Right by led area. Very small.should I begin removal of boards, or other poking/measuring first? I may as well get this on with. Think it killed the transistor sandwich with heat sink?
BA3 to duty, XA25 to hospital.
BA3 to duty, XA25 to hospital.
The way my boards are wired, I believe I can undo the board from mosfets and rotate it to see underside. I've looked at all the active devices, no obvious burn and melt, blackening, etc that is obvious. Maybe I'm lucky and just smoked two resistors? Let's get that board loose. I will likely have to order proper resistor value, don't know if I have these, they are very small in size.
Looks like R21 got over done too. R21, R22 and R24. Will look these up, as well as all these 3 legged creatures, they look good but that may mean nothing! I'm just glad my boards didn't get burnt.
So far only KNOWN casualties are 3 resistors on each side. I will probably order the 3 legged creatures too ...Once before I removed one for test in another amp. It was fine, but I lost a leg and had to replace anyway. I will see what these parts are, then ask about part type if special matching or whatever is required.
I should probably also get the parts for the little sandwich with the heatsink. At least mica and heatsink are reusable!
Russellc
So far only KNOWN casualties are 3 resistors on each side. I will probably order the 3 legged creatures too ...Once before I removed one for test in another amp. It was fine, but I lost a leg and had to replace anyway. I will see what these parts are, then ask about part type if special matching or whatever is required.
I should probably also get the parts for the little sandwich with the heatsink. At least mica and heatsink are reusable!
Russellc
R21 AND R22 = 100R
R24= 43R
1/8 watt or 1/4 watt, preferred type if any, what ever I burnt up was nice....
Actives (dont know if these are dead, look fine as in not burnt)
Q1 BD139 and Q2 BD140 (heatsink pair.
T1, T5 and T7= BC639
T2,T3,T4= BC546
T6= BC640
Any of these require special range or other specification?
While I am a it, and while this is the straight mosfet version, should I trade out ZD3 and ZD4 = 8V2? Or is this not necessary on straight puck-mosfet version?
R24= 43R
1/8 watt or 1/4 watt, preferred type if any, what ever I burnt up was nice....
Actives (dont know if these are dead, look fine as in not burnt)
Q1 BD139 and Q2 BD140 (heatsink pair.
T1, T5 and T7= BC639
T2,T3,T4= BC546
T6= BC640
Any of these require special range or other specification?
While I am a it, and while this is the straight mosfet version, should I trade out ZD3 and ZD4 = 8V2? Or is this not necessary on straight puck-mosfet version?
actives - in all cases suffix ( range) is irrelevant
changing zeners to 8V2 is not necessary, but you can do that for better sleep
changing zeners to 8V2 is not necessary, but you can do that for better sleep
I found the BC 639 and BC 640, BC 546 gave a few different ones, difference being HFE. One 800, one 450, and finally one 220.
Does HFE matter with this piece?
BD 139 is similar, one picture showed a metal piece on back, others appeared all black. Any differences or no matter? The BD 140 isnt available in that type of case so I guess it doesnt matter.
1/8 watt enough for resistors? They are cheap guess I can get both 1/8 and 1/4, extras can go in the resistor bag.
Hopefully mouser is extra quick!
Russellc
Does HFE matter with this piece?
BD 139 is similar, one picture showed a metal piece on back, others appeared all black. Any differences or no matter? The BD 140 isnt available in that type of case so I guess it doesnt matter.
1/8 watt enough for resistors? They are cheap guess I can get both 1/8 and 1/4, extras can go in the resistor bag.
Hopefully mouser is extra quick!
Russellc
I just ordered a bunch too 😃. When you cooked your "sandwich" did you also smoke R21,22 and 24? Were any of the other actives cooked?
Thanks,
Russellc
Thanks,
Russellc
Mine made a good pop noise and I saw two tiny puffs of smoke rise out of lid from both mid sections.
Did your sandwich look cooked? Mine looks fine. Of course, static smoked jfets LOOK fine too....
Did your sandwich look cooked? Mine looks fine. Of course, static smoked jfets LOOK fine too....
The basic number 639 and 640 transistors are out of production. I will list the parts I ordered, fortunately they were inexpensive. Basically they had 639 and 640 with additional numbers tailing after, don't think that's a problem
Apparently, 1/8 ohm resistors are hard to find, either back ordered or need to order 500 to 5000 parts. Got them where I could, filled in with 1/4 watt.
Also had hard time finding 43 ohm part, went with 43.2 ohm 1% pieces
Apparently, 1/8 ohm resistors are hard to find, either back ordered or need to order 500 to 5000 parts. Got them where I could, filled in with 1/4 watt.
Also had hard time finding 43 ohm part, went with 43.2 ohm 1% pieces
I wanted 1/8 watt but keep running into "out" and backorder, or minimums of 500 to 5000If the 1/4 are too long I can mount soldier style.
Oh, mine was damaged by my own carelessness. Flipped on pearl 3 without turning preamp away from that selection. Transient made a pop, and that cooked it. I will have a peek at your deal and see what was up. I remember you were popping resistors.
Mine WAS running and measuring perfect before I messed up.
1/8 because they were generally smaller. Well, some were.
I would replace with exactly what I cooked if I knew brand, and assuming available. At least both channels will be the same after replacement.
Odd, but it drives me crazy if both sides aren't exactly alike. Silly, but best sleep is best sleep. That and taking army of psychiatrists to sort out. Easier to replace both. Here, I have no choice so sleep should be best!
I would replace with exactly what I cooked if I knew brand, and assuming available. At least both channels will be the same after replacement.
Odd, but it drives me crazy if both sides aren't exactly alike. Silly, but best sleep is best sleep. That and taking army of psychiatrists to sort out. Easier to replace both. Here, I have no choice so sleep should be best!