TillM

Re: [BUILD] 1176 Rev A - Back to the beginning...
« Reply #2920 on: May 07, 2018, 03:30:16 PM »
AC Impedance and DC resistance are two different thanks. Dc resistance will tell you if there is a break in the coil.

The DC resistances are about:

1-4: 50Ω
5-8: 12Ω

Mike

Thank you so much Mike !
This helps a lot.
1-4 is 51,2 Ohm and 5-8 is 13,1 Ohm.
So the fault must be on other side.
I will get it, I'm sure that I will find the issue.
Thanks for the help.


Re: [BUILD] 1176 Rev A - Back to the beginning...
« Reply #2921 on: May 08, 2018, 08:16:53 PM »
I am having some trouble getting my 1.2.5 rev A going.  I have followed the troubleshooting guide and am getting correct AC voltages at all test points except the Output Transformer Brown, where I am getting 7.82VAC and across the output pin 2 and 3 I am getting 0.03VAC. 

I am getting all DC voltages as noted on the voltage sheet (+/- 5%) except at Q4 where I am getting 13.67VDC and 4.44VDC (Instead of the 6.6VDC noted on the voltage sheet).  I have checked all resistors and caps in the line amp and have found no errors. 

Any insight into what could possibly be wrong would be amazing.  I feel like at this point I am just spinning my wheels.


Thanks,

Jeff

Hairball Audio

Re: [BUILD] 1176 Rev A - Back to the beginning...
« Reply #2922 on: May 08, 2018, 08:19:30 PM »
I am having some trouble getting my 1.2.5 rev A going.  I have followed the troubleshooting guide and am getting correct AC voltages at all test points except the Output Transformer Brown, where I am getting 7.82VAC and across the output pin 2 and 3 I am getting 0.03VAC. 

I am getting all DC voltages as noted on the voltage sheet (+/- 5%) except at Q4 where I am getting 13.67VDC and 4.44VDC (Instead of the 6.6VDC noted on the voltage sheet).  I have checked all resistors and caps in the line amp and have found no errors. 

Any insight into what could possibly be wrong would be amazing.  I feel like at this point I am just spinning my wheels.


Thanks,

Jeff

Yellow and orange tied together?

Double check all output transformer soldering.
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Re: [BUILD] 1176 Rev A - Back to the beginning...
« Reply #2923 on: May 08, 2018, 08:24:18 PM »
Thanks for the quick reply Mike.

The yellow and orange are tied together.  I just reflowed the output tfr connections to the pcb earlier this evening and the wire colours match the pcb designations.   I am still getting the same readings. 

Is there anyway to check the transformer to see if that might be the issue? 
« Last Edit: May 09, 2018, 10:36:48 AM by jbmacdo3 »

Hairball Audio

Re: [BUILD] 1176 Rev A - Back to the beginning...
« Reply #2924 on: May 14, 2018, 09:33:35 PM »
Thanks for the quick reply Mike.

The yellow and orange are tied together.  I just reflowed the output tfr connections to the pcb earlier this evening and the wire colours match the pcb designations.   I am still getting the same readings. 

Is there anyway to check the transformer to see if that might be the issue?

Have a look at this diagram:

http://library.hairballaudio.com/datasheets/5002.pdf

You can see in the electrical diagram the windings in the transformer. These are just long runs of wire. With you Ω tester measure the resistance of each coil. It'll be less than what is shown on the diagram, that is AC impedance.  Just confirm you don't have a winding that is broken (OL or no continuity) and make sure non of the windings are shorted to each other.

You'll need to unsolder to test.

Mike
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/

Re: [BUILD] 1176 Rev A - Back to the beginning...
« Reply #2925 on: May 18, 2018, 08:57:04 PM »
Hi Mike,


Thanks again for all the help.

I got the following resistances when I desoldered the output transformer and measured:


Red: Blue with Yellow and Orange connected:  47.4 ohms
Yellow and Blue: 25.8 ohms
Orange and Red: 21.7 ohms
Grey Violet: 255.8ohms
Brown and Black: 47.1ohms
WhiteRed WhiteBlack: 1.2ohms

These seem considerably lower than what is on the spec sheet, except for the brown/black.  However, I am no expert here.  Could you please let me know if this transformer is within spec?

Thanks,

Jeff


Hairball Audio

Re: [BUILD] 1176 Rev A - Back to the beginning...
« Reply #2926 on: May 18, 2018, 08:59:39 PM »
Hi Mike,


Thanks again for all the help.

I got the following resistances when I desoldered the output transformer and measured:


Red: Blue with Yellow and Orange connected:  47.4 ohms
Yellow and Blue: 25.8 ohms
Orange and Red: 21.7 ohms
Grey Violet: 255.8ohms
Brown and Black: 47.1ohms
WhiteRed WhiteBlack: 1.2ohms

These seem considerably lower than what is on the spec sheet, except for the brown/black.  However, I am no expert here.  Could you please let me know if this transformer is within spec?

Thanks,

Jeff

Look back at my post.  You're measuring DC resistance, which will be far less than the AC Impedance on the spec sheet.  I'll check those against a working one monday, but you don't seem to have any damaged windings.  Any shorts between these windings?

Mike
Hairball Audio, LLC
DIY Parts and Kits
http://hairballaudio.com/shop

Top secret stuff and upcoming releases:
http://facebook.com/hairballaudio
http://twitter.com/HairballAudio/


 

Related Topics

  Subject / Started by Replies Last post
beginning soldering iron

Started by « 1 2 » The Lab

21 Replies
4573 Views
Last post November 01, 2004, 06:27:59 PM
by BYacey
0 Replies
1163 Views
Last post May 05, 2006, 04:27:28 PM
by soundguy
450 Replies
97310 Views
Last post May 23, 2017, 11:09:20 AM
by Hairball Audio
8 Replies
2104 Views
Last post June 14, 2009, 01:20:44 PM
by Biasrocks