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crwdns2934241:0crwdne2934241:0 Edward Anderson

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Help t-shooting with schematic - Onkyo tx525sv overheating resistors

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This has several resistors and an area about the size of a quarter  that is looking a burnt brown on the pcb near the front of the unit.  There are about 5 or 6 ringed resistors total in this area. Tested and results below. When using the tuner/radio  portion all seems to be fine (uses the bypass mode for radio). When  using the bypass feature (which only utilizes the 2 rear channels I  believe) for the video/theater audio, this works too. The option to use  anything that utilizes the DSP portion is a intermittent. Just a low  hum or his is presenting thru speakers sometimes. Shame to toss this in the trash  because this receiver is an oldy but goody. Seems like I could replace a  few resistors and all would be well? Hopefully the community here will  be familiar with the issue. Thanks in advance! I have located a service  manual but lack the knowlege to read it (link below). I also have pics of the  overheated resistor location.

[image|2457835]

Actual  board part number (I think) is ncar-5121. These are numbers from the  board anyway.

I've  resoldered all of those resistor and transistor contact points plus  re-soldered all the contacts on about 1/3 of this board. I was able to get my magnifying headset on and locate a few bad / cracked solder points as well in other areas. Improvement  has been noticed as not all of the resistors listed below are as hot as  they were with the exception of the 3 listed below. [br]
 [link|http:// https://www.dropbox.com/s/m66gysdhfqyojzm/Results1.png?dl=0|https://www.dropbox.com/s/m66gysdhfqyojzm/Results1.png?dl=0]

Svc manual [link|https://www.dropbox.com/s/9sjwtrqncm77dub/Onkyo-TXSV-525%20Service-Manual.pdf?dl=0|https://www.dropbox.com/s/9sjwtrqncm77dub/Onkyo-TXSV-525%20Service-Manual.pdf?dl=0]

The resistors and their tested values ​​are: [br]
 r930 = 118.8 ohm HOT TO TOUCH! [br]
 r929 = 118.5 ohm HOT TO TOUCH! [br]
 r928 = 18.4 ohm HOT TO TOUCH! [br]
 r935 = 22.1 ohm [br]
 r923 = 1.5 ohm [br]
 r925 = 11.4 ohm [br]
 r926 = 11.5 ohm [br]
 These seem to be within range?

Values  ​​for outputs for these voltage regulators tested by touching the negative to the G (?) Terminal and  pos to the O terminal (is this the correct way to test?): [br]
 Q921 = + 11.7v [br]
 q922 = -11.6v [br]
 q923 = + 6.02v [br]
 '''q924 = - 5.8v then drops to 0 usually (this one drops voltage after heating up)''' [br]
 q925 = + 5.5v

I am currently at a standstill and need help with schematic. I specifically need help with the next troubleshooting step. The service manual is provided and I believe the resistors and regulators in question are on page 36.

If components need replaced could you provide suggestions on comparable replacements if needed? Where to get? Thanks. I've been studying on how to test these voltage regulators as well. To repeat - I do not know how to read schematics. I wouldn't have gotten this far without help. It  took a bit of hard study to be able to read that schematic and still  don't understand much but am able to limp thru so far :) I look forward  to the next step :)

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Home Audio Receiver

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open