Thurlby Thandar QL355 Power Supply - Pt. 2; the innards - Page 1
Forum section: electronics / testgear

author: icon
author_rank: Regular Contributor
timestamp: July 29, 2012, 04:47:57 pm
content: Since there was modest interest in the other thread, I thought I'd post a few photos of the innards of the machine. Hopefully with the aid of the general overview photos at the beginning, you'll be able to work out which bits are where.[Edit to add] I meant to mention that the power supply weighs 12lb on the dot (5.5kg-ish). I know how interested some of you are in how much things weigh.CheersJohn

author: T4P
author_rank: Super Contributor
timestamp: July 29, 2012, 05:05:16 pm
content: Clipped on heatsinksSamwha caps

author: saturation
author_rank: Super Contributor
timestamp: July 29, 2012, 06:09:17 pm
content: Nice photos. If those heatsinks are true Avvids maxclips, those are top notch if not proprietary heat sink designs. Most everything seems to look A#1.Given they could easily get the reputable Japanese Panasonic, Rubycon etc., brands that have been around for decades, I would guess they did their homework for choosing the Korean maker Samwha, I don't know much about them except they have good spec sheets but Digikey doesn't carry them.

author: tom66
author_rank: Super Contributor
timestamp: July 29, 2012, 10:19:33 pm
content: Jamicons too.Samwha are a very new company without proven reliability - they were formed from the old Samsung capacitor business, and Samsung still use them a lot. (I'm not sure if there's a partnership or ownership by Samsung though.)It's clearly had some cost savings applied in the cap area, so maybe there are other savings too? I would prefer passive cooled huge metal heatsink without fan (like my old PS does 35V, 3A continuous without a fan, only gets a bit warm), does fan speed vary with temperature?

author: T4P
author_rank: Super Contributor
timestamp: July 29, 2012, 10:29:38 pm
content: Huge would be huge ...30V 5amps x2 no problem ...

author: Salas
author_rank: Frequent Contributor
timestamp: July 30, 2012, 10:27:25 am
content: I have seen those exact pictured Samwha in linear PSU hi-fi and pro amps giving no problems in a long time span.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 30, 2012, 11:23:29 am
content: Quote from: tom66 on July 29, 2012, 10:19:33 pmQuote from: T4P on July 29, 2012, 10:29:38 pmOf course they do. Now try 1V at max current.Should not be a problem still, but they'll get seriously warm.

author: tom66
author_rank: Super Contributor
timestamp: July 30, 2012, 11:26:58 am
content: Quote from: Short Circuit on July 30, 2012, 11:23:29 amSame thing, gets warm, but no issue. Shorted output is fine took. Max I drew from it once was full 35V at 2.2A when driving an induction motor. It has a multi tap transformer, max power dissipation is 10V drop * 3A = 30W, which is doable using decent heatsinks, and dissipated over three TO-3 power transistors. I have pictures of it somewhere, I'll see if I can find some.

author: tom66
author_rank: Super Contributor
timestamp: July 30, 2012, 11:39:36 am
content: Pics...

author: T4P
author_rank: Super Contributor
timestamp: July 30, 2012, 12:25:47 pm
content: Quote from: Short Circuit on July 30, 2012, 11:23:29 amI'm just saying, this PSU was intended for 3amps but clearly i went all the way to 5amps...1V at 5amps? Not a problem, this psu has 3 taps, 8V tap for the 1-8V range, 16V tap and a 16-30

author: tom66
author_rank: Super Contributor
timestamp: August 04, 2012, 09:31:52 am
content: Oh dear, more bulged Samwhas! Just pulled these from a 40" Samsung LCD. Actually, although there were three bulged (two 1000µF 25V pictured, one 470µF 10V not pictured), only one of them tested really bad (~4 ohm ESR.) The others tested 0.2 - 0.5 ohms or so each, which is still failed but not as bad. So, I suspect the 4 ohm one went out first, and took out the other two. That would point to a QC issue, which makes me suspicious of Samwha caps.After replacing them (with Panasonic and Nichicon), TV works fine now. (Before, it had difficulty powering up from standby, stuck with flashing LED.) Oh, and TV is about 18 months old, and really nice with 1080p, USB and 100 Hz, so Samsung cheap out on even their nice TVs. My main TV now.This brings the number of Samwhas I have replaced to 22.

author: FenderBender
author_rank: Super Contributor
timestamp: August 04, 2012, 06:16:45 pm
content: Quote from: saturation on July 29, 2012, 06:09:17 pmYeah seriously!I feel like we are back in '02 during the electrolytic capacitor crisis! Do these manufacturers really not understand that there is a difference between good and bad quality electrolytics?If they had only put in good caps I would actually have been very happy with the power supply's build, but it's just getting old. Spend $2 more bucks on good caps and you'll have a better and more reliable piece of equipment which means people will actually buy them.

author: tom66
author_rank: Super Contributor
timestamp: August 04, 2012, 07:28:29 pm
content: In my old PS all the electrolytics are Chemicons, except the main bulk one (10000µF 63V) is a Matsushita (old Panasonic.)

author: FenderBender
author_rank: Super Contributor
timestamp: August 04, 2012, 08:18:38 pm
content: Depends on the manufacturer. Mine also. I had a Dell from '01. Chemicon, Rubycon, Nichicon.But motherboards/graphics/PCI cards were notorious for crap caps for whatever dumb reason.

author: tom66
author_rank: Super Contributor
timestamp: August 04, 2012, 10:13:33 pm
content: In this case, I'm referring to my massive 35V, 3A linear supply.But while I have had several power supplies with good caps, I keep encountering ones with poor capacitors. CapXon is my second most common replacement.

author: madires
author_rank: Super Contributor
timestamp: August 04, 2012, 10:32:41 pm
content: Quote from: FenderBender on August 04, 2012, 06:16:45 pmWe think that way, but not the MBAs. If products can be designed to fail after a specific time it's done to increase sales. New sales create revenue, long lasting products don't. Welcome to the wonderful world of consumer electronics :-)

author: tom66
author_rank: Super Contributor
timestamp: August 04, 2012, 11:38:57 pm
content: Designed to fail, sure, that's what you get with LG! This has to be the record for the most caps I've replaced on any TV. All Samwha. I must emphasise - these capacitors -do not- have a good reliable track record. Due to their usage, TTi will not be among my choices for a power supply if I were to order one.Not shown: Three Samwhas which did not bulge but still had high ESR.

author: ju1ce
author_rank: Regular Contributor
timestamp: August 05, 2012, 04:32:12 pm
content: Quote from: tom66 on August 04, 2012, 11:38:57 pmI guess the capacitors in a linear bench supply have a much easier life than those in the SMPS of a TV. Television sets are usually in standby 24/7 whereas decent bench supplies have a mains switch in the front panel.

author: tom66
author_rank: Super Contributor
timestamp: August 05, 2012, 04:51:02 pm
content: Quote from: ju1ce on August 05, 2012, 04:32:12 pmMaybe. But the Samyoung caps survived fine (they were mixed in parallel with the Samwha.) All tested good. Even the Samwha caps after the inductors failed - their ripple current is on the order of a few hundred mA! If they can't handle that, then they are suitable for no task. In standby, a TV should be using less than a watt (legal requirement now anyway.)

author: T4P
author_rank: Super Contributor
timestamp: August 05, 2012, 05:20:42 pm
content: Quote from: ju1ce on August 05, 2012, 04:32:12 pm5 years lifetime or 10 years lifetime pick your choiceWell for one, it's clear, dodgy caps will shorten the lifespan of a equipment whether TTi Bench Supplies or a TV

author: Soertier
author_rank: Contributor
timestamp: October 31, 2012, 09:37:41 am
content: Anyone know the difference between this QL355 (Not P, T, or TP) and the new Series II? Difference capacitors maybe?

author: nukie
author_rank: Frequent Contributor
timestamp: October 31, 2012, 10:22:23 am
content: Colourful wires I like! Thanks for the pictures. Hey guys capacitor lives inside flat panels displays are cooked to death, they don't get adequate air flow thus heat up quickly and reduce lifespan of those already crap brands.

author: icon
author_rank: Regular Contributor
timestamp: October 31, 2012, 03:28:16 pm
content: Quote from: Soertier on October 31, 2012, 09:37:41 amNew features! Great new recipe! Best ever taste! Beats as it sweeps as it cleans! Actually, I couldn't discern any difference - I'm the one who started the thread, and I looked on Thurlby Thandar's website, but couldn't see what made a series II different.On a positive note, it still works, all these weeks later...RegardsJohn

author: Soertier
author_rank: Contributor
timestamp: October 31, 2012, 03:53:40 pm
content: Quote from: icon on October 31, 2012, 03:28:16 pmIn the mean time I have found this, it should explain the differences:http://tti2.com/pr-text/QL-SeriesII-PR.htmlEven if the would use different capacitors, they would not mention it. I doubt most people doubt about TTI products and checks much.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: October 31, 2012, 05:14:40 pm
content: Recently bought a PL series, which still has a big samwha in it.https://www.eevblog.com/forum/product-reviews-photos-and-discussion/thurlby-thandar-not-a-happy-bunny/msg144243/#msg144243

author: Christe4nM
author_rank: Unknown
timestamp: October 31, 2012, 06:52:27 pm
content: First thing I noticed was the big cap located between vent holes and the heat sink. I really hope that fan sucks the air in from the back, otherwise all the heat will pass the large cap before leaving the enclosure.AIM TTi is a company that I still can't figure out with regard to design quality. Their products seem very good to me, yet when seeing the inside of this supply I only can say that it's OK. Maybe my standards are a bit high, but I was kinda disapointed. However, I had the same experience with the Agilent U8000 series. They aren't like the "old" HP ones sadly. Not to say they're bad, on the contrary, yet I think it's safe to say R&D gets less funding nowadays.

author: Soertier
author_rank: Contributor
timestamp: November 02, 2012, 08:38:44 am
content: So what do you think guys? Is this power supply worth it?I mean the features and power is suitable for my needs (on spec looks pretty good), but really, I am not sure regrading the caps and there have been reports of those heatsink metal holders breaking.

author: T4P
author_rank: Super Contributor
timestamp: November 03, 2012, 12:44:51 pm
content: No.Surely i would expect nichicon caps in a 600 dollar power supply, but why TTi, WHY?!Maybe the only reason why their power supplies are a little more in "value" is this

author: tom66
author_rank: Super Contributor
timestamp: November 03, 2012, 01:12:01 pm
content: I would not recommend this simply because I regard Samwha as poor capacitors that are not fit for use in a high-end piece of equipment like this.