help with troubleshooting

[coors]

Stuck, here is where I am at
On checking resistances I am not getting any readings for B3 and B8 and Kreg.
I checked A3 , A8 and Kreg and get the correct readings(As well as all of the others)
I re soldered the areas and checked to make sure there are no shorts and remeasured still no go
when I put in all of the tubes and fired it up all of the LED's on all of the boards light up and the only tubes that do not glow are the EF86.  The fuse does not blow
I did the recheck as well after firing it up.
Don't know what to do next
Thanks

Sam

 

[Paul Birkeland]

Hello Sam,

Sorry to hear of your troubles!

When you say you get no readings, does this mean 0 or infinite?

Have you double checked that both regulators are TL431's? (Not MPS4250's?)

You can always use the A side to check against the B side,  my best guess with this information would be that a black jumper feeding ground to the TL431 is not present.

-PB

 

[coors]

thanks, I am going to try to figure out how you thought it was one of the black jumpers.  I will try first by trying to understand the schematics a little better.
The problem was the black jumper to Kreg, I resoldered it and then I got all of the right readings.  It looked like the teflon went through the whole rather than the wire.
I have it currently plugged in and working.  I think though my cartridge is too low of an output. .25 mv.  I will give it some break in time and then see what's next.
Thanks for the quick, expert response.

Sam

 

[Doc B]

Yes,  a .25mV cartridge will require the use of a step up device after the cartridge. The minimum cartridge output that can be used directly without tube rush intruding is more like 1mV so even a 1:5 step up ratio will probably be OK, though 1:10 might be better and 1:20 would be rockin'.

 

[coors]

I was still having problems with the voltages that I thought I fixed.  I think I finally solved the issue, let me know if this is right.
I plugged the Eros into my system. Prior to putting in the tubes all of the resistances were correct. All of the tubes and the LED's light, however on measuring the DC voltages the B side Kreg measures 0 V DC and on the A side registers correctly at 1 V DC.  Tracing it to the B3 and B8 pins measure 0 V DC, the A3 and A8 voltages measure 1 V DC
Unplugging and checking the resistances with the tubes in,  the B3 and B8 the resistances would climb starting at about 27-28 and on the A3 and A8 would start around .3 and climb. 
After plugging it in even though I had to turn the gain up one channel seemed very muted and distorted.
Unplugged it and started to check numbers again.
I would always get higher climbing resistances on the B3 and B8 when I left the tubes in and unplugged to check. 
On checking voltages with tubes in on the B board I would always get 0 v DC for the Kreg where it should have registered 1 V DC.
Unplugged and checked all of the wiring from the power supply.  I resoldered all of the connections which led up to the Kreg including B3, B8 the terminal strips, jumper wires. 
I then retested and kept getting the same numbers. 
I then switched the tubes around putting A into B and B into A.  When I did this now the B board registered the correct Kreg of 1 V DC and the A board now went to 0 V DC.
So I think the problem is with a bad EF 86EH tube, is this right or am I still missing something?
Is there a way to just check the tubes to see if they are working well?
Thanks
Sam

 

[Doc B]

It does sound like the problem follows the tube. Shoot Eileen an email at queen at bottlehead dot com and she will get a replacement tube out to you pronto.

 

[coors]

Just put tubes in, thanks for the quick new tube.  All voltages check out and currently have it plugged in and playing music!  Looked into the Altec sut but they were too hard to find so I went with the cinemag 1:20.  So far everything working and sounding great, now for some burn in time
Thx for all the help and great product support
Sam

 

[coors]

Arrgh, more problems. 
Ok I was just beginning to get a feel for the way the Eros sounded and the soundstage was off. Most of the sound was coming from the right speaker. 
got in close and yup the left speaker was a lower volume and the sound was distorted.  I know it could not be the speaker because I was listening earlier with my other phono preamp. 
the first thing I did was switch the EF 86 tubes and now the right speaker sounds low and distorted and the left speaker sounds great.
Unfortunately I do not which of the two tubes is the one that was sent out today(the bad one was disposed of, so I know I did not make that mix up).
Is it possible that this is just a bad coincidence or did the tube somehow get damaged from the circuit.  I did check all of the voltages before putting it in my system and everything checked out with the correct voltages with symmetry from A to B.  All LED's lit up fine.  Frustrating!
Unplugged everything and will recheck again, but it does seem like the tube went bad.
Thanks again
Sam

 

[coors]

Ok, I am totally lost. 
I went back and rechecked voltages and now I get the same bad voltages I got before putting in the new tube so it must be something that I did wrong.  I just cannot figure it out.
When I first put in the new tube all of the DC voltages were symmetrical and according to spec.
After plugging it in and listening it sounded like one side was not working well.  I switched the EF 86 tubes and the problem switched to the other speaker.  I did not leave it on long enough to see if it would damage the good side.
Unplugged everything and then rechecked voltages and now I get the same problem on the B side as I did previously
Here are the voltages.
B side A side
Kreg O V DC Kreg 1 V DC
Breg 105 V Breg 98 V DC
OA 140 V         OA 149 V
IA 223 V         IA 223 V
bA 0 V bA 0 V
OB 96 V         OB 96 V


when I take the tubes out and measure resistances I keep getting this discrepancy, this has been consistent all along but did not put any specific weight to it since the resistances climb according to the specs. 
A3 and A8 starts at 1.4 and starts to climb slowly
B3 and B8 starts at 49 and climbs rapidly
I traced these both forward and backwards and had previously re soldered. 
I am not able to figure out what the problem is but it seems like it has to do with B3 and B8 resistances
All LED's light, the fuse does not blow.

Thanks
Sam

 

[coors]

The End of the Saga
After reviewing all other possibilities this is what I am pretty sure of.
the new tube that was sent also failed.
I thought it might be my B side where there was a problem.  I checked everything again and could not find a problem.
I then put in both of the bad tubes , 1 on A side the other on B side and both registered 0 V on Kreg.
I then put in the one good tube and no matter what side I put it on all of the voltages were normal.
So I did a final experiment.  I put the good tube in the B side and one of the bad tubes on the A side.
I then hooked it all up and sent a signal to the pre-amp for a bit over an hour.
I then checked everything again.  The B side continued to demonstrate normal voltages and of course the A side with the bad tube continued to measure 0 V
I then did some research using both the internet and calling audio shops that carry tubes.
There does seem to be a fairly common general consensus that the Electro Harmonix tubes are not very reliable, although I do find it odd that 2/3 tubes would have failed.
So my questions to all of you out there, what has been your experience with the EF86 Electro Harmonix tubes and can you recommend a decent pair of EF86 tubes that are reliable, sound good and not more expensive than the Eros itself(tongue in cheek)

Sam

 

[Prairie Dog]

Sam,
I've only had the 2 that came with the kit, one was ok, the other was quite noisy - "rush" type of noise.  I just bought some Amperex types through eBay (8 for $90), they sound nice, can't vouch for their reliability though.

 

[Grainger49]

Sam,

I have had my Eros since last fall.  I can't tell you about the EH reliability because I rolled them out and Russians in about an hour after I turned it on.  I was prepared with tubes for the three signal positions.  I had been researching for quite a while and the Russian tubes were highly recommended and inexpensive.  

Of course you can always change the tubes with the same number from a different manufacturer.  NOS (New Old Stock) are highly sought after and sound awfully good.  I started a thread on replacement numbers, I.E. a tube that will work the same but has a different number on it:

http://www.bottlehead.com/smf/index.php/topic,1028.0.html

I have been using USSR Military surplus tubes, 6J32P and 6N23P, for quite a few months now.  Noise is very low, soundstage wide and deep and the tonal balance to my taste.  They are also pretty cheap and NOS 60s and 70s can be had for the asking.

 

[coors]

thanks I posted over on your above tube equivalent thread to try to keep things consistent. 
I do think that even though this was a great learning experience , I would recommend better quality control of the tubes or charge a bit more for the kit and include better tubes.
Sam

 

[Doc B]

thanks I posted over on your above tube equivalent thread to try to keep things consistent. 
I do think that even though this was a great learning experience , I would recommend better quality control of the tubes or charge a bit more for the kit and include better tubes.
Sam

We will relay your recommendation to the tube manufacturer, and of course we are sorry that this happened and we're happy to send another replacement. The only other current production EF86 is a JJ and we found them too noisy for this application. I don't recall any other customer getting two bad EH EF86s in a row, in fact I don't recall reports of DOA EH EF86s, though some can be a little on the hissy side. There are better sounding EF86s. I use a pair of Telefunken EF806S and a Telefunken E88CC. If you shop around you can probably find that combo for about $500.

 

[coors]

Worse things have happened.  As I said, I have learned a lot for a noob.  I love your products and your dedicated team so as they say "no harm, no foul".
Sam

 

[Grainger49]

Something else was heard in the early days of the Eros a couple of years ago.  Several owners, not many, had tube rush.  That is a SSSHHHH noise that goes away as the tube cathode forms over 40 to 100 hours.  The EH tubes are new.  The cathodes hadn't been formed at all. 

The EH EF86s that I got were dead quiet.  I rolled them out because I had a stock of replacements and those were more to my liking.

 

[coors]

Here is the update.
First off thanks for all your help and the great support. For the final evaluation I spoke with Shawn and he also helped me troubleshoot as a new tube was on its way.
I put the new tube in.  I had to use a different set up because previously in my zeal to use the Eros  I forgot to turn off my amp and blew out my midrange driver on my floor standing speaker.  Ouch, that is going to be an expensive stupid mistake to fix.
Now to the good news, after hooking my turntable up to the cinemag to my Eros into my SEX amp into my headphones I finally got to hear the music.  Ahhhhhh music again.

At around the same time I went hunting for tubes and found an individual that was very knowledgeable and honest.  After discussing with him, Jim McShane(no affiliation), my system and criteria I purchased 2 Tungsten Sol 806FG and 1 12BH7AEH NOS Japanese tube. 

So in the end it actually was the tubes that were bad.

Back to the music
Sam

 

[Grainger49]

Jim is one of the known good guys in the business.  Good find!