aiwa 660 volume problem

[blah blah]

any help appreciated greatly!!
sounds great until i hit about 5 on the volume then both woofers start having seizures, they pop and vibrate almost like the magnets are sucking them back. turn the volume down and they stop. checked through headphones no problem so it seems speaker oriented in some way. :'-(

possibly a grounding problem?

just fixed the deck and this is driving me nuts. the dsl switch seems to work fine when i turn on and off, but the speakers do it whether on or off if you bring the volume up. does it with tape radio and inline...

any ideas? thanks

 

[monchito]

do you use that box alot?? i remember mine going crazy so i sprayed deoxit on the controls and really it was a long time i did not use the radio

 

[blah blah]

monchito- i deox'd the pots like crazy...sounds awesome, just when the volume is above 5 it goes nuts....i haven't used for a while for sure though...seems like a ground but would that happen at only louder volumes? seems like a bad ground would make it suck all the time.

 

[monchito]

well concidering that all of our boxes are ageing more and more a lot can be atribute to old dried up caps and remember in headphone you can only go so much but with the speakers its a different story ,, you could probably try an external speaker and see how it sounds..

 

[Eric]

Could be power supply or audio amp...just a guess. Does it have the same problem when running on batteries? If so, then I would think there is somthing going on with the main audio amp circuits. Are the speakers in good shape? no rotting edges........bad speakers will play ok at low volume but sound tottal crap at higher volume.

 

[MasterBlaster84]

I agree with Eric and Monchito, this could be an amp or power supply issue likely due to old caps. Try running it on fresh batteries or a strong external source and see if the problem persists, my guess is your power supply is weak but that's just a guess.

 

[blah blah]

thanks guys will check the suggested.. appreciate the input.

 

[blah blah]

well i tried the external speakers, cuts out at higher volumes as well. i guess speakers are ok then... I actually have a new amp chip for this box, but maybe it is power supply issue. whats the best way check that? i never have had to... so somewhat at a loss to test. any quick suggestions? thanks again guys

 

[blah blah]

i am gonna smash this very attractive (yet useless) thing. :annoyed: a rimmer moment is it around here?

after i tried to run it on batteries ( which it wouldn't do, just made the speakers pop and snap) i tried the regular power supply again and now the F**king thing won't play at all, the speakers just pop and snap.

i am beginning to really hate aiwa's. too touchy, to complicated and the decks are a PIA. i have spent more time on this box than any other box i have ever had and it refuses to behave. like a frickin albatross, should be the cs666 .

i had to vent because it forced me to drop the hammer to type....

 

[Superduper]

The actual problem might be something small but without the proper test equipment (simple Ohmmeter) and expertise or experience, a little hard for the average joe to troubleshoot. Unfortunately, I get the feeling that this might be more challenging of a repair than you're comfortable with. You'll need to be able to check voltage at varying points in the circuitry to confirm that #1, the machine is getting the proper voltages and be able to trace the circuitry from the PS to the amp. Also, I don't know who installed the amp chip for you but even new amp chips could be on the fritz if not properly installed or if damaged during the soldering process which is easy to do without the right soldering iron or soldering skill. IC's are especially sensitive to heat related damage.

Don't smash it up. Offer it up and someone more experienced in boombox repair will want it, if nothing else, just for the challenge. OR... if there is sentimental value attached to the radio, then have someone repair it for you.

 

[monchito]

easy man i like i said these are things that we have to deal with when it comes down to it ,, i have one thats not been played with for months so i know once you crank them up something goes wrong very frustrating the least ,, take a deep breath all is not lost most boxes just need more attention than others whatever we can help i know i do not have a problem and i am more than sure norm will not mind either to help you out......

 

[Ken]

"Many Rivers To Cross" in this hobby. You're just experiencing a rather difficault one at the moment. Take a deep breath and remember: If you have a "Rimmer Moment," from what I have gathered in the last month, you're little jewel will never play again...

 

[blah blah]

thanks for chilled advice. i didn't smash it. i actually haven't put the new amp chip in, I just have a spare. i would have no problem with the removal and installation, i can solder fairly well. but superduper your it is a tracking down problem for me!

Anyone know off hand what the ohm readings on the amp chip should be? The weird part was it had the symptom at high volumes, but otherwise sounded good. As soon as I tried batteries it make the symptom sounds constantly. Would batteries be more likely to blow something out like the amp chip?

I actually had to bridge some cracks in the board when I got it and was working fine, got the deck working too, that's why this new problem is so annoying. anyway...i will either fix it or pass it along down the highway.

 

[Superduper]

It really sounds like a poor connection someplace to me. However, you are the only one able to look at it in depth so while we can give you general advice, it's all on you blah blah. The fact that it had a cracked circuit board before means that if it was mine, I would look very carefully at that once again as a possible culprit. Bridging the broken connections might have restored it but unless the crack was stabilized, which is hard to do, it's likely to flex again and thereby break the traces once again. Also, any components that may have been affected by the crack could have a fracture, possibly where the leads enters the component body.

I still think I would start with voltage checks at various points. If someone has a service manual they can share with you (I don't have one), that would go a long way towards helping you trace it down. You don't check ohm readings on the amp module. Voltage checks is the way to go and the service manual is where you would get detailed voltage check information. However, if we knew which module you have, then we can at least check the main power to the amp, which should be about battery voltage. What module does the Aiwa use anyhow? Also, do you know if the Aiwa uses 1 or 2 amp modules? If 2, then I doubt very much that both modules would go out at the same time. In that case, I would focus once again on issues that would be common to both modules, and once again we are back to voltage issues.

 

[monchito]

not sure norm but if my mind remembers correctly it might be the an7145m buy not really sure as it been a long time that i do not look at it

 

[blah blah]

Guys- thanks a lot for your patience and advice!

I checked the traces i repaired and they still have good continuity. This box uses 1 amp chip only (TA7229P).

I will try to get some voltage checks and see if i can make sense of them...

 

[monchito]

thanks for the ic num as i was trying to remember and that is the one good

 

[blah blah]

I took some voltage readings but am a bit confused by where I should be checking? Fuses are good. Maybe the pic will help...thanks!

 

[blah blah]

monchito- now you know i have a spare just in case yours goes kaput

 

[monchito]

yes i see that i was a bit puzzeled as the voltage to the main pc board should be around 15volts if i am not mistaken