SSL 9k : problem with Keith's PSU (?)

Hi All,

I'm building a pair of SSL 9k, using Keith's boards for this project.

I've built two PSU to feed the 9k with ±18v and ±15v, but on this two boards, I have a "problem" on the negative voltage which is about -20v.

The positive voltages are pretty good (+15 and +18, so).

I've try to change the L7815, but the voltage is still -20 on the board, which seems really high for a ±15v PSU ...

Is it really to high ?
Is it really a problem, or the voltage gonna drop when I will plug the SSL boards ?

If it's a problem, how can I solve it ? There is not so much components on this PSU, I don't really understand where can be the issue...

A friend of me is building the PSU too, and have the same problem (same components).

I hope this subject hasn't already be answered on the lab, I've try a search, with no success.

Thanks all.

Yoann

You could try loading the power supply and re-measuring the voltages.

Sometimes they are funny when they are un-loaded.

yes, that is possible, I have seen this too especially with ST parts.

it is also possible that you are not referencing to ground properly on that part, but lack of load is likely your problem.

Yes always load a 3 term I this case try about 10ma loads to start.

1ma is 1v 1k

so say 18V 1k 18ma

Does anyone read the NS app notes?

By the way, can anyone tell me if the two 100uF caps in between the secondary and the diode bridges really need to be rated to 100V? I realise that the diode bridge is working as part of a voltage multiplier, but I'm not sure what voltage rating is safe.

My local electronics store only stores 50V versions. Any ideas?

....

[quote author="Gus"]Does anyone read the NS app notes?[/quote]

always. which is why i don't use Vregs :wink:

golden rule. any active circuit must be loaded to work properly. doesn't matter if you're just measuring or running music aka ac through

unloaded Vregs can do really oddball stuff. when they go, they like to take their surroundings with them down the drain as well

fukkin' beasts

[quote author="rodabod"]By the way, can anyone tell me if the two 100uF caps in between the secondary and the diode bridges really need to be rated to 100V? I realise that the diode bridge is working as part of a voltage multiplier, but I'm not sure what voltage rating is safe.

My local electronics store only stores 50V versions. Any ideas?[/quote]
Roddy
Don't buy anything yet - give me a few days
Pm me address again

gawddamn triple post

[quote author="uk03878"]
Don't buy anything yet - give me a few days
[/quote]



:razz: :thumb:

Hey, thanks all for so many answers !! :thumb: :grin:

I've not finish my 9k boards yet, but it seems I should work harder to plug them, and solve my problem...


Thanks all !
:guinness: :sam:

Yoann

I had exactly the same problem. You need to load the PSU.