How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Rusty Your Own Question

Rusty
Rusty, Music Professional
Category: Electronic Musical Instruments
Satisfied Customers: 5538
Experience:  Sound Engineer, Electrical Issues, Tone Consulting
63817454
Type Your Electronic Musical Instruments Question Here...
Rusty is online now

Hi there I have got a Yamaha Stagepas 500 mixer in for repair

Customer Question

Hi there I have got a Yamaha Stagepas 500 mixer in for repair and ive got no power. any suggestions .cheers Andy
Submitted: 3 years ago.
Category: Electronic Musical Instruments
Expert:  Rusty replied 3 years ago.
Hello, my name is Rusty. Are there any lights on at all? How far have you gotten into the amplifier?
Customer: replied 3 years ago.
Hi rusty no there's no lights on it seems to missing on cn804 pin 1 +44 v(DC).
Expert:  Rusty replied 3 years ago.
I'm sorry, I'm having trouble locating the service manual, as well as having computer issues. If you know of a copy I can look at, I will be happy to assist you. For now, I'm going to open the question back up for other experts.
Customer: replied 3 years ago.


Hi rusty have you got an email address i can send the service manual to

Expert:  Rusty replied 3 years ago.
It will take me a little while to receive it, but send it to:

[email protected]

Tell them it's for Electronics Rusty the Tech, and they will send it to me. If you have a link to the manual, I can get that even quicker. Thanks for your patience.
Customer: replied 3 years ago.


no probs emailed across.cheers

Expert:  Rusty replied 3 years ago.
Thank you, I'll get back to you as soon as they forward the email.
Customer: replied 3 years ago.
Hi rusty just checking you got the schematic.andy
Expert:  Rusty replied 3 years ago.
I haven't gotten it from admin yet. Hang tight, I'll ask the moderators if they can speed up the process. As soon as one of them gets online I'll send the request. Sorry about that, it must be budget cuts combined with the weekend. Thanks for your patience.

If you have a link, or can upload it to an online site then send me the link, that would be the fastest way. If not, the moderators are very helpful, and we can transfer it as soon as they get online.
Expert:  Rusty replied 3 years ago.
Alright Andy, I got in touch with a moderator. Email it to [email protected], and tell her it's for Rusty in Electronics.
Customer: replied 3 years ago.
No worries.if u want to download it from http://www.eserviceinfo.com you'll find the Yamaha stagepass500 service manual there.its in 2 parts u just need to extract them both into a folder.im meantime when I'm back at home ill email it over.cheers Andy
Expert:  Rusty replied 3 years ago.
I saw them on eserviceinfo, but for some reason my laptop isn't allowing me to open the files, and when I get them decompressed, they are faulty. If you send it over, it will go quickly.
Expert:  Rusty replied 3 years ago.
Ok, test the fuse at the power inlet. Also test pin 3 on cn804 for -44v.

There is a thermistor and a power protection switch. Look at page 61 of the service manual, f,g-3,4. Test the resistance across the switch and thermistor.

Those amps are built for protection so that they won't blow. The switches can get stuck. That is where to start. Let me know if you find anything or if they test out.
Customer: replied 3 years ago.
Hi rusty there is voltage coming out of the bridge rectifier 340v ,pin 1 on cn804 isn't measuring +44 it's around 8 v and same for the - voltage
Expert:  Rusty replied 3 years ago.
Did you measure resistance across the switch and the thermistor like I suggested? I'm looking at PC123 and TH803. The switches are usually the thing that goes out when there is a total power loss.
Customer: replied 3 years ago.
Hi rusty yeah I replaced the opto isolators ,ic809 ,ic810 and ic807 also the thermistor is reading 80 ohms
Expert:  Rusty replied 3 years ago.
So testing PC123 you read no resistance?
Customer: replied 3 years ago.
Hi rusty I just replaced pc123 as I had quite few of them but still tested fine.had a resistance on the one set of pins
Customer: replied 3 years ago.
Hi rusty I just replaced pc123 as I had quite few of them but still tested fine.had a resistance on the one set of pins also replaced PWM control chip
Expert:  Rusty replied 3 years ago.
Ok, do you have power present on any of the circuits? This may help pinpoint the problem... Let me know if there is power anywhere, and where it stops. It's one of the darn protection switches. They are supposed to reset when the power is cut, unless there is a short.
Customer: replied 3 years ago.
Any suggestions where to start on the circuit and ill measure the voltage and let u know what I read.cheers
Expert:  Rusty replied 3 years ago.
Hi, I'm back at my desk for the day. I had some field work to do yesterday. If you pin each circuit board at the input from the power supply, just tell me which ones have power. If you find that only the amp circuit is dead, then we'll have a better idea of where to check. If there is nothing at all coming from the power supply, then we know that we have to find the open in the power supply. Once we have it narrowed down, it will take some of the guess work out of it, and we can look at details.
Customer: replied 3 years ago.
Hi rusty havnt had chance yet gonna get back on to the mixer later.one thing I did notice that when I measured the voltage on the PWM chip it was goin to 15 v then dropping cycling .could that indicate the fault is round the ic ?
Expert:  Rusty replied 3 years ago.
I think you might be on to something. Did the input voltage remain constant, or was the change in voltage due to a bad cap? Check the input and output voltages, see if it's constant. If it's the same on the input, work it back a little farther up the signal path.

What Customers are Saying:

 
 
 
  • My Expert answered my question promptly and he resolved the issue totally. This is a great service. I am so glad I found it I will definitely use the service again if needed. One Happy Customer
< Previous | Next >
  • My Expert answered my question promptly and he resolved the issue totally. This is a great service. I am so glad I found it I will definitely use the service again if needed. One Happy Customer
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
 
 
 

Meet The Experts:

 
 
 
  • jaimzness

    jaimzness

    Engineer

    Satisfied Customers:

    117
    DAW and MIDI techniques. Keyboard and synthesizer programming. Electronic repair.
< Last | Next >
  • http://ww2.justanswer.com/uploads/jaimzness/2010-5-5_173549_headshot-64px.jpg jaimzness's Avatar

    jaimzness

    Engineer

    Satisfied Customers:

    117
    DAW and MIDI techniques. Keyboard and synthesizer programming. Electronic repair.
  • http://ww2.justanswer.com/uploads/stereoaz/2010-09-26_161922_js640_IMG_0505.jpg stereoaz's Avatar

    stereoaz

    Technician

    Satisfied Customers:

    25
    20 years repairing electronic musical instruments,amplifiers,speakers.
  • http://ww2.justanswer.com/uploads/TY/TylerOrganist/2014-2-28_42014_DSC0959copy.64x64.jpg Tyler, M.M., CAGO's Avatar

    Tyler, M.M., CAGO

    Professional Musician

    Satisfied Customers:

    289
    20 years training & experience. Familiar with a variety of instruments.
  • http://ww2.justanswer.com/uploads/FH/fhpetrone/2011-12-29_20339_DSC000292.64x64.JPG Federico's Avatar

    Federico

    Musician

    Satisfied Customers:

    32
    Expert in electronic music.
  • http://ww2.justanswer.com/uploads/LI/littlerusty/2015-7-13_19399_eadhot.64x64.jpg Rusty's Avatar

    Rusty

    Music Professional

    Satisfied Customers:

    370
    Sound Engineer, Electrical Issues, Tone Consulting
  • http://ww2.justanswer.com/uploads/SE/SelectTronix/2013-12-28_22514_clrepair.64x64.jpg Carl L's Avatar

    Carl L

    Technician

    Satisfied Customers:

    63
    13+ Years of Computer and Electronics Experience.
  • http://ww2.justanswer.com/uploads/MO/momentouswater/2016-7-25_14535_podcast.64x64.jpg Thomas's Avatar

    Thomas

    Technician

    Satisfied Customers:

    12
    Ready to assist with any and all Electric Instruments