Man you're right, i know... I was considering doing it anyway. I've seen several versions on the net, though...
doen't matter which version you cobble together they all do the same thing.
after looking at these on the net can you guess what function they serve?(no point making one if you don't know what it does or how to use it)
after looking at these on the net can you guess what function they serve?(no point making one if you don't know what it does or how to use it)
I understand the fact that the bulb is in series of the DuT, and i can see how it protects the DuT in case of some short circuit.. But i would think at the main fuse you got before the transformer (when my outs burned, that fuse burned as well).
I can't see how it could protect the fuses after the filtering section.
Another thing.. What kind of bulb you should use? I would try with low wattage at first and maybe increasing if the bulb doesn't light too much. But man.. I don't know.. I mean.. It's like the first time you have sex, you feel strange about it, right? Wonderful but strange. 😀
EDIT
Thanks JMFahey.
I can't see how it could protect the fuses after the filtering section.
Another thing.. What kind of bulb you should use? I would try with low wattage at first and maybe increasing if the bulb doesn't light too much. But man.. I don't know.. I mean.. It's like the first time you have sex, you feel strange about it, right? Wonderful but strange. 😀
EDIT
Thanks JMFahey.
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ok i can tell you have a pretty good idea of what it is and how it functions.
it does rely on incandescent bulbs and estimating what you would expect the current draw to be to figure out what bulb to use.
on most stuff starting with a 60 w lamp is pretty standard for me.
it does rely on incandescent bulbs and estimating what you would expect the current draw to be to figure out what bulb to use.
on most stuff starting with a 60 w lamp is pretty standard for me.
Roger, the light bulb in the AC line is necessary for checking the one that has blown output transistors.
Output transistors are known for blowing other stuff through the base line once they go.
I would say concentrate on the one that has power supply problems in the op amp area. That one you have a chance of fixing in a couple of hours. I had to put 104 components in the amp I bought with 19 blown output transistors, many of which were not obvious.
Output transistors are known for blowing other stuff through the base line once they go.
I would say concentrate on the one that has power supply problems in the op amp area. That one you have a chance of fixing in a couple of hours. I had to put 104 components in the amp I bought with 19 blown output transistors, many of which were not obvious.
Ok indianajo, it could help even psicologically having at least one speaker working..
A question:
I burned my out trans 'cause i didn't mount the dissipator. So, if for instance i had the bulb limiter installed, what would have happened? Maybe the light from low would have become high? I would say that the outs would have burned anyway.
Another thing: the wattage of the bulb determines the resistance (inversely) and therefore the "limiting action" of the limiter. But are we just talking of current or of both voltage and current? I mean.. Is there any chance that a dut would work bad because of a reduced rail voltage or similar?
A question:
I burned my out trans 'cause i didn't mount the dissipator. So, if for instance i had the bulb limiter installed, what would have happened? Maybe the light from low would have become high? I would say that the outs would have burned anyway.
Another thing: the wattage of the bulb determines the resistance (inversely) and therefore the "limiting action" of the limiter. But are we just talking of current or of both voltage and current? I mean.. Is there any chance that a dut would work bad because of a reduced rail voltage or similar?
on the limiter anything that shows up as an increasing trend in current as in "bulb getting brighter" should make you reach for the switch!(you might have been lucky(and fast) enough to save your replacement transistors (it's not a catch all bullet proof device it's an aid for troubleshooting)
and yes things like smps and digital devices aren't most happy with being current limited but we're trying to fix an amp with a linear supply aren't we?
and yes things like smps and digital devices aren't most happy with being current limited but we're trying to fix an amp with a linear supply aren't we?
on the topic of the speaker with the bad preamp board.
i'd grab a magnifiying glass and check the header pins on the connectors linking the two boards(for cracked/bad solder's)if i remember correctly the supply is ok but no voltage at the op-amps means an "open" somewhere oui/non?
i'd grab a magnifiying glass and check the header pins on the connectors linking the two boards(for cracked/bad solder's)if i remember correctly the supply is ok but no voltage at the op-amps means an "open" somewhere oui/non?
Hey,
The light bulb dim works! Really nice, even 'cause i understand why it works, and that is good!
But... I've got a glimpse at the first moment (which makes sense cause i discharged the filter caps before removing the fuse) and a totally still bulbe after it. I mean.. Shouldn't it be reddish or at least just a tiny bright? I started with a 100 w bulb, decreased to 60 now.
I could understand if it would have been a portable radio or so.. Or maybe it gives me a hint of the problem i have?
You're right with the preamp, i have to check again, though.. I am sure that nothing arrives to the board, now i look again for continuity.. 🙂
The light bulb dim works! Really nice, even 'cause i understand why it works, and that is good!
But... I've got a glimpse at the first moment (which makes sense cause i discharged the filter caps before removing the fuse) and a totally still bulbe after it. I mean.. Shouldn't it be reddish or at least just a tiny bright? I started with a 100 w bulb, decreased to 60 now.
I could understand if it would have been a portable radio or so.. Or maybe it gives me a hint of the problem i have?
You're right with the preamp, i have to check again, though.. I am sure that nothing arrives to the board, now i look again for continuity.. 🙂
EDIT
I tried the A power board with the B pre with the bulb dim.. The amp works good in this configuration, and the light follows the sound level, obviously. Thanks Turk for insisting with this bulb thing.
I've also tried the good workin A power board with the A pre, for comparison.
Problem is:
Distortion and less power to the speakers. Light bulb doesn't become bright in any moment. Thats the problem of this pre.
The B pre works well but it doesn't receive any voltage, so i check now the B power amp board.
I am trying to explain myself as good as possible, i know it should be quite difficult to understand for you all. Thanks to all of you.
I tried the A power board with the B pre with the bulb dim.. The amp works good in this configuration, and the light follows the sound level, obviously. Thanks Turk for insisting with this bulb thing.
I've also tried the good workin A power board with the A pre, for comparison.
Problem is:
Distortion and less power to the speakers. Light bulb doesn't become bright in any moment. Thats the problem of this pre.
The B pre works well but it doesn't receive any voltage, so i check now the B power amp board.
I am trying to explain myself as good as possible, i know it should be quite difficult to understand for you all. Thanks to all of you.
Nah, that board is dropping 15 v in both the protection resistors between transformer and the bridge rectifier on the +-15 supply. So he reports. that indicates something after that is shorted, bridge rectifier, filter caps, solder across traces, a local power supply bypass cap with a solder bridge, something. He diode checked the bridge rectifier he says. If the designers were dumb enough to run +-15 through consecutive pins of a connector somewhere, then your theory of cracked housing could be correct. Or a connector could be installed one pin off or something - I blew up a lot of parts when I did that once. That connector has got a blank hole block plug now, my vision isn't getting any better as I age.
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ok before you go randomly just trying things we need to establish a method to first isolate and then resolve the issues if you keep swapping and jumping around it's only going to make matters worse.
one step at a time i understand your anxious to find and fix the problem but a little short term patience will in the end help us get there.
one step at a time i understand your anxious to find and fix the problem but a little short term patience will in the end help us get there.
You're both right and actually, Turk, your first sentence has been kinda premonition..
I was checkin this 15v and i damaged again something else. Mamma mia! I don't know if it's normal or if i am an idiot. Anyway, i think the speaker wire touched themselves of a part in the circuit. So i heard a BANG and blue smoke (again...) . The lamp is now constantly on, obviously the circuit remanis still, something is burned (again).
I made a couple of pictures with the ipad. Hope you can see: there is a burned point in the ground trace (maybe where a wire touched?) on the lower right part, and on the - of KBJ606 bridge (it's for the big rail) on the lower left part of the picture.
Oh boy, oh boy.. Anyway, i obviously tought that the bridge would have been destroyed. But no... Off the board the drops are all correct! Strange, uh?
So much patience you have.. I appreciate, really. I feel an idiot, though!
I was checkin this 15v and i damaged again something else. Mamma mia! I don't know if it's normal or if i am an idiot. Anyway, i think the speaker wire touched themselves of a part in the circuit. So i heard a BANG and blue smoke (again...) . The lamp is now constantly on, obviously the circuit remanis still, something is burned (again).
I made a couple of pictures with the ipad. Hope you can see: there is a burned point in the ground trace (maybe where a wire touched?) on the lower right part, and on the - of KBJ606 bridge (it's for the big rail) on the lower left part of the picture.
Oh boy, oh boy.. Anyway, i obviously tought that the bridge would have been destroyed. But no... Off the board the drops are all correct! Strange, uh?
So much patience you have.. I appreciate, really. I feel an idiot, though!
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eek! SLOW DOWN and make sure that your not going to cause yourself more problems! i thought you where going to check for continuity between the boards?if your doing that with the power on your just asking for more trouble.
Yeah, and i couldn't find any problem. I mean.. It's not a problem of wiring or bad solder, i am quite sure of it.. I just started with the amp turned on when this tragedy happened. Oh boy, oh boy.. 🙁
don't make assumptions or suppositions unless your prepared to take the time to to verify all the possibilities.
you say you didn't find any problems but your not telling us what you do have (and on what boards and where you checked etc etc) so again slow down be methodical and if your not sure or want confirmation just ask...
you say you didn't find any problems but your not telling us what you do have (and on what boards and where you checked etc etc) so again slow down be methodical and if your not sure or want confirmation just ask...
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Well, i am working now on the B board, the one which doesn't provide voltage to the pre board.
I seeked for an interruption of signal somewhere, with the power off and the DMM on the continuity mode (dunno how it's called, i mean the one that makes a sound when you have continuity), and i couldn't find any interruption. But obviously i can only measure from one component to the other, kinda, and so i taught to turn the amp on..
I was just measuring the voltage regulators when the accident happened. Btw, i suspect they are the culprit, cause i always write down what i do and i know for sure that they're output is 0. Which means either they are rotten either simething before, right?
So, i've got now some brand new regulators.. It would make sense to me to replace them..
BUT
Now i have to deal also with the accident.. 'Cause the fantastic bulb limiter is telling me that i've got a short somewhere, through its shiny brightness, and the first place i checked was the bridge of the big rail, the KBJ606 where one of the black points is. Incredible but true, the voltage drops are all correct and i ask myself if that is a guarantee of good working component. It should, uh?
Actually i don't know where to look at.. 🙁
I seeked for an interruption of signal somewhere, with the power off and the DMM on the continuity mode (dunno how it's called, i mean the one that makes a sound when you have continuity), and i couldn't find any interruption. But obviously i can only measure from one component to the other, kinda, and so i taught to turn the amp on..
I was just measuring the voltage regulators when the accident happened. Btw, i suspect they are the culprit, cause i always write down what i do and i know for sure that they're output is 0. Which means either they are rotten either simething before, right?
So, i've got now some brand new regulators.. It would make sense to me to replace them..
BUT
Now i have to deal also with the accident.. 'Cause the fantastic bulb limiter is telling me that i've got a short somewhere, through its shiny brightness, and the first place i checked was the bridge of the big rail, the KBJ606 where one of the black points is. Incredible but true, the voltage drops are all correct and i ask myself if that is a guarantee of good working component. It should, uh?
Actually i don't know where to look at.. 🙁
sorry snow storm caused power outage
now let's see if we can find the new short
make sure the load (speaker) is disconnected from the amp and unplug the preamp board we'll look at that later. check for DC on the output of the amp.if you see anything more than 0.6 VDC power down and check (with your meter) for shorts on output transistors.
now let's see if we can find the new short
make sure the load (speaker) is disconnected from the amp and unplug the preamp board we'll look at that later. check for DC on the output of the amp.if you see anything more than 0.6 VDC power down and check (with your meter) for shorts on output transistors.
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