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chillman
Joined: 09 Apr 2007
Posts: 134
Location: Germany, Bavaria
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| Posted: Mon Dec 10, 2007 11:46 am Post subject: AmPro 3600 Modification |
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Hi,
I just wanted to show you the modification my new AmPro 3600 has: There's a heatsink glued on the convergence output which is cooling Q3, Q5 and CB1. What do you think about that?
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135.35 KB |
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4314 Time(s) |
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| The heatsink with cover closed |
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135.88 KB |
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4314 Time(s) |
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Mon Dec 10, 2007 1:45 pm Post subject: |
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That is entirely too funny! Q3 and Q5 are part of the current limit circuit that protects the power supply. When they limit the current they get hot and trip the thermostat which turns off the registration amps. If one wanted to run without protection it would have been alot easier to short across the transistors.
Scott
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chillman
Joined: 09 Apr 2007
Posts: 134
Location: Germany, Bavaria
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| Posted: Mon Dec 10, 2007 2:15 pm Post subject: |
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So it would probably be a good idea to remove the heatsink? Are Q3 and Q5 normally not connected to a heatsink at all? I think the seller has done this modification to some other sets too, at least I remember to have seen this in some of his other auctions...
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Mon Dec 10, 2007 5:00 pm Post subject: |
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Q3, Q5, and the thermostat are normally attached to a small aluminum plate (about 3 sq in). The transistors are normally saturated, turned full on so as to not drop the voltage going to the amps. When too much current is drawn they come out of saturation and heat up the small plate. It is possible to set the registration controls to a point where the LVPS is overloaded.
Scott
_________________
"Were we directed from Washington when to sow and when to reap, we would soon want bread."
Thomas Jefferson
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Mon Dec 10, 2007 6:38 pm Post subject: |
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SO class what have we learned here? Not all mods are good mods. 
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HD done right!
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chillman
Joined: 09 Apr 2007
Posts: 134
Location: Germany, Bavaria
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| Posted: Mon Dec 10, 2007 6:49 pm Post subject: |
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Yes, I will consider unmounting the heatsink, although this won't be easy as the guy who made the mod has simply glued the two screws holding the heatsink directly onto the board. So it won't be easy removing them without breaking the convergence output board. And I will have a hole in the cover. Kinda sucks...
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Mon Dec 10, 2007 6:52 pm Post subject: |
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How about just putting a vent over it or will that cause a misdirection of the air flow inside?
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Tech support for nothing
CRT.
HD done right!
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chillman
Joined: 09 Apr 2007
Posts: 134
Location: Germany, Bavaria
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| Posted: Mon Dec 10, 2007 6:59 pm Post subject: |
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(edit) Yeah would be a possibility, or I'll just leave the heatsink without connecting it to something.
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chillman
Joined: 09 Apr 2007
Posts: 134
Location: Germany, Bavaria
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| Posted: Tue Dec 11, 2007 4:51 pm Post subject: |
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Ok, so I managed to unmount the heatsink, so now I need a replacement for the original cooler/piece of metal...
Can someone tell me how the original part is shaped or post a pic of it? Like does it have any cooling fins, how thick etc.
Thanks in advance!
EDIT: I've replaced the heatsink with ca. 1x3 inch piece of aluminium from a heatsink out of a old pc power supply.
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Wed Dec 12, 2007 1:45 am Post subject: |
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That should work ok. The heatsink is purposely small.
Scott
_________________
"Were we directed from Washington when to sow and when to reap, we would soon want bread."
Thomas Jefferson
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chillman
Joined: 09 Apr 2007
Posts: 134
Location: Germany, Bavaria
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| Posted: Wed Dec 12, 2007 1:56 pm Post subject: |
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Ok, so thanks for your help!
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