Need to troubleshoot!

[jrihs]

Hi There, I tryed to finished my crack about six months ago. Then I quickly got consumed by other events (huge forest fire and floods in eastern arizona - which affected my job and family big time). It was not working properly. I forget voltage check readings, but there is only one faint(?) channel with the headphones fully inserted. there was two if I pulled the rca plug up halfway. Then I got the volume pot upgrade and installed that. Didn

[Doc B.]

Your headphone jack might be damaged and you could just try replacing it. But since we have no voltage readings to go by it's very hard to say if that is the solution and whether that might be the only problem.

[jrihs]

Thanks, I'll get that tonight(?) I recall geting some zeros on one of the last steps on the v-check list...

[jrihs]

OK...that was fun.
Terminal    std.   measured
1             90       95
2             170     180
3             0        0 .001
4             170     180
5             90       87.2
6             0        0.001
7             100     115.8
8             0        0.001
9             100     110.4
10            0        0.01-0.02
11            0        0
12            0        -0.01
13            170     180.6
14            0        -0.008
15            185     203
20            0        -0.002
21            206     227

A1            90      86,8
A2            0        -0.004
A3            1.5     1.6
A4            0         -0.02
A5            0        -0.02
A6            90      94
A7             0        0
A8            1.5      1.6
A9             0        -0.01 to -0.02

B1             90       95.2
B2            170      181.7
B3            100      115.7
B4            90         87.1
B5            170      181.9
B6            100      110.4
B7             0          0
B8             0          0

Looks OK to me. Anybody see anything else in these #'s?

Thanks!!!

[Doc B.]

Looks pretty OK, so it may very well be the headphone jack that is the problem.

[jrihs]

Thanks, that confirms it then, though that is one part I thought I soldered relatively quickly and efficiently.
ohhh...I forgot to mention (just tested the sound again after months), the headphones crackle with intermittent noise that seems independent of volume....same thing I suspect...

[Laudanum]

Standard reply here ...  aside from sorting out the headphone jack ...  check with different tubes if the crackle and intermittent noise you mention persist after getting the headphone jack sorted out.
Also, I assume that the headphones are know to be working fine?  I've had a similiar issue with a guitar cable plug and the amplifier only amplifying when the plug was inserted partially or otherwise messed with.  Turned out to be a bad plug that looked perfectly fine and even metered OK.  Mono TS plug rather than stereo TRS but still potentially relevant I think.

One more thought ... I wonder if confirming the DC voltage at the headphone jack at turn on would also help confirm the jack.  This is the final check listed in the manual if I recall.   Voltage should climb to around 9 VDC a few second after turn on and then quickly drop to zero in the stock crack.  It's a little higher with film output caps / speedball installed.   Im not a tech guru by any means but just thinking this check could be useful.  It cant hurt anyway.

[jrihs]

Thanks very much,
Will do! I think the headphones are ok but you know I'm not using the good ones for checks...but I think I'll give it a shot. Same with my nos tubes. BTW...I forgot about the headphone jack check! Probably what I remembered as being 0 from way back when....Again, thanks a million guys. Love this forum!

[jrihs]

Hi. Did the headphone jack test again (I do remember doing this last time) and if I'm doing it right, it climbs to about 4 volts then the screen flashes OL and restarts around .03, then .02 then steadies around .01. Now, this is the third or lowest metal element, furthest from the face plate right. Its the only one that shows much activity anyways. What should I do now? The joints all look perfect. resolder anyways?

[Laudanum]

In terms of your DC voltage at start up, meters behave differently but what you describe seems like things are ok.   Of course, that only checks the solder tabs, not the actual contact points inside the jack but if using the standard Neutrik jack that is included with the kit, there really doesnt seem like there is much that could go wrong with it.   Im getting out of my depth here which is very basic to begin with.  But reflowing the connections at the jack cant hurt.  Make sure the jacks ground tab looks good, no broken wires and that there is no solder bridge across L and R signal tabs.  You could double check resistance through the ground wires from the jack and the points that they connect to as well as the L and R signal wires.  And double check the resistors at the jack.   The wooden "chopstick test" while you listen through your test headphones may be indicated here.  I think I would check the connections, if nothing stands out, reflow the the jack.  If that doesnt work, try the Chopstick test.    These are just common sense things that I would check since Doc seems to thing it's related to the jack and none of them can hurt.

[jrihs]

Ran it again for the umteenth time and it got to 7 v.

Well the good news...I solved the stereo/fidelity issue. I'm to embarassed to say what it was...well, lets just say the headphones were working properly when I last checked them on the ipod.

Sound is great on my good phones (30 ohm ATH-1000's)! Some used Hd-800's found on audiogon are on the way!

Now the bad news...the krackel (intermittant and independent of volume) is still there. I thought it was my WE5998a so I swapped it out with a 6sg(?)-something and it was gone. Then I put the WE5998a back in and it was still gone, so it's not that. Same with the 12au7's (tele, amp bb, and those really tall puppies (12au7 substitues)). BTW, the tele smooth plate and 5998 combo rules...need to try the siemens chrome plates next, can't wait to get home from work (which I should get back to). Anyways, so far the krackle starts occuring mostly when its warmed up and varies in magnitude from background noise to hurtfull.

Questions:
Will this krackle damage either the tubes or the headphones (perhaps it already damaged the phones...naw)?
What would be the most likely cause and where should I start?

I have a new locking jack on the way that I will swap out. Maybe this will solve it, but I am skeptical.

I did enjoy an hour of clean music though, celtic (old blind dogs), some bebop, and adult beverages (aaahh).

[Paul Joppa]

Crackle is usually either a bad connection or a tube problem.

Bad connections are usually cold solder joints, but occasionally a faulty component. As the amp heats up, dimensions will change slightly which can lead to connection problemss that are impossible to find with a meter when the amp is cold - very frustrating!

If it's a tube problem, it may disappear after some time - say, 50-100 hours. This would be the case if it's the cathode surface which is not fully formed, or perhaps has deteriorated over years of sitting idle. Sometimes it's small bits of mica or other stuff inside the tube. And sometimes it's just the way that the particular tube fails. I've had several old Chinese 2A3s that failed that way after 1000-1500 hours.

[Laudanum]

I think that I would try to swap in the 6AS7 for the 5998 and listen for a while, a long enough session in which you would definitely hear the crackle.   Or, several sessions, to completely rule out the 5998.    Make sure the tube pins are clean.  Grainger suggests plugging and unplugging into the sockets several times which would help clean both the pins and the socket contacts.  I usually use fine steel wool to clean the pins.  Takes a couple of minutes but works really well. 

Sounds like you are getting there though.  One problem solved one more to go.

[jrihs]

Right on guys!

Here's the shake down:

1) NOS 6080 kit tube (bendix). The harshest crackel in da crack (I spell it Krackel above because it was so close to lunch ;-). I may break it in more just to see if it goes away but why bother right now because...

2) NOS WE 421a (5998), The least crackel of all has cleaned up its act and is as quiet as can be!

3) Chatham JAN-CAHG-6AS7G (lightly used) never had an issue and is a great toob!

I wonder if the whole enchilada just had to get warmed-up and broken in a bit.

PS..put the siemens chrome plate in with the 5998 and began to melt into the chair...then the afro-cuban mix kicked in and I was definitely sold (I really should keep this secret). My new favorite 12au7. Sweet airy highs, punchy as all get-out, wonderful base and very holographic. Midrange is difficult to describe...up front big and 3D. WOW.

[nub]

Right on guys!

Here's the shake down:

1) NOS 6080 kit tube (bendix). The harshest crackel in da crack (I spell it Krackel above because it was so close to lunch ;-). I may break it in more just to see if it goes away but why bother right now because...

2) NOS WE 421a (5998), The least crackel of all has cleaned up its act and is as quiet as can be!

3) Chatham JAN-CAHG-6AS7G (lightly used) never had an issue and is a great toob!

I wonder if the whole enchilada just had to get warmed-up and broken in a bit.

PS..put the siemens chrome plate in with the 5998 and began to melt into the chair...then the afro-cuban mix kicked in and I was definitely sold (I really should keep this secret). My new favorite 12au7. Sweet airy highs, punchy as all get-out, wonderful base and very holographic. Midrange is difficult to describe...up front big and 3D. WOW.

Just looked around for siemens chrome plate 12au7 tubes... wow they are expensive.