Lexicon M300

[Crash]

Looking to see if anyone has repaired a dead vacuum display or seen this behavior and had it repaired. Anyone? Other than the dead display the unit seems to be working alright. Thanks crew.

 

[radardoug]

If this is a custom display and it is faulty you could have a problem. But first you need to check around the display to make sure all the voltages are correct. The M300 came in two versions, one self contained (yours) and the other one using the LARC for display.
You could always get a LARC to display for you assuming the unit has a plug for the LARC.

 

[Crash]

I think we have found the issue. There is a small transformer for the non larc model like mine located at T1 on the power supply board. One leg shows 35volts and some various 5.1volt pathways. The 35 volts line is dead, and the trasformer looks rather dark like it may be good and cooked. This is the transformer for the front panel display. Trying to locate a replacement at the moment and hopefully get this unit back to healthy. As it sits now, all the buttons illuminate and the input meters are qworking just has the dead VFD. I am optimistic this xfmr replacement will get us back up and running.

 

[Crash]

Well poo, the new xfrmr didn't solve my issues yet. All the 5 volt legs are good to go, the 35 volt leg...not so much. The journey continues I guess.

 

[Crash]

Finally looks like we got this sussed out. Removing the cap at C9 after the xfrmer got the VFD back to life.

 

[12afael]

it was a tantalum cap? they go short circuit sometimes.

 

[Crash]

Electrolytic cap, non polarised. A ten cent part brought the VFD to its' knees. Seems to be all good now, went ahead and put in a battery holder as well so when the time comes it will be easier to replace the battery and no iron will be needed.

 

[kosty]

Electrolytic cap, non polarised. A ten cent part brought the VFD to its' knees. Seems to be all good now, went ahead and put in a battery holder as well so when the time comes it will be easier to replace the battery and no iron will be needed.

C9 is shorted as well in my unit. Did you replace the cap or just left it unconnected ?

 

[Crash]

I unfortunately replaced it and it shorted again...once again killing the xformer.  I am going to order another xformer and and leave C9 dangling.

 

[kosty]

I just removed one leg of the cap and the display is working again !

It seems to be just a smoothing cap, shouldn't be a problem leaving it out, I guess.

Many thanks for having posted the solution. I was about to disassemble the front panel.

I now need to fix one not working analogue input.  I think it one of the opamps.

 

[Crash]

I guess I should try that before I order parts. The original xformer cooked itself beyond working so I figured this one was trashed too.

 

[kosty]

I suspected the T1 transformer too  because it looks partialy brown (seems to be grease and dust).
If you need me to check continuity and resistance between the transformer legs, let me know

 

[Crash]

Cut a leg of C9 and the display sprang back to life.  Woohoo.

 

[kosty]

Cut a leg of C9 and the display sprang back to life.  Woohoo.

Yeaaah !

 

[Crash]

My xformer isn't the virginal white it was when I replaced it but not nearly as dark brown as the baked mess that came out in pieces from the first repair.

 

[Evgeny Erokhin]

Hi! I've faced the same issue with the transformer, that put my display on M300 into the dark. It looks like it's dead. So could you point me to what possible replacement exist! I was not able to find any proper replacement (.

 

[collinsmusic]

My xformer isn't the virginal white it was when I replaced it but not nearly as dark brown as the baked mess that came out in pieces from the first repair.

hi...i have this issue...fried xformer and no display....where did you source replacement xformer please? many thanks, James

 

[la-2a]

Hi, I have exactly the same problem. I'm also looking for this transformer....