loud buzz noise on my unisef

[weetabixears]

it plays tape and radio fine but if i knock or press button hard it has this loud feedback / buzzing noise it goes when i turn off and on again if i tap the case it hapens sometimes its random i put a tape in the tape A it happened aswell its as if there is somthing loose in side can anyone give me advise what it is how to fix or find out what it is , got box yesterday and it is my pride and joy just dont want it to get worse , as its random and only when the box gets moved or knocked cheers daz

 

[2steppa]

With the build quality of the Unisef/Crown SZ's it could be a host of reasons!

I would suspect either the record/play changeover switch (the long pcb mounted switch operated by the cassette buttons) if these are dirty, shorting or malfunctioning they can cause a loud squeal sound. Also could be a poor connection at the power switch, loose pcb multiway plugs, edge connectors (if any) and so on..... also, in many cases I have found the rec/play changeover switch to actually be ok but the problem has been the solder pads underneath the pcb, I had this probelm on one of my Pioneer boxes and re-worked all the relevant solder points to effect a repair.

Cleaning with switch cleaner would be the first thing to try........

 

[weetabixears]

hi thanks for reply what sort of switch cleaner do i need to get as im new to hobby so not clued up and when you say switch do you mean on /off switch also i dont think it is to do with tape deck as its done it when tape is not playing but will test again tomorrow also i had a look through tech section could be the transformer inside as its makes a deep bass type buzz not high pitched

 

[baddboybill]

It could be the capacitors in the power supply are going out. Capacitors usually only last 20 years or so hope this helps

 

[weetabixears]

thanks for reply badboybill are they changable cheers daz

 

[baddboybill]

thanks for reply badboybill are they changable cheers daz

Yes caps are replaceable you just have to get right onesAnd know how to desolder and resolder.

 

[2steppa]

i put a tape in the tape A it happened aswell its as if there is somthing loose in side

That's why I suspected the rec/play bar switch, they can also act up without the tape being used if the connections are bad.
Also the fact that when you 'tap' the box it makes that noise suggests some kind of connection issue.

The switch cleaner is purpose made for the job, you can get it from places like Maplin.
Don't be tempted to use aftershave or anything else as it will leave a residue that will cause further problems.

Edit: Sorry, yes I did mean the on/off switch - these can go bad on this type of box too, mine is a bit 'scratchy' when pressed.

 

[baddboybill]

i put a tape in the tape A it happened aswell its as if there is somthing loose in side

That's why I suspected the rec/play bar switch, they can also act up without the tape being used if the connections are bad.
Also the fact that when you 'tap' the box it makes that noise suggests some kind of connection issue.

The switch cleaner is purpose made for the job, you can get it from places like Maplin.
Don't be tempted to use aftershave or anything else as it will leave a residue that will cause further problems.

Edit: Sorry, yes I did mean the on/off switch - these can go bad on this type of box too, mine is a bit 'scratchy' when pressed.

as a 1st easy fix But I have had this problem before and it made the noise all the time only when playing the tape though

 

[monchito]

i have had boxes with a loud buzz which all i did was clean the record bar but that might not be what is wrong with yours ,,caps can also be a factor and a bad solder joint also a broken trace ,,but if you clean all your switches that way you know if that was the problem it the cheapest and easyest before delving in the box to look for problems......

 

[weetabixears]

thanks for replies i first fired it up next to my fridge whch i read cause interference and then moved it the next day to otherside of room and it was all cool i too think there is some thing loose as conection as for a day it was all cool then i flicked the switch from tape to radio and it happened again and thats the first time it done it that way so theres somthing loose cn anyone send a link for the stuff i need to spray please also the on off button has a crackle when pressed butim cluching at straws as i dont have the knowledge as you geezers as ive only few months got me boxes thank you all for replys and any forward replys atb daz

can anyone steer me in the direction of a manual systmatics for my boombox so i know what to sort thank you sorry about the wording but its friday and im sinking a few beers and having trouble seeing the buttons ha ha ha