ok, i have also got protection mode on my harman kardon avr507 amp,
really cheesed off!!
my front left & right was not working but my surround left and right was as well as center channels,
thought id take it into this tv repair shop, he said it would cost about 90 pounds to repair, i thought ok what the hell least it will be all done,
waited 5 days and phoned, he said good news and bad news :/
i asked whats that then,
he replyed" good news is the front left and right are working now,
bad news
he replyed" the left surround is not working.
then he said" i replaced the blown transitors, however the left surround channel, its ok for about 5 mins, but then gets red hot and keeps blowing the transistor,
he then replyed" only thing i can suggest is to see how it goes for 3 months and if its still ok bring it back and i will try and fix the left surround :/
now is it me or dident i not put this in for repair??? dident he say it would be 90 pounds to repair it? i dident think repairing a amp mean half repairing it??
i think either he couldent be bothered or wasent experenced enough for the job, as that come back in 3 months sounds like a fob off to me what you guys think?
also, whats strikes me strange is, my surrounds were ok before it went in but my fronts was not, now only 1 channel on the surround works, and the 2 fronts are working?
protect only comes on if i plug a speaker into left surround.
im very unhappy as its still not fixed :/ so im going to have to look at it myself hope someone can advize me what to look for etc
what do u guys make of this?
really cheesed off!!
my front left & right was not working but my surround left and right was as well as center channels,
thought id take it into this tv repair shop, he said it would cost about 90 pounds to repair, i thought ok what the hell least it will be all done,
waited 5 days and phoned, he said good news and bad news :/
i asked whats that then,
he replyed" good news is the front left and right are working now,
bad news
he replyed" the left surround is not working.
then he said" i replaced the blown transitors, however the left surround channel, its ok for about 5 mins, but then gets red hot and keeps blowing the transistor,
he then replyed" only thing i can suggest is to see how it goes for 3 months and if its still ok bring it back and i will try and fix the left surround :/
now is it me or dident i not put this in for repair??? dident he say it would be 90 pounds to repair it? i dident think repairing a amp mean half repairing it??
i think either he couldent be bothered or wasent experenced enough for the job, as that come back in 3 months sounds like a fob off to me what you guys think?
also, whats strikes me strange is, my surrounds were ok before it went in but my fronts was not, now only 1 channel on the surround works, and the 2 fronts are working?
protect only comes on if i plug a speaker into left surround.
im very unhappy as its still not fixed :/ so im going to have to look at it myself hope someone can advize me what to look for etc
what do u guys make of this?
Probably because he is a TV repair man - the inside of a TV is very different from an amplifier.
It sounds like to me the channel is incorrectly biased too high, so the thing heats up when working with a load and goes past the SOA for the transistor = *bang*
Either that or something is causing the channel to break into oscillation.
Unless you know what you are doing, and have a schematic, don't try and repair it yourself as you will most likely just cause more damage. Power amps are not very forgiving of mistakes.
It sounds like to me the channel is incorrectly biased too high, so the thing heats up when working with a load and goes past the SOA for the transistor = *bang*
Either that or something is causing the channel to break into oscillation.
Unless you know what you are doing, and have a schematic, don't try and repair it yourself as you will most likely just cause more damage. Power amps are not very forgiving of mistakes.
well trouble is i cant find a schematic anyware for this model? or a service manual? ive emailed a few places that sell service manuals but they dont have it in stock 
which strikes me kind of strange??
the amp is a harman kardon avr 507 ltd edition, also heard its similar specs to the Harman Kardon AVR-4550, however i cant even find this schematic or service manual,
if anyones got them please let me know,
just curious why you think it might be the bias setting, as before it went into the shop this channel was perfect,
i have just shelled out alot of money to get this fixed, which is a lot for me as im a poor student, and cant afford to pay another 100 pounds, thats why i said i will have to look at it myself, plus theres only about 45 components of each channel, consisting of resistors, transistors,caps, and couple of diodes, so cant be that hard to test them, as i said i have alittle electrical no how, used to repair consoles, however amps are diffrent, so just need some pointers on the best way to test these with a dmm.
which strikes me kind of strange??the amp is a harman kardon avr 507 ltd edition, also heard its similar specs to the Harman Kardon AVR-4550, however i cant even find this schematic or service manual,
if anyones got them please let me know,
just curious why you think it might be the bias setting, as before it went into the shop this channel was perfect,
i have just shelled out alot of money to get this fixed, which is a lot for me as im a poor student, and cant afford to pay another 100 pounds, thats why i said i will have to look at it myself, plus theres only about 45 components of each channel, consisting of resistors, transistors,caps, and couple of diodes, so cant be that hard to test them, as i said i have alittle electrical no how, used to repair consoles, however amps are diffrent, so just need some pointers on the best way to test these with a dmm.
mrlennon said:
May I suggest http://sound.westhost.com/troubleshooting.htm#comm1 for a starter...
Good luck
ok been busy with my trusty multimeter,
found a few components gone,
can i just double check with you guys, i have got the values right for the resistors, below.
mini resistor, 4 band,
brown,red,red,gold, 1200 ohms
...................................................................................
mini resistor 3 band,
brown, orange, gold, 13 ohms
......................................................................................
mini resistor, 4 band,
brown,silver,red,gold, 1800 ohms
...................................................................................
mini resistor, 4 band,
red,red,orange,gold 22000 ohms
...................................................................................
normal resistor, ( light green body,)
silver,silver,brown,silver,blue, - unsure on value for this one?
also found a ceramic cap, (not charging) but im not sure its value as it only has a number12 printed on it, so i guess im gona need the service manual for this one, however trying to get it is another thing .
cant even find anyware that sells it, and harman kardon wont sell manuals to outsiders only registered repair centers.
also concidering i dont have a proper cap tester handy i might just replace every compnent on the channel, as its only gona cost about 10 pounds, that way i guess i know everythink checks ok then, and alot cheaper than a repair.
found a few components gone,
can i just double check with you guys, i have got the values right for the resistors, below.
mini resistor, 4 band,
brown,red,red,gold, 1200 ohms
...................................................................................
mini resistor 3 band,
brown, orange, gold, 13 ohms
......................................................................................
mini resistor, 4 band,
brown,silver,red,gold, 1800 ohms
...................................................................................
mini resistor, 4 band,
red,red,orange,gold 22000 ohms
...................................................................................
normal resistor, ( light green body,)
silver,silver,brown,silver,blue, - unsure on value for this one?
also found a ceramic cap, (not charging) but im not sure its value as it only has a number12 printed on it, so i guess im gona need the service manual for this one, however trying to get it is another thing .
cant even find anyware that sells it, and harman kardon wont sell manuals to outsiders only registered repair centers. also concidering i dont have a proper cap tester handy i might just replace every compnent on the channel, as its only gona cost about 10 pounds, that way i guess i know everythink checks ok then, and alot cheaper than a repair.
I think your 13 R resistor should be 1R3 given the colour code you gave.
I would just try to repair the channel systematically. Look at the other working surround channel. By just replacing like parts you may just repeat the shop's mistake. The small value caps like ceramics are probably okay. Look for a short as a failure with those.
-Chris
I would just try to repair the channel systematically. Look at the other working surround channel. By just replacing like parts you may just repeat the shop's mistake. The small value caps like ceramics are probably okay. Look for a short as a failure with those.
-Chris
thanks anatech for the reply mate,
im pretty sure looking at it the: green bodied, silver,silver,brown,silver,blue, type resistor is a inducer,
also i really think the ceramic cap is gone as i checked the value with the other working channels, the value rose very high, but the blown channel ceramic rose a tiny amount and stopped ,
so from what i can tell it looks as if its gone, plus 3 resistors, and a transistor.
i said i was going to replace all the components on the blown channel as theres a few trans, and there is a far few on each channel, but if you want i could type out the tested components values on the good channel compaired to the tested components values on the blown channel see what you think.
let me know, maybe you could tell more which ones look dodgy.
im pretty sure looking at it the: green bodied, silver,silver,brown,silver,blue, type resistor is a inducer,
also i really think the ceramic cap is gone as i checked the value with the other working channels, the value rose very high, but the blown channel ceramic rose a tiny amount and stopped ,
so from what i can tell it looks as if its gone, plus 3 resistors, and a transistor.
i said i was going to replace all the components on the blown channel as theres a few trans, and there is a far few on each channel, but if you want i could type out the tested components values on the good channel compaired to the tested components values on the blown channel see what you think.
let me know, maybe you could tell more which ones look dodgy.
Hi mrlennon,
Might be an idea. There is nothing worse than repeating someone else's errors. Do not use ECG or NTE parts. Replace any you do see with the correct part.
Ceramic caps normally will fail with a short across their terminals. You likely measured some other aspect of the circuit behaviour. Of course, nothing is impossible.
TV repair guys are normally very poor at servicing audio. A completely different world. They just don't know it. The state of your set doesn't surprise me at all - sorry about that. You can probably do a better job.
-Chris
Might be an idea. There is nothing worse than repeating someone else's errors. Do not use ECG or NTE parts. Replace any you do see with the correct part.
Ceramic caps normally will fail with a short across their terminals. You likely measured some other aspect of the circuit behaviour. Of course, nothing is impossible.
TV repair guys are normally very poor at servicing audio. A completely different world. They just don't know it. The state of your set doesn't surprise me at all - sorry about that. You can probably do a better job.
-Chris
Quote:
Might be an idea. There is nothing worse than repeating someone else's errors. Do not use ECG or NTE parts. Replace any you do see with the correct part.
Chris is 100% correct here. Never use NTE or ECG replacement parts for audio. Two reasons, 1st, the parts come close to the original parts but are NOT a match. Second, the price is about 10times higher than the actual part cost.
As a general rule never take audio to a TV repair shop. They are good (sometimes) at what they do but are absolutely no good with audio. I have seen this time and time again.
Joe
Might be an idea. There is nothing worse than repeating someone else's errors. Do not use ECG or NTE parts. Replace any you do see with the correct part.
Chris is 100% correct here. Never use NTE or ECG replacement parts for audio. Two reasons, 1st, the parts come close to the original parts but are NOT a match. Second, the price is about 10times higher than the actual part cost.
As a general rule never take audio to a TV repair shop. They are good (sometimes) at what they do but are absolutely no good with audio. I have seen this time and time again.
Joe
yep i guess ur right there,
after i got this back out i noticed 3 scratches on the front this amp was mint when it went in and only noticed 3 days later when i got it out, i phoned him complaing and he denyed scratching it. darn idiot some people dont care what they scratch.
i wanted to keep this in good condition you know as its a limited edition amp, oh well not mint anymore, guess thats a lession learned eh
guys wheres the best place to buy h/k origanal parts in uk?
i guess the resistors are easy enought to get like maplins etc, but the transistors and power transistors and koshin caps are a diffrent story?
after i got this back out i noticed 3 scratches on the front
this amp was mint when it went in and only noticed 3 days later when i got it out, i phoned him complaing and he denyed scratching it. darn idiot some people dont care what they scratch.i wanted to keep this in good condition you know as its a limited edition amp, oh well not mint anymore, guess thats a lession learned eh
guys wheres the best place to buy h/k origanal parts in uk?
i guess the resistors are easy enought to get like maplins etc, but the transistors and power transistors and koshin caps are a diffrent story?
All those parts can be had locally at various jobbers. A substitute arrived at by comparing actual specs will normally work fine. Be sure to get complementary pairs. The Japanese data books will indicate these.
Compare collector - emitter breakdown voltages, ignore collector - base ratings (switch mode).
Sorry to hear about your cosmetic grief. This is also normal for TV shops. It can happen, but you'd think they would have called and appologised. I've had to in the past, but at least the customer gets an honest answer.
-Chris
Compare collector - emitter breakdown voltages, ignore collector - base ratings (switch mode).
Sorry to hear about your cosmetic grief. This is also normal for TV shops. It can happen, but you'd think they would have called and appologised. I've had to in the past, but at least the customer gets an honest answer.
-Chris
trouble is anatech there is not many good honest repairers like yourself mate,
he dident have the decency to tell me about the scratches, i told him the amp was perfect condition before it went in, but he denys scratching it and dont know how they got there
i really wish i read up in the beggining and just thought about replacing all the components on the faulty channels as i wouldent be alot lighter on my pocket and a half working amp
you say use substitute parts, well i want to try and get the origanals if i can, i have been searching the net, no hits yet, for anyware in uk or even usa, but i will keep searching for a place in uk that sells harmon kardon conponents, hell if i have to i will even order from us if needs be.
just dont know whever just to take all the components out of the blown channel and test them all out of curcuit, theres around 40 components on each channel.
he dident have the decency to tell me about the scratches, i told him the amp was perfect condition before it went in, but he denys scratching it and dont know how they got there
i really wish i read up in the beggining and just thought about replacing all the components on the faulty channels as i wouldent be alot lighter on my pocket and a half working amp
you say use substitute parts, well i want to try and get the origanals if i can, i have been searching the net, no hits yet, for anyware in uk or even usa, but i will keep searching for a place in uk that sells harmon kardon conponents, hell if i have to i will even order from us if needs be.
just dont know whever just to take all the components out of the blown channel and test them all out of curcuit, theres around 40 components on each channel.
Hi mrlennon,
Okay, then post the transistor numbers you need & we'll get you spec's and subs. If I don't know there are lot's on the forum who do. I am in Canada so not that familiar with the UK supply chain.
One I've heard of is http://www.dalbani.co.uk/index.php
Pull only the transistors for now. Take a picture that clearly shows the orientation for yourself, or draw a picture. I do that all the time. Now you can check any diodes and resistors and get a better reading.
-Chris
Okay, then post the transistor numbers you need & we'll get you spec's and subs. If I don't know there are lot's on the forum who do. I am in Canada so not that familiar with the UK supply chain.
One I've heard of is http://www.dalbani.co.uk/index.php
Pull only the transistors for now. Take a picture that clearly shows the orientation for yourself, or draw a picture. I do that all the time. Now you can check any diodes and resistors and get a better reading.
-Chris
ok mate i will do that, i will pull all the transistors out of the curcuit,
maybe its me at fault , my dmm, or i am doing somethink wrong but ive always been useless at testing these darn trans, any pointers or help would be appretiated so i can properly test them on my dmm,once ive soldered them out, and while im writing down the part numbers, once ive finished soldering them all out.
maybe its me at fault , my dmm, or i am doing somethink wrong but ive always been useless at testing these darn trans, any pointers or help would be appretiated so i can properly test them on my dmm,once ive soldered them out, and while im writing down the part numbers, once ive finished soldering them all out.
Hi mrlennon,
To test transistors you need a diode test function on your meter. If the meter also has an hFE tester you will be way ahead.
The better DMM's use a current source and measure the voltage drop, normally around 1 mA. You want to limit the test voltage open circuit to 5V or less to avoid reverse breakdown B-E.
You can meaasure for shorts with a normal meter, don't use an AVO meter due to the high open circuit voltage and high low resistance currents available on these.
-Chris
To test transistors you need a diode test function on your meter. If the meter also has an hFE tester you will be way ahead.
The better DMM's use a current source and measure the voltage drop, normally around 1 mA. You want to limit the test voltage open circuit to 5V or less to avoid reverse breakdown B-E.
You can meaasure for shorts with a normal meter, don't use an AVO meter due to the high open circuit voltage and high low resistance currents available on these.
-Chris
Hi Joe,
I used to use carpet but changed to printing "blankets". These are rubber with a cloth base. That way they can be cleaned completely. I found that carpet can hold bits of cast off solder or wire ends. That's how the few I marked early on got marked.
mrlennon needs the parts, but thank you for the offer.
SkinnyBoy, I totally missed your joke. I may be a little dense today but could you explain?
-Chris
I used to use carpet but changed to printing "blankets". These are rubber with a cloth base. That way they can be cleaned completely. I found that carpet can hold bits of cast off solder or wire ends. That's how the few I marked early on got marked.
mrlennon needs the parts, but thank you for the offer.
SkinnyBoy, I totally missed your joke. I may be a little dense today but could you explain?
-Chris
ok to start ive took all the trans out on the blown channel,
my dmm has a hFE tester but i dont seem to be getting a reading only 000 on the muiltimeter useing either pnp or npn ?? testing the small transistors.
heres the numbers on the parts,
a1360, trans
c3423, trans
c2785, trans
d600k trans
d2560, trans
b1647, trans
c2874, trans
c3200, trans,
c3198, trans
a1268, trans
also i think i might have found a place in uk that sells them, im currently going through to see if they have all the parts.
my dmm has a hFE tester but i dont seem to be getting a reading only 000 on the muiltimeter useing either pnp or npn ?? testing the small transistors.
heres the numbers on the parts,
a1360, trans
c3423, trans
c2785, trans
d600k trans
d2560, trans
b1647, trans
c2874, trans
c3200, trans,
c3198, trans
a1268, trans
also i think i might have found a place in uk that sells them, im currently going through to see if they have all the parts.
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