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Build is complete (well sort of), voltage checks done- look ?, plugged in guitar and all is good for about 10 minutes. Then started getting intermittent crackling and popping. Goes away for a minute or so after going to standby. I've changed the tubes around on v1 - v5 and recto, no difference. Only have a 6v6 pair so cannot swap. I did notice both popping and crackling when checking the voltage on the PI pin.

Next steps

Voltages:

No Tubes:
AC Mains 123 VAC
Rectifier
P1 316 VAC
P7 316 VAC

V1, V2, V3
P4 3.1 VAC
P5 3.1 VAC
P9 3.1 VAC

V4, V5
P4 3.1 VAC
P5 3.1 VAC

V6, V7
P2 3.1 VAC
P7 3.1 VAC

B+ wo/rec 434 VDC
w/rec 363 VDC

With Tubes:

V1
P1 148
P3 1
P6 145
P8 1

V2
P1 159
P3 1.2
P6 269
P8 163

V3
P1 203
P2 38
P3 77
P6 203
P7 37
P8 77

V4
P3 10
P7 367
P9 344

V5
P3 10
P7 341
P9 344

V6
P5 56 mVDC
P8 20

V7
P5 36 mVDC
P8 20

_________________
Mark

Mark,

Crackling can usually be traced to a cold solder joint. If you can find the area it happens you can reflow the joints of just systematically do them all is one approach.

Sometimes a bad tube too.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Coco, I think you are right about a solder joint. Last night after I re-tested the voltages and wrote the message the amp had been on for about an hour. Since I had it on blocks upside down I thought that if I plugged in and played it would snap, crackle and pop right away. Well, it didn't crackle once, just roared from every channel Hi and Low, 84's and 6V6, from Zep to ZZ Top. Tonight I'll try to trace down the problem with chopsticks.

Were there any voltage readings that should be looked at

Thanks,
Mark

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Mark

That's good [AKA great ] news. The voltages looked OK.

I've seen sockets act up as well. So wiggle the tube in the socket and see if that makes a difference as well.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

How's the amp these days? Working fine now?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Hi Stephen,

No, I didn't get a chance to re-solder before heading out of town for a bit of vacation . I did notice that while taping the PI pins with chopsticks, most connections produce poping noises. Is this normal? I'll definately re-check that area. I'm also looking forward to installing the VRM mod. I'll report back in 2 weeks.

-Mark

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Mark

Not normal. I'd re-solder those. At least re-heat with a touch of solder. Could be the tube pins too if it's an old tube.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

One problem fixed but have another. Re-flowed the solder on PI seem's to have solve the snap crackle and pop problem .

Now I'm finding that bass and treble pot's don't seem to work. Wiring looks fine, re-flowed solder on V2, still no bass or treble response. Other area's to look at

Thanks,
Mark

_________________
Mark

Mark, how are your solder connections to the copper grounding bus bar? That's probably the most difficult soldering in the whole amp.

Joe G

_________________
Some assembly required,
Brain sold separately...

Joe,

To the naked eye the joints look good. Are there any test's I can try to determine they are in fact good? I've tried probing with chopsticks with no adverse affect.

-Mark

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Mark

If it looks like a solder joint has flowed nicely, bright and shiny, etc. (see my article in Resources), then I would try an ohmmeter next, just to be sure you have 0Ω from the ground bar (from any point on bare copper, not at a solder joint) to the various ground destination points. Try to make your measurements beyond the solder joints (for example up the pot lead itself close to the part body) so you're measuring the solder connection. Also Mark, make sure that if you had to reflow any of the turrets that have a jumper wire on the bottom of the tag board, that the wire hasn't popped off in the process. Check other suspect joints the same way.

PLEASE BE CAREFUL PROBING AROUND IN THERE!!! There is plenty of safety info on this site!

Joe G

_________________
Some assembly required,
Brain sold separately...

Joe thanks, for the suggestions and warning (keep the left hand in pocket at all times):shock: . I thought about the wires under the turret being the problem, so I ran another wire from the top to the pot's to see if it fixed, unfortunately it didn't. Will check the grounds.

-Mark

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Mark

Just checked the grounds and all tested good. I also tested from the wipers to pin 8 on V2 at 2000k and here are the measurements for each. The treble pot seems odd to me.

Bass
0 - 219
10 - 356
Mid
0 - 054
10 - 219
Treble
0 - 219
10 - 230

-Mark

_________________
Mark

Mark, does the amp sound like the treble or bass are up all the way or down all the way? Are the "mid" control and master volume working? Is the other channel working normally? Do you have extra 12AX7's that you can switch in and out? Maybe you could post a few more pics of the pot wiring. Some fresh eyeballs may spot something...
Coffee time!

Joe G

_________________
Some assembly required,
Brain sold separately...

It's alive

If only I could read I would have saved myself a lot of frustration

Was about to give up after staring at the Plexi and V6 layouts, replacing the bass and treble pot's, re-wiring the pot to pot connections, replacing the 500pf and trimming the gain lead and not making any difference in getting the bass and treble to work.

I just happened to look at the treble pot I had just taken out and noticed it was 25K.

Amazing how well the bass, treble and mid work with the right pot's.

Upon reflection, I can say that with the 250K pot in the mid, the channel wasn't bad at all, very similar to the normal channel but with more gain and a little wider tonal range.

Joe, I appreciate all your help.

-Mark

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Mark

Congratulations!!! I give you new guys a lot of credit. That's no easy project to build, let alone troubleshoot. Good work!!!
Don't forget to post some pics!

Joe G

_________________
Some assembly required,
Brain sold separately...

Your next joeyvelour!
You just have a little more experience
But you still haven't experienced a Trinity yet.
The fun hasn't started yet

Should I cancel our Cape Cod vacation to start my build?? Somehow I don't think that would fly with the family

Joe G

_________________
Some assembly required,
Brain sold separately...