Technical Difficulties

chauncey mcdougle · 180

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Offline chauncey mcdougle

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on: March 25, 2024, 01:29:44 PM
Hello!  First time Stereomour II build

I made it through the build the first pass, but wasn't getting sound out of the right channel. 


I re-read the manual and went back over every step.  I also replaced the speaker output posts since the manual said that was a common issue.  Solder had made it in between the nut and post on mine so I had to saw them off and replace them.

In the process of checking my work, something sparked and popped on point 27.  I had trouble tracking down the issue, so I figured I would order new parts from Digikey and start the build over.

So-- desoldered everything and started the build from the beginning with new components.

Second time through, made it past the resistance check.  However, when I plugged the unit in the right channel HLMP6000LEDs exploded (image attached)

I'm stumped!

I just checked resistance values again.  All values are in line with the manual except for point 10.  The range is between 0-100k ohms, which is higher than the manual recommends.




Offline Paul Birkeland

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Reply #1 on: March 25, 2024, 01:54:51 PM
I made it through the build the first pass, but wasn't getting sound out of the right channel. 
Did you pass your voltage check?

I also replaced the speaker output posts since the manual said that was a common issue. 
Could you let me know where that is in the manual? I can't ever remember seeing that...

I figured I would order new parts from Digikey and start the build over.
Did you completely gut the amp and use all new parts? I can't understand the rationale behind this, as you likely had something like a bad solder joint or a miswire.  It is very rare for a component to just not work out of the get go.

Second time through, made it past the resistance check.  However, when I plugged the unit in the right channel HLMP6000LEDs exploded (image attached)
What does the bottom of that board look like?  Did you remove every component on there and replace it with new stuff? 

It's very, very difficult to know where to start with this.  Generally when you have an issue with your kit, you'd come here and let us know what your voltages are and the nature of the problem you're experiencing.  Now it's likely that the underlying issue preventing your amp from functioning originally is still there, but now with extra issues on top of that. 

I would post what the bottom side of your C4S board looks like as well as the 9 pin socket underneath that.  I would order up a replacement C4S board with parts since reworking these boards is quite difficult.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline chauncey mcdougle

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Reply #2 on: March 25, 2024, 02:52:24 PM
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Did you pass your voltage check?
yes -- voltages all looked good.

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Could you let me know where that is in the manual? I can't ever remember seeing that...
Page 71
"The most common issue is that excess solder has run down from the center pin of an RCA input jack or output jack, and shorted it to that jack’s outer shell. Reheat the connection and remove enough solder with solder wick or a desoldering pump to clear the shorted solder bridge."

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Did you completely gut the amp and use all new parts? I can't understand the rationale behind this, as you likely had something like a bad solder joint or a miswire.  It is very rare for a component to just not work out of the get go.
Yes -- gutted it and started over.  Agreed it was probably something small.  Probably shouldn't have redone the whole thing.

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What does the bottom of that board look like?  Did you remove every component on there and replace it with new stuff?
I replaced everything but the LED's.  I'll attach a pic of the board

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Generally when you have an issue with your kit, you'd come here and let us know what your voltages are and the nature of the problem you're experiencing.  Now it's likely that the underlying issue preventing your amp from functioning originally is still there, but now with extra issues on top of that.
Yes -- should have just posted on the forum at the beginning when I was having the right channel issue. 

Thanks for your help!



Offline Paul Birkeland

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Reply #3 on: March 25, 2024, 03:00:23 PM
That quote in the manual is for the input RCA jacks, not the speaker posts. 

If you had good DC voltages, then you almost certainly didn't have any kind of component problem at work. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline chauncey mcdougle

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Reply #4 on: March 25, 2024, 03:58:36 PM
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That quote in the manual is for the input RCA jacks, not the speaker posts.

Gotcha.  I read "output jacks" and my neanderthal brain made the leap to speaker posts.

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If you had good DC voltages, then you almost certainly didn't have any kind of component problem at work.
Roger that.  I didn't suspect any components were faulty on arrival from the kit, but thinking I maybe made an error in installation such as overheating a transistor or something.