Kir_For_Pleasure

Re: console hum
« Reply #20 on: May 06, 2010, 06:35:09 AM »
aha you think 4700uf is enough for c4,c5 they are 10000uf on schematic...cant find any date codes...
Cheers !!
Thomas
Sweden


Kir_For_Pleasure

Re: console hum
« Reply #21 on: May 06, 2010, 12:14:25 PM »
would have been nice with a adjustable lm337 in there insted of the 7815  ::)
Cheers !!
Thomas
Sweden

QUEEF BAG

Re: console hum
« Reply #22 on: May 06, 2010, 12:52:42 PM »
10000uf?  oh, missed that last zero.

that should be plenty, you could just stick in a couple new ones of that
value and it should be fine.  don't think they need to be larger.


Kir_For_Pleasure

Re: console hum
« Reply #23 on: May 06, 2010, 03:46:43 PM »
what do you think of getting 15000uf insted of 10000uf, i ask because the price is better on the bigger ones
Cheers !!
Thomas
Sweden

Kir_For_Pleasure

Re: console hum
« Reply #24 on: May 06, 2010, 05:51:58 PM »
have search for hours after a socket for snap capacitors to go through hole mounting but havent find any..someone knows where to find those if there are any to find ?
Cheers !!
Thomas
Sweden

QUEEF BAG

Re: console hum
« Reply #25 on: May 06, 2010, 08:11:08 PM »
15000uf  should be cool,  it's kinda what i've was thinkin'

Mouser of Digikey would be the first places i would look

got a caliper for measuring hole spacing?

Kir_For_Pleasure

Re: console hum
« Reply #26 on: May 07, 2010, 02:18:13 AM »
15000uf  should be cool,  it's kinda what i've was thinkin'

Nice !

got a caliper for measuring hole spacing?
yepp !
Cheers !!
Thomas
Sweden

Kir_For_Pleasure

Re: console hum
« Reply #27 on: May 07, 2010, 05:00:00 PM »
Trying to find information about the diods 5-8 on the shematic iss133t-77 mounted between the two transistors, top right on the schematic, someone knows anything about them ?

« Last Edit: May 07, 2010, 05:06:15 PM by Kir_For_Pleasure »
Cheers !!
Thomas
Sweden

Andy Peters

Re: console hum
« Reply #28 on: May 14, 2010, 02:14:31 AM »
Trying to find information about the diods 5-8 on the shematic iss133t-77 mounted between the two transistors, top right on the schematic, someone knows anything about them ?

They lift the ground pins of the 7815 and 7915 regulators a couple of diode drops above and below (respectively) ground, so the outputs are a bit over ±16V instead of the expected ±15V.

-a
"On the Internet, nobody can hear you mix a band"

JohnRoberts

Re: console hum
« Reply #29 on: May 14, 2010, 10:42:05 AM »
In addition to what Andy said, there were some early 3 terminal regulators that could latch up at turn on if the wrong rail came up first. More of a problem with half wave rectification, and IIRC only one brand of 3 terminal regulator. I had one (very good) engineer working for me who refused to stop adding these diodes to prevent latch up for years after this ceased to be a problem.

Since you only need one diode to prevent the latch up, and this design uses two in series, I will speculate that they are just going for a little higher output.

Note: putting diode junctions in series with the ground leg, degrades the regulation quality, since differences in regulator ground current modulates the forward diode voltage which is effectively in series with output voltage.  This will also increase regulator voltage sensitivity to change with temperature, but most audio circuitry doesn't require perfect regulation, or they wouldn't use 3 terminal regulation in the first place.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...


Kir_For_Pleasure

Re: console hum
« Reply #30 on: May 14, 2010, 03:17:16 PM »
High five to everyone that helped me with the supply...now i have all the voltage rails up and working  :)
i used 1n4148 diodes for d5-8, the rails measuring +/- 16.33v
Cheers !!
Thomas
Sweden

Kir_For_Pleasure

Re: console hum
« Reply #31 on: May 16, 2010, 05:41:06 PM »
Etched some sil to dip adaptors today to go from the old njm2041 to ne5532, try the master section to begin with....any other fitting opamps to try ?
Cheers !!
Thomas
Sweden

Kir_For_Pleasure

Re: console hum
« Reply #32 on: May 19, 2010, 06:58:44 PM »
I need to etch a new board for the old one got cracks..someone have some improvments to share ? would it be complicated to implant a relay based insert bypass...decoupling caps..here is a schematic of the board

Cheers !!
Thomas
Sweden


 

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