GSSL HELP THREAD!!!

[hotbaby]

Hello,
i finished my GSSL firstly without turbo and sidechain board.
all solder contacts tripplechecked. they are ok. all bridges are in.

if i start it up i just can hear a 108hz noise saw wave. The harmonics change a little bit if i play with the treshhold and makeup.
The meter works and moves to 8db. Sometimes if i start it up the noise output is damn loud and let my soundcard clip for some seconds... than it goes to a lower level.

- I can not hear any music if i feed the machine with it. There stays the 108hz hum...
- Grounding is ok.
- solderpoints does not contact each other..
- the 10 bridges are placed in on the main board, after i figured out that i forgot the two bridges near the power elcos...
- I have bridged on the rotary pcb the bypass and "com" to "on".
- i measure +/-18.6v > on the +/-15v points

anyone who may have an idea what it could be and how i could figure the problem out?

many thanks
aaron.

 

[hotbaby]

Resoldered the whole main pcb today. checked the vcas...
with no luck. no audio arrives the output. just a constant 108hz hum.
if anyone had similar troubles, i d be happy for getting any help.
thank you very much

 

[Harpo]

- i measure +/-18.6v > on the +/-15v points

If you unlikely didn't have placed 7x18 regulators instead of 7x15s, you most probably have placed a 7815 in the spot for the 7915 and vice versa, resulting in this raw DC voltages on your supposed +/-15V rails.

 

[hotbaby]

Harpo, thanks for your reply. i had the same idea today but the ts7815 is on the regular place from the input/output view "right" and the L7915cv "left" near the pcb border. theres something strange with my pcb. all solder points are checked... maybe the regulator is defect, is there an unique way for checking it? many thanks

 

[Harpo]

Unlikeley that both regulators fail the same with these symptoms, but who knows.

Make sure, the transformer center tap is properly connected to 0V on pcb.
Some toroids come with a hard to see isolation paint on their (not pre-tinned) lead ends that has to get scrapped off for a working contact.

More useful if something behind your supply is shorting a rail or drawing too much current, but you could lift all 3 links (2x between onboard transformer and audio-VCA, 1x next to the 2x47K sidechain in resistors) to have your +/-15V supply isolated from the rest of the circuit. Place a (maybe 1K - 1K5, doesn't matter that much) resistor between +15V (the lifted spot at supply side) and 0V and another one between -15V and 0V to draw a min.current load of 10-15mA per rail and measure voltages again. If a rail voltage is off by more than 2%, a) check if raw DC voltage before regulator is at least +/-17V (min.2V larger than your target voltage), b) check the 22uF caps at reg.output, c) replace the probably faulty regulator.
Good luck

 

[MartyMart]

Aaron, I would do a check without the turbo/sidechain boards present.
See if your main board alone has any voltage errors.

MM.

 

[hotbaby]

hmm today i measure 19v on the -/+15v bridges... The AC Power is 17v. after rectivier it is 21.8v. on the first elco i read 6.9v and the second 14,9v. the left regulator seems to work fine with -14.5v but the right one does on the left leg to right 6.8v/0v/5.4v.
The left leg 6.8 just feeds the 15k resistor near the 15v. ok i have on the -15v bridge -14.2v and on the "+" bridge 5.5v (measured with ground). If i measure - and + of the bridges i get 22v.
perhaps i have to bridge something that i oversee... or the regulator death.

@marty i just have installed the normal gssl and will add the other things later if the main thing works.

Maybe pics will tell more.

 

[MartyMart]

Aaron, hard to see from the photo but where is your "audio ground" connection ?
Is it from the output XLR's as I can't see it on the input XLR's ....

( probably stupid but just a thought )

MM.

 

[Harpo]

The AC Power is 17v.
Maybe pics will tell more.

You have a single winding 17V transformer. You need a center tapped 30V or a 2x 15 V transformer.

 

[Kingston]

whoooops! 

 

[MartyMart]

You have a single winding 17V transformer. You need a center tapped 30V or a 2x 15 V transformer.

GOOD eyes !!

Yup wrong mains traffo aaron ....  get a 15-0-15 and minimum 7.5VA rating, perhaps 15VA better for the extra
boards and IC's that you are adding.

MM.

 

[hotbaby]

  oh that is stupid my failing :
Now i understand the 2x 15v written on the pcb... i thought it is meaned just two 15v ac cables  

I have a second 17v ac secondary on the toroid that is not in use at moment. you can see it in the right top corner.
can i twist it with the yellow ac cable together for getting it work?

I used this toroid from banzai:

# Power rating: 30VA
# Core loss, typ: 0,26W
# Copper loss, typ (120 degrees celsius): 5,0W
# Size: 70x32mm
# Primary: 2x115V
# Secondary: 2x15V

http://www.banzaieffects.com/Talema-TRT30215UL-pr-23379.html

thank you guys
puh...

Marty i bended the solder metal stand outs of the xlr´s to pin1 and soldered it together for getting the shortest contact to the chassi.It is not to see on the pics...  

 

[MartyMart]

Aaron , read the side of the transformer for the wire colour details or look up the spec sheet of that exact transformer.
At the GSSL PWR connection at the board, you will end up with three wires, one 15v AC each side and the middle one "0" is
two wires twisted and soldered together.

MM.

 

[hotbaby]

ok i read it:

Pri: 2x115v   yellow-orange / violet - black
sec: 2x15v /1A     green-red / brown-blue

i am a little bit confused how to get it right connected.
At moment i have bonded pri: orange and violet. Yellow is on minus phase and black on switch/phase
cause of 230v usage... but how to make one secondary 0v or do i need an other toroid :?

 

[Harpo]

30VA will power some 4-5 more gssls, but you can use this. 1st winding connects to one AC-in and center pin on pcb, 2nd winding connects to the other AC-in and center pin on pcb. Watch the colour scheme, probably printed on your transformer, so that hot/in phase lead of the 2nd/lower transformer winding connects to the cold/out of phase lead of the 1st/upper winding for the center tap connection.
(just seen your reply before posting, looks like red+brown for center tap connection)
While you're at it, you probably don't want the meter light powered from the 12V on control pcb.

 

[hotbaby]

ok, this makes sense to me.

i will desolder the red ac cable and put it ro the center pin. the brown ac of the second prim. to the center pin too red/brown and the blue one to the left ac pin. now i should have 17v 0v(+~17~-17) 17v. I will try this now.

 

[hotbaby]

Many thanks Harpo for your good eyes now it works perfect [edit].

 

[Harpo]

Maybe reread my last sentence "While you're at it, you probably don't want the meter light powered from the 12V on control pcb." These 78L12 and 79L12 regulators won't supply enough current for additional gimmicks such as power hungry meter lamps. About how to connect your meter-lamp or meter-LED (these are different beasts), read some 2-4 pages back.

 

[hotbaby]

Harpo thanks. All works perfect now, i m to afraid for writing the reason for the phaser effect
Thanks for the meter-lamp advice. Oh this compressor is so great!!! i am already playing around with it... all the difficulty soldering was worth. and it was a very difficulty pcb with lot little barriers many thanks again. ...wow great thing

 

[SSLtech]

-Now Turbo it... and know the joy of TRUE stereo buss limiting!



Keith