Very Worn Out HP DC5100 SFF Computer

[ratdude747]

Re: Very Worn Out HP DC5100 SFF Computer

Thanks for the info. Do you think my next best course of action is to try and remove the glue on the diode to see if I can read the marking?

Well YEAH. Either that, short of a schematic, use a Magic 8 ball .

[juliadream]

Re: Very Worn Out HP DC5100 SFF Computer

as it's direct to the 5v rail then an educated guess would be it's a 5v zener.. used for over voltage protection

[ratdude747]

Re: Very Worn Out HP DC5100 SFF Computer

as it's direct to the 5v rail then an educated guess would be it's a 5v zener.. used for over voltage protection

Well, in that case probably 5.1V, as that's what the nearest standard zener value is. Zeners follow a different set of numbers for "standard" values, probably due to the exact chemistry/physics needed to make such work (similar to how battery voltages are determined by the metals used).

[juliadream]

Re: Very Worn Out HP DC5100 SFF Computer

Well, in that case probably 5.1V, as that's what the nearest standard zener value is. Zeners follow a different set of numbers for "standard" values, probably due to the exact chemistry/physics needed to make such work (similar to how battery voltages are determined by the metals used).

Indeed.. just didn't bother with the .1 .. as they only come in stock values.. 3v3 5v1 etc.. Guess the only thing to be aware of is if it's a 3v3 with a step up resistor.. though why they would in that job might be puzzling.. but I reckon it's there as overvolts/anti surge protection of some kind.. I kinda fit them as standard to old psu's .. because you never know :O

[momaka]

Re: Very Worn Out HP DC5100 SFF Computer

As you can judge by my username, I plan on fixing it up

The god of all Pentium 4 computers

Overall, terrible choices for such a chassis with limited airflow. I mean...just check out that exploded Evercon!

What can I say?... You got ever-CONned.

The other thing that upsets me that HP did, is they put a Prescott P4 in here. A 541 (3.20GHz) to be exact. Not just a Prescott, but a 1M Prescott...

Yeah, such a CPU is a bad idea in a small case - especially one that has the CPU fan blow air into the case after it cools the CPU (if I am not mistaken, that is). I know the HP DC7700 USFF PCs were all like that. Such poor design IMO

I also don't think that heatsink was ever adequate for such a CPU

It is, but just barely enough to keep the CPU from throttling.

I test-ran an Xbox 360 gen-2 CPU heatsink on a P4 630 (Prescott-2M) before, which has pretty much the same TDP as that A541. That Xbox 360 CPU heatsink has a single copper heat-pipe and is about the same size as the one in the picture you attached. I had an 80 mm fan blowing at it full force through a very leaky duct (so overall airflow through the heatsink wasn't very good). Idle temperature was in the upper 40's Celsius and went as high as 58-60C under full load. Would have probably gone a few degrees higher, if this was in a case (I ran the test setup without a case). That said, I don't remember when I did this, so I can't tell you what the ambient temperature of my room was. In the winter, my room is as cool as 20C, and summer I like/keep it around 30C.

What do you guys think?

It's a nice compact system. Could do well with a newer Pentium 4 or Dual Core CPU, especially HTPC.

Is it okay to replace the caps for filtering USB power, LAN ports, etc. with regular low ESR caps such as nichicon PW?

Absolutely.
I've done many HP DC5000 motherboards with Panasonic FR.

Also, the fans in this system spin very slowly. I booted it up just to make sure it worked and I could barely hear the fans spinning even with the top of the case off. That's saying something considering there are two Delta fans

A quiet Delta?!
That CPU must have been

Edit: They used 470mf 16V KZG for all the caps for USB and LAN filtering. Those can't possibly be using 12V?

Well, you could always check.
With multimeter set to continuity test, put one probe on 12V rail (I usually use the ATX connector) and the other on the cap's positive (+) leg. If you get a beep, double-check it with resistance measurement. If low resistance, then that cap is connected to the 12V rail. If not, then possibly not. But, of course, you can also always check continuity to the other rails as well (namely 3.3V and 5V). A bit more time-consuming than usual, but then you know for sure which cap goes where.

The zener in question fits in those holes above 511 resistor. The cathode lead goes on the left. Is it possible to just get an "overspecced" zener for this? As in, equivalence to installing a 10V capacitor on the 3.3V rail?

No.
You have to get a Zener with the same Zener voltage (i.e. same reverse-conducting voltage). Probably best to start a new thread in the PSU subforum and post top and bottom side pictures of the entire PSU. We need to figure out what that opto-coupler is used for in order to get an idea what the Zener diode does.

First, it may not even be a zener diode. Some regular diodes come in glass cases. The 1N4148 is a common example.

I doubt it. Board is clearly marked with "ZDxxx", so it's probably a Zener diode. It could be that they made a later revision and installed a regular diode, but I highly doubt that.

Do you think my next best course of action is to try and remove the glue on the diode to see if I can read the marking?

Yes.
Either that or some type of color-code. Some older Zener diodes had them.

[Pentium4]

Re: Very Worn Out HP DC5100 SFF Computer

Okay so I got back to this project. I could NOT get the markings off the original zener. The glue was just way too strong and the zener was too small. Anyways, I decided I just don't care that much anymore and just picked a zener I had lying around that looks similar in shape, color and markings. This zener is a little more "rounded" than normal zeners. And the markings are strange. It doesn't have the neat 1N 41 48 like normal ones. The one that I picked that looks identical has the big markings, all it says on it is "5" and either "IC" or "1C" under it.

Well....I threw everything together, plugged in the fan, and plugged it in and prayed that it worked. It did! It turned on. I let it run for 5 minutes with just a paperclip and nothing blew up, broke, and no smelly parts. Should I assume it will work now?

The only thing that was strange was the fan ran at full speed. But I'm guessing it spins slow when it is plugged in to the motherboard?

The god of all Pentium 4 computers

thank you sir

Yeah, such a CPU is a bad idea in a small case - especially one that has the CPU fan blow air into the case after it cools the CPU (if I am not mistaken, that is). I know the HP DC7700 USFF PCs were all like that. Such poor design IMO

I'm hoping my 65W Cedar Mill P4 helps a lot Should use a lot less power even at idle. I've read that some people have had trouble getting Cedar Mill procs to work in this board but I guess we will see

[momaka]

Re: Very Worn Out HP DC5100 SFF Computer

Okay so I got back to this project. I could NOT get the markings off the original zener. The glue was just way too strong and the zener was too small. Anyways, I decided I just don't care that much anymore and just picked a zener I had lying around that looks similar in shape, color and markings. This zener is a little more "rounded" than normal zeners... The one that I picked that looks identical has the big markings, all it says on it is "5" and either "IC" or "1C" under it.
... I threw everything together, plugged in the fan, and plugged it in and prayed that it worked. It did! It turned on.

Awesome!

I let it run for 5 minutes with just a paperclip and nothing blew up, broke, and no smelly parts. Should I assume it will work now?

It IS probably okay if nothing blew up or smoked. Now load test it for longer and with something heavier. Look for burned/charred/hot components in the PSU afterwards. If all is well, it is probably good to go.

The only thing that was strange was the fan ran at full speed. But I'm guessing it spins slow when it is plugged in to the motherboard?

Unless that Zener diode had something to do with the fan controller circuit. Would be helpful to know what circuit and/or parts that Zener diode connects to.

It doesn't have the neat 1N 41 48 like normal ones.

^ That would be a 1N4148, which is not a Zener, but a regular diode.
https://cdn.badcaps-static.com/pdfs/...2b6ae7c046.pdf

thank you sir

You're welcome

[Pentium4]

Re: Very Worn Out HP DC5100 SFF Computer

I will do that when I get this mobo all recapped Almost done! For any OCD cap folks out there, you will love this recap job I decided even to replace all the tiny caps, as small as 33μF. All the MCZ caps that weren't bulged tested good. Every 220μF 6.3V Evercon tested perfect, all the 470μF 6.3V Evercon (Except one) failed high capacitance, The 220μF 10V G-Luxon LT were all good, and the KZG were absolutely flawless, all 470μF 6.3V ones reading exactly 470μF. If anyone (I'm looking at you Wester ) are curious about exact capacitance and ESR readings, I can type all that out too. More pictures to come when it's all done. Then I can fully test that PSU.

[goodpsusearch]

Re: Very Worn Out HP DC5100 SFF Computer

Nice!!

[Wester547]

Re: Very Worn Out HP DC5100 SFF Computer

I will do that when I get this mobo all recapped Almost done! For any OCD cap folks out there, you will love this recap job I decided even to replace all the tiny caps, as small as 33μF. All the MCZ caps that weren't bulged tested good. Every 220μF 6.3V Evercon tested perfect, all the 470μF 6.3V Evercon (Except one) failed high capacitance, The 220μF 10V G-Luxon LT were all good, and the KZG were absolutely flawless, all 470μF 6.3V ones reading exactly 470μF. If anyone (I'm looking at you Wester ) are curious about exact capacitance and ESR readings, I can type all that out too. More pictures to come when it's all done. Then I can fully test that PSU.

You mean the 470uF 16V (not 6.3V?) KZGs that hadn't popped were good? What of the lone Panasonic FL?

[Pentium4]

Re: Very Worn Out HP DC5100 SFF Computer

Ha, whoops. Yes 16V KZG. None of them popped. There was a 1000uf 6.3V that also tested good. The 1500 10V Panasonic FL read 1472uf 0.02 ESR. Thing held up really well.

[Wester547]

Re: Very Worn Out HP DC5100 SFF Computer

Ha, whoops. Yes 16V KZG. None of them popped. There was a 1000uf 6.3V that also tested good. The 1500 10V Panasonic FL read 1472uf 0.02 ESR. Thing held up really well.

Ah, so it was the 1000uF 6.3V KZGs that popped. I thought the whole board might have been populated with 470uF 16V KZGs, which would have been an oddity. Both Panasonic FLs tested good (I had mistakenly thought there was only one?)

[Pentium4]

Re: Very Worn Out HP DC5100 SFF Computer

Yeah, 1000uF 6.3V. The other FL read different, it read 1636uF 0.02Ω

[Pentium4]

Re: Very Worn Out HP DC5100 SFF Computer

She works! Fully recapped the PSU, installed the board, plugged everything in and it works. Phew! Dodged a bullet. I plugged in 3GB of RAM and ran a memtest on it with the top cover off. I panicked for a second when I smelled what I thought was burning...Nothing was burning, everything in the system was just getting scorching hot. Damn Prescott!

So, I installed a heatsink on the southbridge chip, and installed the Pentium 4 641 that I have. It's the same clock speed as the 541, but 2MB cache, 65W TDP, and SpeedStep. What a difference that made! Everything is much cooler, especially the CPU heatsink. It's no wonder the 1800uF 16V MCZ bulged by the northbridge. The 330uF 16V Polymer got pretty hot during the memtest.

I think it's ready for another 51,000 running hours now

[momaka]

Re: Very Worn Out HP DC5100 SFF Computer

She works! Fully recapped the PSU, installed the board, plugged everything in and it works.

Knowing how you recap everything down to the smallest cap, I think we can safely say that this PC is now bulletproof.

I think it's ready for another 51,000 running hours now

More like 510,000 hours with those caps ... okay maybe not that many (as that equates to 58 years!!! ). But I'd say those caps will make it at least 25 years, which is 219,000 hours of 24/7 operation.

I panicked for a second when I smelled what I thought was burning...Nothing was burning, everything in the system was just getting scorching hot. Damn Prescott!

And yet if you left that CPU, I'm sure it would go through several more motherboards before going bad .

By the way, one of my PCs with a 2.66 GHz P4 Northwood has that "burning hot" smell as well and fills my room with the "aroma" if I run it for a few hours . Same with one of my Athlon 64 3200+ PCs. Not sure why only these computers have it and not others with similar CPUs and power consumption.

I guess computer parts can be like people in that regard - some are more smelly than others .

[ChaosLegionnaire]

Re: Very Worn Out HP DC5100 SFF Computer

i've always wondered where that smell comes from? especially when its new. if its new, its either the newly applied thermal paste or residual flux from the factory evaporating or maybe the smell of junk caps. but if the smell persists even on a longly used board, i wonder whats causing it? the smell of chemicals released from the pcb cant be too good... at least one can get a computer that matches their body odor...

[Pentium4]

Re: Very Worn Out HP DC5100 SFF Computer

Lol, I'd be happy with another 51,000 hours out of this thing Sadly, it sat completely unused collecting dust until about 8 days ago. I have been using ClearOS 5.2 SP1 as my router for about 5 years but they recently dropped support for it. That was running on a Pentium 4 Northwood 2.00GHz S478. I wanted to upgrade it to the new ClearOS 7.1 but they didn't make a 32 bit version (BTW, the S478 moved 13TB in the 5 years it was in use!)

So I said heyyyy I have a perfectly good 64 bit system collecting dust! I had a 60GB Intel SSD sitting around, which isn't much good for a desktop drive in my opinion, so I threw that in this machine and installed ClearOS 7.2 on the system. With the Pentium 4 641 3.20GHz, 3GB RAM @ 667Mhz, and the SSD, the install was done in about 6 minutes! I set it up as the DHCP server and it acts as the router for my home network. Right now I am working with my best friend who also has a ClearOS 7 system running on his end. We are setting up a site to site VPN so that we can connect our networks

Since this board surprisingly came with onboard Gigabit, I threw in an Intel Gigabit PCI card as the second NIC so it could be a router. My down speeds are about 110mbps so the 10/100 cards in the 478 system were a small bottleneck for max download speeds.

The thing still runs hot, but with literally 100% quality Japanese caps in there, and a SSD over spinning disk, I'm not worried about heat at all. I have the fan speeds at the lowest to reduce noise and dust. This thing will be running until it dies. And, staying true to my name....a once "deemed junk" P4 is "back on the road" and in service for more years to come. The guys at the office calling it a piece of garbage just made me love it that much more

[momaka]

Re: Very Worn Out HP DC5100 SFF Computer

Lol, I'd be happy with another 51,000 hours out of this thing Sadly, it sat completely unused collecting dust until about 8 days ago.

Better than several years or more, as is often the case with my PCs .

(BTW, the S478 moved 13TB in the 5 years it was in use!)

Nice! I love it when "old" hardware gets a good use.
Reminds me of when I left the my Pentium 3 HP Netserver torrenting for nearly 2 days straight on a 100 Mbit service. Moved quite a few tens of GB of data, IIRC. And that was with my shitty D-Link DI-614+ router, which kept dropping and restarting the connection when the traffic speeds exceeded 40 Mbits/s (which was every 5 minutes or so). But anyways, I still keep my Netserver alive. In fact, I have some mods that I've been meaning to put on it for a while, but I keep moving them to the back burner due to other projects.

I had a 60GB Intel SSD sitting around, which isn't much good for a desktop drive in my opinion

Any SSD is good for desktop use! But I guess I say that because I come from a world of old, slow mechanical clunkers.

And, staying true to my name....a once "deemed junk" P4 is "back on the road" and in service for more years to come.

Awesome!

The guys at the office calling it a piece of garbage just made me love it that much more

I think very few IT folks outside of badcaps.net are competent enough to realize how much work a system like yours can do. Never let such people get to you. After many years of my family and close relatives making fun of my old PCs, some of them now have begun to understand me a little better now when their new tablet or laptop keeps "misbehaving".