bernbrue

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #440 on: February 04, 2020, 06:46:28 AM »
Oh, then it needs to be replaced. The TL783 is fine here. What is the max voltage of the caps in your psu and on the mainboard? Check the (wiring of the) resistors for dropping down the voltages as well. The psu needs to be under load, otherwise the voltage can go up quite high.
Bernd


zero

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #441 on: February 04, 2020, 07:40:59 AM »
Oh, then it needs to be replaced. The TL783 is fine here. What is the max voltage of the caps in your psu and on the mainboard? Check the (wiring of the) resistors for dropping down the voltages as well. The psu needs to be under load, otherwise the voltage can go up quite high.
Bernd

The caps voltage is 450v,
Ill replace the TL783 and check the wiring, what bugs me is that it was working fine.
I see! the voltage under load , when it worked fine, 290v, now it´s 385V, with no load 440v ( normal? )

So there is no other way of dropping the voltage from the xformer other than the 3 resistors i have in series after the diode bridge? just a proper transformer?

The only thing i did, before starting to blow fuses, was replacing the R32s with a 18k resistor so i could get more compression with lower input.
Thank  you.
Kind regards,
Pedro.

zero

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #442 on: February 23, 2020, 12:12:21 PM »
Hi Bernd,
Sorry for being such a pain but i´m a little noob at psu design and i am trying to understand  how this circuit works.

i want to calm down the beast as it produces excessive heat, even the front panel gets hot from the 3 resistors in series i have to tame down the dc after the rectifier.

My thinking (maybe wrong), from what i get from the schematic:

-The trafo from don audio outputs 337Vac.
-After the rectifier, from the math Vac*1,414, the 337Vac goes to 476,518Vdc.

What i gathered in my head from the  TL783 , it needs a little over voltage to regulate, like 25V and it´s not easy to read with no load.

I really want to cool the thing down so my idea is to put there a 230Vac/200MAh trafo so it outputs 325Vdc ( 230Vac*1,414=325,22Vdc)

Am i thinking ok?

Will a 230Vac trafo be ok or will the voltage drop under load and something like 275Vac be better?

I still didn´t replace the TL783 to see what´s burning fuses but before i do that i wanna sort this out.

Sorry for any hassle or stupidity.

Cheers,
Pedro.

Kid Squid

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #443 on: April 07, 2020, 07:49:12 AM »
Hi Chaps,
Hope you are all doing well in these crazy times  :)

Just wondering, if any people need cases etc, I'll be doing another run ( order dependant), with a different mains transformer option. If any of you are interested, or know anyone that was missed the first time..

Quote
https://groupdiy.com/index.php?topic=74776.0

Be safe

Steve
It is not the same as 4+12, nor is it the same as 4+8, but 4+12 IS the same as 4+8+12....

http://www.facebook.com/LazyLizardLabs

IanB

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #444 on: April 18, 2020, 09:19:41 AM »
Just plugged in and it works perfectly! I am SO stoked! Using 6386 with 1k R after the rectifier bridge (had to use a huge chassis mount jobby as they were previously actually cooking!!!) & Carnhill input tranny (the 4:1 Colin had made for LA2A builds....I wired it backwards - compresses really nicely and sounds typical Carnhill: great).  Also using Hairball Bournes output attenuator (works a treat!). Using Steve’s beautiful case, power tranny & bypass switch - thank you man!!! (Tempted to get another but not sure I’d use a pair....drums?!).
Thanks B & Z for the boards & wiring diagram & the boys who helped with the bypass and output wiring etc. What a great project.
It’s such a cool feeling! Cheers!

bernbrue

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #445 on: April 18, 2020, 09:37:10 AM »
Glad to hear that you like our stalevel.
Bernd

IanB

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #446 on: May 04, 2020, 09:44:24 AM »
Glad to hear that you like our stalevel.
Bernd

I don’t like it, Bernd.....I LOVE it! Ha!
You’re clever lads. Thanks again!

bernbrue

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #447 on: May 09, 2020, 03:06:06 PM »
 ;D

jazzcrisis

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #448 on: June 08, 2020, 07:06:12 PM »
Does anyone have the meter scales that were linked to in the first post in this thread? The twin-x site seems to be dead!

craig

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #449 on: June 08, 2020, 10:09:13 PM »
Could it be this one.


Kid Squid

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #450 on: June 28, 2020, 09:20:00 AM »
Hi Bernd,

Hope you are well in these crazy times !!

I'm looking into getting another batch of the power transformers for my case design, and I'm curious about the overvoltage that some people are reporting with the v.1 transformer. Is this on the secondary HV windings, or the LV windings ?

Jens, it looks like the 5V winding - Should I increase it to 10V ?


I didn´t read the entire thread, so maybe this has been addressed before. In case not here´s a problem I found:
I´m using Steve´s transformer with 5V AC for V+ and 5V relays. Without regulator installed I get 6,5V DC at the regulator input pin. With regulator installed the voltage drops to 4V at it´s input and I get 3,3V at the output. Several others have mentioned this before, but nobody did care.
The reason for this is that if we want to get 5V out of the LM317 regulator it needs to see at least 3V more at it´s input. But we only have 6,5V instead of necessary 8V. So it shuts down.


Lads, lovely to see the cases being used  ;D, Having a little catchup on posts and they look bloody wonderful !

Best,
Steve
« Last Edit: June 28, 2020, 09:31:10 AM by Kid Squid »
It is not the same as 4+12, nor is it the same as 4+8, but 4+12 IS the same as 4+8+12....

http://www.facebook.com/LazyLizardLabs

bernbrue

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #451 on: June 28, 2020, 03:01:05 PM »
Hi Steve,
the 5V relay voltage should be 9V to get the 3V difference for the LM317 to regulate. I can’t verify if the other voltages were fine or too high, since I haven’t used your poorer tx.
Bernd

Kid Squid

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #452 on: June 30, 2020, 05:59:40 AM »
Hi Bernd,
No problem, I'll get that seen too.

I'll have a read over the whole thread, but I'm pretty sure that some people have been 'choking' back the HT with dropping resistors ?

Not sure if this was for my 'poorer'  ;) transformer, or the one from Don audio..  I'll look into it.

Hope you are doing well in these mad times !

Best,
Steve
It is not the same as 4+12, nor is it the same as 4+8, but 4+12 IS the same as 4+8+12....

http://www.facebook.com/LazyLizardLabs

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #453 on: August 08, 2020, 09:57:25 AM »
Hey guys, maybe I'm just missing something here but I can't find any details about the HTTRIM resistor/trimmer on the PSU board? Any idea where I can find more info on that?

Cheers
Badger Brian

Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
« Reply #454 on: August 17, 2020, 06:49:15 PM »
Does anyone have the Simpson 27 scale image that was posted at the beginning of this thread? I see someone posted a hoyt one. Is it the same? It doesn't look quite the right shape but I may be wrong.

Ryan