Sony CFD-S01 ghetto blaster modifications

[lti]

I would like to modify the audio circuit of this piece of crap. In its current state, there is very little bass with the bass boost disabled and too much bass when the "Mega Bass" feature is enabled. It seems to be controlled using an IC, so it might not be possible to improve the circuit design.

I also want to improve FM radio reception. The signal on every decent station except one is very weak. I can tolerate the sound through the built-in speakers, but when using headphones there is so much static that you can't hear anything. Strangely, plugging in headphones causes the signal to instantly weaken to the point that the stereo indicator turns off. Unplugging the headphones causes the signal to improve and the stereo indicator comes back on.

Finally, the previous/next track buttons (also used to switch between radio presets) are broken. They have to be pressed in the correct location or nothing happens. The button caps have broken loose from the front panel.

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

I don't think I can fix the button. One of the tabs that attaches the button cap to the case has completely broken off.

I also discovered that I can get slightly better sound by replacing the 1uF coupling caps on the output of the volume control IC. The datasheet for the chip (PT2257-S) recommends 10uF coupling caps. I found that 22uF caps would work even better, but I only have one of those. I don't want to use 47uF caps since that might put too much stress on the volume control IC and I don't want to fry it. The caps on the input don't seem to be as critical, even though they are 1uF as well. I will use 10uF caps on the output and 4.7uF caps on the input (if the leads are long enough - the 4.7uF caps are used).

This thing runs just as well without an antenna. It doesn't have any more trouble picking up radio stations than it did with the antenna connected.

There are also a ton of bad solder joints. I could solder surface mounted components better than Sony could, and I have a crappy "50W" soldering iron that cost $20 and may need a new tip.

Finally, someone signed the main board and the front panel board.

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

I replaced those coupling caps, but there still isn't much bass.

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

There was another problem: the sound from the radio was distorted. I discovered that the coupling caps between the tuner and input selector IC had negative voltage across them! The voltage was positive when the boombox was first turned on, but it became negative after about half a second. I replaced these with nonpolarized caps and the sound improved.

Now I will play a CD on this boombox and a properly working CD player to compare the sound quality. The lack of bass might be my crappy headphones.

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

There is almost as much bass as a decent CD player. I may upgrade the coupling caps between the CD player and input selector, but I can't find the ripple current specs on the old FOAI CD110 1uF 50V caps. The datasheet on the Foai website does not load. I have two 4.7uF caps left, but I don't know what brand they are.

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

It sure was nice talking to myself...

Here are the details if anybody wants to do this:
The capacitance of C115 and C215 need to be increased to a value between 10uF and 22uF. C163 and C263 need to be replaced with nonpolarized caps. I improved FM reception by resoldering JW231 and JW232. These are both soldered together and the FM antenna touches these jumpers to make the connection. Three of the four solder joints were cracked and the fourth must have been bad as well. None of the other caps need to be replaced, but I replaced C113 and C213 with 4.7uF caps as well. You can upgrade C162 and C262 as well (the CD player coupling caps), but it won't affect the sound very much.

I didn't have any through hole nonpolarized caps with enough capacitance, so I used surface mounted caps and soldered them on the back of the board. The soldering looks bad on the bottom cap in the first image because both solder pads on the board were damaged. It was easy to lift pads on this board.

[momaka]

Re: Sony CFD-S01 ghetto blaster modifications

It sure was nice talking to myself...

No you're not. Just because no one is replying doesn't mean no one is reading your thread - this thread has 90 views so far .

I'm guessing people aren't replying since no one has anything to add and most people probably don't consider a boombox like this to have enough value to justify in fixing/modifying it.

I too have an old Sony boombox that I got for free many years ago. Problem with mine was bad power supply (linear transformer, open primary). The boombox wasn't really worth my time at all, but I ended up fixing it anyways just by adding a plug to it and connecting it to an external PSU. Works pretty good and has decent bass too. I was actually thinking about modifying it to accept computer input so I can use it as computer speakers.

[Longbow]

Re: Sony CFD-S01 ghetto blaster modifications

the sound from the radio was distorted. I discovered that the coupling caps between the tuner and input selector IC had negative voltage across them! The voltage was positive when the boombox was first turned on, but it became negative after about half a second. I replaced these with nonpolarized caps and the sound improved

Well, I believe you that the sound improved, but I also believe you have missed a possible circuit fault. If you found a polarized cap operating with reversed d.c. voltage, you have a big clue that something nearby is faulty. I'll bet that the waveforms around that capacitor will confirm something is operating at the wrong d.c. level and clipping your audio.

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

That might be a problem, but the tuner section is made up of tiny surface mounted parts. It looked like the negative side of those caps went directly into an IC in the tuner section (under the silver metal shield). The positive side was also connected directly to the input selector.

It might not have been worth messing with, but I wanted a working FM radio that I could connect headphones to. It wasn't very cheap when it was new and is only a couple years old. The sound became distorted after a few weeks and kept getting worse until I replaced those caps. There is now no distortion on stations with strong signals. It happened so quickly that any components that failed and caused the reversed voltage would have been defective from the factory.

[stretch0069]

Re: Sony CFD-S01 ghetto blaster modifications

No you're not. Just because no one is replying doesn't mean no one is reading your thread - this thread has 90 views so far .

I'm guessing people aren't replying since no one has anything to add and most people probably don't consider a boombox like this to have enough value to justify in fixing/modifying it.

i have to agree.......

i like it when people just like to take something....anything....and make it better/different. Nothing wrong with that.

its a nice change in our throw-away world. keep on it!!

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

There haven't been very many times when someone on this forum didn't want me to throw away the device I was trying to repair. I remember an amp from a set of computer speakers, a power supply, and an entire computer.

I didn't even post about the CRT TV I repaired by replacing a single cap. That thread would have been three pages of posts asking, "Why didn't you just throw it away and buy a new TV? They are only $150 new." The cap that was bad was a 100uF 35V. Those don't cost $150, and the old CRT has a better picture than any LCD TV within the $150 price range.

[Th3_uN1Qu3]

Re: Sony CFD-S01 ghetto blaster modifications

There haven't been very many times when someone on this forum didn't want me to throw away the device I was trying to repair. I remember an amp from a set of computer speakers, a power supply, and an entire computer.

I never said anything about the power supply. But the computer speakers and the Compaq computer were more trouble than it's worth. I mean, you can go to your local radio shack and with $10 worth of parts and a couple days to spare you can build a better amp yourself... When you'll start doing this as a job, not only saving money for yourself but also earning money in the process, you'll learn that some devices aren't worth the time they would take to fix.

I gave away a computer of the same vintage as your Compaq for FREE. Just that mine was a Fujitsu and it was working perfectly. After a few years of being used as a router i replaced it with something slightly better because the slow CPU was bottlenecking my bandwidth.

Well, the guy who took it (who i knew from before, he did seem a little retarded, but i didn't know it was that bad), didn't like that the whole computer was full of dust and tobacco residue (it sat in the living room its whole router lifetime, and my mom smokes there). So he decided to clean it. He managed to mess up the proprietary PSU in the process... i'd rather kept the computer if i knew that would happen.

I didn't even post about the CRT TV I repaired by replacing a single cap. That thread would have been three pages of posts asking, "Why didn't you just throw it away and buy a new TV?

You are wrong here.

[lti]

Re: Sony CFD-S01 ghetto blaster modifications

I never said anything about the power supply. But the computer speakers and the Compaq computer were more trouble than it's worth. I mean, you can go to your local radio shack and with $10 worth of parts and a couple days to spare you can build a better amp yourself... When you'll start doing this as a job, not only saving money for yourself but also earning money in the process, you'll learn that some devices aren't worth the time they would take to fix.

You never said anything about a power supply. The power supply was used in a Dell computer that only had cutouts for the power plug and fan on the back of the case. I could have recapped it, but people kept arguing over which caps would work best as replacements and I was finally told that it would be best to replace it and modify the power supply cutout to make the new one fit. I don't know if the person that told me to replace it wanted me to recap the old one and keep it as a spare or just throw it away.

Radio Shack doesn't sell many parts, and the parts they do sell are expensive. The seven caps that needed replaced in the old amp cost $10. They only sell LM386 amplifier chips, and their cheapest transistors cost $1.49 each.

Yes, the Compaq sucks (I haven't seen a Compaq that worked properly), but it is still my only desktop computer and was only needed for old software.

Why are you always arguing with me?

[Th3_uN1Qu3]

Re: Sony CFD-S01 ghetto blaster modifications

[QUOTE=lti;175554]You never said anything about a power supply. The power supply was used in a Dell computer that only had cutouts for the power plug and fan on the back of the case. I could have recapped it, but people kept arguing over which caps would work best as replacements and I was finally told that it would be best to replace it and modify the power supply cutout to make the new one fit. I don't know if the person that told me to replace it wanted me to recap the old one and keep it as a spare or just throw it away.

Radio Shack doesn't sell many parts, and the parts they do sell are expensive. The seven caps that needed replaced in the old amp cost $10. They only sell LM386 amplifier chips, and their cheapest transistors cost $1.49 each.

I don't know the shack in your area was THAT bad. You could order online if that's the case. In my country there even aren't any Radio Shack stores, the brand did not carry till here... but in the stores that are here, you CAN find half-decent stuff at a half-decent price. You still have to order exotic parts, but for the basics they have you covered.

(I haven't seen a Compaq that worked properly)

I have one that i got for free and worked fine. Has been sitting in my closet for the past few years tho.

Why are you always arguing with me?

I'm not.

[momaka]

Re: Sony CFD-S01 ghetto blaster modifications

I don't know the shack in your area was THAT bad.

I think Radio Shack is expensive everywhere (here too, at least). I spent quite a bit of money on parts (particularly LEDs) at Radio Shack when I was a kid. The white and blue LEDs were the biggest killers - $3.50 for a pack of two! I didn't eat lunch for like half a year in high school - and people wonder why I'm so thin . (I have a friend who did a whole year of no lunch so that he could buy a Radeon 9800 Pro ).

[Th3_uN1Qu3]

Re: Sony CFD-S01 ghetto blaster modifications

White and blue LEDs are expensive here too. But i'll order a 100pack from dealextreme for $12. That's funny about your friend - i have a Radeon 9800 Pro handling the display duties of the dual-PIII i am typing on right now... It's soon due to be replaced by a HD4670 (likely the last, and best available AGP card), but yeah, i paid someone top dollar for this particular model back in the day. It's a model with universal AGP (2 notches) - i needed that for it to work with my old BX board which only had AGP 2x.