Need help - Cadet IV Ramps debugging

Forum DIY
1

Hi All,

My Cadet IV Ramp top horizontal section outputs only two “full” outputs (no lines or seperations visible even when attenuated) and one output does not work at all - the trimmers do not seem to change anything either. The bottom (vertical) section puts out horizontal bars though which are a bit confusing as well - are not these supposed to be the other way round?

The trimmers can adjust the width and position of them well in that bottom section. I have taken photos of the outputs and the board as well.

H output:

20190827_164958
20190827_164958.jpg4640×2210 2.13 MB

V output:
20190827_164927
20190827_164927.jpg3280×1562 2.17 MB

Board:
20190827_165128
20190827_165128.jpg1562×3280 2.18 MB

Thanks in advance!

2

1st thing I notice: what is going on with the clutter of resistors in the lower left corner?
I will check it against my Ramps later.

3

I was going to add this too - it was basically a compensation of resistor values, since we did not have the proper ones and sorted out the problem this way. And to tell you the truth the bottom section does work, it is the upper section that does not.

4

can you also post a pic of the backside?

5

Here we go:

20190830_090607
20190830_090607.jpg2210×4640 3.26 MB

6

image
image.jpg1539×2368 1.73 MB

these two should be the same value (100r)

looks like different values on your board

7

I see! Is there anything else we had better look at apart from this?
Thanks!

8

I can’t really tell from the pictures:

image
image.jpg1161×1418 958 KB

these two resisters should be different values from each other. as I have them:
yellow white white black brown (499r)
+
yellow white white brown brown (4.99k)

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9

and C6 is reversed!!!

this is the electrolythic cap at the bottom

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10

Hi,
Thanks! I have tried to identify the parts based on the photos and your recommendations.
Could you please confirm that I am on the right track? Thanks!

  1. R27 & R45 should be 100r
  2. R32 & R50 should be 499r
  3. R2 & R4 should be 4.99r
  4. C6 is reversed
11

disregard the picture with green circles for now. they might be correct
I don’t have a pic of the bare pcb so the value codes are hard to check

the other things are more important:

desolder the cap and make sure the 2x 100r is correct (pict with the purple circles)

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