Hello--
I recently acquired a JVC 5003 from my parents place. It was missing the glass fuse holder cap, so after replacing the holder, I got to fire it up. Luckily no smoke came out, but the only thing it does is produce a moderately loud 60hz hum from all the speaker outputs. None of the other functions do anything, nor does flipping any of the tone controls.
There is a schematic on hifiengine.com (I can post here if need be) however it is missing the power supply portion.
I would be very grateful if someone could walk me through testing the various parts of the board and determining what the issue is!
Attached is the audio recording of the hum, and two pics of the power supply area.
I recently acquired a JVC 5003 from my parents place. It was missing the glass fuse holder cap, so after replacing the holder, I got to fire it up. Luckily no smoke came out, but the only thing it does is produce a moderately loud 60hz hum from all the speaker outputs. None of the other functions do anything, nor does flipping any of the tone controls.
There is a schematic on hifiengine.com (I can post here if need be) however it is missing the power supply portion.
I would be very grateful if someone could walk me through testing the various parts of the board and determining what the issue is!
Attached is the audio recording of the hum, and two pics of the power supply area.
Attachments
Start by changing those old electrolytic capacitors. Start with the PSU first. Put a 100W lamp in series with the amp for further testing to prevent further damage.
Should I just go ahead and recap the entire amp? I can't imagine any of the caps are any good after 50 years.
I've been in the business of "restoring" customer's "vintage" audio for decades.
Number one rule - get it restored before use (something ignored by 100 percent of the population)
I always hear: "But I just wanted to see if it worked/lights up" <---curiousity
In many cases, I now have had to replace even more components due to this curiosity... at the customer's expense.
Number one rule - get it restored before use (something ignored by 100 percent of the population)
I always hear: "But I just wanted to see if it worked/lights up" <---curiousity
In many cases, I now have had to replace even more components due to this curiosity... at the customer's expense.