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Old 05-31-2021, 02:10 PM   #21
zunasthegreat
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Did another try with a washer on the SBR and this time the finding is lets say interesting. Upon having the psu without its top cover there was no hiss or pitch sound while running the pc. Once I screwed the top of the PSU it started singing again ... looked to me like some kind of AC freq noise so I put the 450W laber on the inside where the "bulk" caps-ac part is, hiss sound now is officially gone and the 12V SBR has the plastic washer that always wanted.

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Old 06-01-2021, 12:28 PM   #22
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

"Stage 2" updates

1.New AWG 18 braided 4-pin CPU connector
2.New 8cm fan with better airflow
3.Added more molex cabling
4.Different set of 200V primary caps with some extra capacity (still crap brand OFC )

For stage 3 I'll probably switch 13007's with some spare 13009's and I might update the 3.3V S10C45C. Btw I have some SBL2040CT and S16C45C, which is the more viable update if any ?
The best part is that It boots fine (for how long???) on the test-pc with Phenom II X4 OC'ed @ 3.4GHz 1.3V / HD 5770 and a plain HDD. Even tried some MOBA gaming and it didn't shut down, the heat from the exhaust wasn't that bad. I'm guessing a load of least ~200W.

filter caps :
+5VSB nichicon HD 1000uf 10V
+3.3V panasonic FJ 3300uf 6.3V
+5V nichicon PW 3300uf 10V
+12 nichicon VY 3300uf 16V
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Old 06-01-2021, 12:57 PM   #23
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Unless I missed it, that P/S doesn't have ferrite rod inductors - or a location for them - whose purpose is to reduce turn-on and turn-off spike noise. Nor do any of the semiconductors have beads to reduce spike noise. There probably isn't a meaningful load - if any load condition at all - at which ripple and noise meet the ATX spec.
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Old 06-01-2021, 08:38 PM   #24
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

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Originally Posted by PeteS in CA View Post
There probably isn't a meaningful load - if any load condition at all - at which ripple and noise meet the ATX spec.
Well, I wouldn't go as far as saying that. I have plenty of old and well-built half-bridge PSUs from well-known good manufacturers (Mitac, MeanWell, HiPro, and etc.) that didn't have PI coils on some of the rails, but still produced outputs within ATX spec. It's partly to do with the design, and also partly with the total capacity.

In general, a single 1000 uF cap on a continuous design, at least from what I've seen based on ratings on the abovementioned good PSU brands, is about 6-8 Amps. So that would correspond to ~20 Watts from the 3.3V rail, ~30 Watts from the 5V rail, and ~80 Watts from the 12V rail. On PSUs that bumped the output capacity up to 2200 uF per rail, the output current can be ~2x higher... though again it depends on the output filter design (i.e. main output inductor inductance and current-handling capability.) And with 3300 uF, the current can be up to 20-22 Amps.

Since O/P greatly improved the output capacitor capacity on each rail, the PSU should definitely be able to handle much higher current than before, with or without PI coils. PI coils could help even further, no doubt. Of course, the single cap per output method will still yield rather poor ripple and noise filtering results... but at least in spec now, given a normal PC load.

That said, I'm still would -not- suggest to push the 12V rail to more than 15-16 Amps of current draw, if even that much. For one, again that output inductor looks really small and its core would likely saturate if any higher current is attempted (not to mention the rather thin wires on it.) Also, while Nichicon VY is a pretty good GP cap and likely not to be an issue as a filter cap in this PSU (due to the PSU using half-bridge topology with a relatively slow switching speed), VY is general purpose, so that means it has relatively low ripple current spec. Thus, at high loads on the 12V rail, that cap may start to run very hot (or even overheat?)... not to mention the rest of the nearby components in the PSU are already dumping a lot of heat in the area there. So my only real concern is that the Nichicon VY cap may not last very long under heavier PSU load. But with something like a 100W TDP CPU and nothing else (i.e. no hungry GPU), it will probably last a very long time.

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Originally Posted by zunasthegreat View Post
For stage 3 I'll probably switch 13007's with some spare 13009's
May not be worth it... but if you have them already and they are known genuine 13009's, go for it. Otherwise, I'd avoid the really cheap ones from cheap e-tailers.

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Originally Posted by zunasthegreat View Post
... and I might update the 3.3V S10C45C. Btw I have some SBL2040CT and S16C45C, which is the more viable update if any ?
Probably doesn't really matter too much.
3.3V rail is only really used by RAM and/or chipset VRMs, so both of these will suffice. The SBL2040CT, of course (at least the TO-247 case version) appears to have a lower Vf than the S16C46ct rectifier, so it should produce less heat. But it wouldn't be anything substantial, so probably OK to use whichever part your like.
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Old 06-02-2021, 04:30 AM   #25
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Upon checking for better 12V cap I found the following 16V in the cap-bag : HD 2200uf 16V and PW 2200uf 16V.

I have nothing better than that VY with 3300uf @ 16V, my 3300uf's PW/HD are 10V. Just for the extra endurance will it be any better with a PW/HD 2200uf 16V instead ?

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Old 06-02-2021, 12:44 PM   #26
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Any point adding an X cap (0.22uf 275V) across L-N where AC cord goes ? No room on the pcb anyway ...
Regarding Y caps those without CE are fire hazard I guess, should I get 4.7nf 250V or 400V ?

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Old 06-02-2021, 06:26 PM   #27
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

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Originally Posted by zunasthegreat View Post
I have nothing better than that VY with 3300uf @ 16V, my 3300uf's PW/HD are 10V. Just for the extra endurance will it be any better with a PW/HD 2200uf 16V instead ?
For the endurance alone: yes.

VY series are only rated for 1000 hours (at 105C, max applied voltage, and any diameter, it looks like.) The ripple current is also only 1170 mA for the 16V, 3300 uF can.
Meanwhile, Nichicon PW is rated for 7000 hours (at 105C and max applied voltage) for the 12.5 mm diameter caps. In the case of the 2200 uF 16V can, you get about 1900 mA of ripple current. So the cap will run slightly cooler with the same ripple current produced from the PSU circuit.
And Nichicon HD is rated for 5k hours (again, at 105C and max applied voltage) for 12.5 mm diameter. Here, the 16V 2200 uF cap can withstand 2770 mA of RC.

That said, assuming the VY cap on the 12V rail runs at 55C internally when the PSU is under full load, the cap should still last at least 32000 hours (~3.7 years) - and that's assuming maximum applied voltage on the cap, which here won't be the case. Unfortunately datasheets don't mention how applied voltage affects endurance... but generally, after a certain point, the closer you get to the maximum, the more stressed the cap is. Thus all this considered, the VY will likely last at least around 4 years (again, assuming it runs at 55C internally, which I think is a bit over-estimated... but better that than under-estimated.) In contrast, using the same temperature, the Nichicon PW should -theoretically- last ~26 years.

In terms of filtering, though, the VY may also be the better choice due to the higher capacitance, as higher capacitance = lower ripple current output. And in this case, the ESR of VY series is high enough that filter ringing will not become an issue (though PW also has very modest ESR ratings, so it's well-suited for PSU use.)

So I think it becomes more of a choice: do you want the PSU to be able to handle higher current on the 12V rail (with the VY cap, due to higher capacitance) or will slightly reduced current capability suffice at the exchange of getting better endurance from the 12V caps (with the Nichicon PW or HD.)

I guess since it all appears to work well at this moment (or at least PC is not crashing anymore), perhaps keep the VY. But if you have a type-K thermometer or a laser thermometer, you can try running the PC at maximum load, then quickly shut it down, open it (after disconnecting from AC, of course) and check how hot things got - particularly the output caps. If they've remained relatively cool (especially the VY), then it may just be OK to leave things as-is. Or if you are still a little worried about the endurance, then go with the PW.

I'm tempted to suggest for you to go with the PW... and if space allows, maybe drill holes in the PCB and try to add a 2nd cap on the 12V rail to get slightly higher capacitance. Or if not possible, even having a 2nd cap with slightly longer leads in there may still help a little more. From what I see from the pictures though, if you removed the dummy load resistor on the 12V rail that's right next to the cap and place it somewhere else, you could use its holes on the PCB to attach a 2nd cap to the 12V rail with slightly elongated leads. Then you can have the benefit of the PW and another cap (1000 uF or more) for the extra capacitance too.

Oh and on a different note, your 5VSB circuit appears to be a 2-transistor self-osc. design with a "critical" cap (the one small electrolytic cap on the primary side by the 5VSB transformer.) So you may want to check that and preferably even replace it with a good Japanese brand.

Quote:
Originally Posted by zunasthegreat View Post
Any point adding an X cap (0.22uf 275V) across L-N where AC cord goes ? No room on the pcb anyway ...
Yes, do it.
Since there is no common-mode choke, though, the X cap alone won't be able to reduce as much EMI/RFI. But it's better than having nothing.

Quote:
Originally Posted by zunasthegreat View Post
Regarding Y caps those without CE are fire hazard I guess, should I get 4.7nf 250V or 400V ?
X1Y2 (i.e. standard Y2) will suffice. I think they will be rated for 250V AC / 400V DC. 4.7 nF is a good value. But even 2.2 nF (222) or 3.3 nF (332) will be fine. Get 3 of them: one to install between L and G, one between N and G, and one between primary-side negative [-] rectified bus and ground. At least that's usually the standard way good PSUs seem to do it.

Last edited by momaka; 06-02-2021 at 06:41 PM..
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Old 06-03-2021, 03:08 AM   #28
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Hmm I think I can move that load resistor where the cabling for 12V + GND solder and on the resistor location I can put a slim KY 1000uf 16V or 2X HV 1500uf 16V.

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Old 06-03-2021, 06:39 AM   #29
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Also changed the critical 1uf cap with a nichicon PJ 2.2uf. It was the cap next to the 2 BJT's I think, also changed some 47uf caps with some spare old stock. For the +12V cap situation I have now the psu under testing with a 16V HD 2200uf. Realistically the weak link on this unit will never be its caps anymore ... something else will make this psu to proceed into oblivion. Btw some old (branded?) 5V heavy psu's with 15A Label @ +12V had in stock a single 1500uf cap for filtering.

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Old 06-05-2021, 04:39 PM   #30
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

I messed around a bit with the load resistors and made some changes just for heat reduction near the CAPS. Stock load seemed kinda low-ish for 3.3V (10Ω) and 5V (20Ω).
Ι've switch the 20Ω to the 3.3V and placed a 33Ω (2W) on the 5V. 12V still has a 330Ω but I've moved that res. near the 12V fan header and I've added another 2200uf 16V cap for the 12V.
This will be the end of tampering this gutless FORCE 450W as another champion is about to arrive ... a DR-8600BTX

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Old 06-07-2021, 02:28 AM   #31
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

CWT 405W with PCB discoloration, traces under the pcb that start to crack upon de-soldering and many dead caps. There is a strange burned resistor that looks awful under the C2 cap. Upon checking on the DMM gives 1KΩ, I think I'll have to measure it out of the board.
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Old 06-07-2021, 11:47 AM   #32
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

This is the "mighty" DR-8600BTX I talked earlier, use to have bulged JungFu WG caps I think. Did a partial re-cap on it with GP caps 1-2 years ago and now changed most of them again with "proper ones". There is a version of this PSU with Passive-PFC, mine doesn't have one and fan seems to be hooked @ 12V.

3rd photo is from before the "proper" re-cap.
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Old 06-11-2021, 02:43 PM   #33
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Another familiar SL-8500BTX that needs some care. Any clue which of the two 47uf caps is the critical one for the 5VSB transistors ? I'll have to use 47uf 10V there or choose 100uf 16V ones (PW or KY). This SL-8500BTX is from the crap bunch with just a MBR2060CT for 12V a fake? transformer and some uber-crap fan. Changed the stock 470uf (350uf real) primary caps with a set from the DR-8600BTX and some mixed quality filter caps. The million dollar question, any point to change that 12V 2060CT for a 30100CT ?
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Old 06-11-2021, 04:57 PM   #34
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

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Originally Posted by zunasthegreat View Post
Another familiar SL-8500BTX that needs some care. Any clue which of the two 47uf caps is the critical one for the 5VSB transistors ?
Well, I see an 8-pin IC on the primary in that first picture. So I don't think that PSU uses a 2-transistor 5VSB (but check what is written on that IC first!) The small cap next to it (47 uF) is probably used as a "startup" (and run) cap for the 5VSB in this case, so it's still somewhat critical to the operation of the 5VSB. The only difference is, if that 8-pin chip is a PWM+FET combo IC, then the 5VSB won't nuke itself / go out-of-control with over-voltage if that cap failed badly.

I still recommend you replace both of those 47 uF caps, if you have enough in stock. The 2nd one is used for filtering power to the main PS PWM IC when the PSU is in soft-off mode. Don't go lower than 35V on the rating, though.

Quote:
Originally Posted by zunasthegreat View Post
This SL-8500BTX is from the crap bunch with just a MBR2060CT for 12V a fake? transformer and some uber-crap fan.
IMHO, that SL-8500BTX is a 8500 times better than the Force 450W.
MBR2060CT is honestly quite acceptable, given the rest of the build quality of that PSU. The main "fake"(?) transformer appears to be normal ERL-35 size... or so it seems from the picture (measure it and see if it's 35 mm across the top.) So if that's the case, it's really not that bad of a PSU. If anything, I think the limitation is going to be those BJTs on the primary side - they appear to be TO-220 devices. This puts a limit on this PSU to probably around 300 to 350 Watts absolute max before the magic smoke comes out. I would realistically rate this PSU as capable of about 200W for continuous running and 250W max, with maybe very short peaks up to 300W... but certainly not more, given the rest of the components. The heatsinks seem enough for about 200-300W for an old design like this. And you can also see the snubber resistor on the primary side for the main PS (2nd picture, top left corner) appears smaller than the space left for it on the PCB.

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The million dollar question, any point to change that 12V 2060CT for a 30100CT ?
Probably not.
I don't think you would want to pull more than 20 Amps from the 12V rail anyways. (That's 240 Watts already. )

That said, the secondary heatsink might run cooler with the 30100ct... but that may not necessarily be desirable, if the fan is connected to a controller and its speed based on the temperature of the secondary heatsink. In such case, it may be better to let the secondary heatsink heat up slightly to crank the fan up, which will in turn keep other components cooler. So that's always something to keep in mind. Also, diodes have lower voltage drop at higher temperatures, which means the PSU will run more efficiently with the secondary heatsink hotter (but only up to a point, of course.)

Now since I did answer your million dollar question, in the event you do find the answer to be correct, when could I expect to see that million dollars in my bank account?

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Originally Posted by zunasthegreat View Post
This is the "mighty" DR-8600BTX I talked earlier, use to have bulged JungFu WG caps I think. Did a partial re-cap on it with GP caps 1-2 years ago and now changed most of them again with "proper ones". There is a version of this PSU with Passive-PFC, mine doesn't have one and fan seems to be hooked @ 12V.

3rd photo is from before the "proper" re-cap.
Not bad at all. That appears to be one of the better-built Deer/L&C/Solytech units.
I can see the windings showing on the main transformer, though. Does the height on that transformer appear to be "normal" relative to other "proper" ERL-35 transformers? If not, I suspect Deer might have cut a corner or two on the insulation between the layers here to fit all of the windings - hence why they seem so visible. On better-made transformers (especially the small ones for the 5VSB and similar), the windings shouldn't be visible, as there is often electrical insulating material in there to keep the primary and secondary better separated from arc-overs.

Quote:
Originally Posted by zunasthegreat View Post
CWT 405W with PCB discoloration, traces under the pcb that start to crack upon de-soldering and many dead caps. There is a strange burned resistor that looks awful under the C2 cap. Upon checking on the DMM gives 1KΩ, I think I'll have to measure it out of the board.
That appears to be the ISO series from CWT, which aren't half-bad when built properly. This one appears to be built quite well.

I think that burned resistor might be part of the driver circuit (on the secondary side) for the main PS BJTs. If so, around 1 KOhm (1.5 KOhm usually) is correct for that, I think. If this is indeed that resistor and it's burned, check the 5VSB output caps and 5VSB "critical" cap, along with secondary-side auxiliary supply cap (probably that small cap next to it.) If all of these test OK, check the primary-side BJTs and also secondary-side driver BJTs (typically 2x TO-92 transistors connected to the middle/driver transformer.)
Quote:
Originally Posted by zunasthegreat View Post
I messed around a bit with the load resistors and made some changes just for heat reduction near the CAPS. Stock load seemed kinda low-ish for 3.3V (10Ω) and 5V (20Ω).
Ι've switch the 20Ω to the 3.3V and placed a 33Ω (2W) on the 5V. 12V still has a 330Ω but I've moved that res. near the 12V fan header and I've added another 2200uf 16V cap for the 12V.
Nice work!
That's actually a lot better than what it was originally... and probably as good as this PSU will ever get. It's still a gutless wonder PSU, but at least it's not downright hazardous for the hardware connected to it anymore... or at least the output ripple should be much better. The effectiveness of the PSU's protections (if any functioning properly at all), of course, are yet to be seen. Hopefully this PSU never gets to see a situation like that.

Last edited by momaka; 06-11-2021 at 05:03 PM..
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Old 06-12-2021, 01:04 AM   #35
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

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Well, I see an 8-pin IC on the primary in that first picture.
Impressive you caught that!
Seems to be a FSQ0165RN nice!
https://www.onsemi.com/products/powe...tors/fsq0165rn
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Old 06-12-2021, 02:16 AM   #36
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

8-pin IC is the DL0165R and main transistors are .... 13007.
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Old 06-12-2021, 07:23 AM   #37
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

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Check the 5VSB output caps and 5VSB "critical" cap, along with secondary-side auxiliary supply cap (probably that small cap next to it.) If all of these test OK, check the primary-side BJTs and also secondary-side driver BJTs (typically 2x TO-92 transistors connected to the middle/driver transformer.)
All small Caps look dodgy and one koshin 47uf 50V shows ESR ... 6.9Ω on the meter. Put a new "fattier" 1K resistor and some nichicon caps and now works just fine.
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Old 07-06-2021, 05:35 AM   #38
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

I recently got for cheap a 750 Ti with an Inter-tech SL-550 PSU. This PSU is 95% same as the NitroX from my other thread. Upon checking for similarities I finally found the 2nd long lost 12V Filter cap, a 16V 100uf near the Fan connector. The new model has no PCIe cables but comes fully *loaded* with ChengX CAPS, no bulged or funny leaks just increased capacity atm (4-5y of use). Upon bench-testing them with the 750Ti I found this odd behavior. New unit works just fine with re-cap (KY's) and some higher Ω resistors for 3.3V / 5V. The old model (nitrox) works not so fine (similar caps - load resistors) as it will make a horrible hiss sound while 3D-Loaded with the 750Ti card, no such sound on CPU Stress test or GPU stress with the HD 5770 I have for tests. This 750Ti has PCIe 6-pin connector for extra power (I doubt it needs it). Same thing happens on a second board and I think I had the same strange sound with more load towards 3.3V / 5V. Should I just go brute force and replace all coil - caps SBR's there ?
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Old 07-07-2021, 11:37 AM   #39
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Might be that the impedance of the KY parts is sufficiently lower that the originals that the control loop is unstable. Depending on the age of a P/S, sometimes a PW (or LXZ), PJ, or PS series (Nichicon) is a better choice. There can be such a thing as "too good" when it comes to output caps.
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Old 07-08-2021, 05:45 AM   #40
zunasthegreat
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Default Re: Chieftec GPS-550AB-A (Delta OEM)

Same caps on both models dunno whats the deal with it. I'm now testing it with only 1X 12V SBR (MBR20200CT), stock had 2X Mospec F12C20C. Also swapped for 10th time the 5V caps and I now use 10V PW 3300uf and 16V 2200uf ones for 12V line. This model came with Niccon and the other SL-550 had ChengX GR. Looks OK so far no funny hiss sound on the P4 test pc with a 9600 XT under stress.
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