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Soundcraftsmen EQ slider replacement

slater529 said:
Forgot to mention that both PE2217-Rs that I own have the same issue, each to a differing extent.

I never had this sort of issue with my old SP4001 back in the day... of course it was new at the time, and all my current Soundcraftsmen gear is very vintage!
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Took a chance recently on a SP4001 I saw on fleabay. Advertised as "powers up, no further testing." It looked good cosmetically, and the price was right so I pulled the trigger.

I'm happy to say it turned out to be a real bargain! All it needed was new 1000uf, 35V power supply caps to fix a low level buzz that was audible with no signal applied. I had the caps in stock and the repair took all of 30 minutes. So glad I rolled the dice on this unit!

SP4001.jpg
 
slater529 said:
Took a chance recently on a SP4001 I saw on fleabay. Advertised as "powers up, no further testing." It looked good cosmetically, and the price was right so I pulled the trigger.

I'm happy to say it turned out to be a real bargain! All it needed was new 1000uf, 35V power supply caps to fix a low level buzz that was audible with no signal applied. I had the caps in stock and the repair took all of 30 minutes. So glad I rolled the dice on this unit!

View attachment 3485314
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Looks great. How are the sliders?
 
These are photos of the DX4100 when I got it.

The trick to removing those old crusty labels and tape; is to use slow acting environmentally friendly paint stripper. Brush it on the tape and wait just long enough to soften the material, Then gently scrape it off and wash the surface.
IMG_3533.JPGIMG_3532.JPG
 
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Here's a PE2217 I just finished replacing the sliders on using Bourns 45 mm faders, with the kind guidance of @Racingh11 . The replacement involved making two brackets from half inch aluminum L-channel, mounting the faders to the brackets, and then mounting that to the chassis using half inch standoffs. It's tight... "file to fit, paint to match" as my engineering mentor used to say, but these do in fact fit in the space available. It may be possible to spin a 0.032" PCB to accomplish the same thing but for a one-off, it made more sense to do it this way. Generic fader knobs from Amazon (link here) fit the faders perfectly. I did have to knock off about 1/8" or so from the level set knobs with a lathe, but overall it looks pretty close to stock.

I still need to sniff out the test lights in the right channel, which aren't coming on, and re-rework the power supply caps as they are a little low on the voltage rating for my tastes. There is a little noise in the eq switch as well I think. But, the phono pre in this thing really sounds nice, as does the very minimalist line stage. This will be paired with a PM860 I restored earlier this year for a dear friend and mentor.

PE1.jpgPE2.jpg
 
ruckerfoad said:
Here's a PE2217 I just finished replacing the sliders on using Bourns 45 mm faders, with the kind guidance of @Racingh11 . The replacement involved making two brackets from half inch aluminum L-channel, mounting the faders to the brackets, and then mounting that to the chassis using half inch standoffs. It's tight... "file to fit, paint to match" as my engineering mentor used to say, but these do in fact fit in the space available. It may be possible to spin a 0.032" PCB to accomplish the same thing but for a one-off, it made more sense to do it this way. Generic fader knobs from Amazon (link here) fit the faders perfectly. I did have to knock off about 1/8" or so from the level set knobs with a lathe, but overall it looks pretty close to stock.

I still need to sniff out the test lights in the right channel, which aren't coming on, and re-rework the power supply caps as they are a little low on the voltage rating for my tastes. There is a little noise in the eq switch as well I think. But, the phono pre in this thing really sounds nice, as does the very minimalist line stage. This will be paired with a PM860 I restored earlier this year for a dear friend and mentor.

View attachment 3529853View attachment 3529854
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Job well done. Nice find on those slider caps too.
 
ruckerfoad said:
Here's a PE2217 I just finished replacing the sliders on using Bourns 45 mm faders, with the kind guidance of @Racingh11 . The replacement involved making two brackets from half inch aluminum L-channel, mounting the faders to the brackets, and then mounting that to the chassis using half inch standoffs. It's tight... "file to fit, paint to match" as my engineering mentor used to say, but these do in fact fit in the space available. It may be possible to spin a 0.032" PCB to accomplish the same thing but for a one-off, it made more sense to do it this way. Generic fader knobs from Amazon (link here) fit the faders perfectly. I did have to knock off about 1/8" or so from the level set knobs with a lathe, but overall it looks pretty close to stock.

I still need to sniff out the test lights in the right channel, which aren't coming on, and re-rework the power supply caps as they are a little low on the voltage rating for my tastes. There is a little noise in the eq switch as well I think. But, the phono pre in this thing really sounds nice, as does the very minimalist line stage. This will be paired with a PM860 I restored earlier this year for a dear friend and mentor.

View attachment 3529853View attachment 3529854
Click to expand...
Nicely done! That looks fantastic!
 
Thanks! I managed to trace the noise in the EQ back to the power supply ground connection... some of those wire wraps weren't the tightest and had gone a little flaky at some point in the last fifty-ish years. No such luck on the test lights, will have to get out the scope for that one I think.
 
One additional note for anyone who wants to attempt this on a PE2217: the three pins on the Bourns faders are somewhat delicate, so be careful with how you dress your flying leads. In testing I found five had gone open on either end or the wiper connection due to mechanical strain since I had to change my lead-out scheme a few times. A real pain to replace but they test OK now. The best thing to do is to use buss wire on either end and then a single flying lead out, mimicking what the original fader arrangement had.

Does any member happen to know the calibration procedure for the potentiometers on the light board? I am guessing it would be line level in and then adjust for equal light intensity with the level faders being set to the middle position.
 
I shotgunned in new transistors in the right channel LED driver board--2N3904 for the 239C and 2N3906 for the 309B--and, naturally, it was the very last transistor I swapped that was faulty, the NPN input transistor from the EQ board after the 0.22 uF cap. Working as intended now. Lacking any cal info I just set my bench oscillator to 316 mVrms (-10 dBv), set the level sliders to the middle position, and then adjusted the trimpots on the light board for equal intensity. Seems to be about right.

This thing has really burned in nicely, it's a little shocking how good the line stage sounds, and the phono stage is really nice as well.
 
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