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Old 8th January 2013, 03:53 AM   #71
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I ordered the thermal grease. They sent me two confirmations. the second one listed only item three: The thermal grease.

Heat sinks are small bent metal pieces shaped like a U the sides are cut like fingers. A heat sink. I know you have seen them.

I'm excited!
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Old 8th January 2013, 03:57 AM   #72
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Heat Sink

273-AB - WAKEFIELD SOLUTIONS - HEAT SINK | Newark
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Old 8th January 2013, 11:49 AM   #73
JMFahey is offline JMFahey  Argentina
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Quote:
I'm excited!
Cool, way to go.
Now, I don't know what you ordered those heatsinks for, the FM212 already has its own (much larger , by the way).
You must re-mount everything as it was originally.
But I'm happy too, we are in the good path.
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Old 8th January 2013, 10:31 PM   #74
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Cool Heat Sinks

The heat sinks were 61 cents each. I was going to ask you about mounting them on top of the transistors via the anchor screw since they apparently run so hot. And I figured if you said no I wasn't out much anyway.

BR
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Old 10th January 2013, 01:10 AM   #75
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My new parts arrived today. I carefully removed the transistors and installed the new one and connected the wires and flipped the switch with no speaker and the light on the current limiter came on. So that was a disappointment. Now I am going over everything again trying to fine what I could have possibly done wrong with this thing. Not sure what to check now.
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Old 10th January 2013, 01:17 AM   #76
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I would next check the rest of the transistors in the driver stages for shorts.
You could also check the resistors are the correct values and haven't burned out.
Check any capacitors for shorts.

I have seen me resort to taking out all the transistors out and checking the gain on a meter.
I had one amp with 12 transistors and by sods law it was the last transistor that had failed with a gain of 1.

I found that after removing all the transistors it was easier to check all the passive components.
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Old 10th January 2013, 01:21 AM   #77
JMFahey is offline JMFahey  Argentina
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Quote:
trying to fine what I could have possibly done wrong with this thing
I think yoy replaced transistors right (hope so), but maybe there are still other problems.
Start by:
1) with amp off and unplugged from mains, and multimeter set on diode test, check lack of continuity betwen each new transistor collector (centerleg) and ground.
You might have had some burr under the micas, or over pressed the silpads, it's not that hard to go through them, they are as hard as a piece of a kid's Birthday balloon.
And don't despair, sometimes you get lucky on first try (I hoped so), sometimes you must test a little more.
Good luck.
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Old 10th January 2013, 02:28 AM   #78
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Default New Resistors

Transistor Collector test, meter set to Diode Test:

Q20 - .002
Q18 - .002
Q19 - .002
Q21 - see pic
Attached Images
File Type: jpg New Transistors.jpg (613.6 KB, 42 views)
File Type: jpg Q18.jpg (489.2 KB, 41 views)
File Type: jpg Q18 and Q19.jpg (574.4 KB, 38 views)
File Type: jpg Q20.jpg (514.3 KB, 38 views)
File Type: jpg Q 21 Collector Test.jpg (476.1 KB, 36 views)
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Old 10th January 2013, 10:40 AM   #79
JMFahey is offline JMFahey  Argentina
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Well, I see a nice, solid *short* there.
Two of them in fact.
*My* fault, of course.
I should have warned you that the original Japanese transistor has a built-in plastic insulated tab and the hole in it, while the TIP has an exposed metal tab and mounting hole.
That's why the Japanese has a 3 mm hole, and the American has a larger 4 mm one, so you can fit an insulated nipple there, which both insulates the hole inside and the screw head:
You need this, which you won't have to order, I'm sure local Radio Shack or equivalent has it:
Click the image to open in full size.
You needn't solder anything, just pull the screw, push the nipple in the hole and replace screw.
Sorry
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Old 10th January 2013, 06:35 PM   #80
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I installed the insulators as instructed and hooked the power and the current limiter lit but just barely. So I hooked directly to power and flipped the switch and the fuse did not blow. S I then hooked up the speakers and my guitar and there is no sound coming out. I adjusted all the knobs and got nothing. I tried the drive and more drive channels and still nothing.

At idle there is a very slight hum or buzz. Its almost inaudible. I have to really listen to hear it.

The Q 18, 19, 20 and 21 are pretty hot. I imagine they run hot since they need such a large heat sink but these are pretty hot. I'm talking burn my finger hot. Is that normal?

I don't want to turn this back on till here back from you but when I do fire it up I have a laser thermometer I can get the surface temp if you need it.

Thanks!

BR
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