car audio electronics

aidanki

just a question hopefully someone might be able to help me

im driving a 2005 corolla with a radio like this one in it

http://www.toyotaownersclub.com/foru...howtopic=54126

it runs for a minute sometimes more times 30 secs and then cuts out, no sound from either radio or CD, radio doesnt go dead its still receiving etc, clock keeps time it displays temperature all quite accurate

I took it out at the weekend expecting to find a loose wire but no luck

had a chat with a man today that does starters and alternators for his living, his diagnosis is that the amplifier is gone in the radio, its a built in amplifier obviously, no seperate amp

I could get one from a scrappie but fancy a go at fixing it myself

anyone ever replaced an amplifier in a radio

radio is a panasonic W58814 or might be known as CQ-TS7471Lc?

anyone got any links to tutorials about examining radio circuitery and replacing amps
any bright ideas?

mawk

detached from the heatsink maybe? if you switch off the engine and start again will it work for another while?

aidanki

mawk wrote: »

detached from the heatsink maybe? if you switch off the engine and start again will it work for another while?

yes if you switch it off leave it for a while then it goes again for a few secs or a minute maybe

mawk

what if you don't leave it a while. just off and back on?

aidanki

mawk wrote: »

what if you don't leave it a while. just off and back on?

tried it this evening no sound when turned on initially and no sound when turned off then turned back on, this was after being left for 9-10hrs without using the car

usually after it cutting out and leave it for a while it will turn on for a few secs
but after it cutting out an turning on immediately no sound

mawk

not a thermal issue so. some capacitor or diode breaking down somewhere? unless its very obviously burnt out, it would be a terrible job to find it.

how much does a scrappy want for an amp/stereo unit? it's got to be less cash than the time spent maybe fixing it

DublinDilbert

More thank likely the pins on the amp chip need thier solder re-flowed. There is probably cracks here in the solder. I've fixed quite a few car stereo's with this problem.

mawk

if thats the case then surely the audio would kick in and out when the car is moving, not be time dependent?

godtabh

Might get more answers here

DublinDilbert

You'd be suprised what can happen with some cracked solder. It could be when it heats up a little there's slight movement.

Worth looking over the pins of the amplifier with a magnifying glass seeing if you can spot anything.

iamthemanwork

After the sound goes off check and see if the radio will seek and find a station of its own accord. If it does pick up stations then most likely the opic-- output amp-- needs replacing or you have a faulty speaker.
If it does not pick a station then you have a power supply fault which is common enough in Toyota units. Either way your radio is repairable--- audio repair is my job.

aidanki

DublinDilbert wrote: »

You'd be suprised what can happen with some cracked solder. It could be when it heats up a little there's slight movement.

Worth looking over the pins of the amplifier with a magnifying glass seeing if you can spot anything.

could you expand on that one, what am I looking for ?

something like one of these amps....or something different

http://www.quasarelectronics.com/audio-amplifiers.htm

im an engineer by profession, and have a good understaning of resistors capacitors and impedence but ashamed to say not sure what to look for when looking for an amp....is the amp built into the radio circutry or is it a seperate piece of circuitry attached to radio circuit board

probably seems like a v stupid question......

iamthemanwork

The amp in this radio is part of the main motherboard.

aidanki

iamthemanwork wrote: »

After the sound goes off check and see if the radio will seek and find a station of its own accord. If it does pick up stations then most likely the opic-- output amp-- needs replacing or you have a faulty speaker.
If it does not pick a station then you have a power supply fault which is common enough in Toyota units. Either way your radio is repairable--- audio repair is my job.

yes it will seek

iamthemanwork

Does it stop and pick up a station.

aidanki

iamthemanwork wrote: »

Does it stop and pick up a station.

yes it will

iamthemanwork

Most likely the output amp needs to be replaced. There is a slim chance that there is corrosion around the pins. Remove radio from car and inspect the pcb around general area of power supply which is to the back of the board.

aidanki

have found a manual online and been able to figure out the part number


who do you all use for electronic supplies?

Ive had a look on farnell and radionics and don't see it listed,

I see it listed here in USA but out of stock
http://ceiparts.com/productdetail.as...PPC1BA00000345

wouldn't mind a shot at fixing it myself, as everyday is a school day isn't it

iamthemanwork

I have 1000s parts in stock. Let me know the TA or TDA part no. and I may have it

aidanki

iamthemanwork wrote: »

I have 1000s parts in stock. Let me know the TA or TDA part no. and I may have it

reference number IC231 part number C1BA00000345

thats as good as it gets from reading the manual

aidanki

opened up my radio today

the chip is a toshiba TA8271H, plenty of them for sale on the net so no problem there

its a 25pin arrangement, 2 rows of 12pins, this is the one if anyone is interested http://www.datasheetcatalog.org/data...shiba/1399.pdf

it sure gets hot when you switch on radio, one thing that amazed me is that no sign of any thermal paste attaching the chip to the heat sink, thought that was my problem first so put some moisture on the back of the chip using fingers but no luck, to be sure chip was making good contact with the heat sink, I used some tinfoil as a filler and screwed on heat sink over the chip good and tight but no luck

anyone know the easy way to swap such a chip in and out?

iamthemanwork

A sound output chip should be warm but not hot, so I would say that yours is certainly faulty. Going from approx 39 years repairing car audio systems I know with certainty that seldom does an output amp go faulty as a result of wear and tear. It goes faulty because perhaps one of the speakers is faulty or wiring to one of them might be s/c . Make sure you have eliminated all possible causes of fault from car before you power up radio and after you have repaced the amp.

aidanki

iamthemanwork wrote: »

A sound output chip should be warm but not hot, so I would say that yours is certainly faulty. Going from approx 39 years repairing car audio systems I know with certainty that seldom does an output amp go faulty as a result of wear and tear. It goes faulty because perhaps one of the speakers is faulty or wiring to one of them might be s/c . Make sure you have eliminated all possible causes of fault from car before you power up radio and after you have repaced the amp.

will get the multimeter out and measure the resistance of wiring going to each speaker, it should be between about 2 and 8ohms correct?

iamthemanwork

Impedence should be from 4 to 8 ohms. Check each speaker individually for s/c to ground --- reading should be o ohms

aidanki

whats s/c? probably something v simple that I don't recognise......

pred racer

S/c = short circuit. Ie direct connection to ground or itself.

Unless you are very handy with a soldering iron/solder sucker
25 pin ic's are not easy to remove/replace, the boards are designed to be wave soldered. And you can often do more harm than good.
(btw not casting doubt on your abilities, just friendly advice;) )

But fcuk it go for it, its not working now, whats the worst that could happen

aidanki

tested impedence at the weekend 3.6ohms each speaker circuit car off or on

iamthemanwork

Most likely replacing the opic will solve your problem. This is a double sided pcb so removing the chip will not be easy. I suggest you give repair to a competent service engineer who after component is fitted will be able to do proper tests making sure there is no more likelihood of fault reoccurring .