Sanyo MCDZX220m cassette desk no sound

[carolmaille]

Hello
Please can anyone help and give me some ideas?
Sanyo MCDZX220m cassette desk no sound except a buzz/drone but the mechanism works. I tried to trace the route of the sound and see some kind of wave seems to be on the chip TC4052B - a multiplexer - when cassette is selected - this is on the board with the output to the speaker. The speaker has a low resistance so I don't suppose it is faulty.
There is a TA8227 I dont know what this does and cant see a data sheet about it. Thank you
The LCD ? display for the CD player is blank and the CD controls dont work and no radio output either
It is for an elderly lady who wants to listen to her cassettes.

 

[Doug]

I dont know the unit.
If it has a record playback switch I would put it in record mode with a record able tape and push the record button back and forth..the contacts usually need clean.
After just putting it in record about 10 times Recheck the unit

 

[rjenkinsgb]

There is a manual here for the 200 series, if that helps?

SANYO MCD-ZX200F SERVICE MANUAL Pdf Download

View and Download Sanyo MCD-ZX200F service manual online. CD Portable Radio Cassette Recorder. MCD-ZX200F cassette player pdf manual download. Also for: Mcd-zx200xe.

www.manualslib.com

I was also going to suggest the same a Doug - it's a common problem with old audio gear, just tarnished switches.

 

[carolmaille]

Hello there's no audio record on.this device - there's a CD Radio and cassette deck - no display or control on.the CD player-
I can hear something à blip.when I switch from.CD/Cassette to radio but no radio sound
The casette mechanism.works but only hum output
So I guess I can at first clean the switches with isopropyl alcohol.- and buy some cleaning spray
Also buy some batteries as it's easier/safer to work on. Thank you

 

[Nigel Goodwin]

Hello there's no audio record on.this device - there's a CD Radio and cassette deck -

Of course there is, it's clearly called a 'cassette RECORDER', and the service manual (freely available to download) clearly shows the record/play switch, and the bias oscillator etc.

 

[carolmaille]

So there IS ! Id completely forgotten that with cassette recorders you 'usually' ? could record and this is no exception. Oh good I can try that - that would be a good fix, not having to desolder things. Thanks

 

[Nigel Goodwin]

So there IS ! Id completely forgotten that with cassette recorders you 'usually' ? could record and this is no exception. Oh good I can try that - that would be a good fix, not having to desolder things. Thanks

The record/play switches usually switch the heads from record to play, so you're talking a high level of signal (record) and a very small level of signal (playback). Even a slight resistance in the record play switch will make it oscillate - it was a common fault back when I was repairing such things.

A small squirt of WD40 or similar in the switch, and working it back and forwards a few times, usually cures it. We used WD40 for decades at work, as it worked better than any 'switch cleaner' products.

 

[ChrisP58]

On a side note, I would suggest copying the contents of the cassette tapes to another storage medium.

 

[carolmaille]

Thanks I'll get back to this very soon. The switch was stuck and WD 40 has helped and I have also just got together my tools. I think.theres maybe still.a problem but I'll let you know for sûre ! I can't get in.xith it as quickly as I'd like right now but I will

 

[carolmaille]

Well there is power getting to the audio board so maybe it is a capacitor on the amplifier circuit as there is no sound - and I have not checked the selection switch between radio/CD/Cassette player

 

[carolmaille]

Surely this is a burnt resistor ? It is only 2.2 ohms and is next to the CD/Radio/Cassette selection switch. R333 . On my circuit diagram there is a triangle with an exclamation mark in it near this presumably as something that can blow. It is also by a couple of capacitors and an IC KA7808

 

[Nigel Goodwin]

What voltage readings do you get each side of it?, R333 feeds 12V into an 8V regulator IC.

Obviously it's over heated and needs replacing, but measuring the voltages might show if replacing it will just burn up again.

 

[carolmaille]

Your questions resistor across it I think it is 16V on one side and 2.8v on the other side. (so 16-2.8 is 13.2v) which I measured on the voltage regulator inputs I think. So I think there is 16V coming in where there ought to be 12V ? I think I found the reference earth. There may be nothing coming out of the voltage regulator into the variable resistor volume but I guess the first thing is to get the right voltage going into it ? Photo: So on the left, if this is the volt reg middle pin going to the volume control the track is damaged and maybe it has been previously repaired. The burnt resistor is just below bottom left photo. Maybe that 2.2 ohm resistor goes to a capacitor also the C333. Thank you very very much, I have to stop now for a while.

 

[Nigel Goodwin]

13.3V it is too high - maybe why it overheated ? It seems to be 2.8v going into the variable resistor (volume) but I am not sure which pins I am across. I think the voltage going in to the board could be high if I check that coming out of the power circuit ?

Measure BOTH sides of the resistor (from chassis), the input should be (roughly) 12V - 13.3V would be fine, but what's coming out of it. There's no point measuring voltages on the volume control.

 

[carolmaille]

I will check it again later when I can, without making any hypotheses just measuring it. Now I know I can get some help !

 

[carolmaille]

The resistor R333 has 16V on one side (not 12V) and 2.2-2.8V on the other side (so connected to the voltage regulator is only about 2.2 V). I thought voltage either side of R333 should be the same, so it implies some current flow -
And perhaps the capacitor that is in parallel with the resistor and across the regulator input has blown (C333). It's not holding the voltage. The output voltage on the regulator is the same as the input which is not high enough to give an 8V output ? There is no 8V output ? If the power supply output is 16V because it does not have the usual loading - ? (Although one capacitor C1114 4700 uF does look as if it is bulging a bit. ) Thanks for any help.

 

[carolmaille]

Hello so I thought I would just put a resistor across where the 2.2 ohm blown up one is and I had a 12 ohm one (the nearest in size), So I soldered it on, the radio it just fuzz, but there is now 8V coming out of the voltage regulator. AND the cassette is working even the volume control ! BUT I dont know if it will last or if it will blow up again but maybe I should just put it together and leave it for a while. But the fact it was a 2.2 ohm and it blew if I put in a larger one and it does not blow up when it ought to something else could get damaged? Still I am so glad the cassette is playing (for now).

 

[carolmaille]

Well all parts are playing now - although there is a very slight hum I think on the cassette playback. But maybe I will leave it running for a while then take a look at the resistor again, as I say it is 20 ohm not 2.2 ohm as the postage for ordering the right component was more than it was worth to get it.

 

[Nigel Goodwin]

Well all parts are playing now - although there is a very slight hum I think on the cassette playback. But maybe I will leave it running for a while then take a look at the resistor again, as I say it is 20 ohm not 2.2 ohm as the postage for ordering the right component was more than it was worth to get it.

The service manual clearly shows it as 2.2 ohms - as for the burn up, either there's been a temporary short on the output side, or it's a cheap carbon resistor that has drifted higher and higher, causing excessive dissipation, making it worse.

If it's working OK with 12 ohm, then there's no short on the output, get a 2.2 ohm when you have the chance. To be fair, the value isn't critical, but 12 ohm sounds rather too high, and is likely to run too hot.

 

[carolmaille]

Thank you so much I will get and replace it with the 2.2 ohm when I can, I am not sure about this 16V input to the Voltage regulator when it ought to be 12V but I can see if it works and I guess not to leave on and go out. Run too hot? So that is overloading it - too much current going through it