"planet audio" 1250w d amp repair, need cross for cap - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th January 2009, 05:42 PM   #1
ppia600 is offline ppia600  United States
diyAudio Member
 
Join Date: Jun 2007
Location: Louis y ana
Default "planet audio" 1250w d amp repair, need cross for cap

I've got a cheapo "planet audio" amp that blew the large 200v caps on the output end as well as the small blue square cap that is in series with a resistor that measures about 1100 ohms. There are also two other blue square caps that read 224j100 that got hot and melted down closer to the power supply. I tried ampguts but the only similar amp I could find was a power acoustik and the pics aren't clear enough for me to zoom and check the part number for the tiny blue cap on the output. I'm also wondering how 200v 105c caps on the output end would give out when the 80v power supply caps are fine. ????? So I need to verify the tiny output cap p/n and possibly the actual capacitance of the 224j100 caps. I believe they are 100v, but need a refresher on how to use the 224j to get the capacitance measurement. Thanks for any help

Pic of the output terminal section. The tiny blue cap is gone that is supposed to be to the right of the large resistor, it was basically disintegrated, but there was a small piece of the blue plastic. I've also already removed the 4 200v caps.

Click the image to open in full size.

And here are the two blue caps that melted and exploded, I cleaned most of the mess off of the board


Click the image to open in full size.
__________________
Don't worry... you can always turn the gain down!
  Reply With Quote
Old 11th January 2009, 06:37 PM   #2
ppia600 is offline ppia600  United States
diyAudio Member
 
Join Date: Jun 2007
Location: Louis y ana
Also forgot to mention, I replaced the four 200v caps and it plays fine. Just has the switching noise that hopefully will be cured by replacing the two melted blue caps and the one on the output end.
__________________
Don't worry... you can always turn the gain down!
  Reply With Quote
Old 11th January 2009, 09:17 PM   #3
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The blue caps are 0.22uf/100v/5%. The resistor is supposed to be 1000 ohms.

If you still have switching noise on the outputs, you may have a shorted inductor. Move the inductors to see if the noise changes. The inductors fail when the insulation wears through. The problem generally occurs where the lead winding passes over the top/inside of the other windings. This is VERY common on ALL of the amps that use this design.

The shorted (possibly intermittently shorted) inductors could have caused the capacitors to fail.

The capacitors (particularly the smaller caps) fail because they receive too much voltage. As the capacitance of the electrolytic caps decreases (often due to overheating caused by shorted inductors), the output voltage on the inductors goes WELL above rail voltage and will cause all of the caps on the output to fail.

Is R101 near the RCA jacks intact?
  Reply With Quote
Old 11th January 2009, 10:48 PM   #4
ppia600 is offline ppia600  United States
diyAudio Member
 
Join Date: Jun 2007
Location: Louis y ana
Wow, thanks for the info, Perry. The noise isn't really loud, just a little louder than the noise you can hear on most class d amps if you have the volume down and put your ear close to the woofer. And R101 looks fine, no signs of overheating. It reads at 217 ohms.
Would you recommend any specific type or tolerance for replacement of the .22 caps? Mylar, polyester, ceramic, etc... 5%,10%,20%...? I'll check the windings and see if the noise changes. They all seem to be firmly attached to the board.
__________________
Don't worry... you can always turn the gain down!
  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
Rega Planet "power-out" joostein Digital Source 16 9th October 2012 08:47 AM
Seeking advice on "Circlotron" cross-coupled feedback OTL design arteitle Tubes / Valves 8 5th March 2010 09:55 PM
What makes Nichicon "muse"/"for audio" caps different ? percy Parts 2 3rd October 2009 05:53 PM
Is it possible to repair nakamichi cd pickup "home" laser? whiterabbit Car Audio 77 1st August 2009 03:42 PM
Effect of cross-coupled "local" FB on plate load of previous stage ray_moth Tubes / Valves 23 27th April 2005 08:55 AM


New To Site? Need Help?

All times are GMT. The time now is 12:01 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