Amp start up not to good.....

[mcrracer]

Not to nit pick but it appears that the IEC ground wire is going to a transformer screw. Big NO NO. Always take it to its' own dedicated screw by itself. That is all.

[Bob-I]

Also, watch your color code on your power wiring. You have a green wire going to the fuse holder.
Traditionally, green is for earth ground only in that spot.
You should use black wire for the hot AC wire path and white for the neutral path.

I may be colorblind, but I'm seeing a white wire going from the EIA socket to the fuse, green goes straight to the xformer lug, so that's all correctly wired, just incorrectly colorcoded.

It also appears that you are grounding your buss wire down near the pilot light fixture.
I would terminate the buss wire at the other end, near the input jack since that is a much "quieter" area of the amp.[/quote]

I'm not seeing the buss ground at all. Tom's right, it should be near the input.

[Structo]

Yep.

Drill a hole and use a screw and locking nut on the ground wire.
Use a proper solder lug that has a star inset for good contact and tighten down hard.
I would drill the hole as close to the IEC connector as practical, but so that you can get a tool on the lock nut to get it tight.
I like using the nylok type locking nuts. They don't come loose.

Also, rather than use the transformer bolts as a grounding point.
It really is better to have a dedicated hole with solder ground lugs.
You can put two to three on the same screw.
That way you can solder your transformer center taps, your main filter ground there.
They look like the two on the left.

[img:206:162]http://www.pinrestore.com/images/Img85.jpg[/img]

[playonit]

Wow you guys are killing me!!!!! I kid...... thanks for all the info.... I found one myself... I had one of the choke wires going to the wrong cap... ?

I had another bias cap and switched that out and installed it in the right direction.. changed the mis-placed choke wire.. Now the hums gone and I get the infamous motorboat sound?? I have not performed the ground changes you mentioned above..I pulled out D. Hunters book and it doesn't guide me in the right direction..

Wow my fine tooth comb wasn't fine enough... the once overs will now become twice overs!!!

will fixing the grounds solve the motor boating? Also, plugged the guitar in and can't hear it.. don't know if that's relevant at this point???

Wow guy's thanks for helping me try to figure this out..

[Bob-I]

I had another bias cap and switched that out and installed it in the right direction.. changed the mis-placed choke wire.. Now the hums gone and I get the infamous motorboat sound??

Motorboating can be hard to troubleshoot. This CAN be because of the the OT wire reversed. An easy check is to remove the NFB lead from the impedance switch, if it goes away, reverse the plate leads on the output tube sockets.

Wow my fine tooth comb wasn't fine enough... the once overs will now become twice overs!!!

Only TWICE...

will fixing the grounds solve the motor boating? Also, plugged the guitar in and can't hear it.. don't know if that's relevant at this point???

I'm confused, you mean with the guitar plugged in there's no motorboating? If yes, check the input jack wiring and scratch what I said about the NFB.

[rp]

Not to nit pick but it appears that the IEC ground wire is going to a transformer screw. Big NO NO. Always take it to its' own dedicated screw by itself. That is all.

I've sometimes done this and seen it done many times. Why is it so bad?

[playonit]

I had another bias cap and switched that out and installed it in the right direction.. changed the mis-placed choke wire.. Now the hums gone and I get the infamous motorboat sound??

Motorboating can be hard to troubleshoot. This CAN be because of the the OT wire reversed. An easy check is to remove the NFB lead from the impedance switch, if it goes away, reverse the plate leads on the output tube sockets.

Wow my fine tooth comb wasn't fine enough... the once overs will now become twice overs!!!

Only TWICE...

will fixing the grounds solve the motor boating? Also, plugged the guitar in and can't hear it.. don't know if that's relevant at this point???

I'm confused, you mean with the guitar plugged in there's no motorboating? If yes, check the input jack wiring and scratch what I said about the NFB.

Yes with the guitar plugged in you can hear the motorboating not the guitar....



I have searched Motorboating and there does seem to be many causes...

I had mentioned hooking up a choke wire to the wrong cap... could it have done any harm to that cap?? I will try the NFB wire tip and report back...

[paulster]

They can work loose from vibration from the transformer.

A safety earth (ground) should always be on its own dedicated mounting as close to the inlet as possible and should have a shakeproof washer and/or locknut to ensure the longevity and integrity of the chassis connection.

[rp]

That's what I figured. When I've done it I've always used a star washer and cranked the bolt down + some locktite or dope.

[Structo]

Motorboating can be caused by lead dress, wires too close together.
Bad filter caps or leaky coupling caps.

Check that wires between stages have good separation.

If you suspect leaky caps, then disconnect the end away from the tube and measure the DC voltage from the free end of the cap to ground.
If you get anything close to or over .5 v then the cap is trash.

[Bob-I]

They can work loose from vibration from the transformer.

In 50 years of playing guitar through tube amps, I've never had a transformer work loose.

[Bob-I]

Yes with the guitar plugged in you can hear the motorboating not the guitar....

Ok, standard troubleshooting techniques now.

Start by grounding out the grid of each stage. Start with pin 2 of V1, next pin 7 of V2, then pin 2 of V2, do not ground pin 7 of V2 as there's voltage on that one.

If any of these stop the motorboating, you've located the stage when the issue is starting.

[playonit]

Yes with the guitar plugged in you can hear the motorboating not the guitar....

Ok, standard troubleshooting techniques now.

Start by grounding out the grid of each stage. Start with pin 2 of V1, next pin 7 of V2, then pin 2 of V2, do not ground pin 7 of V2 as there's voltage on that one.

If any of these stop the motorboating, you've located the stage when the issue is starting.

Thanks Bob....... Is the best method for grounding using a jumper from pin to chassis? definitely taking safety into account....

[Bob-I]

Thanks Bob....... Is the best method for grounding using a jumper from pin to chassis? definitely taking safety into account....

Yes. Make a jumper with an alligator clip on one end, long insulated probe on the other. Ground the alligator clip and touch the pin with the probe. Left hand behind your back always (LEFT HAND because it's closer to the heart, I don't care if you're left handed like me ).

[playonit]

Thanks Bob....... Is the best method for grounding using a jumper from pin to chassis? definitely taking safety into account....

Yes. Make a jumper with an alligator clip on one end, long insulated probe on the other. Ground the alligator clip and touch the pin with the probe. Left hand behind your back always (LEFT HAND because it's closer to the heart, I don't care if you're left handed like me ).

Great thanks for the tip..... I am left handed and have always put my right in my pocket..... I will report back later tonight as I am at work and my Daughter has violin tonight.......