lm 317t voltage reg

[dacen]

Well spoken Andrew T.

[Edwar65]

hi, ok will do later tonight and I will let you know the results. Thanks for all the advice chaps..........
tom.

[Edwar65]

hi, will check out later and let you know the results,thanks for the very informative help,especially the pics,
many thanks,
tom

[dacen]

Hope this is of some help to you. I have been using this reg. for many years and I have never experienced one that has failed. That is, following the datasheet.

http://www.ee.buffalo.edu/courses/elab/LM117.pdf

[Edwar65]

hi all, readings as follows;
all supply fuses show continuity,

U501 - 10.85V/ 8.22V,

U502 - 10.80V/ 5V

U507 - 5V/3.66V

Looks as though all voltage regs, are within tolerance? Where next?
thanks,
tom,.

[Mooly]

Where next

We do more checks on the PSU and confirm ALL the other rails are OK too. If you look at the circuit you will see three more regulators each with a diode across it that makes it easy to measure the voltages just like before. The difference here is that U504 and U505 are fed from a relay and so this means the player must be fully ON (not in standby) to measure these.

So you should have plus and minus 12 volts as "switched" supplies that appear only when the player is fully on and also a minus 30 volt supply.

So confirming all these rails are correct is the next step.

[Edwar65]

Hi, all other vr's tested reults as follows:

U503
-28.56
-29.86

U504
11.55
18.22

U505
-18.25
-11.48

U506
18.75
5.72

many thanks,
tom.

[Mooly]

Hi Tom,

I'm on 'tother PC without the circuit...

The plus and minus -12 look OK, thats U504 and U505.
The minus 30 again looks OK although no real differential between input and output... I'll have to look at the circuit for that.

U506. Again I'll have to look at the circuit. The numbers look OK although tbh I don't remember just seeing another 5 volt reg.

Wait 'till I have the circuit, but all seems reasonable up to now.

[Mooly]

All those look OK Tom although I am puzzled at the minus 30 volt rail (although its only for the display) because there should be a "more than minus 30" going into the reg. The manual shows it as a minus 30 volt regulated rail value so the reg would need at least minus 35v ish to work properly. Thats the junction of D505 and D523. Even if there is a problem there it shouldn't affect the rest of the player.

Don't know how I missed U506... but your reading is spot on.

Have we checked U502. I've lost track of all these . Its another 5 volt rail.

If that checks out then we can be pretty sure the PSU is OK. So what fault are you actually seeing now ???

I assume the player powers up OK, display lights and the tray opens and closes correctly.

We probably covered this in the other thread but does the lens move up and down 3 or so times when the tray is closed and no disc inserted ?

If you unplug the machine and manually move the sled away from its normal rest position near the centre of the disc and then switch on does the sled move back to rest position ?

[Edwar65]

hi, U502 readings were: 10.80/5v respectively.
Still showing no disc error on display, even with disc in,everything operates as normal and yes, laser does move up/down approx 3 times,also moves to rest position if moved before power up, only thing I can't see is any light from laser?
Can I assume been sent a duff replacement laser from ebay seller,as with the replacement in, it was making weird high pitched noises on power up and there was no rotation of cd with replacement in situ,I am now running on original unit(which may also be duff)?
I have now located a seller selling(reportedly) genuine stamped sony lasers not unbranded item that I have in my possession,do you think it would be worth trying a new sony laser?
The workhop manual suggests looking at microswitches, although I can't see anything like this near mechanism?
many thanks,
tom.