DixieMan1994
Active Member
I can get the leads in there but the transistor sits at an angle
Recapping SX-737
- Thread starter DixieMan1994
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POST a Picture.
Two things off the top of my head: you've either got it mounted to the wrong side of the heat sink as compared with how they mounted the original one, thus moving it further physically from the hole, or, the hole in the heat sink is too high for the transistor (i.e. the legs are now too short).
Solution: either change the side of the heat sink you've got the Q mounted to for the first situation, or if the problem is the second, you could purchase new heat sinks with the hole closer to the board, fill in the old hole with JB Weld and drill a new one (tapping it for threads if needed), drill a new hole and not worry about filling the old, or drill a new hole and not bother tapping it...using a nut and bolt to secure it if it didn't use one originally.
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I presume the 2073 you are having trouble with is Q3 on the edge of the board. Like Jheu said flip the heatsink around 180*. The hole on the heatsink IIRC is offset to one end so you'll have some space on one way and not enough on the other. You want the longer side (hole to end) facing UP away from the board.
If you need to drill a new hole, Install the transistor so it's sitting straight up (or as close as you can to vertical), then set the heatsink behind the transistor on a couple of pieces of paper (shims) and mark the hole on the heatsink. Drill and then clean off the burrs. Then get the TO-220 kit and install. IF the heatsink won't work, then RATSHACK has a black finned heatsink you can use. Actually it works quite well. I've used it on my 790 for the voltage regulators (which you can fry eggs on), and they stay cool. a computer heatsink cut down to fit will work.
If you need to drill a new hole, Install the transistor so it's sitting straight up (or as close as you can to vertical), then set the heatsink behind the transistor on a couple of pieces of paper (shims) and mark the hole on the heatsink. Drill and then clean off the burrs. Then get the TO-220 kit and install. IF the heatsink won't work, then RATSHACK has a black finned heatsink you can use. Actually it works quite well. I've used it on my 790 for the voltage regulators (which you can fry eggs on), and they stay cool. a computer heatsink cut down to fit will work.
DixieMan1994
Active Member
I might try the Ratshack one, apologies I didnt think to post a pic earlier and I am currently away from the unit. Ill try and get a pic posted up if I can.
DixieMan1994
Active Member
I have it mounted the correct way on the heatsink, it sits at the exact same height as it did on the old one (I used a taller heatsink that I had laying around). The new heatsink I used is exactly the same as the old one with about a half inch added to the top. I would have re used the old one but the thermal grease on it was so cooked on there that I would have been scraping for a good while to get it off
Acetone or rubbing alcohol cleans it off really easily.
DixieMan1994
Active Member
Well I was able to make it work pretty well with that other heatsink. Flipped the heatsink upside down and it gave me enough room to get the transistor mounted properly in all three holes. Still had enough surface area on the heatsink to properly contact the body of the transistor and allow for good heat transfer. I did use the TO-220 kit btw.
DixieMan1994
Active Member
Ok. Got all the transistors replaced, everything cleaned up, checked solder joints, etc. Put it on the DBT on a 60, 75, and 100w. Checked out on the DBT, but still no relay click. Everything seems fine other than the relay not engaging. :headscrat
I haven't tried wall voltage on it this time. What are your guy's thoughts?
I haven't tried wall voltage on it this time. What are your guy's thoughts?
voltage measurements.
power supply, then power amplifier and protection.
power supply, then power amplifier and protection.
