REPAIR GUIDE - TurboDuo/PC Engine Duo/R/RX: Laser Swap & Adjustment Guide

[Keith Courage]

Please take some pictures. I can't think of anything that could have gotten messed up other than some wires getting pulled.

Just to make sure I have this right. Your old lens worked before trying to install a new one but now neither will work?

[Tempest_2084]

Yes that's correct.  The old lens not working is what's really stumping me.

Pictures.  Note that the board to the left is a RGB mod and has nothing to do with the laser (everything including the RGB mod was working before I tried to install the new laser).

[Keith Courage]

Did you ever at one point try to adjust the pot on the lens itself? If so you should check the contacts for said pot since sometimes turning them can sometimes crack the solder joints.

[crans]

The points at the start of this thread are great at getting you moving.It would best start with the best music cd you have to test the new laser.

The cap work on this looks factory quality so that cant be it. Where did you get this "new" laser? I have had my share of "new" old broken, reworked,china CRAP!

[Tempest_2084]

I did go through the guide here first, but nothing helped.  I really REALLY don't want to adjust the pots as I hear you can screw crap up that way and they worked with the old laser anyway.  I did play with the pot that supposed to control the CD spindle, but I put it back to where it was after that didn't do anything and the CD wasn't spinning before anyway so I don't think that could have done anything.  I never touched the pots before that.

I got the laser off ebay from the seller a lot of people get theirs from (he's from the USA, that's all I remember).  However if it was a bad laser or pot setting I can't see why the old one wouldn't work, that's the mystery.  To me that points to bad or broken wiring, but I did a continuity test on the wires and they all seem ok as far as I can tell.

I tried a music CD but it still won't spin.  What wires control the CD spinning? 

[thesteve]

wont spin is an early fail
no cd in
door switch pressed
hit run
the laser sled must bump the center switch, then bob
laser must light
check and report

[Tempest_2084]

Yes it does all that.  I assume by 'center switch' you mean the cd spindle? 

[thesteve]

there is a switch by the spindle the laser sled must hit before looking for the disc

[Tempest_2084]

Ok I think I see it.  The sled does bump that switch, but it doesn't look like it pushes it in very far.  I moved the sled over so it totally pushed the switch in, but still no spin.    How much does it normally push that switch in?

EDIT: Looks like that switch just makes the laser go back to the left. I held it in and the laser went all the way the other direction.  So that would make sense if it only bumped the switch lightly and bounced back a bit.

I did a continuity check on the two wires going to that switch.  They seem alright.

[thesteve]

next 1 will be harder to see
disc in run
centers, laser bobs 1 time and locks on

[Tempest_2084]

It's hard to see, but from what I can tell the laser bobs two or three times before giving up and saying Set Disc.  I don't think it's locking on after one bob.

[thesteve]

thats what i suspected
it means its not flagging the mirror pin (cant see its reflection)
possible causes laser/wiring/CXA1081

[Tempest_2084]

Ok that's what I suspected as well.  Someone told me that if the laser doesn't detect the disc it won't spin.

possible causes laser/wiring/CXA1081

I think we can eliminate the laser because even if the new laser was bad, the old laser which worked before is no longer working.  I can't believe I could have damaged it taking it out of the system.

Which wire controls the flagging of the mirror pin?  I thought I tested all the wires in the two ribbon cables and they all tested fine for continuity.  The only one that I'm not sure about is the larger yellow wire that appears to go from the motherboard into a taped up area of the wire bundle.  I don't know where it ends so I couldn't test it for continuity.

Where is the CXA1081?  Is is easily replaceable or is it soldered in?

[thesteve]

mirror pin is from the CXA1081
under the board by the connectors
mirror is acheived by the laser sensors responding back to the CXA1081
mirror is sent to the other CXA/CXD chips to switch the system to closed loop
scope pin 2 of connector 5 (P2 of P5) to see the output of the laser/amp

[Tempest_2084]

Unfortunately I don't have a scope, just a really crappy volt meter.

I think I've done about as much as I can on my own.   I'm going to send this off to a friend who thinks he can fix it.  I'll report back when I get some news.  I appreciate everyone's help and I'll pass along this info to my friend.