Redlight of Death Repair

[wullboy]

duo circuit diagramm

Here you are m8... hope it opens ok...??

 

[gadjit]

Where did you send it please ? and cost thx johno

I need to get mine fixed , could you PMMe the details or can anyone on here give me some details on who could fix this for me

 

[gadjit]

I need to get mine fixed , could you PMMe the details or can anyone on here give me some details on who could fix this for me

REd light capacitor change

 

[gadjit]

can u pm me pls

 

[clippert]

I have 3 boxes. this fix has saved 2 out of the three boxes. Thanks to the o.p. :thumbsup::thumbsup::thumbsup:

 

[cactikid]

i wonder is it worth it if you cant do it yourself on an old slow receiver?

 

[BRAVEHEART]

just have a read, might solve a problem or two >>>> http://www.world-of-satellite.com/s...le-question-VU-DUO-as-I-can-t-find-the-answer

 

[Hamram]

I have measured some voltages on the IC'sView attachment 28156View attachment 28157

H4R7/I in my box, gives only 0,68 volts, but how to determine where the error is..? Is it one of the regulators, and if so, how to determine which one..? Any ideas..? What is correct output from the regulators?

 

[omega99]

well it lasted a whil, but now got the RLOD again,
I noticed caps C14 & C15 on the psu board have slightly domed at the top - any body know how to test the psu while unplugged from the m/board?

 

[omega99]

pulled both c15 supposed to be 1500uF measure around 1950uF & c14 was about 2189uF

 

[mcquaim]

well it lasted a whil, but now got the RLOD again,
I noticed caps C14 & C15 on the psu board have slightly domed at the top - any body know how to test the psu while unplugged from the m/board?

I had a Duo back a few months ago where it had the red light issue.

I changed the usual but no difference but like you I noticed those two caps on the Power board bulged so I changed them also and bingo, back in action.. I had another Duo that had died about 6 months previously and I’d given up on it but after this fix worked I tried it on that also and it was the issue there too :thumbsup:

Worth a try I guess, only cost a few cents for me...

 

[cactikid]

question i ask myself is it worth doing again as when blind as a bat i would need to send it out to a repair centre.
is there much life left in these old slow boxes is repaired again?

 

[Sicilian]

Upgrade to much faster box for only £79 https://www.world-of-satellite.co.uk/formuler/formuler_f1

 

[ronand]

If you are able to do the repair yourself its a cheap fix and worth doing (even just to keep the box as a spare). But yes the duo is a slow box compared to what is available cheaply now. Its always nice to have a good excuse to upgrade to something faster even though I like repairing equipment.

 

[omega99]

I had a Duo back a few months ago where it had the red light issue.

I changed the usual but no difference but like you I noticed those two caps on the Power board bulged so I changed them also and bingo, back in action.. I had another Duo that had died about 6 months previously and I’d given up on it but after this fix worked I tried it on that also and it was the issue there too :thumbsup:

Worth a try I guess, only cost a few cents for me...

changed both the caps but sadly the red dot of death remains, they where cheaps caps when measure on the fluke meter 1540Mfd & 1550Mfd when they are supposed to be 1500Mfd

 

[adm]

changed both the caps but sadly the red dot of death remains, they where cheaps caps when measure on the fluke meter 1540Mfd & 1550Mfd when they are supposed to be 1500Mfd

Nothing to do with being cheap capacitors. Even the highest quality electrolytic capacitors have a tolerance of +/-20% of their marked value so anything between 1200uF and 1800uF is within tolerance.

Even the lowest quality electrolytic capacitor probably will have fixed the fault if the component you replaced had been the fault (assuming that the component was fitted correctly as electrolytic capacitors have a polarity)

The difference between a high quality capacitor and a lower quality capacitor in these types of application is likely to be the life expectancy of the component.

A capacitor life expectancy is rated in a number of hours at a certain temperature.
Typically for a lower specified capacitor this may be 5000 hours at 85 degrees C where the life expectancy may double for every 10 degrees C below 85C that the capacitor is actually operated at. For a higher specified device the specification may be typically 5000 hours at 105 degrees C, again doubling for every 10C below 105C. In a power supply the capacitor may be positioned close to a heat sink in an ambient temperature of, say, 55C. In these conditions the lower specified capacitor may have a life expectancy of 15,000 hours whereas the higher specified capacitor this is 25,000 hours.

Unfortunately it's not just as simple as this. capacitors have a ESR (Equivalent Series Resistance) and in a switched mode power supply the lower this value the better. Higher values of ESR cause more self heating in the capacitor and temperature affects the life. Furthermore as the capacitor degrades the ESR will increase causing greater self heating. A lower specified capacitor is likely to have a high ESR value[[1] whereas a higher specified capacitor, for a switched mode power supply, will have a very low value.

[1] You may not actually find a ESR value on some data sheets for lower specified capacitors as they are not recommended for use in some locations in a switched mode power supply.

Some manufactures capacitors such a Panasonic, Rubycon and a few other respected brands seem to perform to their published specification while capacitors from some (Korean) manufactures, such as Samyoung, with similar specifications seem to fail prematurely.

So if replacing a capacitor in a switched mode supply ideally:
i) Select one with 105C temperature rating
ii) Select one which claims a low ESR or low Z. Avoid any capacitors where there is no data given on this parameter. Not all 105C components are low ESR/low Z
iii) Ideally buy a reputable brand
iv) Buy from a reputable source. In the UK this may be CPC, RS or Rapid Electronics - there may be many more reputable UK suppliers but like anything else there are fake branded capacitors in the marketplace or subtly worded misleading listings where the the no-name components is claimed to be equivalent to the branded item's part number

The difference in price between a low and high specified capacitor may be of the order of 0.20 GBP . This difference may be significant for a manufacturer buying in 10,000s of components but insignificant for a DIY repair when buying very small quantities.

 

[omega99]

I have measured some voltages on the IC'sView attachment 28156View attachment 28157

from H4R7's
I = 1.9v supposed to be 2.59v
F = 0.7v supposed to be 1.25v
C = 1.2v supposed to be 1.25v

would it be the cap or the H802 that would cause F to be at 0.7v

 

[omega99]

from H4R7's
I = 1.9v supposed to be 2.59v
F = 0.7v supposed to be 1.25v
C = 1.2v supposed to be 1.25v

would it be the cap or the H802 that would cause F to be at 0.7v

replaced c814 220uF with one I had lying about as I had nothing to lose at this stage & hey presto away she went again. Forgot to measure the voltages out of the 4R7's

 

[liveaboard]

I just had the red light issue again; opened it up and it's the same capacitor.
I find that odd; there must be over voltage on it or something, all the other caps appear fine.
Anyway, I replaced it again [had a couple of spares from last time], and the old VU duo is working again.
After tightening the beam, we no longer get astra here in southern Portugal, so the box is of very limited use.
I'm not going to replace it if it dies.

 

[liveaboard]

I'm copying my post over from another thread as it could be relevant here.


We've been using the VU+ only as a video player, and it died, red light of death again.
In the meantime, I've picked up a handful of capacitors, so I opened it up.
I replaced C807 [the famous], for the third time, but that wasn't it.
I saw a blown 1,500 mf on the power board, changed that and its brother, no dice.
I changed all the caps listed by others above, and the box booted again [yay!], but as before won't power the lnb. it would power the light on my satellite finder, but when I connect the LNB [on the bench now], the power to it switches off and won't come back until a reboot.
I had some 100 mf caps left; so I changed 3 out of 4 100mf caps near the antenna connection block.
And it works!!

It will now power the 90ma single invacom, but when I connect the old invacom quad which draws more power, it still shuts off.
So far, this is still on the bench, I haven't reinstalled it all yet.

I suspect that most or all of the caps in the old VU+ are faulty; probably just a bit out of spec and fading. I find it highly unlikely that I just happened to luck out and hit the bad one.

I don't know if anyone else is keeping one of these old boxes alive; if so, just buy a lot of capacitors and start soldering.