Amp ticking like metronome

[navdave]

Got a Sovtek Mig 100 that ticks like a metronome after warming up. I replaced the output jacks and the input jacks thinking this would cure the problem that it was a grounding issue. Oddly enough the input jacks are the ground point for the preamp and the old ones were loose without even having lockwashers. Seemed like all was well after firing it up but about 15 minutes into it the tick came back. Only other thing I can think of is a bad filter cap or coupling cap. Any suggestions? Here's a video of the amp ticking.

http://youtu.be/LrRwLM5_KMM

[Paul1453]

I might suggest documenting the issue 1st.
I mean make a 30-60 sec recording of the ticking sounds.
Now you have a baseline to compare with after making any changes,
and you have something you can post for others to hear that might give them a clue to help you.

Then, if you have them, I would suggest a complete tube line-up swap out with known good.
This is easy and can help rule out the tubes as the source.
If the ticking continues with all new tubes after warming up,
you can pretty much rule out the tubes as the problem.

If with new tubes in, the problem doesn't return in an hour or two of use.
Indicating at least 1 or more of the tubes as the cause.
I'd try swapping in the old tubes, 1 or 2 at a time.
Until the problem reappears.

What do you think about those suggestions?   

[sluckey]

Filter caps would be at the top of my suspect list.

[navdave]

 I have a video that I uploaded to YouTube but its still finalizing so I can't post it yet.  I've tried swapping in and out different preamp tubes with the same results. Right now I have a different set of power tubes in it's been on for about 20 minutes and the ticking has not returned got my fingers crossed.

[navdave]

I spoke to soon it took about a half hour for the tick to come back with different power tubes in. Guess I'm gonna have to do a cap job on this thing.

Filter caps would be at the top of my suspect list.

[whoops]

Is it still ticking?

[navdave]

Yup just like a clock... I have not ordered any filter caps it's safe to say this amp is over 20 years old so I know it won't hurt to put new caps in it. I can't help but think that it's a grounding issue this amps grounding scheme is weird.

Is it still ticking?

[shooter]

not sure if pulsing DC filaments would cause chirping, might put a meter on V1s Fil and see if it's pulsing with the chirps

[navdave]

 That was the first thing I did I removed the DC heaters and jumped over from V2's AC heater  supply and it still did the same ticking  away like a metronome.

not sure if pulsing DC filaments would cause chirping, might put a meter on V1s Fil and see if it's pulsing with the chirps

[Paul1453]

Those stacked E-caps before the standby switch.

How do they look?  Do they get hot when the amp is ticking?

Those look like the ones I'd try replacing first.   

[sluckey]

I have not ordered any filter caps it's safe to say this amp is over 20 years old so I know it won't hurt to put new caps in it.

You can take a single electrolytic cap with proper voltage rating and gator clip it across the filter caps one at a time. I would start with the cap that supplies the trem oscillator first. This is a valid troubleshooting technique for many filter cap problems. You may just find the problem cap for your ticking symptom. That is if a filter cap is the problem.

[navdave]

I did that to first on every preamp stage node. Then the main plate and grid caps for the power tubes jumping two caps across each node cuz they are in series for the plates and grids. The only caps I could not jump across were the bias and dc heater caps because they are radial caps mounted flush to the board.

You can take a single electrolytic cap with proper voltage rating and gator clip it across the filter caps one at a time. I would start with the cap that supplies the trem oscillator first. This is a valid troubleshooting technique for many filter cap problems. You may just find the problem cap for your ticking symptom. That is if a filter cap is the problem.

[navdave]

They look good no bubbling no signs of anything leaking they are all Illinois caps except the bias and dc filament caps those are Russian made aluminum cap cans.

Those stacked E-caps before the standby switch.

How do they look?  Do they get hot when the amp is ticking?

Those look like the ones I'd try replacing first.