Tenma 72-8345 bench PSU review - Page 1
Forum section: electronics / general

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 13, 2012, 08:23:40 am
content: http://cpc.farnell.com/tenma/72-8345/power-supply-1-36vdc-0-3a/dp/IN05539?in_merch=Featured%20Products

author: T4P
author_rank: Super Contributor
timestamp: June 13, 2012, 09:08:31 am
content: I found the OEM again, it's a Manson supply again.Farnell ...BUSTED!

author: LEECH666
author_rank: Frequent Contributor
timestamp: June 13, 2012, 10:09:43 am
content: Yep. I was just about to remark that this PSU seems to be solder under different badges.I've eyed this supply for some while now.In Germany you can get this supply (Manson branded) for ~80 €.For example herehttp://j.mp/K1fiKg(shortened link to reichelt.de).Nice review Mike. I like your resistor mod. Deffo seems like an improvement over the original unit.Thanks for sharing.Florian

author: gtsili
author_rank: Contributor
timestamp: June 13, 2012, 12:00:02 pm
content: Perfect timing. I was looking to buy a bench PSU that will not cost me an arm and a leg and that it is decent quality. I just ordered one from Reichelt Elektronik. A bit less than 100 euros including VAT, posting and bank fees. Thanks Mike and Florian.I loved the mods you suggested Mike. Let us know how it goes with the oscillator mod.

author: baljemmett
author_rank: Unknown
timestamp: June 13, 2012, 01:28:43 pm
content: Nice review, Mike; I have what I guess is the baby brother of this one, which does 0-20V at 0-5A instead -- mine's branded as a Maplin N93CX.Externally they look identical, except mine has three-digit instead of four-digit meters (with the polariser the other way around!), and uses a pair of single-turn pots instead of encoders. The latter make it a little fiddly to adjust, especially combined with the slight lag in the display, so I'm tempted to pop the back off when I get a spare moment and see if I can make a similar mod to increase the update rate. The modular construction means the pots might find themselves upgraded to ten-turn models as well...By the way -- the "joker on eBay" you mentioned sounds like the chap who basically lists vast swathes of Farnell's catalogue at 100% - 200% markup? I'm not sure I understand how such a business model can prove successful, frankly!

author: Bored@Work
author_rank: Super Contributor
timestamp: June 13, 2012, 02:36:53 pm
content: Quote from: baljemmett on June 13, 2012, 01:28:43 pmEasy, as e.g. the Raspbery Pi foundation had to learnt the hard way after signing a contract with Farnell. In a bunch of countries Farnell does not ship to individuals. In the RPi case it seemed even the Farnell headquarters were surprised (or acted surprised) finding that out.Of course, if you need a part and the Farnell tossers don't ship to you, you start to look elsewhere. If you then happen to find such an eBay shop and have no other alternative ...

author: codeboy2k
author_rank: Super Contributor
timestamp: June 13, 2012, 03:25:46 pm
content: Nice review Mike! Thanks!I really can't stand digital encoders like that; sometimes if you turn it too fast they just miss. oh, nice mod to fix it up too.....and I'm going to hack into your scope now....[root@sillyputty]# telnet 192.168.1.60Trying 192.168.1.60...Connected to 192.168.1.60.Escape character is '^]'.Bugger off!Connection closed by foreign host.[root@sillyputty]#must be firewalled

author: Rufus
author_rank: Super Contributor
timestamp: June 13, 2012, 03:35:54 pm
content: Quote from: Bored@Work on June 13, 2012, 02:36:53 pmI mentioned this 'joker' in another thread. He has about 115k listings scraped from the Farnell web site, very annoying with his items often turning up in search results.He is a drop shipper. He places orders on Farnell, they deliver to his buyers (for free), he pockets the typically 100% markup. He only ships to the UK so it isn't the case he supplies to people in countries where Farnell won't.==================================Thanks for the review Mike, Manson stuff seems to be generally well made and re-badged for anyone that asks. Their model number is NRP-3630http://www.manson.com.hk/en/dcpowersupplies_detail.php?m=3&id=16. Sometimes searching for their model will turn up service information but not in this case it seems.

author: MikeK
author_rank: Super Contributor
timestamp: June 13, 2012, 10:35:28 pm
content: Nice review.Was the resistor added to the chip's RC oscillator, to get faster screen updates?

author: LEECH666
author_rank: Frequent Contributor
timestamp: June 13, 2012, 11:15:55 pm
content: Yes, MikeK. I would have to rewatch the video to determine the value of the resitor the other Mike mentioned, but I think I remember it being 220 Ohms.Florian

author: Pickers
author_rank: Newbie
timestamp: June 14, 2012, 12:01:41 am
content: Interesting review, comes at a good time as I'm looking at buying a new bench PSU. Will definitely give the resistor mod a go if I get that model.Cheers,Kris.

author: Monkeh
author_rank: Super Contributor
timestamp: June 14, 2012, 12:20:01 am
content: Quote from: LEECH666 on June 13, 2012, 11:15:55 pm22k. Pins 1 and 40, whatever they are.

author: IanB
author_rank: Super Contributor
timestamp: June 14, 2012, 02:29:55 am
content: Going by the form factor, it looks like a stripped down and simplified version of the Extech 382260:http://www.extech.com/instruments/product.asp?catid=39&prodid=207The Extech fixes most of your complaints as well as having more features (for example it has remote voltage sensing and master-slave connections on the back for connecting several units in parallel).I've posted before how much I like it. I'll have to do some of the same tests on voltage and current regulation to see what I find.

author: ivan747
author_rank: Super Contributor
timestamp: June 14, 2012, 02:42:09 am
content: A slightly different version is sold by BK Precision:http://www.tequipment.net/pdf/BK/1550_datasheet.pdfIt has push buttons instead of encoders. It may be annoying. It has binding posts.Where can I get a version of this with the encoders and preferably with binding posts on the US without having to pay extra for buying a BK Precision brand supply? I'm OK with the BK, but if I find something the same price with the encoders, I would get that.

author: ivan747
author_rank: Super Contributor
timestamp: June 14, 2012, 03:01:10 am
content: The entire series and the BK one are available at the US Farnell for the same price ($150). Pick yours: rotary encoder and trusted quality or USB power+binding posts at the expense of a crappy control system.

author: T4P
author_rank: Super Contributor
timestamp: June 14, 2012, 05:17:18 am
content: Quote from: IanB on June 14, 2012, 02:29:55 amWhich is also from manson ...

author: LEECH666
author_rank: Frequent Contributor
timestamp: June 14, 2012, 09:15:11 am
content: Quote from: Monkeh on June 14, 2012, 12:20:01 amDamn you short term memory, you've fooled me once again!Quote from: DaveXRQ on June 14, 2012, 05:17:18 amIndeed:http://www.reichelt.de/Labornetzgeraete/SSP-7080/3//index.html?ACTION=3&GROUPID=4952&ARTICLE=102569&SHOW=1&START=0&OFFSET=16&Sorry no short link this time, all URL shorteners are blocked @work.Why am I here anyway?

author: quarros
author_rank: Regular Contributor
timestamp: September 27, 2012, 04:29:31 am
content: It seems this power supply is also sold by Peaktech:http://www.peaktech.de/productdetail/kategorie/schaltnetzteile/produkt/p-6135.htmlHow many more brand we will see I wonder.

author: miciotta
author_rank: Newbie
timestamp: October 12, 2012, 04:56:27 pm
content: manson cost a little bit minus like peaktech !I found that :TENMA 72-8345 = MANSON 2050 = PEAKTECH P6095Is the same power supply !Now, is a best buy ? I not use for work but only for hobby…I buy this power supply ?Thanks , Mery.P.S. I see there is a modify for this (by Mike) ? what is this modAnd for what ?HELP ME BOY ??

author: LEECH666
author_rank: Frequent Contributor
timestamp: October 16, 2012, 06:49:16 pm
content: I think it might be worth it for hobbyist usage.The mod Mike did to his unit changes the display update speed (it's a lot faster with his mod). He also mentioned that it might impact accuracy a little bit, but it's probably neglectable.Cheers,Florian

author: markm6164
author_rank: Contributor
timestamp: December 30, 2013, 10:48:11 pm
content: I know this is an old post but i have the same power supply but the 20v 5A version from Maplins. I notice the output has voltage on it when the output is turned off with no load. Even at maximum 20v. Shorting the output removes the voltage. Also under light loads the output voltage is slow to drop when turned down. Anyone else seen this or have a modification to improve it?

author: mariush
author_rank: Super Contributor
timestamp: December 30, 2013, 11:05:16 pm
content: Add a small resistor in parallel with the capacitor on the output to discharge that capacitor. I think 1-10 kohm should do it...

author: simontay1984
author_rank: Newbie
timestamp: February 17, 2014, 09:56:30 pm
content: I have the 20V 5A version of this PSU from Maplin in the UK. I was going to do the resistor mod like Mike did but the 20V 5A version uses intercil ICL7106CPLZ display ICs, not Microchip TC7129's. They have different pinouts.I looked at the datasheets for both ICs and Pin 1 on the ICL7106CPLZ is +9V, pin 40 is OSC1 and pin 39 is OSC2.If you have the 20V 5A version do NOT connect a resistor between pin 1 and 40, you will damage the IC. Connect it between pin 39 (OSC2) and pin 40 (OSC1) instead. The existing resistor is 100K. Experiment with different resistors to change the RC oscillator speed to something you're happy with..How would I increase the max output voltage of my unit to 36V. I realise that i'd need to replace the output caps with higher voltage ones and that it obviously won't deliver the full 5A at 36V. I'd set the current limit to 2.5A when at 36V. I expect something in the feedback circuit somewhere?

author: electronics man
author_rank: Frequent Contributor
timestamp: February 18, 2014, 01:08:53 pm
content: everyone is selling ithttp://www.rapidonline.com/Electrical-Power/Rapid-100W-Switch-Mode-Bench-PSU-78617and it was featured on the bbc's the one show

author: dexters_lab
author_rank: Unknown
timestamp: February 18, 2014, 09:09:09 pm
content: Quote from: electronics man on February 18, 2014, 01:08:53 pmfeatured on the One Show? I am intrigued!

author: electronics man
author_rank: Frequent Contributor
timestamp: February 18, 2014, 09:13:10 pm
content: That's what it says on the rapid electronics listing

author: zapta
author_rank: Super Contributor
timestamp: May 25, 2015, 09:11:34 pm
content: I am looking for a small footprint, simple and silent (as in non fan) bench power supply and stumbled upon this review and thread. Of the three models I am thinking of the 20V 5A version. Is this still a good choice or are there new competitors?http://www.newark.com/tenma/72-8350a/power-supply-1ch-20v-5a-programmable/dp/95W5650The main issue I have with it are the lack of binding posts (I am thinking using something like thesehttp://www.t2retail.co.uk/Components/Binding-Post-To-Banana-Plug-Adapter-Pk-2) and the need to short the output to read the current limit value (does it make sense to add a high current momentary switch to simplify it?)