netlist
this is the lowdown
we were playing and the 8.5 smoked
now for whats blown is the mps-6533/34 transistior is completely gone
and mje-15031 driver transistior looks to have a hole in it
other than just replace the part that gone what else should be checked? i do have use of a dvm. is there a way to check the driver tran on the board
thanks
this is the lowdown
we were playing and the 8.5 smoked
now for whats blown is the mps-6533/34 transistior is completely gone
and mje-15031 driver transistior looks to have a hole in it
other than just replace the part that gone what else should be checked? i do have use of a dvm. is there a way to check the driver tran on the board
thanks
Fellowesman,
this is not just random component failure but a rather major problem.
You will have to take out all output transistors and drivers and it will be best to replace them all if you want a good repair. Every diode and resistor will need to be checked in the output stage. Again, if you are not familiar with this kind of amps, I strongly suggest to take it to a good service point.
/Hugo
this is not just random component failure but a rather major problem.
You will have to take out all output transistors and drivers and it will be best to replace them all if you want a good repair. Every diode and resistor will need to be checked in the output stage. Again, if you are not familiar with this kind of amps, I strongly suggest to take it to a good service point.
/Hugo
netlist
as you seen in earler post was just sent home after haveing a heart
attack. have plenty of time on my hands and very little money.
i did check with a repair shop near here and was told "just return it to
peavey" they would not even look at it. i have found that very few
places will fix i mean repair anything (replace componets) they just
want to replace the whole board!
i have the part lay out and the schematcs for this amp and the use of
a dvm. i should replace parts 200 204 and 100 104 along with parts
202 203 and 102 103
thanks
as you seen in earler post was just sent home after haveing a heart
attack. have plenty of time on my hands and very little money.
i did check with a repair shop near here and was told "just return it to
peavey" they would not even look at it. i have found that very few
places will fix i mean repair anything (replace componets) they just
want to replace the whole board!
i have the part lay out and the schematcs for this amp and the use of
a dvm. i should replace parts 200 204 and 100 104 along with parts
202 203 and 102 103
thanks
Of course you are correct. We are talking driver board. I had the output board in mind. My schematic is so bad I can hardly read the part numbers.
So, check all you can, the visually damaged parts are definitely to be replaced, take out every transistor that measures slightly suspicious on that board and measure it out of circuit. Same with the diodes.
As for the output board, failure of the driver board could have damaged one or more outputs. Take your time and check them as well.
I hate to ask but do you know how to measure a semiconductor?
I'll gladly explain if not.
/Hugo
So, check all you can, the visually damaged parts are definitely to be replaced, take out every transistor that measures slightly suspicious on that board and measure it out of circuit. Same with the diodes.
As for the output board, failure of the driver board could have damaged one or more outputs. Take your time and check them as well.
I hate to ask but do you know how to measure a semiconductor?
I'll gladly explain if not.
/Hugo
Hi.
Can I recommend starting a new thread for your amp rather than adding on at the end of a thread that died 10 years ago.
The cause of shorted outputs? WHo knows, it could be anything. Bad speaker cables, bad speaker loads, static electric charge, etc. You just have to start troubleshooting and doing the repairs.
First, Peavey uses crowbar circuits across the outputs, look on the schematic near the speaker connection and you should see a triac to ground. If the amp goes to DC - a failure mode - that triac turns on and shunts the output to ground. it usually gives its life in the process, but it also blows the fuse and thus prevents a fire. SO measure resistance between the red and black speaker posts on each channel. If either appears shorted across, then that channel triac is probably the short.
Within each channel, start by looking for shorted output transistors.
Can I recommend starting a new thread for your amp rather than adding on at the end of a thread that died 10 years ago.
The cause of shorted outputs? WHo knows, it could be anything. Bad speaker cables, bad speaker loads, static electric charge, etc. You just have to start troubleshooting and doing the repairs.
First, Peavey uses crowbar circuits across the outputs, look on the schematic near the speaker connection and you should see a triac to ground. If the amp goes to DC - a failure mode - that triac turns on and shunts the output to ground. it usually gives its life in the process, but it also blows the fuse and thus prevents a fire. SO measure resistance between the red and black speaker posts on each channel. If either appears shorted across, then that channel triac is probably the short.
Within each channel, start by looking for shorted output transistors.
Enzo ,Thanks for the advice ,But this seem strange as it may appear the fault may be common to both A and B side .A few of the out put transistors shorted out ,so i took them all out and use my bk transistor meter to test all out put transistors .I then took some from side B and put with A .I could not get the origanal peavy transistors so i got some replacement and mix them on side B .I checked all components an the out put boards and i found no fault ,I then power it up then the both sides shot again . Could the fault be on the driver board - i mean the board on the side with the chip please tell me .
Just because both sides failed, doesn;t mean they are connected. The connection could be as simple as the guy that blew it up was abusing both channels at the same time.
What did you use for replacement? Peavey (and me) do not recommend mixing transistors on those outputs. The original Motorola types (Now made by On Semi) are still available from PV or in the market. PV publishes a semi cross reference. The old SJ numbers were superceded by 704xxxxx numbers for the same parts. All the old Moto parts with those house numbers were still regular parts under the skin, such as MJ15024 or MJ15003, and so on. PLEASE do not go get NTE stuff for this.
Pick one channel first and fix it, then and only then, go fix the other channel. Moving parts back and forth is asking for trouble.
Did you measure resistance from black to red speaker posts? Shorted triacs will just blow up good new parts you install.
You need to test outputs fro shorts, then check all associated resistors, like the 5w and 10w fractional ohm ballast resistors as well as any base circuit resistors plus the small resistors that sample voltage off the ballasts.
ANy time outputs are blown, you must check the drivers and predrivers on that output board. Don;t forget R120 between them, as well as all those bias diodes CR100/101/109/107.
Could there be issues back on the driver boards? Yes, of course, but we need to get the output board set.
From your post I get the idea you replaced some parts and flipped it on. No no no. Look up light bulb limiter, make one (they are simple), and USE it. if you have a variac and ammeter, get that out as well. We never flip it on and hope.
And work with NO speaker or load until the amp is stable and working.
What did you use for replacement? Peavey (and me) do not recommend mixing transistors on those outputs. The original Motorola types (Now made by On Semi) are still available from PV or in the market. PV publishes a semi cross reference. The old SJ numbers were superceded by 704xxxxx numbers for the same parts. All the old Moto parts with those house numbers were still regular parts under the skin, such as MJ15024 or MJ15003, and so on. PLEASE do not go get NTE stuff for this.
Pick one channel first and fix it, then and only then, go fix the other channel. Moving parts back and forth is asking for trouble.
Did you measure resistance from black to red speaker posts? Shorted triacs will just blow up good new parts you install.
You need to test outputs fro shorts, then check all associated resistors, like the 5w and 10w fractional ohm ballast resistors as well as any base circuit resistors plus the small resistors that sample voltage off the ballasts.
ANy time outputs are blown, you must check the drivers and predrivers on that output board. Don;t forget R120 between them, as well as all those bias diodes CR100/101/109/107.
Could there be issues back on the driver boards? Yes, of course, but we need to get the output board set.
From your post I get the idea you replaced some parts and flipped it on. No no no. Look up light bulb limiter, make one (they are simple), and USE it. if you have a variac and ammeter, get that out as well. We never flip it on and hope.
And work with NO speaker or load until the amp is stable and working.
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