LP1502iq - bridge (?) to be replaced - diyAudio
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Old 25th March 2008, 05:58 PM   #1
manina is offline manina  Germany
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Default LP1502iq - bridge (?) to be replaced

I opened my Linear Power 1502iq and noticed that a bridge (on the mainbord is br1a1)) is cocked (overheated) - the component is labelled ctu-2r 29302.

I have not found any info googling around while I can find info on the other one (br1a2 on the mainboard) labelled GI FEP16ct 9010.

What can be used to replace it?

It looks like it's the only component that have to be replaced - amp is working but claerly not 100%

btw - anyone has the schema of the ampli?

Thanks
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Old 25th March 2008, 06:49 PM   #2
shagone is offline shagone  United States
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those should be your positive and negative rectifiers (dual diodes) for your main positive and negative rail voltages. most 16amp rectifiers in the same TO-220AB package should work fine. remeber one is positive and one is negative. i would change both i were you and investigate why it blew. check for shorted caps and shorted stransitors in the power supply.
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Old 25th March 2008, 06:54 PM   #3
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Try these:

MUR1620CTR
FEP16CTA
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Old 26th March 2008, 09:59 AM   #4
manina is offline manina  Germany
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Quote:
Originally posted by shagone
those should be your positive and negative rectifiers (dual diodes) for your main positive and negative rail voltages. most 16amp rectifiers in the same TO-220AB package should work fine. remeber one is positive and one is negative. i would change both i were you and investigate why it blew. check for shorted caps and shorted stransitors in the power supply.

Yes, there are two of them, one for each side - one positive and one negative.

I have inspected the amp and all looks OK - amp is working. It's just the rectifier that looks coocked but still working.

Thanks also to Perry.
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Old 26th March 2008, 06:24 PM   #5
shagone is offline shagone  United States
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Quote:
Originally posted by manina



Yes, there are two of them, one for each side - one positive and one negative.

I have inspected the amp and all looks OK - amp is working. It's just the rectifier that looks coocked but still working.

Thanks also to Perry.

when you say it looks "coocked" in what way? is there black soot around it? have you checked it for shorts with a multimeter? it could just be old dried up flux on the board. you could always clean it up ad remove all the old solder and add new solder.

check your positive and negative rail voltages. are they close to the same besides the + and - ? be sure to have the board mounted to the sync while testing or the amp could overheat fast, especially an older one like this.

you could also post a photo for us to see.
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Old 26th March 2008, 10:12 PM   #6
manina is offline manina  Germany
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Quote:
Originally posted by shagone



when you say it looks "coocked" in what way? is there black soot around it? have you checked it for shorts with a multimeter? it could just be old dried up flux on the board. you could always clean it up ad remove all the old solder and add new solder.

check your positive and negative rail voltages. are they close to the same besides the + and - ? be sure to have the board mounted to the sync while testing or the amp could overheat fast, especially an older one like this.

you could also post a photo for us to see.

With "coocked" I mean that the top metal is turned to yellow while all the other elements are still of the original "metal" colour. Tomorrow I'll take a picture
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Old 27th March 2008, 12:15 PM   #7
manina is offline manina  Germany
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Quote:
Originally posted by manina



With "coocked" I mean that the top metal is turned to yellow while all the other elements are still of the original "metal" colour. Tomorrow I'll take a picture

Here it is a snapshoot with the rectifier circled -
Attached Images
File Type: jpg rectifier lp1502.jpg (91.3 KB, 186 views)
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Old 27th March 2008, 07:57 PM   #8
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Is the insulator damaged/cut under the rectifier?
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Old 28th March 2008, 07:38 PM   #9
manina is offline manina  Germany
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Quote:
Originally posted by Perry Babin
Is the insulator damaged/cut under the rectifier?

The insulator looks OK however the termal paste (the white one) seems dryed out.
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Old 28th March 2008, 08:18 PM   #10
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If the amp works, then don't worry about the rectifiers. Rectifiers either work or don't (in this application). When they fail on these amps, they short out completely and the amp won't turn on. If the amp still has problems, look elsewhere.

These rectifiers are FEP16 (positive voltage, dual diode fast-recovery modules) or FEN16 (negative).

The coloring you see on the tab of the FEP device is red felt pen used to differentiate the positive and negative (used black felt pen) devices to simplify board assembly.

The 1502iq amp is the same as their 952 amp (with some PCB tweeks and a speaker relay installed) with the rail voltages bumped up to gain spome power and to gain some sales dollars.

I'll see if I can post the 952 schematics later. I just replied to a post on a 2002 amp in this forum a bit earlier.
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