EG651P-VE FMA Recap Problem

**gonzo0815** · 04-13-2008, 04:48 AM

Re: EG651P-VE FMA Recap Problem

I am using a very cheap temperature controlled mains powered soldering iron with a ceramic heating element (similar like this one, but with an temperature selection knob: http://cgi.ebay.de/Turbo-Loetkolben-...QQcmdZViewItem).
If i put temperature on highest setting, wait until it is fully heated up and adding some some fresh solder, it is not a big problem melting even those big junks of solder. So i think getting a real hot or temperature regulated iron and it should work. Before i owned this iron, i used to use a big 80w cheapi, but this was running really hot, thus some car has to be taken to prevent delaminating of any PCB material.
Tip wasting was astronomically fast.

But may be your problem was a short due to the loose PCB screw. Or simply a problem in the auxiliary supply. If there are some bad caps left, heating them up with a hair-dryer should bring the psu up in no time.
The you may have to replace even a few of the lower uF capacitors.

**JEWilson** · 04-13-2008, 08:50 AM

Re: EG651P-VE FMA Recap Problem

Thx for responding

I use an Antex 50W TCS mobile iron
Ranges from 200 - 450 deg C
see further (at bottom of web page)
http://www.theelectronicsshop.co.uk/...20tempcont.htm

It appears even at 450 deg C - max output is suggested to be 50W.

Do you think this would be enough or purchases the iron you suggested?

Thanks again

**JEWilson** · 04-13-2008, 09:07 AM

Re: EG651P-VE FMA Recap Problem

Ok

I'm looking for a temp controlled iron

Quick scan of ebay.co.uk finds

100W Antec - no tempco
http://cgi.ebay.co.uk/100W-ANTEX-UK-...QQcmdZViewItem

Gas Iron - tempco
http://cgi.ebay.co.uk/25W-120W-Gas-A...QQcmdZViewItem

**kc8adu** · 04-13-2008, 10:15 AM

Re: EG651P-VE FMA Recap Problem

the problem is often not wattage but mass.
weight stores heat.
you can have a 1000w heater on the end of a needle but it will still go cold when you touch it to a ground/power plane on a mobo.
the heavy copper on a mobo is a great heatsink.

**JEWilson** · 04-13-2008, 12:02 PM

Re: EG651P-VE FMA Recap Problem

kc8adu - Thanks for the comments

Is there a particular type of iron you would suggest for
this issue?

I would only add, as I have a number of Antex irons for
differing applications, I have purchased a number of
bits/tips for these.

So far as I referenced a two further higher wattage from eBay.co.uk
It was with the matter of tips and such like in mind.

**JEWilson** · 04-13-2008, 12:17 PM

Re: EG651P-VE FMA Recap Problem

kc8adu - Thanks for the comments

Is there a particular type of iron you would suggest for this issue?

I would only add, as I have a number of Antex irons for
differing applications, I have purchased a number of
bits/tips for these.

So far as I referenced two further, higher wattage from eBay.co.uk
It was with the matter of tips and such like in mind.

For PSU recaps, I normall use the bit (seems to work well) here;
http://www.antex.co.uk/product.asp?s...D=193&P_ID=982

Noteworthy even so, is the point, the high power and gas irons
have a range of tips/bits made particularyl for those irons.

I will try to make good with the 50W TCS and raise the temp up to
near max and attempt to get the solder to flow.

Other wise, an alternative iron or bit will be required.

**JEWilson** · 04-17-2008, 07:00 PM

Re: EG651P-VE FMA Recap Problem

Running the Antec TCS 50W at max. temp seems to have
sone the trick with large solder areas as discussed

Thx

**JEWilson** · 05-08-2008, 05:40 AM

Re: EG651P-VE FMA Recap Problem

Appears this PSU is getting start up problems

In the PC in which installed, I require to;
1. Either press and release the power button slowly to get the PC to POST or
2. Press and release the reset button once powered on but failed to POST
I believe this is symptomatic of power requiring to ramp up to full load

The PC in which installed has only;
1. Barton XP-M 133 2200MHz
2. 2 of Reg ECC PC2100 DIMMs
4. 3 of Seagate 80GB PATA
5. 1 of WDC 40GB PATA
6. Promise SX6000 6-ch PATA RAID Card
7. 3COM NIC
8. FireGL 8800 128MB AGP 4x W/Station Card
9. DVD-RW
10. FDD
11. 5 12V Fans

I got the estimated power requirements for all of this and
is well within the spec. of the PSU even accounting for cap
aging. Even so, recently recapped the O/P filter caps as discussed

Is this indicative of a larger problem with the PSU?

Any help appreciated

**gonzo0815** · 05-08-2008, 04:51 PM

Re: EG651P-VE FMA Recap Problem

I duno about this particular unit, but in my EG365AX-FMA there was an Topswitch used in the 5vSb supply.
If you overdo it with capacitance (>1000uF) this could lead to start up problems.
But sure, as you already mentioned, it may be a problem with ramp up caused by bad solder joint or an short somewhere at the secondary side.
Or simply to high or low ESR capacitors for the given design......

**JEWilson** · 05-09-2008, 09:56 AM

Re: EG651P-VE FMA Recap Problem

Well...

I did raise the capacitance on the +5VSB rail to 2000uF
It was formerly, 1100, 1 of 1000uF 10V and 100uF 16V

Thanks for the information
I will change this back to 1100uF first before looking for further problems

Thanks again

**gonzo0815** · 05-10-2008, 04:41 AM

Re: EG651P-VE FMA Recap Problem

I would suggest to go <=1000uf, as good capacitors usually stray more in the + range. I have used up to 1200uF in an Seasonic ss400FS PSu (wich is equipped with an Topswitch too) w/o problems, but the data sheet as well as some theoretically more inclined people here suggested not to go beyond 1000uF.

**JEWilson** · 05-10-2008, 04:08 PM

Re: EG651P-VE FMA Recap Problem

I've just checked the PSU pcb

In fact, the switch is an On semiconductor UC3842BN
Still, I will try with values as suggested;
perhaps 100uF 10V with 870uF 10V for +5VSB in line with your suggestions

Thx

**gonzo0815** · 05-11-2008, 04:15 AM

Re: EG651P-VE FMA Recap Problem

Well i thought 2x 1000uF in the output phi filter of 5v Sb circuit. At least that is what i have seen in most topwsitcher circuits.
But 2x 470uF is common too.

Is the UC3842BN realy used for 5v sb? or is it the main controller chip?

**JEWilson** · 05-11-2008, 06:22 AM

Re: EG651P-VE FMA Recap Problem

Y - correct, the UC3842BN is the main controller IC

As far as I can determine, the +5VSB is designed with discretes;
The main rectification diode is a large power device.
A shunt regulator, a TL431C sets the voltage reference etc and
a further Zener is used as a clamp (I think).

The original configuration is set out, that is, 1 of 100uF and 1 of 1000uF

I have attached a sketch of the cct I traced

Thanks for your consideration

Attached Files

Img001.pdf (117.1 KB, 16 views)

**linuxguru** · 05-11-2008, 07:06 AM

Re: EG651P-VE FMA Recap Problem

I've used 2 x 1000uF if it's a discrete flyback converter with a 2N60 MOSFET switch or a BJT switch. OTOH, if it's a TOPSwitch, it's better to stick with 2 x 470uF max., because the overload protection circuitry of the TOPSwitch will shut it down if the secondary voltage doesn't rise fast enough. If there's a pi-filter with inductor, you can still go with 2 x1000 uF, but if there's no inductor, it's best not to exceed 1000 uF total capacitance on +5Vsb.

Edit: 100uF is rather low as the inboard cap for a flyback converter. There's got to be a reason it's this low, so it's probably not advisable to exceed 220uF, preferably 25v.

**JEWilson** · 05-12-2008, 03:42 PM

Re: EG651P-VE FMA Recap Problem

That's a valid point

As I recall, the caps values should be switched around in the
attachment I posted. Apologise for the confusion

So... I've attached a corrected image

Also, I will trace the remainder of this cct. as best I can to try
to make sense of this design

Thanks for the info.

Attached Files

Img001.pdf (115.7 KB, 17 views)

**JEWilson** · 05-17-2008, 03:48 AM

Re: EG651P-VE FMA Recap Problem

I have replaced the caps for +5VSB back to the original configuration.
I did a quick, go-no go test with a PSU tester and found
the 5.0V rail out of regulation (only slightly at 5.4V).
The POST problem also persists, that is the PC fails to POST
on occasion.

I am beginning to suspect the C9 cap on pin 7 of the UC3842BN
controller may be at fault and I have overlooked this prior to.
It reads 1.1Z with an ESR meter. The cap is a PCE-TUR 22uf 50V
It may be the voltage regulation as spec'd for ATX is not
settling correctly albeit I have replaced all of the O/P filter caps.
I believe the max line voltage of the controller is 30V according to page 2
Also, the schematic on page 16 Fig 34.27 typifies a cap of some 100uF.
see further
http://www.alldatasheet.com/datashee.../UC3842BN.html

I have resolved problems with out of regualtion conditions
where the PSU will start with replacement of the controller
IC supply cap. I usually replace these with Pana FC 35V 100uF

What are your views on this?

**linuxguru** · 05-17-2008, 11:13 AM

Re: EG651P-VE FMA Recap Problem

If the cap value is too high, the controller may not start up quickly enough. However, if the datasheet specifies 100 uF, there's probably no harm in trying it out.

**gonzo0815** · 05-17-2008, 03:57 PM

Re: EG651P-VE FMA Recap Problem

1R isn`t that high for such an small value capacitor, but may be it has reduced capacity too, which would certainly explain why it caused problems.
I have replaces those supply capacitors in several PSU`s, and in some cases it lead to a noticeable increase in start up time.
But sure, i have used up to 220uF, which is certainly way to much.

EG651P-VE FMA Recap Problem

EG651P-VE FMA Recap Problem

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Related Topics