Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting Audio Equipment
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 08-25-2020, 06:11 PM   #121
SluggerB
Member
 
Join Date: Aug 2020
City & State: Philadelphia, PA
My Country: US
I'm a: Knowledge Seeker
Posts: 74
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

OK, I soldered the 2W resistor in. With chips A-E & the power LED connected (F, G, and the CD IC disconnected), I read 6.23v across it.

I soldered back in the resistors to connect up chips F & G. With chips A-G & the power LED connected (CD IC disconnected) I read 7.66v across it. The VCC+ of chip F & G were around 5v each (A-E are ~10v)

I soldered back on the resistors and all the other components connecting the CD IC to the board, and read 11.70v across the new resistor. I took out my thermometer and the temp seems to stabilize at 137F-139F degrees. Certainly to hot to touch for more than a second, but I saw no white smoke and no burning resistor smell.

Now here is where I earn my idiot reward. I was checking the fan, and I disconnected it to the board and connected the ends to a 9v battery, and it spun. So I thought maybe somehting is wrong with the board not turning it on, how about I just wire it right to the main power supply going into the unit? Nothing bad could happen by dumping 120 AC into a small 12v DC fan, could it?

So yeah, now I need a new fan. And annoyingly its a 60mm fan and all I have on hand are 80mm fans, and even more annoyingly the unit is like 75mm tall so I can't fit an 80 in there as a replacement. Sigh

So I'm ordering a new 60mm fan, I don't want to run the unit for a long time without the cooling fan attached, so while it's back together I have not extensively tested it yet. When I get the new fan in and run it through it's paces I will let you know what happens.
SluggerB is offline   Reply With Quote
Old 08-25-2020, 06:49 PM   #122
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 38,511
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Quote:
Originally Posted by SluggerB View Post
OK, I soldered the 2W resistor in. With chips A-E & the power LED connected (F, G, and the CD IC disconnected), I read 6.23v across it.

I soldered back in the resistors to connect up chips F & G. With chips A-G & the power LED connected (CD IC disconnected) I read 7.66v across it. The VCC+ of chip F & G were around 5v each (A-E are ~10v)

I soldered back on the resistors and all the other components connecting the CD IC to the board, and read 11.70v across the new resistor. I took out my thermometer and the temp seems to stabilize at 137F-139F degrees. Certainly to hot to touch for more than a second, but I saw no white smoke and no burning resistor smell.

Now here is where I earn my idiot reward. I was checking the fan, and I disconnected it to the board and connected the ends to a 9v battery, and it spun. So I thought maybe something is wrong with the board not turning it on, how about I just wire it right to the main power supply going into the unit? Nothing bad could happen by dumping 120 AC into a small 12v DC fan, could it?

So yeah, now I need a new fan. And annoyingly its a 60mm fan and all I have on hand are 80mm fans, and even more annoyingly the unit is like 75mm tall so I can't fit an 80 in there as a replacement. Sigh

So I'm ordering a new 60mm fan, I don't want to run the unit for a long time without the cooling fan attached, so while it's back together I have not extensively tested it yet. When I get the new fan in and run it through it's paces I will let you know what happens.
So those Voltages are for the 180 Ohms 2W for the V+ only? No change in the reading for the 180 Ohms for the V-, correct?

"I took out my thermometer and the temp seems to stabilize at 137F-139F degrees."
So if room temp is 70F then temp rise is 69F (about 20c rise), so that is way below the handling spec of two Watts resistor.
According to the chart for 2W with power dissipation of 0.76W (11.70V on 180 Ohms, 37.50 % of power rating ratio), the temp rise is expected to be
50c (122F), so the resistor is cooler than expected since temp rise is only 69F.. less rise than using 1W dissipating 0.76W.
Attached Images
File Type: jpg KOA MOX Temp rise.jpg (116.1 KB, 1 views)
__________________
Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
budm is offline   Reply With Quote
Old 08-25-2020, 07:13 PM   #123
SluggerB
Member
 
Join Date: Aug 2020
City & State: Philadelphia, PA
My Country: US
I'm a: Knowledge Seeker
Posts: 74
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Quote:
Originally Posted by budm View Post
So those Voltages are for the 180 Ohms 2W for the V+ only? No change in the reading for the 180 Ohms for the V-, correct?
Yes. I didn't check voltage on the V- cause I didn't add anything back onto it.


Quote:
So if room temp is 70F then temp rise is 69F (about 20c rise), so that is way below the handling spec of two Watts resistor.
According to the chart for 2W with power dissipation of 0.76W (11.70V on 180 Ohms, 37.50 % of power rating ratio), the temp rise is expected to be
50c (122F), so the resistor is cooler than expected since temp rise is only 69F.. less rise than using 1W dissipating 0.76W.
The room was about 64 degree that I was working in. So about a 76F rise. But that's still less than 122F. I also mounted the resistor about as far above the board as the legs would lift it.
SluggerB is offline   Reply With Quote
Old 08-25-2020, 09:19 PM   #124
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 38,511
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Quote:
Originally Posted by SluggerB View Post
Yes. I didn't check voltage on the V- cause I didn't add anything back onto it.

The room was about 64 degree that I was working in. So about a 76F rise. But that's still less than 122F. I also mounted the resistor about as far above the board as the legs would lift it.
"But that's still less than 122F" Do you want to see 122F temp rise instead?

Well, it is good that the measured temp rise is not 122F, if it is then the resistor will be 191F!, the lower the measured temp rise you see the better.

Last edited by budm; 08-25-2020 at 09:22 PM..
budm is offline   Reply With Quote
Old 08-26-2020, 12:08 PM   #125
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 38,511
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

BTW, can you get a hold of Oscilloscope and know how to use it?
budm is offline   Reply With Quote
Old 08-27-2020, 01:00 PM   #126
SluggerB
Member
 
Join Date: Aug 2020
City & State: Philadelphia, PA
My Country: US
I'm a: Knowledge Seeker
Posts: 74
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Quote:
Originally Posted by budm View Post
BTW, can you get a hold of Oscilloscope and know how to use it?
That would be a no and no.

Replacement fans showed up, tonight I install the new fan, button everything up, and run the unit for 30 minutes straight and see if it holds up. If it passes that test it's back to the owner on Saturday.
SluggerB is offline   Reply With Quote
Old 08-27-2020, 01:01 PM   #127
SluggerB
Member
 
Join Date: Aug 2020
City & State: Philadelphia, PA
My Country: US
I'm a: Knowledge Seeker
Posts: 74
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Quote:
Originally Posted by budm View Post
"But that's still less than 122F" Do you want to see 122F temp rise instead?
No, I was saying it's less than 122F, which is a good thing.
SluggerB is offline   Reply With Quote
Old 08-27-2020, 06:35 PM   #128
SluggerB
Member
 
Join Date: Aug 2020
City & State: Philadelphia, PA
My Country: US
I'm a: Knowledge Seeker
Posts: 74
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Final update: I installed the new fan, plugged in a speaker, connected to my phone's Bluetooth, and played about 30 minutes of music. I kept the thermal probe resting on the new 2W resistor and it held steady at 137-139F the whole time. I reassembled the unit, gave it one last test run, and I'm calling it fixed. It goes back to the owner on Sat.

Again huge huge huge thanks to budm for all the help, I've learned a ton and had a blast! Here's to the next one!
SluggerB is offline   Reply With Quote
Old 08-27-2020, 06:55 PM   #129
petehall347
Badcaps Veteran
 
Join Date: Jan 2015
City & State: worcester
My Country: United Kingdom
I'm a: Knowledge Seeker
Posts: 2,344
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

59.4444C sounds lots better than in F ... if the owner is happy that is what matters . if it comes back graft in a better power supply for that circuit and maybe add a fuse or 2 .
petehall347 is offline   Reply With Quote
Old 08-27-2020, 08:16 PM   #130
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 38,511
Default Re: Help diagnosing Pyle Receiver PTA66BT with burned resistors

Quote:
Originally Posted by SluggerB View Post
Final update: I installed the new fan, plugged in a speaker, connected to my phone's Bluetooth, and played about 30 minutes of music. I kept the thermal probe resting on the new 2W resistor and it held steady at 137-139F the whole time. I reassembled the unit, gave it one last test run, and I'm calling it fixed. It goes back to the owner on Sat.

Again huge huge huge thanks to budm for all the help, I've learned a ton and had a blast! Here's to the next one!
Thanks for the follow-up.
budm is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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

Forum Jump



Badcaps.net Technical Forums 2003 - 2020
Powered by vBulletin ®
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 10:14 AM.
Did you find this forum helpful?