trying to fix broken reduction

lesouthern · 3502

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Offline lesouthern

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on: January 08, 2023, 12:07:09 PM
Hi just did a resistance test on my reduction, This was a previously working build that no longer does.
Everything was correct except terminal 23, which reads 0 resistance.
I assume I need a new 0.47 400V capacitor?



Offline Paul Birkeland

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Reply #1 on: January 08, 2023, 12:37:23 PM
If you remove the cap, do you still get 0 ohms of resistance at terminal 23? I am willing to bet that you will.

That cap could be a dead short on the inside and it won't give you a 0 ohm resistance there, but solder that has spilled over from the center pin of the output jack to the shell of the output jack will, and that's something that is pretty common to see.  Terminals 24 and 22 are also at ground potential, so if there is debris between 23 and either of these terminals, that will also provide an unwanted ground.


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline lesouthern

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Reply #2 on: January 08, 2023, 01:09:11 PM
I see what you mean about the overflow solder on the output jack. that would explain a lot of the issues I've been having

Do you have a recommended technique on solder removal?

thanks

Larry



Offline ccmccull

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Reply #3 on: January 08, 2023, 02:21:55 PM
I have used two methods.

(1) the wick

https://www.amazon.com/gp/product/B0195UVWJ8

with flux

https://www.amazon.com/gp/product/B01N8ZX7ZQ


(2) But I usually like the solder sucker better

https://www.mouser.com/ProductDetail/Aven/17535?qs=uwxL4vQweFN2pPL0dfbuoA%3D%3D

Make sure you wear good eye protection with the sucker!

Colin
{Ortofon 2m Blue > U-Turn Orbit > Eros 2} & {Roon Ropieee RPi4 > hifiberry-digi2-pro > ANK DAC 2.1} > Moreplay > S.E.X. > {{Spendor_S3/5r2 & SVS_SB-1000 (x3)} & Grado_sr325x}


Offline Paul Birkeland

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Reply #4 on: January 08, 2023, 02:51:19 PM
The blue sucker works very well.  You can also get a pair of decent side cutters (CHP-170) and just cut away the solder so it isn't shorting out the jack.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline lesouthern

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Reply #5 on: February 04, 2023, 09:34:02 AM
Update on this-- after fiddling with it, and doing some RTFM, I see the real problem was that there was no 475k ohm resistor from 22L and 23L

Could I get some guidance as to where to buy such a resistor? Or can they not be bought just in this resistance? and I have to buy a kit of various resistances?



Offline Larpy

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Reply #6 on: February 04, 2023, 11:13:36 AM
Assuming 1 watt is enough (I'm not familiar with the Reduction), this will do just fine:

https://www.mouser.com/ProductDetail/Vishay-Dale/CMF60475K00FHEK?qs=sGAEpiMZZMtG0KNrPCHnjUNCkyaEQtesDY0%252BDdpR%252BLI%3D

Larry


Offline lesouthern

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Reply #7 on: February 04, 2023, 01:44:25 PM
These things are so small, shipping them costs more than the item themselve

I live in the Bay Area. I know this sounds old fashioned, but are there any specialty stores that stock these anymore? Or do I have to purchase them online?

Again I'm looking for a 475k ohm resistor that goes from 22L to 23L on the Reduction

thanks



Offline maryc27182

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Reply #8 on: February 04, 2023, 03:41:14 PM
Anchor Electronics in Santa Clara https://anchor-electronics.com/

Electronics Plus in San Rafael https://electronicplus.com/

Do you know if that resistor is 1/8W or 1/4W or something else? I didn't build the Reduction, but did build an Eros. Hopefully your manual will have that info.


DIY 2-ways (TAD TD-2002, AE TD15M), Stereomour 45
Fostex TH-500RP, S.E.X. 2.1
Eros Phono


Offline Paul Joppa

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Reply #9 on: February 04, 2023, 05:02:05 PM
The stock resistor was 1/8 watt. It's not a critical or precision part - anything from 250K to 1 Meg would do the job, and there's no DC flow through it. I'd use metal film, but carbon film is also acceptable. You can probably get some from replacement [email protected], or use DigiKey which offers free shipping and no minimum order (see http://www.4sqrp.com/resource/parts_vendors/digimous.htm for details).

Paul Joppa