Commercial Gainclone kit- building instructions - Page 65 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Audio Sector

Audio Sector Kits & PC boards from AudioSector

Reply
 
Thread Tools Search this Thread
Old 2nd May 2009, 05:30 PM   #641
tbrooke is offline tbrooke  United States
diyAudio Member
 
tbrooke's Avatar
 
Join Date: Apr 2007
Location: China Grove, NC
Default Problem solved maybe

My amp still overheats and isn't right but I think I figured out the problem. I looked back at the instructions and I believe I have input and output wires wrong.

I have a picture and the black and white wires are input output; you can see the connection to the terminals for the output. I think I should move them to the Cz Rz locations

(I hope the picture link works it's my first try)

It lClick the image to open in full size.
  Reply With Quote
Old 2nd May 2009, 06:42 PM   #642
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Don't move anything to Cz, Rz, those pads are not being used.

It should be obvious that IN means input and OUT stands for output

One other thing; the nuts on mounting screws are two big, while power plains are protected by solder mask, it is not enough isolation and you are risking shorting the rails to the chassis: use either plastic isolation washers or screws with small heads.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 3rd May 2009, 02:52 AM   #643
tbrooke is offline tbrooke  United States
diyAudio Member
 
tbrooke's Avatar
 
Join Date: Apr 2007
Location: China Grove, NC
Default Grounding RCA Jacks

Quote:
The RCAs need to be isolated from a chassis. You are using what looks like Cardas RCAs, they should come with plastic isolation washers.
I saw this earlier and noticed that my RCA input jacks clearly aren't isolated from the chassis. Actually I have them screwing fairly tightly into the chassis and there is no isolation washer. Could this be my

Are there isolated and unisolated RCA Jacks?

Tom
  Reply With Quote
Old 3rd May 2009, 03:11 AM   #644
diyAudio Member
 
Join Date: Dec 2008
Location: Victoria, BC
Default Re: Grounding RCA Jacks

Quote:
Originally posted by tbrooke

Are there isolated and unisolated RCA Jacks?

Tom-
The isolated type come with plastic washers and require a larger hole.
Alternatively you can mount the non-isolated style on a plastic/phenolic plate, so they are electrically isolated from the rest of the chassis.

Cheers
John
Attached Images
File Type: jpg rcas.jpg (8.7 KB, 371 views)
  Reply With Quote
Old 3rd May 2009, 11:42 AM   #645
cyxg is offline cyxg  Australia
diyAudio Member
 
Join Date: Mar 2009
Location: Melbourne,Australia
Hi,Peter

I finished my 3875 chip amp, sound very good!
Attached Images
File Type: jpg p1000656-2.jpg (85.5 KB, 696 views)
  Reply With Quote
Old 3rd May 2009, 11:46 AM   #646
cyxg is offline cyxg  Australia
diyAudio Member
 
Join Date: Mar 2009
Location: Melbourne,Australia
Peter

i measured DC offset at speaker terminals - 8om speaker load

Right - 8 mV
Left - oscillates between 10mV -14 mV

I can hear the transformer humming a little.
Attached Images
File Type: jpg p1000650-2.jpg (70.4 KB, 552 views)
  Reply With Quote
Old 3rd May 2009, 11:55 AM   #647
cyxg is offline cyxg  Australia
diyAudio Member
 
Join Date: Mar 2009
Location: Melbourne,Australia
it's really good.
Attached Images
File Type: jpg p1000663-2.jpg (91.8 KB, 835 views)
  Reply With Quote
Old 3rd May 2009, 11:59 AM   #648
cyxg is offline cyxg  Australia
diyAudio Member
 
Join Date: Mar 2009
Location: Melbourne,Australia
the amp is 14.5kg.
Attached Images
File Type: jpg p1000662-2.jpg (87.0 KB, 1003 views)
  Reply With Quote
Old 4th May 2009, 12:37 AM   #649
tbrooke is offline tbrooke  United States
diyAudio Member
 
tbrooke's Avatar
 
Join Date: Apr 2007
Location: China Grove, NC
Default More Troubleshooting (newby)

I can't figure out what to do next

So far I have

1. measured voltages at V+ PG+ V- PG- etc its about 35 volts

2. Checked DC Offset on output terminals - it varies between
.005 V .050V I have tried it with a 8 ohm load and I used a preamp to vary the input and I have even played music which does come out but unamplified and distorted.

3. Removed the bolts that held amp boards down and may have caused a short

see picture:
http://picasaweb.google.com/tom.broo...79046144343858

4. Insulated RCA input jacks.

Amp still get very hot, no sound except for static

I ran continuity checks with my multimeter and it seems almost everything may be shorted to ground but then again maybe this is the way it is supposed to be - it is ground - maybe continuity isn't the way to check for shorts

So
1. Anything else to check and how?
Visually soldering looks ok

2. Could I have damaged the LM3875? How do I check?

3. Anyone in NC that can check it?

4. Should I order a new kit and start from scratch?

Tom
  Reply With Quote
Old 4th May 2009, 06:06 AM   #650
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
One other thing to check is if you place resistors in right places. I recall someone had sililar problems and it was because of mixed up resistors. You can find some pics here: http://www.diyaudio.com/forums/showt...48#post1508848

R1 which is 220R looks slightly different now, but the other two 22K should be the same.

If the chip shows offset, that may indicate it's not damaged.

If you won't be able to make it work, you can ship it back to me and I will fix it


Quote:
Originally posted by cyxg
I finished my 3875 chip amp, sound very good!
Congratulations, it looks really good
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Commercial complete Gainclone kit for a beginner? gychang Chip Amps 365 4th October 2011 08:19 AM


New To Site? Need Help?

All times are GMT. The time now is 03:54 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2