SSlmixed.com Forum
Tech discussion => 4K,6K,8K Series => Topic started by: Nick on November 09, 2013, 03:11:50 AM
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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
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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 .
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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
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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
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Wondering if anyone has psu lineup procedure?
I would like to know how you guys set current overflow and over voltage alignments?
-Paavo
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Wondering if anyone has psu lineup procedure?
I would like to know how you guys set current overflow and over voltage alignments?
-Paavo
+1 !!!
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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.
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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
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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
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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
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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?
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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
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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.
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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
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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......
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I am going to post here what keith Skerrett wrote on the SSLMIXED Facebook page.
quote:
"I saw when I was lurking on the forum that the group was looking for a PSU lineup procedure, so I thought I'd offer my thoughts on the matter for the +/- 18V as a starter as at this time of night and after a beer or two I can't remember all the values for the other rails.
Before starting, read all of what I have written below and if any of it doesn't make sense then do not attempt to do it. These supplies have exposed high voltages and you could quite easily do more harm than good to it or yourself.
So, Turn the V trip preset fully clockwise and adjust the V out on the + 18V rail to 22.5V. Then back off the V trip until the rail just shuts down. Turn the Vout down to minimum and restart the supply. Then repeat this for the -18V.
The I trip is set in a similar way by drawing 25A from the +18V rail using load resistors and backing off the I Trip preset until the output voltage just begins to drop. Repeat this for the -18V.
The I sc preset is set so that when you short out the + or -18V rails the current delivered is 5A. Yes you really do need to short circuit the output to do this that's why it's called I sc.
You may want to short circuit the 25A fuses in the +/- 18 V rails before doing this for obvious reasons.
Set the output voltages to + and - 18V and then connect to console and calibrate in the usual way for the correct voltages measured at the desk centre section.
All measurements are made at the connector on the rear of the supply, with no console connected.
Any question feel free to ask on our Recycled Audio Ltd facebook page.
By the way I was the one who told Graham how to do it."
and then he added :
"OK, here are the values that were missing from my post last night.
For the 7V rail ISC should be set to 2A, Imax should set at 7.3A. For the 250V rail ISC is set for 0.15A, Imax should be 0.55A. There is no Vtrip preset for 7V or 250V rails. For the 48V rail ISC should be 0.15A, Imax should be 0.5A and Vtrip set at 52.5V"
Mattia.
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Awesome! Thanks Mattia and Keith, the lurker ;-)
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Hey this is awesome!!
Keith rocks! ;) if he is seeing this post... THANKS KEIIIIIIIIIIIIIIIIIIITHHH!!!! \o/ \o/ \o/
Maybe if someone is adventurous enough to be the first one to try this out and live to tell the story could turn this into a document with a step by step + photographs procedure? This would be really really awesome! :D
Cheers,
Artur
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Great info!
-Paavo
p.s copied info to tech area
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Awesome info!
Something I wondered about, Where in the centre section do I check these voltages? Anyone knows?
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You slide the centre section up, and on the right side (green backside of motherboard PCB) you will find the rails if you look closely. More towards the bottom, clearly marked -18, +18, +7, etc. - let me know how you go, don't have a photo at hand right now.
Something I wondered about, Where in the centre section do I check these voltages? Anyone knows?
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You slide the centre section up, and on the right side (green backside of motherboard PCB) you will find the rails if you look closely. More towards the bottom, clearly marked -18, +18, +7, etc. - let me know how you go, don't have a photo at hand right now.
Something I wondered about, Where in the centre section do I check these voltages? Anyone knows?
Thanks alot, today I will have a tech look at my PSU´s since I have had my fuse blown a couple of weeks ago. Did the measurements and found this at centre section:
estimated : +48 -18 +18 +11 +13
measured: +39 -17,5 +16,2 +9,8 +9,4
not good right? He´s a very good tech, just not an SSL one, is there anything me or the forum can help him with? I got the manuals and printed the lineup procedure (Big thanks to Keith for that)
Thanks in advance
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Surprised to see 48v as low as 39,.. just to throw this in the mix, I had a similar situation, and it transpired.. the battery in my multimeter needed changing.
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Ye it looks very low
I´ll see what happens when first of all the PSU´s are fine, and then I guess other factors could be involved, like the changeover unit, or is this only related to PSU?
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Don't think the 39 on the +48 rail are a problem, but the rest looks WAY OFF!!
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You should check the voltages at the power supply as well if it is this far off. If there is too much difference between them, then you should investigate the condition of your cabling between the board and the psu.
Anyone have a quantification of what "too much difference" is for the standard cabling? In my experience its either been good or painfully obvious.
While 39V will allow many mics to work with phantom, quite a number will not. Also, that gives cause for concern in the power supply as to why it is so far off.
Alan
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I havent had any issues with phantom power, but realise its not very good.
Cant say i know much about Electronic and dont wanna misquote the tech but it seemed the difference between +18 and -18 was his biggest concern
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the question for me is WHY is it that far off?
the difference on the 18V rails is not great, but to me the real question is WHY.
Obviously those voltages will allow the board to work, it will be better with designed values, but this should be taken care of as it moves everything toward not working correctly.
Alan
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is your PSU (or your PSUs) set for the right mains voltage where you are?
M.
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I have full confidence in the tech so im sure he will fix it, I report back when he has found the problem, If the problem lies in the psu's, Ive taken vacation mean while :)