Need Help,power supply on pioneer vsx-806-rds Stereo Receiver - Page 1
Forum section: electronics / beginners

author: pawlaks93
author_rank: Newbie
timestamp: June 20, 2014, 02:36:03 pm
content: Dear usersToday I tried to switch back on my Pioneer and it did not switch on for some reason, so I check the fuses but they are all(the ones i could find) are ok.So I got my multimeter out and start probing the basic stuff but didn't really find anything(for my knowledge)That's why I'm here asking for help, I have included a link to schematics and couple photos for help If you have any questions that would help solve this problem feel free;)http://www.hifiengine.com/manual_library/pioneer/vsx-806rds.shtmlhttp://www.hifiengine.com/hfe_downloads/index.php?pioneer/pioneer_vsx-806rds_service.pdf(Download if you can't be bothered to create an account)Thanks for your helpPawel

author: David_AVD
author_rank: Super Contributor
timestamp: June 20, 2014, 08:40:20 pm
content: Have you measured the primary winding on the main power and auxiliary transformers to make sure they are not open circuit?

author: techricky
author_rank: Contributor
timestamp: June 21, 2014, 02:45:56 am
content: No reading on the main power transformer connections there, if the fuses are ok, means the blue main power relay RY51 is not being turned on, ie the receiver is not coming out of standby.Is the standby led on? if not check that the standby power supply from that small transformer is ok, reading 5.6V between pins 1 and 2 of that small white connector CN51. If that is ok and it wont power up from the power button or remote then there is some problem with the system control to look into..Someone else might be familiar with common faults on this unit?

author: What_NZ
author_rank: Regular Contributor
timestamp: June 21, 2014, 04:28:36 am
content: Your link to the Service Manual is no-longer working but this one ishttp://elektrotanya.com/pioneer_vsx-806rds_rrv1769_sm.pdf/download.html

author: What_NZ
author_rank: Regular Contributor
timestamp: June 21, 2014, 05:04:22 am
content: Techricky is correct.This is all on Page 25 of the Service Manual.If Relay RY51 is not turning on it won't power up. Check for 5.6volts DC at the place he mentioned also you could measure the DC Voltage on CN51 pin 1 (Ground/Negative) to the Cathode of D55 (Positive) the voltages are shown on the circuit. Do this when the Power Cord is plugged in and the unit is turned on by the Power Switch S91. I take it that there is some sort of SOFT power button you press as well.You could also check (With the Power Cord unplugged and wait 5 minutes) Resistor R54 it should be ~27 OHMS.I am not sure of your skill level with electrical or electronic equipment. Please be very very careful when you are touching anything inside the unit, there are voltages which could KILL you.

author: pawlaks93
author_rank: Newbie
timestamp: June 24, 2014, 06:52:50 pm
content: Hello thereThanks for all the response@David_AVD I have not. I'm not quite sure how to do this.@techricky no the standby led is not on, I'm not quite sure how to check the transformer, i did check the voltage on the CN51 connector between pins 1 and 2 and there was 0 DC volts@What_NZ thanks for the link, i Check the voltage on CN51 pin 1 and D55 cathode and i got 0 DC Volts the resistor R54 is 27.2 Ohms. I finished electrical instalation in college so I have basic knowledge of electronics and the danger, thanks for the advice anyway.Thanks to all of you for a help if anyone is interested I will be waiting for further advices and measurements I can do to help solve this problemThanks Pawel

author: What_NZ
author_rank: Regular Contributor
timestamp: June 25, 2014, 12:16:33 am
content: From what you have said, having 0 DC Volts at D55 cathode is a problem.Since it is safe to assume RY51's contacts are open circuit the T1 Transformer is not connected. That means you can easily measure the resistance across the Primary windings of Power Transformer T51.Steps -1/ Start by unplugging the Power Cord and turning the Switch S91 ON. Then put your Multimeter onto the OHMs range and the Probes on the Phase (L) and Neutral (N) pins of the Power Cord. There should be a low resistance.If not,Then use the OHMs range to check each path i.e Phase (L) of the Power Cord to T51 Pin 4 and then Neutral (N) of the Power Cord back to T51 pin 1. Each path should be low resistance, nearly 0 ohms.2/ Measure the resistance directly across T51 pins 1 and 4. They should be low resistance. Of course make sure the Power Cord is Uplugged.3/ While the Power Cord is unplugged measure the resistance across the Secondary winding of T51 pins 5 and 8. It should be a low resistance.so, if in -Step 1 you measure a high resistance, it means something is wrong with the AC input to or the T51 transformer itself.Step 2 will check T51, if it is high resistance then T51 is faulty, check the soldering of it to the PCB.Step 3 will check the Secondary of T51 if it high resistance then T51 is faulty, check the soldering of it to the PCB.I think that is enough for now.

author: What_NZ
author_rank: Regular Contributor
timestamp: June 25, 2014, 02:44:59 am
content: Just as a side note -Anyone else think it is a bit strange that T51 is not protected by a Fuse? Maybe it has an internal fuse but not shown in the part picture.Still it seems strange there is not a MOV or Fuse on the AC input. I thought this would be mandatory for compliance with regulations. Although it may not be for the country it is designed for.

author: pawlaks93
author_rank: Newbie
timestamp: June 25, 2014, 10:26:20 am
content: Hi thereFollowing your steps I had a bit of trouble identifying pins on the transformer I hope I did it correctly, I marked the pins on the picture I'm not sure if they are correct if so I got the following readingsLive-Neutral =No Reading neither on PCB or the plug cordLive-Pin 1 =00.4 OhmsNeutral- Pin 4 =00.4 OhmsPin 1- Pin 4 =No readingPin 5- Pin 8 =26.3 OhmsI also measured the probes of multimeter on its own and they are 00.3 Ohms so I will assume that you could deduct 00.3 Ohms from the results aboveI have re soldered Pin 5 that's why it looks different from othersThanks for your help What_NZ, I will be keep checking for further updates on this postBest RegardsPawel

author: What_NZ
author_rank: Regular Contributor
timestamp: June 25, 2014, 11:11:51 am
content: Pin 1- Pin 4 =No readingOk just going by your reading above, the Transformer T51 has an Open circuit Primary.You can try and carefully de-solder T51 from the PCB. Once you have it out, check around pins 1 and 4 and see if there is a tiny wire wrapped around the pin and then it goes off inside the transformer. If the wire is broken you can try to repair it. It is possible there could be an encapsulated fuse mounted to the bottom of the transformer to. If there is check the resistance of it.Please post a hires picture of the bottom of the Transformer T51. Focus on the pin 1 and 4 area.It is possible that the wire is broken inside the transformer and therefore probably not repairable.Some people would say just substitute a replacement transformer but I would suggest contacting a few local service centres or Pioneer to see if you can get a genuine replacement.

author: pawlaks93
author_rank: Newbie
timestamp: June 25, 2014, 12:09:52 pm
content: Thanks for the answer, I have called authorized repair/warranty agents for Pioneer and they said that the production for power transformer ATT7019 is discontinued, unfortunately I am not able to de solder the power transformer right now as I don't have the correct equipment to do so, I will have it hopefully on Monday 30 June so I can follow further steps that you have advice me to.Thanks for your help, when I find some time next week to de solder the transformer and take some pictures, I will keep you updated.Best Regard Pawel

author: What_NZ
author_rank: Regular Contributor
timestamp: June 25, 2014, 01:37:30 pm
content: Quote from: pawlaks93 on June 25, 2014, 12:09:52 pmOk then.... waiting.......I hope you enjoyed the fault finding process, little logical steps makes it easier.Oh btw how about putting your country in your profile so we know where you are from. It could help us to find the parts you need later.

author: pawlaks93
author_rank: Newbie
timestamp: June 30, 2014, 05:15:25 pm
content: HelloSo today I managed to get the transformer out and check if the little wires goes to the pin and it does, so as you mentioned before it's probably broken inside, is there any way I could check how many windings it has so i could get a genuine replacement? As the only ones I found is in US and I don't think they do shipping to UKBest Regards Pawel

author: What_NZ
author_rank: Regular Contributor
timestamp: July 01, 2014, 05:30:05 am
content: When the primary winding is open circuit, you can't do much unless you can see where the break is.Please post a hires picture of the bottom of the Transformer T51 and then another focusing on the pin 1 and 4 area.In regards to your question, maybe someone with more knowledge of transformers could answer.The UK mains voltage is 230Volts AC 50Hz, correct?My best approximation is the secondary voltage is 9VAC but how many Watts is the Transformer?I never liked halfwave power supplies as calculating the DC output voltage accurately is difficult as it depends on the load and in this case we don't really know what the load is. The load is made up of the following - It would appear that there is around 100mA of current through the Relay RY51 when it is energised - assuming the voltage on C52 doesn't change or changes very little. There would be minimal current flowing through D54 so it's safe to ignore that. IC51 Datasheet says it is good for up to 500mA so no help there. So more than 100mA but less than say 500mA???If you had a variable DC power supply up to 15voltsDC, it could help. Or we knew the voltage drop across R901 on Page 10 or the voltage across C52 page 25 in PWR ON.