You shouldn't have to pay more than $1 for any of the small transistors. The sub is likely an NTE part and shouldn't be used.
You have to pull them to check them. You can't get definitive readings while the transistors are in the circuit. If none are defective, you can reinstall all of them. Since the 1027s and 1023s are in parallel, if one is defective, both in the pair need to be replaced. The two used in parallel should have the same date/production code. You may have to buy extras to help ensure that you receive a pair with the same date code.
Order the Zener from the same place you get the FETs.
Continuity isn't a black/white thing. You can have continuity through a lamp but it's not a direct short or an open circuit. When the meter beeps, it likely means that the voltage across the leads is less than 0.7v. If you're unsure about the transistors, use the form on the basic repair page (link below) and email me the screen caps. Check them on both ohms and diode check. That page also explains how to check the transistors (and provides links to show you how to check other semiconductors).
You have to pull them to check them. You can't get definitive readings while the transistors are in the circuit. If none are defective, you can reinstall all of them. Since the 1027s and 1023s are in parallel, if one is defective, both in the pair need to be replaced. The two used in parallel should have the same date/production code. You may have to buy extras to help ensure that you receive a pair with the same date code.
Order the Zener from the same place you get the FETs.
Continuity isn't a black/white thing. You can have continuity through a lamp but it's not a direct short or an open circuit. When the meter beeps, it likely means that the voltage across the leads is less than 0.7v. If you're unsure about the transistors, use the form on the basic repair page (link below) and email me the screen caps. Check them on both ohms and diode check. That page also explains how to check the transistors (and provides links to show you how to check other semiconductors).
i still cant find the zener diode. i ordered the new part number that was reccomended (1n5242B) from mcmc in hopes that i could match it to one that looks the same that is on the board. i cant find anything on the board that looks like these.
i replaced a diode at location D751 (there is a picture a couple posts back) i thought this might be a zener diode but it is a different part number.
i can post more pictures if someone could help me find it. how many are there? i ordered 10 of them
i replaced a diode at location D751 (there is a picture a couple posts back) i thought this might be a zener diode but it is a different part number.
i can post more pictures if someone could help me find it. how many are there? i ordered 10 of them
The originals may be marked 1N759 and may be silver instead of orange. There are 4 of them. The only ones that are likely to have failed are the ones nearest to the outputs that failed.
Their circuit board designations will be one of the following:
D201
D301
D231
D331
They are near the pairs of large resistors with red, red, red, gold bands.
Their circuit board designations will be one of the following:
D201
D301
D231
D331
They are near the pairs of large resistors with red, red, red, gold bands.
so i have replaced all the burnt out components i even replaced the diodes at all 4 of those locations.
when i apply 12v to it the ground wire gets super hot and starts smoking. there is a small lightbulb in the middle of the board it shines super bright when i first apply power then it slowly dims then goes off. it does this everytime i put power to the board.
nothing is smoking or starting on fire except the ground wire. and there is no sound at all
when i apply 12v to it the ground wire gets super hot and starts smoking. there is a small lightbulb in the middle of the board it shines super bright when i first apply power then it slowly dims then goes off. it does this everytime i put power to the board.
nothing is smoking or starting on fire except the ground wire. and there is no sound at all
You should have powered it up via a 15 amp fuse or a current limiter. If you haven't done so, read through the basic repair page of my site. Pay special attention to the information in the yellow table/box.
You need to re-check all of the FETs in the amp. Excessive current flow could have caused 1 or more to fail.
The lamp in the center of the board is on the 12v side of the power supply and only indicates that the power has switched on. It goes dim because the 12v supply voltage is dropping.
You should pull the rectifiers to see if the amp will power up with them out of the circuit. If it does, the problem is likely in the audio section. If it still won't power up with the rectifiers removed, the problem is most likely in the power supply circuit.
You need to re-check all of the FETs in the amp. Excessive current flow could have caused 1 or more to fail.
The lamp in the center of the board is on the 12v side of the power supply and only indicates that the power has switched on. It goes dim because the 12v supply voltage is dropping.
You should pull the rectifiers to see if the amp will power up with them out of the circuit. If it does, the problem is likely in the audio section. If it still won't power up with the rectifiers removed, the problem is most likely in the power supply circuit.
i did use a big ceramic resistor to power it up and i am using a 10 amp fuse to test. i still went through and checked all the transistors. they seem fine.
i pulled the MUR3040 (there are 4) and i tried to power the amp up with the resistor again. im getting the same symptoms.
from the audio side i changed out all the zener diodes that you mentioned. (D 201,301,231.331) with part number 1N5242B from MCM. i also changed out as many 2SA1023 as i could find nearest the failed IRF9640 AND IRF640. these locations were Q403,Q335,Q334,Q302,Q303Q103. i know i was told to change them with new 1027s but i didnt. i just changed out as many as i could see on that side of the board. im guessing that this could be my problem. i kept all the old ones and i was careful when i took them out i can put them back in if need be.
i also changed the parts at location d751, q751, q506 and d741
there is a picture a couple posts back of those parts.
is there anything else i should be checking or looking at?
i pulled the MUR3040 (there are 4) and i tried to power the amp up with the resistor again. im getting the same symptoms.
from the audio side i changed out all the zener diodes that you mentioned. (D 201,301,231.331) with part number 1N5242B from MCM. i also changed out as many 2SA1023 as i could find nearest the failed IRF9640 AND IRF640. these locations were Q403,Q335,Q334,Q302,Q303Q103. i know i was told to change them with new 1027s but i didnt. i just changed out as many as i could see on that side of the board. im guessing that this could be my problem. i kept all the old ones and i was careful when i took them out i can put them back in if need be.
i also changed the parts at location d751, q751, q506 and d741
there is a picture a couple posts back of those parts.
is there anything else i should be checking or looking at?
What value is the ceramic resistor?
With the rectifiers removed, all transistors clamped to the sink and only the 10 amp fuse in series with the B+ line (no resistor), does the 10 amp fuse blow when you power up the amp?
You stated that you are 'getting the same symptoms'. What are they? Previously, the power wire was smoking. That isn't likely with the 10 amp fuse in series with the B+ line. The light will dim (especially with the resistor in series).
With the rectifiers removed, all transistors clamped to the sink and only the 10 amp fuse in series with the B+ line (no resistor), does the 10 amp fuse blow when you power up the amp?
You stated that you are 'getting the same symptoms'. What are they? Previously, the power wire was smoking. That isn't likely with the 10 amp fuse in series with the B+ line. The light will dim (especially with the resistor in series).
After the relay clicks, what is the DC voltage on the center leg of the power supply FETs?
What is the DC voltage on the first leg of the power supply FETs?
Measure the voltage on 'all' of them. They should be the same but you need to confirm that they're the same. You only need to post 2 voltages if the voltage is essentially the same on all of the power supply FETs.
What is the DC voltage on the first leg of the power supply FETs?
Measure the voltage on 'all' of them. They should be the same but you need to confirm that they're the same. You only need to post 2 voltages if the voltage is essentially the same on all of the power supply FETs.
i have an auto ranging multimeter and when i measure the voltage to the ones i have labeled X to X. it is jumping around all over the place and beeping. it goes to xx hertz and xx% and the dc voltage for a second. it is difficult to get a read on those legs. i have 2 more power supply FETs but they are equally as goofy as these ones.
Attachments
The 3205s are the power supply FETs. These are the rectifiers.
Pull the 4 rectifiers to see if the amp will power up with them out of the circuit. If it powers up normally, you should read something near 5v on the first leg of the power supply FETs and ~12v on the center leg of the power supply FETs.
Pull the 4 rectifiers to see if the amp will power up with them out of the circuit. If it powers up normally, you should read something near 5v on the first leg of the power supply FETs and ~12v on the center leg of the power supply FETs.
i just had those rectifiers out this morning and the amp did the same thing.
i have 10.5 volts at the power supply and that is what i am getting at the center leg of each of the power supply fets (3205) the 1st leg is giving me 3v. im guessing its a little low due to the power drain?
should i pull the 3040s again?
i have 10.5 volts at the power supply and that is what i am getting at the center leg of each of the power supply fets (3205) the 1st leg is giving me 3v. im guessing its a little low due to the power drain?
should i pull the 3040s again?
If nothing is getting warm even after being on for 15 minutes or more, the amp may be OK.
The supply is obviously having trouble powering it but it may be good enough to test at very low levels. Connect a speaker and a signal source to the amp to see if it will produce audio. It won't produce any audio until after the replay clicks. If driven to any significant output, the amp is likely to shut down due to low supply voltage.
If it works on the small supply, reconnect it in the vehicle but do so through a 15 amp fuse. It should play to a reasonable level before blowing the 15 amp. After you blow the 15 amp fuse, turn the volume down and power it up through another 15 amp fuse to confirm that the amp is still in good working order. After you know it's OK, you can remove the 15 amp fuse from the B+ line. Initially, play it at a very low level for 10 minutes while monitoring the temperature. Nothing should heat up.
If you're going to connect it to the same speakers/wiring, check both to make sure there are not shorts to ground or across the speaker wires.
The supply is obviously having trouble powering it but it may be good enough to test at very low levels. Connect a speaker and a signal source to the amp to see if it will produce audio. It won't produce any audio until after the replay clicks. If driven to any significant output, the amp is likely to shut down due to low supply voltage.
If it works on the small supply, reconnect it in the vehicle but do so through a 15 amp fuse. It should play to a reasonable level before blowing the 15 amp. After you blow the 15 amp fuse, turn the volume down and power it up through another 15 amp fuse to confirm that the amp is still in good working order. After you know it's OK, you can remove the 15 amp fuse from the B+ line. Initially, play it at a very low level for 10 minutes while monitoring the temperature. Nothing should heat up.
If you're going to connect it to the same speakers/wiring, check both to make sure there are not shorts to ground or across the speaker wires.
i used a larger guage ground wire and it seems that the furthest IRF640 was getting hot so i pulled it then the one next to it got hot so i pulled that one too an so on and so on till i pulled 4 of them. it now seems to power up and not smoke ground wire and non of the other transistors are getting hot.
i know you say over and over again how incredibly detrimental it is to put power with out all the fets clamped down. but why is it so bad? is it a ground thing? a heat thing? if i watch it closely it a situation like this is it ok ofr a second? i put solder paste over all the transistors on both sides so i could tell quickly which one was getting hot. when it started to bubble and smoke i deisengaged power. am i cause uneeded load or strain on parts by doing this?
so far i have attemed to fix about 3 amps and i seem to be getting a simalr problem with my solder techniques. it seems that after i solder in a new transistor where the solder pad meets the circut board there are little sparks. sometimes they go away on there own and sometimes i need to dig a little hole and get rid of the carbon. its always white and bright sparks sometimes very small and sometimes pretty crazy.
i still havent bothered to hook sound up to this ill go and get some new irf640 and 9640s before i try and start over again.
i know you say over and over again how incredibly detrimental it is to put power with out all the fets clamped down. but why is it so bad? is it a ground thing? a heat thing? if i watch it closely it a situation like this is it ok ofr a second? i put solder paste over all the transistors on both sides so i could tell quickly which one was getting hot. when it started to bubble and smoke i deisengaged power. am i cause uneeded load or strain on parts by doing this?
so far i have attemed to fix about 3 amps and i seem to be getting a simalr problem with my solder techniques. it seems that after i solder in a new transistor where the solder pad meets the circut board there are little sparks. sometimes they go away on there own and sometimes i need to dig a little hole and get rid of the carbon. its always white and bright sparks sometimes very small and sometimes pretty crazy.
i still havent bothered to hook sound up to this ill go and get some new irf640 and 9640s before i try and start over again.
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