no way to do this. If you change the values of voltage and/or current , they will be programmed to the active memory place (here M1) automatically, so next time you press M1, the unit runs with 2,9 Volt and you need to change it back. GrrrrrI have no idea why they did not implement a (at least for me) logical programming feature of the memory settings: long press of M1-M4: save current settings; short press: recall values. And as there is no "free mode", any change will always be programmed to a memory place.

author: TopLoser
author_rank: Unknown
timestamp: June 09, 2015, 07:26:05 am
content: I've got 8 or 10 of these at the moment. I'll post ghem for sale early next week when I get back in the office.

author: tszaboo
author_rank: Super Contributor
timestamp: June 09, 2015, 07:47:27 am
content: We have some in the office (well, with +5V output) and I hate them. My favorite part is when the screen glitches when I'm measuring some power equipment, and I almost get a heart attack.

author: Pinkus
author_rank: Frequent Contributor
timestamp: June 09, 2015, 08:02:00 am
content: ?? What screen glitches ?? Do you mean the LED values of the power supply? I have never seen this.Maybe it is a problem with older Korads?Just a week ago I connected two of the supplys in parallel (by the way, at one supply the parallel/serial function is not working, I had to do the wiring manually - need to ask Toploser about it), so I got 24V and 4x5A = 480 Watt in total for testing a H-Bridge with a high power motor. The supplys did what they had to do, no problem at all, even when I was driving the motor with PWM (well the build-in fans were becoming turbines with this load, but who cares).

author: neslekkim
author_rank: Super Contributor
timestamp: June 09, 2015, 08:16:08 am
content: Quote from: TopLoser on June 09, 2015, 07:26:05 amAnyone of the programmable type?

author: neslekkim
author_rank: Super Contributor
timestamp: June 09, 2015, 08:19:31 am
content: Quote from: Pinkus on June 09, 2015, 07:22:24 amAha, so this is how they work maybe?, i thought it was something wrong with mine, Often it resets the values, so the M* buttons is kinda of no use for me.Btw, i have tested serial and paralell on mine, works very good, you ofcourse need to wire it as in the documentation, but it works fine.One thing I'm struggling a bit about, is the CC and CV mode, it seems that it selects the modes on it's own, It's easy to controll amps, but I cannot find a way of controlling CV, but maybe it's my head that doesn't follow the logic here. (been testing various high-power COB leds)

author: Pinkus
author_rank: Frequent Contributor
timestamp: June 09, 2015, 10:23:16 am
content: Quote from: neslekkim on June 09, 2015, 08:19:31 amWell, probably there is some strange Korean logic behind it. Nobody I know likes the way it is, but they did not change it in years, so either nobody is complaining (I did at Korad but they never answered) or they do not want to change it.Quote from: neslekkim on June 09, 2015, 08:19:31 amI always try to remember to switch to channel 4beforechanging to temporarily used values, so I do not change my memory places M1 - M3 .... but I often just forget it .... and then I always accurse the autosave "feature"Quote from: neslekkim on June 09, 2015, 08:19:31 amYes I know. It is working on one unit, the other behaves as it would contain two single supplys in one housing. There is no interaction between them. Pressing Parallel or Serial results in OCP / OVP as on the left unit. Something is wrong there either with the communication between both supplies or with the right main board. If I have some time I will open the unit and check where the problem is.... Luckily I have two (one faulty, one working correctly), this makes it easier to track down the problem. But it is not a big deal, everything else is working fine.

author: neslekkim
author_rank: Super Contributor
timestamp: June 09, 2015, 11:35:20 am
content: Quote from: Pinkus on June 09, 2015, 10:23:16 amYou haven't seen any schematics for these either?

author: Pinkus
author_rank: Frequent Contributor
timestamp: June 09, 2015, 12:58:19 pm
content: Nothing official. Somebody did post some handdrawn schematic of some parts of the supply (not all) at EEV blog.I did not find the link/entry now. I assume by reading all entries regarding Korad power supplies you will find it.

author: commongrounder
author_rank: Frequent Contributor
timestamp: June 09, 2015, 01:27:42 pm
content: Yes.pomonabill221had traced out part of the wiring, in hopes of improving the supply performance. The thread is in the Repair area.https://www.eevblog.com/forum/repair/korad-ka3005p-power-supply-calibration/msg386858/#msg386858

author: tszaboo
author_rank: Super Contributor
timestamp: June 09, 2015, 02:00:27 pm
content: Quote from: Pinkus on June 09, 2015, 08:02:00 amYeah. Like the LED suddenly shows instead of 50mA it jumps to 3150mA for a split second. It is a Tenma 72-10505. Sold by Farnell. I've seen this on more than one supply already.

author: TopLoser
author_rank: Unknown
timestamp: June 09, 2015, 03:10:07 pm
content: My opinion is they are cheap crap that I wouldn't rely on. Somebody once called them single use' devices and I think that's a bit harsh but I understand the comment. I don't know how the manufacturers make a profit on them, you do get a lot for the money.They are big and heavy 10Kg and the packaging and construction is crap, they suffer all sorts of unusual damage in shipping. I only sell then on here because it seems wrong to throw them in the garbage. I fully anticipate making hardly any profit on this batch after dealing with all the 'issues' that people discover with them that I didn't notice. They're very 'glitchy' in hardware and software behaviour, never seen 2 that you could put side by side and call twins.I really should just dump this lot, PayPal and the shipping companies are the only people that make any profit from them.

author: neslekkim
author_rank: Super Contributor
timestamp: June 09, 2015, 06:15:55 pm
content: Quote from: TopLoser on June 09, 2015, 03:10:07 pmMaybe, works for me at least, I couldn't find a better one for an reasonable price.I wanted to buy one of the Rigol dp83x versions, but after all the rubbish around those, I definately don't want that.Other psu's that are reasonable good and good priced for hobbyist use?, I know, there are lots of psu's on ebay, but you said it, shipping is the problem.I don't think anyone is doing anything with electronics in this country, cant find anywhere good stuff to purchase

author: TopLoser
author_rank: Unknown
timestamp: June 09, 2015, 06:36:49 pm
content: Quote from: neslekkim on June 09, 2015, 06:15:55 pmThat's the problem - there isn't anything close in terms of value for money. They must sell millions of them.

author: neslekkim
author_rank: Super Contributor
timestamp: June 09, 2015, 08:04:53 pm
content: You mentioned in another thread that you scrapped some, and kept the pcb's from them, but I don't remember if it was the 72-10495 modelDo you have a complete set of pcb's from this model?, or maybe I should wait and see what you come up with when you dump next load.

author: bitwelder
author_rank: Super Contributor
timestamp: June 10, 2015, 05:27:52 am
content: Is there some particular section of the circuit of the TENMA that is more critical, is it quality of the used components or what does it make them 'glitchy', and in different ways from each other ?