Thermal Paste [message #11930] |
Tue, 22 September 2009 12:28 ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
LZBass
Messages: 16 Registered: September 2009
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Junior Member |
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I'm in process of repairing my first K2001-A. Does it make sense to replace the thermal compound on the power transistors while I'm inside? The head was manufactured around 1968 and I'm sure nothing has been done to it since it left the factory.
Thanks for the help!
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Re: Thermal Paste [message #11931 is a reply to message #11930] |
Tue, 22 September 2009 12:53 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
chicagobill
Messages: 2005 Registered: April 2003
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Senior Member |
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It certainly wouldn't hurt.
Whenever I buy a Kustom amp, I will always go through it to see what has been done to it in the past. I also check for any loose parts, wires, etc.
And in order to know that the transistors are mounted correctly, I will remove all the old grease and re-mount them. It only takes a half an hour or so, and then I know that they are ok.
I'd suggest that you at least tighten up the mounting screws.
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Re: Thermal Paste [message #11933 is a reply to message #11932] |
Tue, 22 September 2009 18:10 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
chicagobill
Messages: 2005 Registered: April 2003
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Senior Member |
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The original fuse was probably soldered in, but I'd have to check my A series head to be sure.
In any case the originals used 3AG sized fuses rated for 3 amps.
If the fuse is blown, I'd check the output transistors and the bridge rectifier for shorts.
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Re: Thermal Paste [message #11943 is a reply to message #11942] |
Wed, 23 September 2009 11:35 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
chicagobill
Messages: 2005 Registered: April 2003
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Senior Member |
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7 1/2 amp is way too high a value for that fuse.
The fuse located on the front panel near the power switch is the main ac line fuse. The standard value is 3 amps. The original one was probably a soldered in pigtail fuse.
The one on the power amp pc board is the speaker protection fuse. It is rated at 8 amps. Its real purpose is only to help prevent damage to the speakers in case an output transistor should short and place dc voltage across the speaker output.
Normally if an output transistor shorts, the main fuse will blow long before the speaker protection fuse does. If the main fuse was replaced with one with too large a value, then the output fuse would still be there to help protect the speakers from damage.
Because the Kustom ac line fuse was inside the chassis and was soldered in, it would take a lot of effort to try and bypass the main fuse. I've seen a lot of amps damaged by people that would use tin foil and gum wrappers to replace a blown fuse.
On the later B-series heads the speaker fuse was removed from the design, as they weren't really needed.
For my own Kustom amps, if I need to replace a power fuse, I remove the existing terminal block and replace it with a fuse holder that will accept standard size fuses.
In your photos, there are two green wires added to the power switch. What are they there for?
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Re: Thermal Paste [message #11960 is a reply to message #11943] |
Wed, 23 September 2009 21:51 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) |
LZBass
Messages: 16 Registered: September 2009
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Junior Member |
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The installation of the fuse holder seems to have been done by a tech as they even installed an isulator to the front chassis between the chassis and the fuse holder. Looks like a clean install. I wonder what else was done...
It appears that the original power ON lamp was replaced with a 110v AC lamp. That's where the two green wires are attached.
Was the chassis used as a common ground? Doesn't seem like it from what I can tell.
Thanks again for all your help.
-- Phil --
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