Pics of "183

[Oddvar R]

Hi. I am just about to plug in my Dumble build. I would appreciate if you guys would have a look and spot major fault, which I am sure there must be.

https://www.dropbox.com/s/t97eljyb9906e ... 7.JPG?dl=0
https://www.dropbox.com/s/rp2x2arjqnkq4 ... 5.JPG?dl=0
https://www.dropbox.com/s/dnoi8j8lu9fvk ... 4.JPG?dl=0
https://www.dropbox.com/s/0y8wncq0t6qb9 ... 6.JPG?dl=0

[erwin_ve]

Hi Oddvar,

General: pls take a look at https://thesubjectmatter.com/dumblearchive.html. There are several hi quality pics of #124. Take that as a benchmark.

You have a lot of flying leads, cathode wires/ plate wiresd (almost) touching grid resistors. Blue plate wire v2a bare metal is almost touching the grid resistor.
The possiblity of moving wires is big and therefore a big chance of a unstable amp. (Oscillations, hum etc.)
See some cold solder joints, eyelets need heat so the solder flows on the entire eyelet

Ps filter has a 2R7 dropping resistor? Brown dropping resistor on the PS is that a 2w? it looks like an ancient 1 w metal film.
Also which layout for the PS filter did you use. Take a good look at the Electrolytic connected to the white 2R7 it's reversed and likely to explode on startup (BOOOOOMMMM ) If you ever experienced it you want to triplecheck that.

[Oddvar R]

Thank for that, I used the layout from Taylor on the filtercaps. All the resistors are as valued in the layout. The brown one in ps is ohm and wattage as described.

[erwin_ve]

Can you make a link to the layout you used for the ps?
Ive seen 2k7 in the dropping string between b2 en b3 in originals, not 2R7 in your amp.. The polarity for the elektrolytic capacitor is a big thing. If it explodes your amp and part of your house will be covered with shrapnel from the lytic, not even mentioning safety issues for eyes.

[martin manning]

Looks like those boards were made from my eyelet board drawings as shown here: https://ampgarage.com/forum/viewtopic.php?f=5&t=29630
The first dropping resistor is definitely the wrong value, and ALL of the smaller (22uF) filters are reversed in polarity!

[sluckey]

Hi. I am just about to plug in my Dumble build.

Please post a video.

[erwin_ve]

Hi. I am just about to plug in my Dumble build.

Please post a video.

This is a builders forum not Chinese New Year.

[sluckey]

Sometimes it's all the same.

[Guitarman18]

Oddvar R,

As others have mentioned, you really need to sort out the polarity of your filter caps, particularly the F&T's. They will explode spectacularly if you keep them as they are!

Also, as much as we all have opinions on components choice etc, the one thing I think we all agree on, that is crucial to a quiet, good sounding build, is the lead dress. If you completely disregard the guidance in the layouts etc. you are at best building a poor replica of an ODS that has no hope of sounding any good and, at worst, just a collection of parts that won't work.

If I were you, after sorting out the very serious safety concerns, I would spend some time sorting out the lead dress.

Cheers,

Paul.

[drew]

Looks like those boards were made from my eyelet board drawings as shown here: https://ampgarage.com/forum/viewtopic.php?f=5&t=29630
The first dropping resistor is definitely the wrong value, and ALL of the smaller (22uF) filters are reversed in polarity!

Compare to the third photo in this thread:
https://ampgarage.com/forum/viewtopic.php?f=4&t=31072


Easy enough thing to fix, though. Keep at it. The idea that others have suggested of printing out a big copy of the layout and then meticulously going through every single part of it, comparing it to your build and marking the layout with a highlighter pen bit by bit, is a good, proven approach.

[donvan]

Hi Oddvar,
Looks like you got some helpful advice in this thread. A followup would be interesting and maybe helpful to others.