Sony CFS 88 "machine gun" problem wih power supply ?

Hello,

today I found a Sony CFS 88 L. It looked good but i had no cable or batts with me, and the owner said he couldn´t test it. I buyed it for some Euros and took it home.

But the only thing i can hear when it powers up is a sound similar to a "slow machine gun" that becomes faster.
I can switch between radio, tape etc but nothing happens.

Is this an error in the mains supply circuit ? or any other ideas what needs to be checked.

I´d like to know if it´s worth saving it, because no parts missing, only few scratches outside and I like the optic when speakers are open.


regards, Lukas

check power supply for voltage.

also , disconnect radio from original power source,

and supply with good power supply.

that way you will have more conclusions.

Kavinsky1983 said:

Hello,

today I found a Sony CFS 88 L. It looked good but i had no cable or batts with me, and the owner said he couldn´t test it. I buyed it for some Euros and took it home.

But the only thing i can hear when it powers up is a sound similar to a "slow machine gun" that becomes faster.
I can switch between radio, tape etc but nothing happens.

Is this an error in the mains supply circuit ? or any other ideas what needs to be checked.

I´d like to know if it´s worth saving it, because no parts missing, only few scratches outside and I like the optic when speakers are open.


regards, Lukas

Click to expand...

I had a CFS-88S , cool wide machine! First thing I would check is the power supply..if it is switchable between European and North American voltage, start by cleaning that switch.If not, see if it takes an adapter, like a 12 volt, and try it on that, and then try batteries. If it works on batteries, then the main is shot. You can also test the output of the transformer where it attaches to the board.
Try all of these hopefully 1 will work.. Is it worth it? Beauty is in the eye of he beholder , and this one to me was one of the coolest that I`ve seen, especially closed up looking like a cube!

I'll bet a cleaning and recapping would fix that machine up nicely.

Thanks for your answers,

I´m going to open it after the december 8th, until then i´ve got not enough time and my volt meter is gone, so i need to buy a new one.

When using batteries it´s the same noise like using line current.

I´ll keep you updated.....

Kavinsky1983 said:

Thanks for your answers,

I´m going to open it after the december 8th, until then i´ve got not enough time and my volt meter is gone, so i need to buy a new one.

When using batteries it´s the same noise like using line current.

I´ll keep you updated.....

Click to expand...

yeah ok friend.

maybe something in between PS and radio,

but maybe something on those boards.

good luck.

Sounds like your BBX does the same as my Dynasty on a power supply. My lights "machine gun" but really slow, about 1 blink per second, no noise either. Batteries work and ac cord work. Both good up to about 1/2 volume.

blu_fuz said:

Sounds like your BBX does the same as my Dynasty on a power supply. My lights "machine gun" but really slow, about 1 blink per second, no noise either. Batteries work and ac cord work. Both good up to about 1/2 volume.

Click to expand...

that is usually due to a bad connection on some of the SWITCHES

on the box.

mainly the POWER / SELECTOR one.

open it / clean it, ( or use some compressed air can to blow inside it, or some de ox )

because there is bad contact in there. ( be careful with it. ) or even bypass it and SHUNT directly.

be careful, dont ruin your box. test and do what you know only.

i mean higher resistance instead of DIRECT CURRENT,

which lowers the INPUT voltage.

should be that.

at least what you tell me about the volume only going half way it has thseo symptoms.

cheers

Hello,

today i finally found some time to open my sony.

I checked the voltage coming to the board, with batteries over 12 volts. So this is ok.

Next I cleaned the power switch. Good idea because now the "power led" is lightning and I hear a litte noise out of both speakers as usual.

But rest isn´t working, no radio no tape. But this was a step forward.

In this picture you can see a transister, it looks "cooked" to me. At it´s top is a melted black cap i can take of.

url=http://www.abload.de/image.php?img=dsc02755lhd6.jpg] [/url]

Oh yeah, that transistor looks bad. Just change it to take that problem out of the equation. Good luck.

Not really. That looks like a power transistor and the black plastic you see looks like shrink wrap sleeving to protect the back heatsink to keep it from shorting to ground. That transistor is likely to get HOT, which is normal since it's not being sinked and the shrink tubing could exhibit symptoms of heat.

Again, The actual transistor is that square chicklet looking thing below. The upper part is just a metal tab with a hole to attach to heatsink.

hello there. good to know theres improvment sir.

well i would in fact substitute that transistor.

seems a bit burned , but, in fact transistors usually crack when they are burned.

maybe it has deteriorated. it is possible.

anyway , you should keep on tracing the current, i mean the 12v that you measured coming out of the

power supply, then see where it enters the board, then, FOLLOW IT,

seeing where it goes.

AND, see carefully, ( this part may confuse you lots of wires and tracks ),

WHERE the DECK gets its power , and the RADIO. see if they FEED properly .

should be 12V but some parts operate on 6V. i would say 90% chance, it operates fully on 12V.


try to FOLLOW the current, see where it is broken, or deteriorates.

that will help you.

Godspeed.

I agree with super. That looks like a regulator transistor. They usually run hot anyway, especially without a heatsink. That black stuff is heatshrink to stop the back tab shorting to anything if it gets bent. And the yellow stuff looks like some kind of glue.
The symptom your describing is called "motorboating". Could be the power supply but could also be the amp section.

Its also questionable, if your DMM would be able measure the ripple, if its on the power supply.

The 2 main regulators are Q307 & Q310 check the voltages there with respect to the chassis.
Also check fusable resistor R356, should read 5.6ohms.