karloff70

G7 alive and beautiful!!!
« Reply #60 on: July 30, 2008, 09:54:02 AM »
Just tried cutting the offending trace, but result stays the same.....

Would this connection have blown any of my parts, as I have fired it up with it countless times rather than severing it before...??


karloff70

G7 alive and beautiful!!!
« Reply #61 on: July 30, 2008, 11:39:08 AM »
HOOOORAY!!

The stupidest little thing hid from me all this time:

Inside the original XLR connector, which I'd kept from chinese original including the little leadstumps was the problem. The lead for the positive output (pin 3 at mic) was sat in its heatshrink looking unsuspicious, but when I pulled the shrink back to measure continuity he just came out. Been loose all the time...........

So now there is loud and proud signal.

There is also loud and proud hum and 'windstorm' type stuff, which makes me think my grounding is somehow not right. I've wired pin 1 and pin 7 at the pcb xlr end to chassis as this is how I understood Jakob's advice in a thread in the meta......I'll have another search......only ONE more little thing  :green:

THANK YOU SO MUCH EVERYONE !!!!

Off I go to search and hopefully record tonight.......

karloff70

G7 alive and beautiful!!!
« Reply #62 on: July 30, 2008, 01:36:57 PM »
.....and here I go again.......

There WAS sound.....and loads of interference I thought was a grounding issue. So I searched, didn't find anything I hadn't already read, so tried to disconnect pin7 in the mic from ground. Put it back since, as I realised it needs to be there as my pcb doesn't join the top pin 1 and 7 and Jakob says they need to be connected in the mic.

Now, since then I have NO actual signal anymore and ONLY the loud (amp definitely works!) interference I was trying to get rid of......haven't changed anything though........

Tried more cleaning around the capsule connections and 1G resistors....no change....... :cry:

ioaudio

G7 alive and beautiful!!!
« Reply #63 on: July 30, 2008, 04:11:44 PM »
slowly. take a deep breath of air  :cool:

look at the schematics, follow the signal, try to understand the circuit (building point to point  from the schematics teaches a lot in this regards!)
if it hums, the amp works, something around the capsule to grid seems wrong now. but if you have no signal, stop cleaning the high-z part - probably the connection capsule - pcb, or some grounding issue (since you messed with it)
maybe start all over again, with new parts.

-max

karloff70

G7 alive and beautiful!!!
« Reply #64 on: July 31, 2008, 04:41:25 AM »
Found on closer inspection (Thanks Roddy!!!) that it seems I have blown up the voltage regulator for the heater voltage in my psu.....=no more heating.

Must have had a short somewhere for a second.

Off to Maplins to get a handful of LM317's and go into battle again...... :green:

karloff70

G7 alive and beautiful!!!
« Reply #65 on: July 31, 2008, 09:23:42 AM »
Hmmm....new LM317 in the psu, still no sign of heater voltage...... :?:

rodabod

G7 alive and beautiful!!!
« Reply #66 on: July 31, 2008, 09:46:29 AM »
Quote from: "karloff70"
Hmmm....new LM317 in the psu, still no sign of heater voltage...... :?:


Oh man...

Right, can you meter what voltage is at the input pin as per this drawing:



I'm going to guess it will be something roughly in the range of 12V or so.
Quote from: tv
punchy fat bastard chip

karloff70

G7 alive and beautiful!!!
« Reply #67 on: July 31, 2008, 10:20:54 AM »
Hi Roddy.....mmmm

It says 0.03 V. Something unhealthy before the LM317 it seems.....

The transformer should have 9.5V output, but at the direct from the transformer AC 9.5V output I get 10.6 V AC.

I'm out of my depth like never before...... :oops:

rodabod

G7 alive and beautiful!!!
« Reply #68 on: July 31, 2008, 10:29:21 AM »
Quote from: "karloff70"

It says 0.03 V. Something unhealthy before the LM317 it seems.....


Ok, don't start worrying.

Look here for a reference for the original supply (courtesy of Vertiges) :

http://www.vertigesproductions.com/diy/psu-stellar-2.jpg

Now, you've proven that the transformer is ok. Can you now check the positive leg of C8 (assuming the tech has left this section intact). This will let us see if the diode bridge (the square-looking arrangement of diodes) is working ok. The voltage will be very ripple-y, but set your meter to DC and see what you are getting out.
Quote from: tv
punchy fat bastard chip

karloff70

G7 alive and beautiful!!!
« Reply #69 on: July 31, 2008, 10:45:57 AM »
Hi ....

No voltage at all on C8 positive leg. Nil.


rodabod

G7 alive and beautiful!!!
« Reply #70 on: July 31, 2008, 11:10:52 AM »
Quote from: "karloff70"
Hi ....

No voltage at all on C8 positive leg. Nil.


Balls. It would have been a better idea to check the diodes before assuming that the regulator may have been shot. Never mind.

If you are getting voltage at the secondary as per the diagram for the PSU, but nothing at the positive leg of C8 (ie. just after the diode bridge) then this suggests that the diodes may have died. I'm kind of surprised that your fuse didn't blow though.

I'd try swapping out the diode bridge and take it from there.
Quote from: tv
punchy fat bastard chip

karloff70

G7 alive and beautiful!!!
« Reply #71 on: July 31, 2008, 11:26:58 AM »
You wouldn't be so surprised if you knew what I just saw....being that the fuse in this thing is actually a dud. Meaning, it's not connected to ANYTHING! Just can't see that until you look under the pcb........it's literally just sitting there for decoration........

Nice.

So I need 4 more diodes.....can't face another Maplins run today, will have to be in the morning.....

What makes me safe in thinking the new ones won't just blow aswell though.....

karloff70

G7 alive and beautiful!!!
« Reply #72 on: July 31, 2008, 11:33:13 AM »
They're 1N4007 diodes. Any difference if I get glass or silicone ones (1N4007G/1N4007S)??

rodabod

G7 alive and beautiful!!!
« Reply #73 on: July 31, 2008, 12:35:50 PM »
Quote from: "karloff70"

What makes me safe in thinking the new ones won't just blow aswell though.....


Well, you can measure the "load", ie. the resistance that the diode bridge and also the regulator are likely to see. That's why I suhhested measuring the resistance of the filament in case there was a short circuit to ground (which would cause damage to the regulator and or the diodes as a short circuit means lots of current...) It sounds as if it is ok though.

Quote from: "karloff70"
They're 1N4007 diodes. Any difference if I get glass or silicone ones (1N4007G/1N4007S)??


I think they are silicon ones in the unit. I have some in my house and the offer is still there if you decide you want a hand.
Quote from: tv
punchy fat bastard chip

karloff70

G7 alive and beautiful!!!
« Reply #74 on: July 31, 2008, 02:01:13 PM »
Thanks for the offer, you've been almost unnatural in a beautiful way in your helpfulness!!

I shall do another Maplins run in the morning and see if I can get it going tomorrow, if not, I might just take you up on it.........

I'll post my results tomorrow.

ioaudio

G7 alive and beautiful!!!
« Reply #75 on: July 31, 2008, 02:17:49 PM »
please install the fuse.

karloff70

G7 alive and beautiful!!!
« Reply #76 on: August 06, 2008, 02:34:41 AM »
HOOOOORAYY!!

The beast is live and sounds rather bigger than expected!!!

Thanks are in order in a massive way, especially to Roddy (rodabod) who in an abstract attack of random kindness spent an entire day yesterday helping me to track down every f***up and problem my noobness had caused and brought the beast 'to birth'!!!! Too kind, sire, too kind!!

Also massive thanks to Jakob for putting such a beastly design at everyone's fingertips!! What a beautiful act of stealth for music and the recorders of it everywhere!!! Thank you!!

Must now set it to run in for a while and then get right into the recording bubble, foresaking the internet accordingly .......

Thanks for everyone else's helpful tips aswell, this site is a beautiful thing!

Boris :green:  :green:  :green:

ward

G7 alive and beautiful!!!
« Reply #77 on: August 06, 2008, 03:19:59 AM »
congrats!!!

zebra50

G7 alive and beautiful!!!
« Reply #78 on: August 06, 2008, 05:02:26 AM »
...Roddy's ya man!

Glad you got there in the end. Was it one thing, or a few issues? Multiple problems can be really hard to track down.

Enjoy the recording.  :thumb:
Ribbon microphone services
http://www.xaudia.com
Microphone blog

karloff70

G7 alive and beautiful!!!
« Reply #79 on: August 06, 2008, 06:13:46 AM »
Was a few....short had blown a resistor in the psu (took a minute to hunt down...)and there where some issues with the primary of the transformer, as there are tracks very close on the pcb= great fat oscillation/motorboat sensation.....

Thanks again everyone!! :green:


 

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