Original Eros resistance check tolerances

dhherring · 593

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Offline dhherring

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on: May 26, 2024, 09:59:25 AM
I assembled my orginal Eros phono about 10-12 years ago.  At the time, I'm sure all the resistance and voltage test checked out, because I did use it for several years before getting away from playing LPs.

A couple of months ago, for some reason I decided to blow the dust off my LP's get back to spinning vinyl.  At some point while listening to an album, I left the volume up on my amp while flipping sides and noticed a strange hum.

After checking all of the components in the signal chain, I determined that the hum was originating from the Eros.  It was not strong enough to be heard while playing an album, but it was there.

I had a few othter things to take care of on my stereo, and today, I finally got around to troubleshooting the Eros.

As per the manual, I started with a resistance check.  Off the bat, I noticed that terminals 2, 4, 9, 10, 12, and 14 where all reading 19% to 20% high.  Terminals 6 and 7 tested fine.

I says, OK and turn the amp around to test the other terminal strip.

Immiediantly, I noticed a bit of a lead sitting across T21 and T22.  That didn't look right, so I went back through the dox and could not see that was ever supposed to be there.  So, I clipped it, and the hum went away. 

Yahoo!  Probable ground loop, and I ceased my troubleshooting at this point.

Away, with all that out of the way, my question (and purpose of this post) is do I need to be concerned with those higher than spec resistance values on the front terminal strip?   I know from my tinkering around with tube based guitar amps,  20% variances from the spec'd values are no big deal.  Just didn't know if that would apply to the Eros (or other Bottlehead components)


« Last Edit: May 27, 2024, 01:32:36 AM by dhherring »

Vinyl: Technics SL-1200GR2 w/Denon DL-110 -> Eros Phono Pre -> Stereomour -> Klipsch Heresys
Digital: Jriver MC/Tidal -> Schiit Bifrost 2/64 -> Mainline -> Sennheiser HD-650

Offline Paul Birkeland

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Reply #1 on: May 27, 2024, 08:36:05 AM
There are caps and other components back in the EQ circuit that can cause those values to measure differently depending on the meter used, so really it's just important to make sure the terminals that are supposed to be 0 ohms are very close to zero, and nothing else shows up as zero that shouldn't be.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man