How hard can it be to find a 9,8V, 75W PSU? - Page 1
Forum section: electronics / general

author: oh2ftu
author_rank: Regular Contributor
timestamp: January 01, 2022, 09:41:45 am
content: Hello there.I already put up a post in the classifieds, but I'll also try here for other solutions.I've had a Powersolve PSE65-9V8 / Autrodyne/Sinpro SPU65-104 power supply go bad.It powers a bank charger for radios, and thus the correct voltage (including sense) is vital.Searching on eBay, mouser, digikey etc have been in vain. Most adjustable are from 10 or 11V up.From what I gathered, MW does not have anything that fits.Also, as this is going to be used in the field by normal people, the desktop PSU format is preferred.There's one ad for a SPU65-104 in the US, but it will kill me including shipping (almost 200e total).What are my alternatives?

author: Emo
author_rank: Regular Contributor
timestamp: January 01, 2022, 10:06:19 am
content: Hi,The 12V LRS Meanwell supplies can be adjusted from as low as 10.2V So by just adding a diode in series the output will drop within the desired range.Eric

author: Kjelt
author_rank: Super Contributor
timestamp: January 01, 2022, 10:59:00 am
content: Other alternative would be two identical 5V 40W (8A) power supplies in series.

author: rsjsouza
author_rank: Super Contributor
timestamp: January 01, 2022, 12:10:41 pm
content: Quote from: Emo on January 01, 2022, 10:06:19 amIndeed. Also,HEPcan down to 10.8V if you are looking for an enclosed model.

author: Gregg
author_rank: Super Contributor
timestamp: January 01, 2022, 07:39:52 pm
content: Gophert NPS-1600 is a nicely packaged switch mode 0 to16 volt, 0 to10 amp CV, CC 100W power supply available from Aliexpress for a reasonable price.

author: Whales
author_rank: Super Contributor
timestamp: January 01, 2022, 10:51:06 pm
content: If you want cheap: you may be able to take a standard ATX computer power supply and modify the feedback resistors for the 12V rail, so it outputs 9.8V instead.I recommend getting some second hand ATX PSUs and avoiding the really good quality/expensive ones, because those may have multiple brownout detect circuits. Something with a single DIP controller chip would probably be your best bet, these are likely to be simpler. Some power supplies even have a pot already installed (I think I had a Delta one that did this?) but you'll have to still modify the resistors near it to give it range down near 9.8V.EDIT: or buy new of those 12V supplies off ebay (better sources?) with the cheesegrater grill and line of screw terminals on one side.

author: oh2ftu
author_rank: Regular Contributor
timestamp: January 02, 2022, 01:33:43 pm
content: Thank you for your input.The solution I'm looking for will need it to be safe for normal people to use.As the intended use in the field, 12 and 24V vehicular input would be awesome.Also, I have an abundance of 12V 7A power supplies.Maybe a DC/DC-converter with 9-36V input? and adjustable output to 9.8V?

author: tunk
author_rank: Super Contributor
timestamp: January 02, 2022, 06:00:15 pm
content: QuoteMaybe you could open one and post some photos.It may be as simple as to replace a resistor to get 9.8V.

author: oh2ftu
author_rank: Regular Contributor
timestamp: January 02, 2022, 06:29:52 pm
content: Quote from: tunk on January 02, 2022, 06:00:15 pmActually not a stupid idea.The supply that's busted is SPU65-104, and I have SPU65-105 PSU's.Anyone got a schematic lying around? :-)I will pop both open and post pictures

author: Nusa
author_rank: Super Contributor
timestamp: January 02, 2022, 06:34:00 pm
content: I note that the spec sheet for SPU65-104 says it's a 10 VDC 7.5 A supply. So could be that 9.8V is not actually your best target number?

author: oh2ftu
author_rank: Regular Contributor
timestamp: January 02, 2022, 07:04:58 pm
content: The -104 can be internally adjusted 8-11V. -105 can be adjusted from 11-13V.Too bad the 105 I have are without remote sense :-(

author: Siwastaja
author_rank: Super Contributor
timestamp: January 02, 2022, 07:07:44 pm
content: What is a "bank charger" and why it requires extremely well regulated voltage to the point where wiring resistance is a problem? Chargers usually, by definition, do their own voltage and current regulation.Sounds to me like this "bank charger" is a problem and should be replaced with something suitable, but first I'd like to know what it supposedly does, being such special snowflake. Or maybe the voltage accuracy requirement is just an assumption, not a fact?

author: madires
author_rank: Super Contributor
timestamp: January 02, 2022, 07:28:48 pm
content: Take the next best 12V power brick and modify the voltage divider for the feedback?

author: bw2341
author_rank: Regular Contributor
timestamp: January 02, 2022, 08:30:21 pm
content: If it really is for use by normal people, I would buy the original power supply from an official seller of the radio system. The inflated price would be worth it to me to avoid any liability for safety issues.I found some pictures of the Powersolve PSE65-9V8 from an online seller. It looks like a 9.8V 7.65A DC power supply with a 4-pin Power DIN connector (Kycon KPXJ?) with remote sense connections.The Powersolve website doesn't seem to mention this series of power supply. Maybe it's been discontinued? Sinpro SPU65-104 seem to refer a series and a voltage range and is not specific enough to identify an exact connector. The series datasheet does not mention remote sense at all.If I had to solve this problem for my own personal use, I would open up the radio charger to figure out the charging circuit. The DC input is likely connected to a charge controller chip or voltage regulator so I would figure out the acceptable voltage range and whether or not the remote sense is necessary.

author: oh2ftu
author_rank: Regular Contributor
timestamp: January 03, 2022, 06:32:27 am
content: Hello,The radio charger in question is a Sepura 300-384.It includes a power distribution board (no regulators identified) that distribute power to six individual pcb's, each capable of charging a radio and battery simultaneously.The radio receives the input power directly, and the radio manual states the following:Charging voltage range: Vchgmin = 9,3V Vchgmax = 9.7VAbsolute maximun transient voltage: Vchgmax = 13,5V (must not exceed 10us in duration e.g. under hot insertion or mains switch on conditions)The power supply (and charger for that matter) is NLA. Also, all charger internal boards are from Powersolve.Attached are some pictures

author: Zero999
author_rank: Super Contributor
timestamp: January 03, 2022, 09:32:29 am
content: Quote from: Emo on January 01, 2022, 10:06:19 amThat will work, but might not be accurate enough, as the diode drop will vary with the current.A low drop-out regulator could be used to reduce the output voltage to 9.8Vhttp://ww1.microchip.com/downloads/en/DeviceDoc/MIC29712-7point5A-Fast-Response-LDO-Regulator-DS20006068A.pdfhttps://www.analog.com/media/en/technical-documentation/data-sheets/108345fh.pdfQuote from: madires on January 02, 2022, 07:28:48 pmYes, the typical feedback circuit uses the TL431, with an opto-coupler for feedback. Changing the feedback resistors normally works, but you might also need to alter the resistor in series with the emitter, as 9.8V will lower the forward current, and there's a chance of instability, in which case a compensation capacitor will need to be added/changed.In this case 9.8V is only a little lower, so just changing the feedback will probably work. Here are a few links.https://www.instructables.com/Changing-the-output-voltage-of-a-cheap-power-suppl/https://www.homemade-circuits.com/how-to-make-variable-current-smps/https://www.onsemi.com/pub/Collateral/TND381-D.PDF

author: BrokenYugo
author_rank: Super Contributor
timestamp: January 04, 2022, 06:36:43 pm
content: I'd regulate down a common 12V supply or fix the existing one, looks like something on the secondary side popped?

author: thm_w
author_rank: Super Contributor
timestamp: January 04, 2022, 10:05:20 pm
content: I assume they are using Q1 to regulate the voltage into a 2S Lipo. So 7.4V termination voltage.I doubt the input voltage is that critical. Maybe if its too high, Q1 will heat up.In that case, putting in a series diode or two on a tweaked 12V supply is a complete non-issue. Even 9V supply may work.This page says 10V input:https://www.sepura.com/accessories/1-1-desktop-charger

author: oh2ftu
author_rank: Regular Contributor
timestamp: January 06, 2022, 05:11:48 pm
content: Here's a short follow up.As I have an extra charger which I intended to make use of, I decided to check it out.Good thing I did, the charger pcb's inside are gone (corrosion).also, before that, I contacted powersolve which would've been able to supply the correct PSU for about 200 eur including shipping and taxes.At least they are available..

author: madires
author_rank: Super Contributor
timestamp: January 06, 2022, 05:51:16 pm
content: A Meanwell 12V 100W power brick is EUR 41. This reminds of a friend who lost the charger for his Bosch cordless screwdriver. 28 bucks for a 5V 400mA wall wart. WTF! Next best mobile phone charger from the box full of old PSUs plus some unsusual sized barrel plug for EUR 2.80 (incl. shipping) and the problem is solved.