API 312 Thread!

[robomatique]

[quote author="Mike Keith"]If you use a LED for the phantom use a 15K in series, you could also place a 33K across the 48V will also dissipate the voltage a little quicker. That's what I use on my JM 130 mic pre and works just fine..[/quote]

So you mean a 33K resistor permanently across the 48V and 48V ground? That doesn't effect the normal phantom? Or would it be better to use a lower value and just swap it in when phantom is bypassed? Or does it matter?

Thanks again!!!!!!!!!

Robetr

 

[Mike Keith]

I keep it on line all the time , its only about a milliamp, does not hurt a thing.

 

[Flatpicker]

[quote author="Mike Keith"]I was referring to directl across the 48 volts, 200 ohms at 48 volts would pop the LED in a few seconds...[/quote]We posted at the same time - I was referring to the bleeder only.

 

[Svart]

i am having a slight problem with the switch circuit.. when i turn on more than one relay, the relay leds all go out and the relays unlatch.. it stays like this until i power off the unit.. all the relays that are ON will quickly click ON and all of their LEDs will also come on for a second then everything goes off.

It seems that I am tripping the current protection on the regulator? it happens even when i turn on the phantom switches.. but the leds just dim considerably... not sure what is going on here..

(edit) more info: there is no series resistor from the phantom reg to the 5v reg(s). I have even tried to parallel a bunch of them up! there is no pull down of the phantom voltage which leads me to believe that the regs are shutting off.

(edit again..) I just paralleled 5 v regs and was able to get more than one switch/LED combo to work.. still does not pull the phantom down and switching on more than one switch starts to dim the LEDs considerably to the point of all relays failing to stay latched..

:?

 

[pmroz]

.
Svart, I'm not the smartest guy here by a longshot, but sounds like the PS isn't supplying enough current to the 48 and 5v rails. The TQ2-5v relays draw a bit of current, 28.1ma each. BTW dropout is 0.5v and hookup is 3.5v on those.
Fabio's PS? How many channels? What toroid rating? How many relays on before it happens, only 2?

If Fabio's PS, 48v and 5v rails 'share' the same rectifier. Maybe a backward diode in the 48v/5v bridge or backward smoothing cap before the 48v reg. 48v and 5v PS rails test okay?
Paul

 

[Svart]

hey, the phantom rail stays steady. the 5v rail is good until you switch on relays then it pulls it down:

1 relay=2.91vdc
2 relay=1.52vdc
3 relay=.91vdc
4 relay= dead

not sure what is going on but the series resistor before the 5v Vreg has been replaced with a jumper and the same happens.

it seems that the Vreg is not regulating properly.. but i have replaced them two or three different times.. and i've paralleled them up to find that doing so does drive them a little better..

If there was not enough current available then it would pull the phantom rail down too..

again the relays and leds work properly for a split second after turning the system on but then all die until you switch the unit off and then they all turn on for a second again and then turn off.

the setup is 2 channels.

:?

 

[pmroz]

.
svart, sorry, was posting as you edited...
http://www.thediypill.phx.com.br/forumfiles/psu312sch_v1.pdf
cool, DIYpill's back online.

You mentioned R10 was jumpered. geez, this is a big thread... somewhere earlier JLM i think suggested to jumper R10 directly to [junction of D1/R1] ????, and avoid 48v reg altogether. Please recheck back in the thread I got that right... looks right on the schem. Maybe worth a try, looks like the same thing you're getting?

At one point people were having trouble with multiple channels/relays engaged, so I changed the rail to 12v/12v relays, otherwise could at least give some readings on the bench.

You're farther advanced in theory than I, but (consider this 'view from the rear') are the LEDs 3mm? Don't know if 5mm would work on 5v, maybe I'm wrong?

 

[louder]

alo
just finished connecting 4 fabio`s api,with 5v relays(4 each board),and when turn on all the swiths all voltages stay the same.sure the psu heatsink gets hot....well, i can keep my fingers on it.
if it shuts down,maybe it is a heat problem,or a too small power tranny.
try connecting the vr to the box with proper insulation.
maybe it helps with12v,or 24v relays since they consume less current(as someone told in this thread).
ps:i`m using a power station jlm.
only a small matter it`s that 48v takes a hell of a time to go down,when turned off.
best regards
pedro

 

[Svart]

i'll be playing with it over the next few weeks and i'll post what I figure out. the only problem that i keep coming back to is the possibility of the Vreg shutting down due to overvoltage/overcurrent. the 7805 doesn't normally like to see over 35v on it's input.. these are seeing 44+.. unless i stick a high value resistor in series with it and then it will limit the current to the vreg...

the LEDs i am using are 3mm 20ma each.. pretty much "normal" LEDs.

on the bright side though.. the preamps sound wonderful! I have the original output trafo, lundahl input and melcor opamps right now.. i tried my 2520s that i stuffed but they don't work.. no output. I used some substitute BJTs because i didn't have the right ones on hand so i'll be rechecking my calculations.. or since I finally got the right ones i'll just restuff..


:thumb:

 

[Greg]

I did the mod suggested by JLM. Read back... I think it's in here somewhere. I also added diode protection to the 5V regulator.

 

[Svart]

ok found the info about halfway back! connected the 5v reg to r1/c1 as suggested and everything is working perfectly now!

now i just need to scrape together the money for a case!

thanks everyone!

 

[pmroz]

.

on the bright side though.. the preamps sound wonderful!

Great! Glad it's sorted. The 2520BCs sound nice too. I'm using a couple of each, with assorted in trafos, for slightly different flavors. Prefer the BC channels on most things. If the right transistors don't get them working, there was some discussion/revision... a thread named 'ours sound like the 2*5*2*0' or similar. A link is... somewhere... else... in... this.... thread.
Anybody know a way to search within a single thread?

 

[AnalogPackrat]

[quote author="pmroz"].
A link is... somewhere... else... in... this.... thread.
Anybody know a way to search within a single thread?[/quote]

Look at the bottom right corner of each page in thread view. There's a search box and a "Search Thread" button which does just what you want. Don't feel bad, I never noticed it either until Ethan pointed it out in another thread a while back

BTW, thanks for the opinion on the 2520BCs. I'll be building a couple of 312s and have been wondering about the DOA options.

A P

 

[pmroz]

.
ahhhhh haaaaaaaaaaa thanks
was trying to get google to do it.
Paul

 

[Svart]

ok so i spoke too soon.. the 5v rail lasted for a while then quit. it now acts like it did before..???

:evil:

i'm tired, i'll look at it in the morning.

:guinness:

 

[Bauman]

Ohh. Chris, nice! Looks like I´m too late. Yea connecting to R1/C1, that´s what I do

cheers!
Fabio

 

[Svart]

hmm now the regulator is overheating.. gets nice and steamy hot then shits itself.. hmm I have seen many regulators get much hotter than this and still work.. must be current limiting too..

 

[pmroz]

.
Guess putting R10 back between C1/R1 and reg would remove the possibility of reg current limiting.

 

[Svart]

yes but then it limits voltage.. :? :?

I just stuck a huge heatsink on it and it has been working ok for about 15 minutes now.. i think i'll order some of the 2A parts and plan on mounting those regs to the chassis..

 

[Mike Keith]

How much voltage do you have on the input of the regulators?