Installing FUSEs on the Power Supply **SOLVED**

[Nick]

Hi everybody,
i'm following this great forum from the beginning and it's growing big !
Great people and great posts !

I'm in the process of restoring a wonderful 4064 E/G.

This is just my 2cents about the installing of the FUSES (25A) between the rectifier/reservoir capacitor junction, and the SCR/regulator circuit .
It's a MUST mod to do to preserve it.
Also i've recapped all the electrolitics and cleaned the fans for a nice flow of cooling air .

Cheers

Nick

Uploaded with ImageShack.com
Uploaded with ImageShack.com
Uploaded with ImageShack.com
Uploaded with ImageShack.com
Uploaded with ImageShack.com

[marcmozart]

Hi Nick,
thanks for posting - can you elaborate a bit more in detail on your mod? What type of fuses / where to buy. What exactly is the purpose of this?

Also, talking about power supplies - a tech once told me that the regulators for the different rails in the Power Supply are interchangeable. I looked into the schematic and the were different??

The Power Supplies are a topic we have only touched on lightly in this forum, so it's great to see your post. Perhaps we can build some kind of "Power Supply FAQ".

Hi everybody,
i'm following this great forum from the beginning and it's growing big !
Great people and great posts !

I'm in the process of restoring a wonderful 4064 E/G.

This is just my 2cents about the installing of the FUSES (25A) between the rectifier/reservoir capacitor junction, and the SCR/regulator circuit .
It's a MUST mod to do to preserve it.
Also i've recapped all the electrolitics and cleaned the fans for a nice flow of cooling air .

[waltzingbear]

the supplies have a crow-bar circuit that can blow the regulator when tripped and cause more damage than it should. To address that, SSL began installing fuses in later issues of the power supply. The mod mentioned is an update to older supplies to add that feature. A good idea.

With this update, the crowbar engages and blows the fuse, not the supply.

The regulator cards (those little plug in cards in the back of the supply) are all the same. They do need to be set up for each supply, current overload point and voltage primarily.

Alan

[marcmozart]

Thanks! I'll check but I'm pretty sure my G-Series supplies from 1991 might already have this update.

the supplies have a crow-bar circuit that can blow the regulator when tripped and cause more damage than it should. To address that, SSL began installing fuses in later issues of the power supply. The mod mentioned is an update to older supplies to add that feature. A good idea.

With this update, the crowbar engages and blows the fuse, not the supply.

The regulator cards (those little plug in cards in the back of the supply) are all the same. They do need to be set up for each supply, current overload point and voltage primarily.

Alan

[kilmister]

Wondering if anyone has psu lineup procedure?
I would like to know how you guys set current overflow and over voltage alignments?

-Paavo

[marcmozart]

Wondering if anyone has psu lineup procedure?
I would like to know how you guys set current overflow and over voltage alignments?

-Paavo

+1 !!!

[Matt Sartori]

Wondering if anyone has psu lineup procedure?
I would like to know how you guys set current overflow and over voltage alignments?

-Paavo

AH LOOONG time question.

there is a guy that does all the funky junk refurbished PSUs and he has a (expensive) test jig where it put the PSU under full load and set it up...
then it shorts out all the outputs to test the SCR and the crow bar....
I have asked him to pop in here but he does not like computers..
I will see if I can get him to write down the procedure...
"with one of these PSU you can WELD metal" quote.

Mattia.

[Nick]

Thanks Waltzingbear, that's exaclty what i've done.
Fot thoese interested, here is the shopping list from farnell:

Fuse holder
https://it.farnell.com/jsp/search/productdetail.jsp?SKU=556154

Fuses
http://it.farnell.com/jsp/search/productdetail.jsp?SKU=1202409

Nick

[marcmozart]

Can one of the experienced techs on here post a PSU lineup procedure? How to set current overflow and over voltage alignments?

That'd be awesome. I just recapped my regulator cards, so next step need to calibrate a PSU. BTW, on my 1991 G-Series Power Supplies, the fuses are installed.

More on regulator cards here: http://forum.sslmixed.com/index.php?topic=580.0

[michaeldtech]

That was something the factory did on the bench with dummy loads connected.  I never got hold of those adjustments.  Best thing to do is take a good picture of the pot positions and if they were really dirty before a vaccing clean them with a pot cleaner, exercise, and return to original position.  The actual voltage balancing adjust is the one thing to do on-site and has been covered here I think.
Maybe Jim has some dusty back-office docs in his container?
Mike

[Showcase]

I had one 25A fuse blown just a week ago, strange thing was my second psu's -20 +20 was also dead but with a powerdown and up it was good to go, so it got me thinking it has some other kind of protection aswell?

[waltzingbear]

a crowbar trip will blow the fuse (that's the purpose of the fuse being there). If it was a transitory event, you may not see what caused it upon replacing the fuse. I could also believe that if it occurred, it *may* have caused the other supply to shut down as well.

Remember different version of the supply have different levels of protection installed, most (all?) have overvoltage and overcurrent sensing on the regulator cards that plug in. In other ords, no simple answer across the board, the buildout of *your* psu needs to be considered.

my schematics are not at hand so I can 't comment further.

Alan

[Matt Sartori]

Can one of the experienced techs on here post a PSU lineup procedure? How to set current overflow and over voltage alignments?

That'd be awesome. I just recapped my regulator cards, so next step need to calibrate a PSU. BTW, on my 1991 G-Series Power Supplies, the fuses are installed.

More on regulator cards here: http://forum.sslmixed.com/index.php?topic=580.0

I have begged funky junk tech that does all of their supplies for the line up procedure.
unfortunately it won't happen..it's more secretive than CIA...

M.

[xmax]

I can help set up a alignment procedure, but you will need about 600w of dummy a load,
and some connectors (less than $100), Trouble is I don't have a 661 here, I will borrow
one and figure it out within a month, I say for now leave the current limit pot alone! N

[waltzingbear]

there are two ways to line up psu's like these. One with actual values and adjust trimmers to trip points, ie dummy load and causing overvoltage and current conditions into test jig. Or calculating the trip points in the circuit. The first means you need a few specific pieces of test gear which most do not have, and the second is not quite as foolproof, but can be very close.

In cases where I have needed to set up these in the past, I have used the calculation method, with some degree of post evaluation. Do I trust it empirically, NO, do I think its adequate for the field, yes.

I will go back to my notes and see what I can write up, its really not that difficult to calculate the trip points and set them up or at least make sure they seem reasonable.  No manuals at hand. (and another board to finish first)

Alan


ps, I agree with Norm, if you don't have to, leave the current limit alone. But if you are putting a new card in......