in good shape, isolde - part 16

It must be true that the more you have, the more maintenance there is. A few weeks ago, my neighbor came by when I was working on something in Isolde. I showed them the recently updated audio system that I have been so happy with. I put in a CD by Angelique Kidjo that I really like for them to audition. They were impressed, and asked to borrow the CD.

I proceed to eject it to put it into the case to lend to them. The CD transport of the Alpine CDE-143BT whined but the CD did no eject. You could hear something is wrong with the mechanism, and after a few more seconds, the head unit displayed an error message. I tried a number of things including removing the face plate, cycle power, and nothing worked.

I know all too well the chance of I am being able to diagnose and repair it is next to nil because of the complex nature of the transport, as well as the miniaturization of these modern audio head units. I have been considering purchasing a replacement since I have 3 of these similar units that I am very happy with. Bad luck, I thought but such is the way these consumer electronics are. They are essentially disposable products.

Today, not having my hope high, I proceeded to dismantle it since I have nothing to lose, and I have to recover the CD anyway. The dismantling was more straight forward than I expect. All the fasteners are very easy to spot as which do what. By taking the unit apart, one can really appreciate the excellence artistry of mobile electronics.

there is just one PCB; the level of optimization for extremely efficient manufacturing sure is impressive

all 4 channels of audio power amplifiers are in two integrated circuit located at the back and on the side attaching to aluminum heat-sinks; note the fan mount provision which might be used for higher end models

One thing that stands out is the absence of IF transformers for the AM and FM radio. There is only one by the antenna input. The Bluetooth function appears to occupy the the small rectangular area at the left front. Now I regret that I didn't take many closeup photos of the mainboard.

just one flexible ribbon cable connecting to the CD transport; there is decade of stepwise refinements that went into it making it possible to build such excellent product at this low price point

at first glance I thought the wormgear is stripped but it turned out just the color of the grease gave it the appearance

I proceeded to remove the CD transport from the main chassis

the CD transport is removed and you can see the Angelique Kidjo CD inside

one of the two aluminium heat-sinks for the audio power amplifier IC

reattaching the ribbon cable for the CD transport

one of the most impressive aspects of the design and construction is how perfect the sheet metal forming that affords the plastic piece parts to snap in and lock securely; hence very few screws are required in the entire assembly of the major subassemblies

I managed to free the CD after reassembling the unit; it is now all back together

Today I spent a few moment doing a bit of study of the design based on these few photos that I took. I now wish I took some closeup photos of the main board, and spent some time tracing some circuits.

the mainboard is a 2-layer FR4 PCB - to keep the cost low; this is only possible that all the VLSI components are designed for it

I did my best to infer the functional areas on the main PCB, without the benefit of studying it more closely while I had the chance. I rely on this single photo to make these inferences. I am a bit unsure about the power IC module on the left that has a heatsink which I infer as one of the two audio power amplifier IC. My inclination is to think the one at the back supports all 4 channels. However, I cannot think of what left of this other power IC. I will definitely get to the bottom of it should I need to open the unit again in the future.