Most resistors of a given type are made of the same basic materials so the size determines wattage. Measure the resistor and order the same size.
The old resistor messures 4.8mm in the center and 15mm in length. The 1w resistor I got is only 3.4mm in center and 10mm in length. So I guess that could be a 3w? I just have no idea. Sites don't list there messurements in regards to resistor size. Well not that I can find?
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So having a look on mouser it seems to be a 4w resistor. Well that's as close to the messuremt as I could get.
Regardless I can't get any resistor in either 2w.3w.4w in Australia.
I'm just going to have to try the 5w wire wound resistor and hope to God it does not cause trouble.
I hope they used 4w resistors to cut on cost and by using the wire wound will only add stability.
It will likely be OK but when doing repairs, your job it to return the amp to its original condition. Too many (not referring to you) try to improve an amp by 'upgrading' various components. Too many believe that they somehow know better than a person who makes their living designing electronic equipment.
Use what you can get if there are no other options.
Use what you can get if there are no other options.
Hey guys. So unfortunately I'm having another issue with this amp. Has me a bit stumped.
Amp will work fine however if you move the bass boost trim pot off 0db. The Amp will go into protect then come out of protect but with no audio.
If you move it back to the 0db range it will go into protect then come out of protect then there is audio. 99% of the range of the bass boost there will be no audio.
I checked the reisitance of the trim pot in 0db position. Reads 2.4ohms.
Move it about a mm above 0db and it will read 1.52k ohms.
And goes up from there into the k ohms.
Do these sposed to be at 2.4ohms when fully turned one way then spike to k ohms when moved slightly?
Why would moving it make the Amp go into protect then come out with no audio?
If i put the Amp into slave mode u can turn the bass boost without it going into protect.
I've checked most the resistors in the section but all seem OK?
It's a b20k pot. And reading the one next to it which is also a b20k. It reads in the k ohms all the way.
So faulty pot mabey? That does not explain why u only have audio when it's a 2.4ohms? And no audio when it's in the k ohms?
All the rest of the trim pots can be moved with no protect.
Amp will work fine however if you move the bass boost trim pot off 0db. The Amp will go into protect then come out of protect but with no audio.
If you move it back to the 0db range it will go into protect then come out of protect then there is audio. 99% of the range of the bass boost there will be no audio.
I checked the reisitance of the trim pot in 0db position. Reads 2.4ohms.
Move it about a mm above 0db and it will read 1.52k ohms.
And goes up from there into the k ohms.
Do these sposed to be at 2.4ohms when fully turned one way then spike to k ohms when moved slightly?
Why would moving it make the Amp go into protect then come out with no audio?
If i put the Amp into slave mode u can turn the bass boost without it going into protect.
I've checked most the resistors in the section but all seem OK?
It's a b20k pot. And reading the one next to it which is also a b20k. It reads in the k ohms all the way.
So faulty pot mabey? That does not explain why u only have audio when it's a 2.4ohms? And no audio when it's in the k ohms?
All the rest of the trim pots can be moved with no protect.
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The resistance should vary from the center terminal to either of the outer terminals smoothly. It will read approximately 0 ohms from one outer terminal to the center terminal at one extreme and approximately 0 ohms from the center terminal to the other outer terminal when rotated to the other extreme.
The potentiometer page of the bcae1.com site may nelp.
The potentiometer page of the bcae1.com site may nelp.
The green lines are the traces. The red circles are where I tested for resistance.
None of the other pots come close to 0ohms.
So I'd say this pot is buggered. However I can't see how that could activate the protection curcut. And even worse make the Amp produce no audio output?..
My limited knowledge would suggest the protection circuit is detecting DC voltage on the outputs but how this can be related to the bass boost I have no idea....
Not that I use bass boost but I'd rather this amp 100% working. Seems the output is a bit low. Compared to the other amp... All the drivers have been replaced.all the mosfets check out fine.
None of the other pots come close to 0ohms.
So I'd say this pot is buggered. However I can't see how that could activate the protection curcut. And even worse make the Amp produce no audio output?..
My limited knowledge would suggest the protection circuit is detecting DC voltage on the outputs but how this can be related to the bass boost I have no idea....
Not that I use bass boost but I'd rather this amp 100% working. Seems the output is a bit low. Compared to the other amp... All the drivers have been replaced.all the mosfets check out fine.
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If no other pots go to near 0 ohms, you have more bad pots from what I see on the board.
What are the chances of getting a special pot if you cannot get a resistor?
Low audio is almost always a preamp section problem.
What are the chances of getting a special pot if you cannot get a resistor?
Low audio is almost always a preamp section problem.
I was just going off all the other pots that work including gain and a few others are twin stack pots. They all work fine as far as modifying the audio.
Some of the pots quad stacked.
My oscilloscope bit the dust yesterday so I'm unable to check components properly. Only got a multimeter now.
Both the rca inputs are working.
Are you sure these pots are sposed to be 2.4ohm then with a slight turn go into the k ohm?
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You didn't read what I wrote.
Did you go to the potentiomenter page of that site?
Why couldn't you have purchased the right resistor from that site/distributor?
Did you go to the potentiomenter page of that site?
Why couldn't you have purchased the right resistor from that site/distributor?
HI sorry perry I did not understand what you ment.
I didn't realize the resistor was broken when I purchased the driver chips. And shipping was $40 I could not afford another $40 shipping for a resistor so I just went to my local parts shop and got a large 22ohm resistor.
I don't think that resistor I replaced is cause of this bass boost fault.
That 15k resitor I was initially talking about that was getting hot turned out to be normal so I just put that back on the board.
Seemed to run cooler after I replaced the 22ohm. I don't have a schematic lanzar never replied so it's hard to know what's what.
And by no means do I have much idea of how the pre amp section works.
I just can't understand how this 1 trim pot will only allow the Amp to output signal when it's in a place it's not designed for. 1k to 500k is the range of those pots. Not 2.4ohm.
So just a recap of what I've done.
I got the Amp that was cycling in and out of protect.
I found there was a blown driver chip ir2113.
I got a new one of them and the Amp was working fine however the inductors and 1 resistor was getting very hot very fast.
I then found a broken leg on a 22ohm resistor near the output fets. It was a 3w? Anyway I could not get a 3w so went a 5w.
Replaced that amp seemed to work fine.
I then moved the bass boost pot and went into protect. Came out but no audio.
I checked the pot and at 0db of bass boost its reading 2.4ohm. Which is not correct for a b50k pot.
But what's more wierd is it will only work (output) when bass boost is at 0db.(2.4ohm)
Throughout the rest of the bass boost range it reads into the k ohms as it should. However there is no audio output....
I got the Amp that was cycling in and out of protect.
I found there was a blown driver chip ir2113.
I got a new one of them and the Amp was working fine however the inductors and 1 resistor was getting very hot very fast.
I then found a broken leg on a 22ohm resistor near the output fets. It was a 3w? Anyway I could not get a 3w so went a 5w.
Replaced that amp seemed to work fine.
I then moved the bass boost pot and went into protect. Came out but no audio.
I checked the pot and at 0db of bass boost its reading 2.4ohm. Which is not correct for a b50k pot.
But what's more wierd is it will only work (output) when bass boost is at 0db.(2.4ohm)
Throughout the rest of the bass boost range it reads into the k ohms as it should. However there is no audio output....
Sounds like a bad pot, I would pull it to verify.
Sometimes I find it easier to check pots out of circuit to eliminate any parallel resistance that may be present.
Sometimes I find it easier to check pots out of circuit to eliminate any parallel resistance that may be present.
If the pot is going to be removed for checking, bear in mind that it's VERY easy to apply too much heat which will affect the contact pressure between the terminals and the resistive element. This pot is likely defective but don't pull pots that don't need to be replaced.
If there are two identical amps, compare the readings between the two.
If there are two identical amps, compare the readings between the two.
HI I don't want to pull the working amp apart as those heat sink clamps are not my friend.
I'll just order a new b50k pot and hope that eliminates the issue.
Highly unlikely as there seems to be another issue in the pre amp section. As with normal readings on that pot the Amp will not work.
However when it is reading 2.4ohm the Amp works.
I've got a pretty good soldering iron ill try my best to not destroy it. It's got 6 pins but only 2 are connected to the traces on the board. Well 4 but 2 are linked to each other.
