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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Sat Sep 12, 2009 1:05 am Post subject: |
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Yeah, almost all the small 1/8W size resistors on the Marquee bds are this type. They are 1/2W but are tiny. Generally the ones used for protection are raised up off the pcb.
Scott
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Sep 12, 2009 1:06 am Post subject: |
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| macgyver655 wrote: | | No offense here at all Drag but I'm having a hard time swallowing even the 8 ohm off as the problem. But you never know. You sure that maybe there was a bad solder joint on one of these resistors and replacing them was what fixed that issue. |
believe me I looked with a jewelers loop at every solder pad on the F-in thing. I don't think 8ohms off is that far fetched though? I mean if it's 61 ohm rated then 8 ohms out is a 13% error? That's almsot triple it's allowed deviance and more than enough to cause a FET to go flaky no?
i'm just guessing here, i lay no claim to board tech proficiency.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Sat Sep 12, 2009 1:06 am Post subject: |
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Drags did you measure that Resistor R618 while on the board? Sometimes thats a no no, always lift one end when testing. this is why...., thats not a 61 ohm according to the schematics. its one of the safety resistors and a 1 ohm value and one of the ones I replaced with a better fusible type.
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Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Sep 12, 2009 1:08 am Post subject: |
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| tse wrote: | Yeah, almost all the small 1/8W size resistors on the Marquee bds are this type. They are 1/2W but are tiny. Generally the ones used for protection are raised up off the pcb.
Scott |
thanks Scott, Ill put the new ones in same way, up off the board. BTW like your signature line,a sign of our times for sure.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Sep 12, 2009 1:11 am Post subject: |
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| Nashou66 wrote: | | Drags did you measure that Resistor R618 while on the board? Sometimes thats a no no, always lift one end when testing. this is why...., thats not a 61 ohm according to the schematics. its one of the safety resistors and a 1 ohm value and one of the ones I replaced with a better fusible type. |
it measured 69 ohms both in and out. I've been using the better fusibles too, your right it's R618. I just looked again, the problem resistor for me was R623. Sorry about that.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Sat Sep 12, 2009 1:16 am Post subject: |
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| draganm wrote: | | Nashou66 wrote: | | Drags did you measure that Resistor R618 while on the board? Sometimes thats a no no, always lift one end when testing. this is why...., thats not a 61 ohm according to the schematics. its one of the safety resistors and a 1 ohm value and one of the ones I replaced with a better fusible type. |
it measured 69 ohms both in and out. I've been using the better fusibles too, your right it's R618. I just looked again, the problem resistor for me was R623. Sorry about that. |
Hmm R623 is a 68 ohm Fusible so it really wasn't off. It must have been something else you replaced , weird... I hate when your not really sure what it is.
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sat Sep 12, 2009 1:21 am Post subject: |
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| draganm wrote: | | macgyver655 wrote: | | No offense here at all Drag but I'm having a hard time swallowing even the 8 ohm off as the problem. But you never know. You sure that maybe there was a bad solder joint on one of these resistors and replacing them was what fixed that issue. |
believe me I looked with a jewelers loop at every solder pad on the F-in thing. I don't think 8ohms off is that far fetched though? I mean if it's 61 ohm rated then 8 ohms out is a 13% error? That's almsot triple it's allowed deviance and more than enough to cause a FET to go flaky no?
i'm just guessing here, i lay no claim to board tech proficiency. |
The 5% spec is for the resistor when new, meaning that even new it can have a 5% variation of its rated value. It has nothing to do with the circuit that its used in. The circuit can have a much wider range of tolerance value.
This situation would bother me so much that I would have to reinstall the original resistor just to verify that it again doesn't work with that one installed.... 
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Sat Sep 12, 2009 1:27 am Post subject: |
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| macgyver655 wrote: | | draganm wrote: | | macgyver655 wrote: | | No offense here at all Drag but I'm having a hard time swallowing even the 8 ohm off as the problem. But you never know. You sure that maybe there was a bad solder joint on one of these resistors and replacing them was what fixed that issue. |
believe me I looked with a jewelers loop at every solder pad on the F-in thing. I don't think 8ohms off is that far fetched though? I mean if it's 61 ohm rated then 8 ohms out is a 13% error? That's almsot triple it's allowed deviance and more than enough to cause a FET to go flaky no?
i'm just guessing here, i lay no claim to board tech proficiency. |
The 5% spec is for the resistor when new, meaning that even new it can have a 5% variation of its rated value. It has nothing to do with the circuit that its used in. The circuit can have a much wider range of tolerance value.
This situation would bother me so much that I would have to reinstall the original resistor just to verify that it again doesn't work with that one installed.... |
Exactly!!! I'm dying to find out if that was really the issue!!!
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Sat Sep 12, 2009 1:50 am Post subject: |
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I remember Scott mentioning a re-settable fusible resistor to use in the marquee. I found his post on My Marquee thread so I'll repost it here:
| tse wrote: | These are a neat alternative to fusible resistors. Polyswitch resettable fuses. If one "blows" you just turn off the power for a minute and the device resets itself. No resoldering resitors if you do a slip with the test probe or drop something in a bad place. Of course, if something is shorted, the "fuse" will just blow again when you turn on the power.
For 1 ohm resistors use RXEF075
For 2.2 ohm resistors use RXEF050
For 10 ohm resistors use RXEF020
For two 1 ohm resistors soldered in parallel use RXEF135
That should cover most of the resistor "fuses" used in the Marquee.
Attachment shows Marquee resistor "fuse" and RXE040 which is smaller than RXEF050 and a bit larger than RXEF020.
Scott |
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Sep 12, 2009 3:24 am Post subject: |
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Well I'd like to know too. I tried it Wednesday night and it didn't work. Then Thursday night the only thing I changed was R623. Parts list does in fact shows 68ohm fusible but why are the bands wrong. 68 ohm would be Blue-silver-black. The second band is brown on this one I took out? I guess I should have looked at the parts list last night, it was 12AM by the time I put everything away though.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sat Sep 12, 2009 3:39 am Post subject: |
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I like my repair better. I use a penny nail to bypass all of those silly fusistors.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sat Sep 12, 2009 4:06 am Post subject: |
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| Curt Palme wrote: | | I like my repair better. I use a penny nail to bypass all of those silly fusistors. |
ok, that mede me laugh 
it does raise a question. anyone ever known a fusible resistor to be intermittent? Like it checks OK with a meter but as soon as you put power to it opens?
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sat Sep 12, 2009 4:11 am Post subject: |
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No, I don't buy that, but it's easy to check: Meter the voltage on either side when it's powered up.
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