PCE Duo laser and low caps issues

[Slypty]

A friend recapped my Duo for me, but it came out with the low sound problem.  I'd like to try the guide someone posted on how to troubleshoot the low sound, but the laser also doesn't turn CDs.  It tries to start, but you just hear a 'click' and then it doesn't spin.

  It used to spin for a while, but stopped shortly after recap.  When I looked closely at his recap job, 4 caps were put on backwards.  I corrected that, but it didn't make any difference at all.. I'm wondering what sort of impact having them on backwards could do, and if it needs to be recapped all over, or if I should start messing with the on board POTs.  Anything I can check for laser troubleshooting for this type of issue?  Thanks

[Keith Courage]

Having them backwards shouldn't have hurt anything.

Your problem is probably due to bad traces or shorts in vias due to old cap leakage/damage. I would start checking every capacitor lead with a muti-meter to make sure the cap solder pads have the same voltage as the traces and vias do.

[SignOfZeta]

I don't know. A guy who puts four caps in backwards could have done anything.

[blueraven]

I don't know. A guy who puts four caps in backwards could have done anything.

[Slypty]

I won't mention names but he is on the forums.

  Good guy overall, but ya 4 caps backwards was a shocker.   

 I'll take a go at testing the caps voltage as mentioned, should the pads read the same amount with the power on, or should I allow for tolerance of 10% or so for voltage, but more accurate with uF?

[Slypty]

I won't mention names but he is on the forums. 

Not for anybody to worry about if they are getting a recap done on these forums, the guy who did my repair is a local friend and doesn't reach out on these forums for individual repairs.. so no worries for anybody sending a console in to PCFX forums repair guys.

[Slypty]

Having them backwards shouldn't have hurt anything.

Your problem is probably due to bad traces or shorts in vias due to old cap leakage/damage. I would start checking every capacitor lead with a muti-meter to make sure the cap solder pads have the same voltage as the traces and vias do.

So I went ahead and tested Voltages running across the caps when the power was On, and basically everything except for a few caps are 5V, I double checked with another Duo for confirmation and didn't find anything that unusual.

 The only oddities I could find;
- The Op Amp VDC in is about 7V, on my other Duo it's between 3-5V. 
- The V105 Pot reads 369 Ohms on the non working Duo, and 5.88KOhms on the other board I have
- There's a small cap above the Hu Card, C517, I noticed if I bridged the Cap the laser will actually spin..for a second or so.  Bridging it will make the Console go wonky, but at least I can rule out the motor and that it's a separate issue. 
   
  Any insights at this point, since this Duo seems to be on the way out would be terrific, thanks

[Slypty]

Sound solved!  Sorta 

  By connecting the 2nd leg on the Op Amp (counting from the right, bottom as 1), I  noticed it would come to life by touching it or bridging it to positive output on caps.  So, I attached a wire to it and probed for a consistent audio feedback, and came to C322 as the culprit.  I just soldered the wire to the C322 positive out, finding the exact trace seems like a lot of work.

  Now that f'n laser!  22uF Cap, C517 when bridged will spin the CD.. as mentioned this is my current problem, it's not spinning.  I might try the same technique with this cap, and bridging it to potential shorted areas to see what I get.

[Keith Courage]

Hold the board up to some light and you should be able to see where the trace is supposed to go so you can tap in a wire to the correct place.

[Slypty]

The POTS seem to be out of whack, after adjusting I managed to get the laser spinning, but won't read audio cds.  I'm doing minor tweaking here and there, but not sure how to get it right. 

  I don't want to burn the laser out so I am just using small adjustments. 

  I'm thinking of picking up this oscilliscope, but don't know my ranges required on Duos, so I'm hoping someone can say whether this scope will do the job:

https://www.aliexpress.com/item/DSO138-2-4-TFT-Handheld-Pocket-size-Digital-Oscilloscope-Kit-DIY-Parts-SMD-Soldered-Electronic-Learning/32589231581.html?spm=2114.search0104.3.79.1dd81126K4rbTN&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10151_10065_10344_10068_10130_10342_10547_10343_10340_10548_10341_10696_10084_10083_10618_10139_10307_5711215_10313_10059_10534_100031_10103_10624_10623_443_10622_5711315_10621_10620_5722415,searchweb201603_1,ppcSwitch_5&algo_expid=e51cfe92-0717-4603-8b5b-e2f5621c4c03-14&algo_pvid=e51cfe92-0717-4603-8b5b-e2f5621c4c03&transAbTest=ae803_4&priceBeautifyAB=0

[Slypty]

Well after tweaking the POTS for a while, I got a CD to run.  I'm having some issues with getting it past certain songs, for instance it will play up to song #6 fine, but after that I've only had it run to song #15 out of 20 once. 

 I also noticed that when the laser extends to the edge of the disc, it has trouble finding and reading that it's near the edge, and returning to the middle.  I'm not sure if a POT controls the distance the laser is supposed to travel, but it seems to get stuck there and I think it's the main reason songs aren't being read consistently.  Anyone experience this issue?

[crossmanbx]

Juste would like to thank you Slypty for the trick about the second leg of the op-amp and the + of the cap. Worked fine for me too ! Like you, I m going now to try to solve the CD chapter ! 

[Keith Courage]

try adjusting the V101 pot. usually this helps with issues reading near the end of the disc. Also, try turning up the lens gain on the lens itself slightly.