gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #300 on: September 19, 2013, 11:53:27 AM »
V2 is looking much better,

V1 still is a concern.

Check R6,7,8,9. Voltage across R6 should not be 39 volts. Try to measure the voltage across R6 directly.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."


Benny

Re: [BUILD] GIX-51X tube preamp
« Reply #301 on: September 19, 2013, 01:47:17 PM »
I checked R6,7,8,9. Their values are o.k. Voltage across R6 is 0.9mV.

gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #302 on: September 19, 2013, 01:58:45 PM »
Hmmm... not sure what is happening. Power off, pull the tube and measure continuity between pin 7 and 8.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

Benny

Re: [BUILD] GIX-51X tube preamp
« Reply #303 on: September 19, 2013, 02:58:49 PM »
Continuity between pin 7 and 8 with both tubes taken out:

V1 - 0.996MOhms
V2 - 1.498kOhms

gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #304 on: September 19, 2013, 08:42:38 PM »
Well... that seems okay.

Your input stage biasing is off, but without good pics of the board and related components, I can't tell why.

If you've double checked resistors, checked for solder bridges/shorts between pins or other pads, then try injecting a signal and measure the level at the different stages. Start with a 100mV sine, 1KHz, right into the instrument jack. Turn the gain all the way down, output pot all the way up. Check AC signal voltage at each stage.

Also, post pics if possible.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

Toure14

Re: [BUILD] GIX-51X tube preamp
« Reply #305 on: September 21, 2013, 12:22:46 PM »
Hey Rodney I have a quick question. My C506 Capacitor is small so it fit right in the small lead spacing but looking at it I see neither leg toches the trace is this a problem?

Toure14

Re: [BUILD] GIX-51X tube preamp
« Reply #306 on: September 21, 2013, 12:24:32 PM »
Again the cap I used doesn't touch the trace. A pic from the bottom view of C506

Benny

Re: [BUILD] GIX-51X tube preamp
« Reply #307 on: September 21, 2013, 03:30:45 PM »
Hey Rodney I have a quick question. My C506 Capacitor is small so it fit right in the small lead spacing but looking at it I see neither leg toches the trace is this a problem?

Hi,

you should put C506 in the two holes with the wider lead spacing. There are different lead spacings for different sizes/brands of caps. The way you've put it in, both pins are connected together.

gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #308 on: September 21, 2013, 06:41:26 PM »
Benny, you're correct. The you have it now, toure, the cap is just soldered to both ground pads.

Are you sure that cap is a 100nF/250V? It looks ceramic, which is fine, but just looks a little small.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

Toure14

Re: [BUILD] GIX-51X tube preamp
« Reply #309 on: September 21, 2013, 08:21:23 PM »
Yes it is polyester film but I already cut the leads so off to radio shack I go


Toure14

Re: [BUILD] GIX-51X tube preamp
« Reply #310 on: September 21, 2013, 11:21:42 PM »
Rodney is it ok to clean the boards with alcohol after everything is soldered on?

gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #311 on: September 22, 2013, 12:04:12 AM »
That's what I usually do. I prefer to use 99% alcohol, rather than the 70% that some stores carry for medical use. It's probably very clean but the water content may cause some residue/noise in high impedance areas.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

Benny

Re: [BUILD] GIX-51X tube preamp
« Reply #312 on: September 22, 2013, 05:49:07 AM »
Well... that seems okay.

Your input stage biasing is off, but without good pics of the board and related components, I can't tell why.

If you've double checked resistors, checked for solder bridges/shorts between pins or other pads, then try injecting a signal and measure the level at the different stages. Start with a 100mV sine, 1KHz, right into the instrument jack. Turn the gain all the way down, output pot all the way up. Check AC signal voltage at each stage.

Also, post pics if possible.

I checked all resistors twice, today and they all seem o.k. I'll post some pics later today.

Toure14

Re: [BUILD] GIX-51X tube preamp
« Reply #313 on: September 26, 2013, 05:34:44 PM »
Almost Done with my Black face and my White face I have a question. In the instructions it left out the "FIL" pads do I just solder some wire to those pads? or I do not need them?

gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #314 on: September 26, 2013, 06:01:13 PM »
Yes, connect the filament pads. Any two conductor wire will work, I used a pair of solid 18ga twisted together.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

Toure14

Re: [BUILD] GIX-51X tube preamp
« Reply #315 on: September 26, 2013, 10:46:08 PM »
Who sells the OEP transformers in USA?

gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #316 on: September 27, 2013, 01:35:39 AM »
Newark.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

Toure14

Re: [BUILD] GIX-51X tube preamp
« Reply #317 on: September 27, 2013, 01:54:58 AM »
Rodney I'm gonna shoot you a pm...but for now I'll ask another question. Seeing as how this pre has no lighting indication is there a test procedure to make sure everything is working upon initial startup?

tonycamp

Re: [BUILD] GIX-51X tube preamp
« Reply #318 on: September 27, 2013, 02:50:21 AM »
Hi Rodney, i've been mia on this thread for a bit, been cutting my teeth on a lot of projects possessing lower voltages ;D love the way everyones been contributing to smoothing the bumps out of this unique 500 tube pre project! I should be starting my pair soon, but mostly wanted to chime in to say congrats on being a new Dad!

T

gemini86

Re: [BUILD] GIX-51X tube preamp
« Reply #319 on: September 27, 2013, 11:50:05 AM »
Haha, thanks tony!
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."


 

Related Topics

  Subject / Started by Replies Last post
141 Replies
41409 Views
Last post April 24, 2019, 06:18:12 PM
by Mrosso
370 Replies
77283 Views
Last post July 23, 2019, 01:04:02 AM
by boji
232 Replies
80939 Views
Last post January 09, 2020, 04:17:23 PM
by tron23
69 Replies
12252 Views
Last post June 10, 2015, 07:04:14 AM
by delmonton