- Joined
- May 14, 2014
- Messages
- 2,348
- Location
- Southwest Kootenays BC
- Tagline
- No such things as bad days, just bad moments
I agreed to try fixing a friends Akai AC-3800 music center. It consists of a 25wpc receiver, cassette deck and turntable. As those things go, this one isn't god awful. She got it from someone else and it did not work when she got it.
It does not power up. No lights, no functions, no audio.
Internal fuses are good, the power switch is good and wall power is present. I lifted an end of the rectifier diodes and DMM readings are good. I found a service manual online and proceeded to measure voltages on the transformer wires. This section of the schematic has voltages printed for the various wires which are identified by colour.
Both violet wires are supposed to have 26 volts and I measured 23 volts.
Both grey wires are supposed to have 28 volts and I measured 29 volts.
But the green, yellow and orange wires are far apart.
Green wire is supposet to have 11 volts and I measured 2.8 volts.
Yellow wire is supposed to have 8 volts and I measured 25.8 volts
Orange wire is supposed to have 0 volts and I measured 9.6 volts.
As mentioned earlier, no lights light up. The yellow wire looks to me like it feeds the lamp board. And if 25.8 volts is present where there should be 8 volts, would that not burn out the bulbs and explain why none of them light up?
I posted this question on AK and was told that the transformer voltages looked OK but I don't understand how that could be. My thought was that the transformer was history.
I did not post here first because I didn't want to ask questions about a lowly combo unit. There is some semblance of quality about it and the owner would like it to be in working condition. Unfortunately, there is no longer such service available in this or in the surrounding area. No trustworthy service anyway which is why she asked me.
I cautioned her that I like to tinker but am not a tech. I guess she felt I was better than nothing.
It does not power up. No lights, no functions, no audio.
Internal fuses are good, the power switch is good and wall power is present. I lifted an end of the rectifier diodes and DMM readings are good. I found a service manual online and proceeded to measure voltages on the transformer wires. This section of the schematic has voltages printed for the various wires which are identified by colour.
Both violet wires are supposed to have 26 volts and I measured 23 volts.
Both grey wires are supposed to have 28 volts and I measured 29 volts.
But the green, yellow and orange wires are far apart.
Green wire is supposet to have 11 volts and I measured 2.8 volts.
Yellow wire is supposed to have 8 volts and I measured 25.8 volts
Orange wire is supposed to have 0 volts and I measured 9.6 volts.
As mentioned earlier, no lights light up. The yellow wire looks to me like it feeds the lamp board. And if 25.8 volts is present where there should be 8 volts, would that not burn out the bulbs and explain why none of them light up?
I posted this question on AK and was told that the transformer voltages looked OK but I don't understand how that could be. My thought was that the transformer was history.
I did not post here first because I didn't want to ask questions about a lowly combo unit. There is some semblance of quality about it and the owner would like it to be in working condition. Unfortunately, there is no longer such service available in this or in the surrounding area. No trustworthy service anyway which is why she asked me.
I cautioned her that I like to tinker but am not a tech. I guess she felt I was better than nothing.
