Trace Elliot TA60CR

[dpm309]

I have a TC TA60CR acoustic amp that makes a loud popping noise when powering down. From what I can find on the web, I might need to add a relay/delay to eliminate the popping noise. Any suggestions?
Found this: https://diyaudiostore.com/products/soft-start-speaker-turn-on-delay-and-dc-protector-boards?_pos=1&_sid=6f035846d&_ss=rIt is a Soft Start & Speaker Turn-On Delay/DC Protector Combo. Would this work or is there an easier solution.
Thanks

[shooter]

got a schematic?

you can try hanging .1uF across(one side + other side -) the big filter caps in the PS

here's a design I reference, the left bottom is the soft start - never used it, the stuff after the PT I use

[dpm309]

Yes, I have attached the schematic.

[shooter]

has it always been popping?

If so;
I'd decorate C9-10 and DR1 with .1uf's (look at my example cs1-4)

IF not;
how old are the Ecaps?

[PRR]

Replace C3. Use a 25V part this time. But also check the voltage there. Nominally 15V (so a 16V cap was cutting it close); anything much different means other trouble.

These shut-down noises can be hard to tame. It does no damage on a stage amp. But if it makes the crowd jump, a relay "may" be the simple fix.

On this case, simplest may be a 120V relay across the switched 120V power to PT. It will cut-out faster than the caps can start to drain.

But don't rush. I *may* know a guy who knows this amp. It may not be the guy. He may not remember it. He may deny he remembers the 1990s. But maybe...

[PRR]

"TR4 in the power amp schematic was the power on / off mute circuit, it looks like something around there has blown. I would suggest he take a look at the signal on TR4 gate with a scope during power up and power down. If it looks good then maybe the J111 has blown. Otherwise it's probably 25 year old capacitors which have dried out."

[dpm309]

The amp has been popping since I got it. Looks like all original caps. I did run across another solution that involves installing a "speaker standby" switch on the hot lead. You would turn off the standby switch first, then the power switch. Since this is a solid state amp, would not have to worry about damaging an OT. To turn it on, you would turn on the standby switch, then the power switch. This seems like the simplest solution but don't know if I want to install an additional switch.

[PRR]

FET TR4 is the mute. I missed the clear label until it was pointed out. It didn't thump when new. Fix is it works as intended and it should be fine.

[shooter]

guessing L2 is the mute LED

You get more beer money when it all works 

EDIT: wrong TR4 

[PRR]

L2 L3 are in the preamp (apparently a different designer/drawer) and seem to be overload lights.

The Power Stage mute works two places: TR4 clamping an output transistor, and TR8 clamping the power amp input.

[shooter]

 
ya, once I scrolled down I caught up

[dpm309]

Thanks for the suggestions. Checked the Hoffman parts catalog and do not see any speaker relays. Searching Mouser did not come up with any speaker relay/delays. Who would carry something like this?

[dpm309]

I have another question. First I am going to connect a 0.1uf cap across the switch contacts like they do in Peavey solid state amps to see if this solves the popping problem. Would an Orange Cap 0.1uf/600V work? This is the only high voltage cap I have on hand.

[shooter]

any cap works given the correct voltage n 600v should be fine

as to relays on speakers, a relay is a switch, a switch is cheaper n easier to wire

[dpm309]

I'll probably go with the switch. Thanks for everyone's input.