Wonderland/JM100 build

[Charlie Wilson]

Deleted

[Charlie Wilson]

Sorry, I don't know what I did but I ended up with a bunch of unwanted posts.
CW

[norburybrook]

Progress on the filament string and pilot light.

Could the diodes be not up to the task? they just standard IN4007

1N4007 should be fine as they are rated at 1kV and will see about 1.4x the VAC, so ~400(1.4)=560V. What TM is getting at is if the standby was open when the fuse blew then I'd suspect a shorted diode. If it was closed then the problem is downstream.

Standby was on standby not play.

My initial thought now is to disconnect the wire from the FWBR to the power board and see if that is OK.

I'm away for the morning now so will get back to this later I the day, which will be perfect as you guys are all behind me time wise.


thanks for the continued help

Marcus

[martin manning]

That sounds like a good plan. If you still have high current draw then replace the bridge diodes.

[norburybrook]

Hey first post here, just like to point out your schematic and layout on pg.4 do not match at the 220uf caps and 220k r.
your problem may be in that area, if you could post a pic of the caps and wiring there may be helpful,
according to schematic those caps should be totem poled and resisters in parallel with each.


dave

Indeed, the layout for the power board is missing a wire. There should be a diaganol wire under the board from the hot side of the first 220uf to the negative side of the second 220uf. The chassis ground then goes to the negative side of the first 220uf. Finally, the B+ and OT CT goes to the hot side of the second 220uf. Someone please verify this.
CW

just re read this Charlie and that doesn't tally with the schematic and layout or maybe I've got it wrong.

here's how I've got it wired, I've got the second cap grounded not the first as you say.

Wonderland 100w power connections.jpg

is this all OK

Marcus

[martin manning]

The correction I posted earlier is correct, with the reservoir ground on the second 220u cap. I believe CW acknowledges that above.

[norburybrook]

thanks. I'm actually going to replace the diodes now anyway just to make sure and disconnect the lead to the power board while I'm at it.

TBC

M

[norburybrook]

Ah..I've just gone over this and after doing my drawing I can see I don't have the second wire running from the standby to the screen node, which would also male the connection for the choke as well.

This might be pertinent...although I presume that isn't in circuit until the standby is set to play.


I'll replace the diodes anyway as I've got them out now.

As i'm in the process of re-doing things, what's the best method for removing and replacing components with eyelet boards? I always find this is the bit that messes up things.

I've a solder sucker and braid to hand.

marcus

[martin manning]

I usually use braid first to remove excess solder from the eyelet, then reheat while lifting the lead wire out with long-nose pliers. Some people prefer the solder sucker. If you have burned flux around the eyelet you can clean that up with a q-tip (that's a cotton bud to you) dipped in isopropyl alcohol before installing the new components.

[norburybrook]

thanks martin.

Was I correct that the wiring errors would have no bearing on the shorting when on standby?

Marcus

[martin manning]

Sorry, the two wires from the down-stream side of the standby are the OT CT, and one of the choke leads. It's the other choke lead that goes to the screen supply cap positive.

[norburybrook]

Success.

I've replaced the diodes in the FWBR.

Fired up on the light bulb limiter, nice dim glow, turned standby on and a quick bright flash followed by a lovely dim glow

So, shorted diode?

right time to check voltages on full mains.


Marcus

[norburybrook]

Sorry, the two wires from the down-stream side of the standby are the OT CT, and one of the choke leads. It's the other choke lead that goes to the screen supply cap positive.

damnn.. so I've added an unnecessary connection then, bypassing the filter caps.....Doh!! Ok I'll remove that pronto.......

the shorting is sorted however.

marcus

[martin manning]

Ok, progress! Yes probably a failed diode.

[norburybrook]

right got to go out now. Quickly while I think of it. What's the 'correct' way to tie off the unused center taps on the transformer?

I presume I could cut them off and heat shrink separately then together. Or is it best to keep them long in case of re using down the line? not that I can see that ever happening.

Marcus