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Offline KevO

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Eros test issue
« on: November 09, 2012, 09:23:05 AM »
Greetings,

I have my Eros all wired and looking good, but it tests out of spec. 

When testing resistance on A4, B4 and C4 I read 620 ohms. I was very careful on these crowded C4,C5 connections and they look wired correctly per the photo.

The instructions though (pg. 49) say wire a cap from C4 to T13. The photo shows thaat cap wired to T8. I went to T8.

The caps show 1 microfarad when tested.

Any ideas?

Thanks!

-Kevin

Offline Paul Joppa

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Re: Eros test issue
« Reply #1 on: November 09, 2012, 09:40:22 AM »
C4 looks like a misprint, all three tubes should read the same 624 ohms +/-2% at pin 4.

The mention of T13 is clearly also a misprint; 13 is the same center terminal but on the third T-strip, not the second which is adjacent to socket C.

Good call to follow the pictures when in doubt; the photographs are of the prototype which is tested and known to work correctly before the kit is released.
Paul Joppa

Offline KevO

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Re: Eros test issue
« Reply #2 on: November 09, 2012, 09:56:52 AM »
Hooray!

Thank you!

I have read what was said to xcortes about 130k ohms and he read 200k ohms. Me too. So I figure that isn't an issue.

Also, whenever I test for 0 ohms, I read .2 ohms. I  hope that is OK.

I put a new battery and leads in the Fluke. Same result.

This is the most complex component I've built, and want to take this fresh experience to the next kit. A BeePre.

I'll post photos soon.

-Kevin

Offline Grainger49

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Re: Eros test issue
« Reply #3 on: November 09, 2012, 01:20:00 PM »
Kevin,

Look at FAQ #6.  Each meter will read slightly differently on zero and infinite readings.
« Last Edit: April 01, 2014, 03:37:24 AM by Grainger49 »

Offline KevO

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Re: Eros test issue
« Reply #4 on: November 09, 2012, 01:25:08 PM »
Hi,

Another newbie question. I just did the power test. here are the results.

                 A Board         B Board       Goal
KREG             1.9v              1.69v           1v
BREG           96.6v              97.7v        100v
OA              157.8v            157.6v       170v
IA                221v               223v          225v
BA                    0                     0              0
OB               94.8v                96v          100v

Question: I saw no perceptible 'glow' in the EF86. But after the test, they felt a bit warm. Normal??

Thanks!

-Kevin

Offline Grainger49

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Re: Eros test issue
« Reply #5 on: November 09, 2012, 01:48:42 PM »
Kevin,

As the instructions suggest you need only worry about those measurements that are +/- 15% out of spec.  So all those on Breg are fine.  Same for BA and OB.

That leaves the Kreg voltages over 15% out. 
« Last Edit: April 01, 2014, 03:38:28 AM by Grainger49 »

Offline KevO

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Re: Eros test issue
« Reply #6 on: November 09, 2012, 01:57:08 PM »
Grainger,

Thank you!

So, as a newbie, I have no idea what to do about the KREG being over it's voltage spec.

Any help is appreciated.

-Kevin

Offline Paul Joppa

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Re: Eros test issue
« Reply #7 on: November 09, 2012, 02:58:07 PM »
Be glad! The high kreg voltage indicates you EF86s have more than enough emission - usually when we find a crap tube it runs less than 1 volt, which is a risk for loading down the cartridge.

We have always just measured the voltages on the frst prototype (the one in the manual) and put them at the end with a note that as long as you are close to these voltages, you probably built it right. But some of them are quite tight because they are regulated, and some can vary quite a bit without any problem. (Eros kreg is one of the latter.) Perhaps we should be more explicit in future manuals ...

As implied by Grainger, if those voltages are accurate then the EF86 is working, whether you can see the glow or not.

I think you are ready to try it with some music!
Paul Joppa

Offline Grainger49

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Re: Eros test issue
« Reply #8 on: November 09, 2012, 03:03:53 PM »
Kevin,

I looked at the schematic.  It doesn't show "Kreg" on it.  So at the moment I will have to sort through the instructions and mark up a print out of the schematic. 

An educated guess says to me that Kreg connects to the 2N2222 transistor, the 2200uF 4V capacitor and the two resistors that are on the 2N2222 base.  One is a 27k ohm resistor the other is a 174 ohm resistor.

In case my guess is right look to verify that:

1) the stripe on the capacitor is as pictured in the manual
2) the 2N2222 has the legs as pictured in the manual
3) the two transistors measure the resistance they should and are in the places indicated in the manual

And I see Paul Joppa, the guy who designed the Eros posted as I was typing.  Give music a try.  If it sounds good, not distorted, have a cold one, or two and start spinning vinyl (oops) reels.
« Last Edit: April 01, 2014, 03:38:57 AM by Grainger49 »

Offline KevO

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Re: Eros test issue
« Reply #9 on: November 09, 2012, 03:17:18 PM »
Thanks guys!

This Eros is for playing tape! Time to tackle the tape recorder mods.

-Kevin