GSSL HELP THREAD!!!

[dukasound]

Hi
I will use 2180 instead 2181 what I have now.
Can I use all of three on place 2150 (without trimer on two). Any changings on sidechain if I use 2180?
Thanks
Duka

 

[bubba_b]

So I decided to just start yanking parts off the board and test them for good or badness, since I didn't know where the problem was. I knew it was in the left output section, so I started there. I found a couple bad caps (I assumed they were bad since a good one measured about 8megohms and these measured about 1.5megohms and another was in the 30+megohm range). After replacing those caps and tidying up all the other good parts I took out, I fired it up and now it works fine......except. Yes, there's a butt. The meter does not move. The unit functions perfectly, all controls are good, but no meter and it's not hooked up backwards (I thought that and checked). Brand new 1mA meter, too. $18 one.

Thoughts?

 

[Greg]

Is it the Modutec meter?

 

[bubba_b]

No, it's an edgewise meter made by Shurite, model 350. It's a 1mA. Here is a pic and spec sheet for it from Prime Technology's website.

 

[gyraf]

Bub,

Look at the schematic. The meter is driven from 1/4 TL074, through a 2K resistor. Check that voltage is changing with compression at the output pin of the TL074. Check resistor value. Check continuity all the way to the meter. Check your panelmeter with your ohmmeter (it should move when ohm'ed in the 200Ohms range)

Jakob E.

 

[Flundran]

A few weeks ago I put togehter my first SSL and found out a had a voltage drop on the +15V rail. Here I got only +3.7V.
Because of various problems with the PCB (bad drilling etc), I decided to move the components to a new PCB. Today I put i all together. Guess what? Same voltage drop at the +15 rail. I still got only +3.7V.

Is it possible the shortout lies on the control pcb?

How do i check a capasitor with a voltmeter?

/Flundran

 

[gyraf]

Check that your regulators are alright - cut the connection to the rest of the pcb and mesure. If it measures right, solder a link back on the pcb where you cut it.

If regulators are alright, then there must be something drawing the rail down - a short somewhere, or a broken component (IC).

Try first with no IC's mounted (this is why it's a good idea to use sockets) - and make sure your DC voltages (including the +/-12V) are good.

Then mount the IC's - OBSERVE ORIENTATION! - one at a time, measuring voltages in between - untill you've found what IC that does the mess..

Change that for a new one...

Jakob E.

 

[Flundran]

Ok, I have sockets to all IC:s and all IC:s has been taken out. I checked the 7815 regulator and did cut the connection to the rest of the PCB and measured it. It shows +10.6V. The 7915 (still soldered) measure -12V

I've tried with a new 7815, with the same result...


I'm really confused. My trafo is a toroid without ground connection. When a do measurements on the PCB I connect my voltmeter to the pcb ground. Is this the right way?

/F

 

[gyraf]

[quote author="Flundran"] My trafo is a toroid without ground connection. [/quote]

What do you mean by that?

You need three wires from the transformer: 15-0-15V AC - that is 30V with a centre tap, also named 2x15V in Europe..

What is the input voltage to your regulators? Measure at the diode bridge..

Jakob E.

 

[Flundran]

Here is a picture of my toroid connections I just drew:

I haven't mounted trafo or PCB's in a box yet, I'm still waiting for the box to arrive..

/R

 

[gyraf]

2x15V 30VA gr-re/br-bu

If this is what is actually written on the transformer, then:

Connect red and brown together to connect to the centre point of the power inlet connector on the PCB. Green and blue to the outer pins.

Jakob E.

 

[Flundran]

Now I've got correct values at all rails, even with IC's on the PCB. Thanks Jakob!

 

[Flundran]

I've traced the problem to the 'THRESHOLD' pot.. I have a loud humming noise from the "-" rail it seems... If I turn the 'THRESHOLD' all the way up OR down the signal dies...

What does this mean?

 

[gyraf]

Look at the schematic. Check that the resistors around that pot are right. Check that the pot's centre connection dosen't short to anything. Last, try with a new TL074.

Jakob E.

 

[Flundran]

I have done some resoldering and this is the situation now:

I get clean signal on both channels. However, there's no compression going on.
When I search for a short-out I use a multi-meter and set it to 'resistance'. Then I connect one node at the PCB ground and the other at the spot I want to check. If the meter read zero resistance, there's a shortcut. Is this the correct way to do?

/Flundran

 

[neilwight]

anyone got any codes for the rotary switches they are using in this build, ones for RS would be nice as im probably going to just get almost everything from them here in the UK.

i had thought 665-203 and 665-219 looked correct but can anyone confirm. theres no mention regarding shaft diameter or the likes and ive not received my PCBs yet so cant check pin diameter and number either.
if anyone can advise id be most grateful.

also, anyone got any favourites for the potentiometers? since im ordering online i cant get in to give them a twist for feel.

thanks,
neil

 

[neilwight]

couple more questions,

regarding the external sidechain switch on the SSL G series unit.

am i correct in thinking (since i dont have schematics for original) that this cuts CV to sidechain if activated, allowing only external signal to control?

if so am i then correct in thinking that if i wire a switch in between the 100R (sitting directly below 56KR) coming of the TL072 and the input on the 470R that it goes to i will be creating a replica of this function?

also regarding using an external (off board) transformer. im a little confused as to where i attach my two 15v wires and the 0v wire. do these go to the three pins in the top left corner with 0v in the middle and 15v's either side?
where it says "mount these only if external transformer" surely this doesnt mean i link one 15v input to the + as indicated by arrows does it. is it refering only to the fact that these pins and that piece need only be used if using an external transoformer.
if using this do i still need to insert the same piece at the other side of the two big capacitors also. it appears that it would now be redundant
actually what are these, am i right in thinking its a bridge rectifier?

finally, any guidance regarding current requirements for a toroidal to use, id looked at a 50va with an output of 2x15v, 1.67A. is this overkill, i think im going to fit lit bypass switches as per original. meter is unlit however.

sorry for all the questions but hope you guys can help out.
neil

 

[gyraf]

[quote author="Flundran"] When I search for a short-out I use a multi-meter and set it to 'resistance'. Then I connect one node at the PCB ground and the other at the spot I want to check. If the meter read zero resistance, there's a shortcut. Is this the correct way to do?[/quote]

Yes. And some meters have a beeper to indicate (close to) zero Ohms.

If you have no compression, but the unit is otherwise working, then check and recheck the wireing of the bypass switch. Compare to schematic while doing this.

Neil,

If you read through all of this thread and/or the SSL Meta, I'm pretty sure you would have all your questions answered...

But to cut it short: All pcb-mounted Lorlin switches will fit the pcb. Pot quality is not important, as they pass DC only, no audio. The sidechain thingy is for sidechain audio - DO NOT MESS WITH THE DC, this messes up compression ratios very easily. The transformer is mounted with three wires, 15-0-15VAC, when using external transformer (not onboard), mount only the bridge rectifier marked for this. Current consumption is some 2x100mA at the most, but a larger transformer allows for good meter light.

Jakob E.

 

[neilwight]

jakob,

thank you for taking the time to reply to me.

i had read through this thread over the last couple of days but had still felt a little unsure of my understanding even though some points seemed to have been raised. apologies if it seemed like i was asking to be mothered a little too much, perhaps in hindsight this was actually the case.

i know feel much clearer though and am really keen to get cracking on my first project.

neil

 

[j180ec]

Hi. I just finished building the SSL clone and wanted to say thanks to everyone for their input on this project, especially Gyraf for his patience and Gustav for supplying the professional PCB's. This was my first DIY so I had lots of questions. But because of all you kind people, I was able to find all of the answers in these threads. So thanks again for making this project a total success.

Now, to start planning the next project! Hmmm, I think the Pultec EQ would make a good addition to my rack.

Cheers, John D