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Camarada78
Member
Last Activity: 10-15-2024, 01:09 PM
Joined: 01-27-2021
Location: Rio de Janeiro
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  • Camarada78
    started a topic Carvin PA620 shutting down
    in Troubleshooting Audio Equipment

    Carvin PA620 shutting down

    I have a Carvin PA620 powered mixer with a weird problem: channel one shuts down the entire speaker output when plugged in. Its not a short because it still outputs sound through the line outs.

    1. voltages are somewhat correct (-42/+42, -26, -17/+17, when it should be +-43, -24, +-18).
    2. Channel 2 if plugged works normally, no issues, any volume.
    3. Channel 1 if plugged very low volume, works normally. if goes a little louder, it shuts down everything (both speaker channels)
    4. line out works normally in any situation, even after shutting down the speakers.
    ...
    See more | Go to post
  • Camarada78
    started a topic Source for SKT-433-130
    in Troubleshooting Audio Equipment

    Source for SKT-433-130

    Hello, i'm looking for an original SANYO SKT-433-130 to repair a subwoofer. All "brand new" i've found on ebay (and similar websites) are fake and do not work.

    I know sony used to use them on many late 90s and 2000s systems and active subwoofers, but they are too many to purchase on a guess.

    Is there a good reliable way to get them? it doesnt need to be brand new, but working.

    thanks, have a good day
    See more | Go to post
  • Camarada78
    started a topic Boss delay DD-3 (square ship taiwan) problem
    in Troubleshooting Audio Equipment

    Boss delay DD-3 (square ship taiwan) problem

    I have a Boss DD-3 (square chip taiwan version) in my bench with a very weird problem. I found no similar problem online, nor a solution for it. It is driving me nuts.

    It passes sound on bypass no problem but as i turn it on it has a constant a noise (that can be clearly shaped by Delay Time, Volume and Mode, but very subtle by Feedback).

    - sounds ok on bypass
    - noise is there even without input connected.
    - all electrolitic caps were changed (!)
    - all tantalum caps were checked, ok.
    - most ceramics were cheked. too many to keep track....
    See more | Go to post
  • Camarada78
    started a topic Ampeg PF-350 low volume and other issues
    in Troubleshooting Audio Equipment

    Ampeg PF-350 low volume and other issues

    Hello,

    i have an Ampeg Portaflex PF-350 on my bench for repair. It works but with very low volume, 1/3 of what you'd expect. Much lower than any 100-150w amp i have around.

    It has SMPS and a class D amplification. Looking inside i found two issues:


    - found R94 and R98 burned near the Q10 and Q13.
    - found that i'm gettin +80v/-80v instead of the +55v/-55v shown on schematics.

    The overvoltage is probably the reason why the R94/R98 keep burning. But i cant find what is causing it. the SMPS side seems ok. I'm getting 176v...
    See more | Go to post
  • Camarada78
    replied to Samson Auro X12D no sound
    in Troubleshooting Audio Equipment
    Re: Samson Auro X12D no sound

    UPDATE:

    After exhausting hours today, i fixed both of them: similar problemas

    - xd15 had a broke pin on the L4 coil, on the SMPS board.
    - Xd12 had two broken pins on one of the secondary caps, near this L4 coil.

    Weird similarity causing similar problem: powers on, plays for while, then goes mute into protection mode.

    ****
    Remember to always start with the simple stuff before getting into the complexities of SMD circuits.
    See more | Go to post

    Leave a comment:

  • Camarada78
    replied to Samson Auro X12D no sound
    in Troubleshooting Audio Equipment
    Re: Samson Auro X12D no sound

    Bump.

    Mine still faulty and now a friend has an Auro X15D with the same problem. Damn!
    See more | Go to post

    Leave a comment:

  • Camarada78
    started a topic Gigabyte B450 Aorus M capacitor value needed
    in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

    Gigabyte B450 Aorus M capacitor value needed

    Hello,

    I'm having troubles with my motherboard due to humitidity (i live near the beach) and after cleaning i noticed that there is a capacitor missing to corrosion and i want to replace it.

    the motherboard gets to post, but no display. I think that might be the cause.

    I couldnt find the schematic online, so I will post a photo in hopes someone with the same board could measure for me.

    *Two attachments with the image of the board*

    [ATTACH]261585[/ATTACH]

    [ATTACH]261586[/ATTACH]Hello,

    I'm...
    See more | Go to post
  • Camarada78
    started a topic Samson Auro X12D no sound
    in Troubleshooting Audio Equipment

    Samson Auro X12D no sound

    Hello,

    I have in my bench a Samson Auro X12D for repair. It turns on, the indicator shows audio coming in but after a few minutes playing the "fault" light turns on and no audio comes out.

    It is a class D amp using a TDA8954. The power supply is fine. i think the problem is something on the heat detection or on the mute function of the TDA, but it seems ok so far.

    I could not find the schematics and the circuit is not the same as Samson Auro d412, it has some similarites but not the same. different design on the amp section.

    ...
    See more | Go to post
  • Camarada78
    replied to MXR Carbon Copy High Pitched Noise
    in Troubleshooting Audio Equipment
    Re: MXR Carbon Copy High Pitched Noise

    I tried new batteries, three different power supplies (two linear, one smps), all had the same issue.
    See more | Go to post

    Leave a comment:

  • Camarada78
    replied to MXR Carbon Copy High Pitched Noise
    in Troubleshooting Audio Equipment
    Re: MXR Carbon Copy High Pitched Noise

    [ATTACH]238523[/ATTACH]

    Above a .rar containing a .mp4 video of the problem (high pitched noise).Re: MXR Carbon Copy High Pitched Noise

    [ATTACH]238523[/ATTACH]

    Above a .rar containing a .mp4 video of the problem (high pitched noise)....
    See more | Go to post

    Leave a comment:

  • Camarada78
    replied to MXR Carbon Copy High Pitched Noise
    in Troubleshooting Audio Equipment
    Re: MXR Carbon Copy High Pitched Noise

    [attach]238521[/attach]

    [attach]238522[/attach]Re: MXR Carbon Copy High Pitched Noise

    [attach]238521[/attach]

    [attach]238522[/attach]...
    See more | Go to post

    Leave a comment:

  • Camarada78
    replied to MXR Carbon Copy High Pitched Noise
    in Troubleshooting Audio Equipment
    Re: MXR Carbon Copy High Pitched Noise

    Yes, but without the schematic it is rather difficult to find. much guesswork.

    the schematic that floats around the web is for the ancient version of the Analog delay. not the carbon copy.
    See more | Go to post

    Leave a comment:

  • Camarada78
    started a topic MXR Carbon Copy High Pitched Noise
    in Troubleshooting Audio Equipment

    MXR Carbon Copy High Pitched Noise

    Hello,

    I have a MXR Guitar Pedal here that turns on, passes audio but does not add the effect. It has a high pitched squeal that varies tone depending on delay speed.

    Its a analog delay pedal using four BBD (BL3208A), one compander (SA571D), one clock (cd4047), one TL082 and one 33178.

    This pedal is prone to some issues (ESD), but i replaced the common faulty transistors and the problem remained. In fact, the original ones were still good (tested on component tester).

    Anyone familiar with this pedal to give me some light?
    ...
    See more | Go to post
  • Camarada78
    started a topic Boss DD-3 Repair (low volume)
    in Troubleshooting Audio Equipment

    Boss DD-3 Repair (low volume)

    I have in my bench a first generation Boss DD3 delay pedal from the 80s or early 90s.

    it was dead. I managed to get it to power on again but the fx volume is too low.

    it can be heard when i play the guitar but its suttle, a faint delay on the background, even with everything on max setting.

    First i thought of a bad coupling cap, but i dont know, checked a few of them (there are many on the audio path) and so far nothing.

    Am I missing something stupid?

    have a goood day
    See more | Go to post
  • Camarada78
    started a topic Crate PowerBlock 150 very low volume
    in Troubleshooting Audio Equipment

    Crate PowerBlock 150 very low volume

    Hello,

    I have a Crate Powerblock cpb150 on bench right now.

    It has very low volume, although everything appears to be working fine.

    The powersupply (a common issue on this unit) is giving me all the juice needed but i still have low volume.

    It uses a lot of 072 as preamps and a tda8920th as the class d poweramp.

    The class D is receiving the +/- 25 volts as it should.

    The volume is low either on 8 ohms, or 4 ohms stereo and on the heaphone amp as well.

    I think its a preamp issue, but i dont know. i'm...
    See more | Go to post
  • Camarada78
    replied to Repairing Alesis M1 Active mk2 Monitor Speakers
    in Troubleshooting Audio Equipment
    Re: Repairing Alesis M1 Active mk2 Monitor Speakers



    I'm getting -178/+178 volts that should be normal.

    I replaced the caps with another c8 105º low ESR one and still no oscilating voltage between pin 5 and 7. I get constant 0.153 volts.

    Could this be a faulty q1, q3 or q4? In cirtuit they dont appear faulty (no shorts whatsoever).

    jesus i should've bought the main PS board since the begining. this circuit was blackened by the burnt cap....
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  • Camarada78
    replied to Repairing Alesis M1 Active mk2 Monitor Speakers
    in Troubleshooting Audio Equipment
    Re: Repairing Alesis M1 Active mk2 Monitor Speakers



    After 4 weeks working, it stopped again.

    Huge bulge in one of the Elna main caps (390uF). replaced it, nothing.
    Everything seems normal, took out of the board and measured

    I'm getting normal -170/+170

    i´m getting no DC oscilating between pin 7 and pin 5. In fact i get a 0.2V constant difference between them. I suspect that c8 is bad again....
    See more | Go to post

    Leave a comment:

  • Camarada78
    replied to best cheap/free scores 1.1
    in General Computer & Tech Discussion
    Re: best cheap/free scores 1.1

    I got a 1954 RCA 44BX ribbon microphone in working condition for around 500USD. Repaired the grid, new cloth and cable. Resold for 3000USD a few months later.
    See more | Go to post

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  • Camarada78
    replied to Repairing Alesis M1 Active mk2 Monitor Speakers
    in Troubleshooting Audio Equipment
    Re: Repairing Alesis M1 Active mk2 Monitor Speakers



    I fixed mine, Khron.

    Thanks a lot for the help.

    In the end the problem (besides all the stuff that burned and was replaced) it was a short on C35 due to overheating and the holes being too close to each other). tha prevented the oscilation....
    See more | Go to post

    Leave a comment:

  • Camarada78
    replied to Repairing Alesis M1 Active mk2 Monitor Speakers
    in Troubleshooting Audio Equipment
    Re: Repairing Alesis M1 Active mk2 Monitor Speakers



    That was the only one i had already. The other i have is a chinese Topmay-40+105º 330uF 50v. These topmay i have showed 0.00ohms on the ESR (component tester).

    For better ones i have to order online. No store nearby has them.

    Thanks for your patience khron...
    See more | Go to post
    Last edited by Camarada78; 02-04-2021, 05:40 PM.

    Leave a comment:

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