Hi all, I need the schematic of a QUBE PA-140 amplifier. Can someone help me?? Thank you.
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Repairing a Roland SPA-120 amplifier, a solid-state early-mid 80's part of the Roland Rack. The PCB is Labled AP-124B. Was thinking lytics would resolve the nasty output on scope but all tested 100% for values, ESR, and leakage (very surprised!). Symptom is nasty wave form on both channels in Stereo mode, but clean in single channel mono (BTL) mode. The Output transistors test ok at room temp, but still could be faulty once heated up. Anyway, a schematic and some test point voltages would sure save some time. Thx!
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I'm trying to troubleshoot a JTC B-28 Cardmp3player amplifier which had a power supply failure. I've replaced the damaged str transistor with a 3wire power module and now it's powering up fine but it has very low and poor quality audio output.
A schematic of this 12vDC/220vAC Power amplifier will be of great help.11-25-2023, 09:10 PM -
Hello, I have an issue with the motherboard. Specifically, it doesn't power on, more precisely, the POST initialization doesn't occur.
Let me start from the beginning, the motherboard suddenly stopped working one day. There are no beep signals from the speaker, and the debug LEDs are not lighting up. After inspecting it under a microscope and using thermal imaging, I didn't find anything that could be damaged.
After that, I began voltage measurements, in which I noticed the absence of VDDQ, VDDP, VTT, and VPP lines. Later, I checked if there is an EN state on these lines,... -
Hey everyone,
I'm currently working on a mid-70s Sharp Electronic Digital Clock Radio, Model FY-70CH. I found the service manual online, printed it out, and have been studying it for a while. My main reasons for tackling this are: (1) I want to learn electronics and figured I'd start with something I had on hand, and (2) I want to fix its issues. Right now, the radio sounds awful, has about 5V DC at the speaker terminals, and the alarm time setting doesn't work. But I'm not asking how to fix these problems.
Instead, here's what's been bugging me so far:
The schematic... -
Ii wonder if anyone can help me. I have a Acer x163w monitor which is not powering up. The PSU main capacitor's one leg had completly come off - I replaced it but the PSU is still not outputting DC. I found the monitor in questions service manual here on manuals lib but the schematic in there is a completely different - the schematic shows no mosfet to drive the transformer while the one I have does use a mosfet - also the schematic shows only one optocoupler but mine has two.
The PSU board is labelled FM-20A02-AAA made by APD as per the image below. I am trying to find a schematic for this...