Monkeymatic ODS #183

[dcribbs1412]

Great looking build xtian, congrats!
Like to here how you like it live.

D

[Guy77]

PanelCraft is great. Steve is currently cutting the faceplate for the rocket amp I finished a while ago.
Really nice lead dress xtian!

Cheers
Guy

[ToneMerc]

Sweet build!

TM

[Bob S]

Man! That is nice xtian.
Very well done.

[xtian]

Amp performed very well last night. Outdoor show, playing in concrete bandshell, got to play at a decent volume. Chassis got very hot to the touch--90 degrees ambient--but nothing burned, logos on EL34s still nice and new looking.

But I thought I'd cool the bias a bit and see if it still sounds good. And here's where I'm lodging my complaint. Despite the externally accessible bias test points and bias pot, the pot is actually NOT accessible without burning your hand by reaching between two power tubes. I'll have to remove the chassis from the cabinet each time I want to adjust.

So if you're building using the CE style chassis, keep this in mind. Next time, I'd mount the bias pot on the rear panel between the IEC power inlet and the fuse holder.

[JazzGuitarGimp]

And here's where I'm lodging my complaint. Despite the externally accessible bias test points and bias pot, the pot is actually NOT accessible without burning your hand by reaching between two power tubes. I'll have to remove the chassis from the cabinet each time I want to adjust.

So if you're building using the CE style chassis, keep this in mind. Next time, I'd mount the bias pot on the rear panel between the IEC power inlet and the fuse holder.

You might consider moving the pot to the back panel next time you have the chassis out.

That's a nifty-lloking yellow board in there...

[martin manning]

Despite the externally accessible bias test points and bias pot, the pot is actually NOT accessible without burning your hand by reaching between two power tubes. I'll have to remove the chassis from the cabinet each time I want to adjust.

So if you're building using the CE style chassis, keep this in mind. Next time, I'd mount the bias pot on the rear panel between the IEC power inlet and the fuse holder.

HAD never intended for the bias to be adjusted that way, as there were no test jacks included on the originals. The jacks would need to be located on the back panel as well to make it really user friendly.

[drew]

I wonder if you could buy or make a special tool along the lines of this: https://www.amazon.com/10mm-Honda-Valve ... B004QK2APS ?

[Mr. dB]

Amp performed very well last night. Outdoor show, playing in concrete bandshell, got to play at a decent volume. Chassis got very hot to the touch--90 degrees ambient--but nothing burned, logos on EL34s still nice and new looking.

But I thought I'd cool the bias a bit and see if it still sounds good. And here's where I'm lodging my complaint. Despite the externally accessible bias test points and bias pot, the pot is actually NOT accessible without burning your hand by reaching between two power tubes. I'll have to remove the chassis from the cabinet each time I want to adjust.

So if you're building using the CE style chassis, keep this in mind. Next time, I'd mount the bias pot on the rear panel between the IEC power inlet and the fuse holder.

Or use a pot with a slotted shaft so you can turn it with a flat head screwdriver.

[ToneMerc]

Amp performed very well last night. Outdoor show, playing in concrete bandshell, got to play at a decent volume. Chassis got very hot to the touch--90 degrees ambient--but nothing burned, logos on EL34s still nice and new looking.

But I thought I'd cool the bias a bit and see if it still sounds good. And here's where I'm lodging my complaint. Despite the externally accessible bias test points and bias pot, the pot is actually NOT accessible without burning your hand by reaching between two power tubes. I'll have to remove the chassis from the cabinet each time I want to adjust.

So if you're building using the CE style chassis, keep this in mind. Next time, I'd mount the bias pot on the rear panel between the IEC power inlet and the fuse holder.

I've never run into a problem in the CE chassis when using the larger 3/8 bushing pot shaft and a pot adjustment tool or slim flat blade screwdriver, even with the fat bottle 6CA7. At that location you are asking to get to get burned using the mini AB locking pot and having to remove its small locking nut for adjustment.

TM

[amplifiednation]

Nice looking build!

[stephenl]

Great looking amp. Your attention to detail is impressive.

What kind of hookup wire did you use, TopCoat?

[xtian]

Thanks, Steve. Yes, wire is topcoat from Mojotone.

[xtian]

I have a ground issue with my switching system. It's a bit noisy (hum) when OD is engaged, and much noisier when the footpedal is attached. Currently, the +5v/0v leads from the 5v PSU are connected to the relay boards and to the switching DIN jack, but I do not have the 0v return connected to the chassis anywhere. What's best practice here?

EDIT: The DC from the 5v PSU is currently reading 1.5v/-3.5v WRT chassis. I tried grounding the 0v lead to chassis, and that gets me a significant HUM in the output.

I just tried grounding the 0v lead from the switching PSU to chassis, and my jumper wire heated up quickly--so there's quite a bit of current flowing.

What did I do wrong?

[Colossal]

I have a ground issue with my switching system. It's a bit noisy (hum) when OD is engaged, and much noisier when the footpedal is attached. Currently, the +5v/0v leads from the 5v PSU are connected to the relay boards and to the switching DIN jack, but I do not have the 0v return connected to the chassis anywhere. What's best practice here?

EDIT: The DC from the 5v PSU is currently reading 1.5v/-3.5v WRT chassis. I tried grounding the 0v lead to chassis, and that gets me a significant HUM in the output.

I just tried grounding the 0v lead from the switching PSU to chassis, and my jumper wire heated up quickly--so there's quite a bit of current flowing.

What did I do wrong?

I can't quite tell from your photo, but does the PT you are using to power the relay board have a centertap? If it does and the centertap is grounded, it probably smoked the bridge rectifier on the board. The PS board should only have a non-centertapped AC supply.

If the transformer is not centertapped and correctly supplying the board, measure the AC voltage going in and the DC voltage coming out of the rectifier (at the 1000uF cap). Lift the DC supply to the relay boards, floating the supply, and then measure the DC output from the PS board. With the supply floating you shoud see 4.99-5.03VDC out...if the board is working correctly.