1994 Ls400 Radio Back Lights

[Malc]

Hi guys,

For the first time yesterday the radio backlights didn't appear until about 15 miles into my journey !

Radio / CD worked fine, just no lights. The car hadn't been used since Sunday tho' and I just wonder if it's going to be a recurring feature or if it's just damp or whatever coz it's not been used for 5 days.

It shoudn't be the bulbs coz they all sprung to life eventually.

Any thoughts ?

Thanks

Malc

[Malc]

Not sure how I managed to get this post in this Section ...... sorry !!

malc

[The-Acre]

Not sure how I managed to get this post in this Section ...... sorry !!

malc

....and I was just about to ask if you had the radio wired into your brake pad wear sensors!...

[SteveLS400]

Hi guys,

For the first time yesterday the radio backlights didn't appear until about 15 miles into my journey !

Radio / CD worked fine, just no lights. The car hadn't been used since Sunday tho' and I just wonder if it's going to be a recurring feature or if it's just damp or whatever coz it's not been used for 5 days.

It shoudn't be the bulbs coz they all sprung to life eventually.

Any thoughts ?

Thanks

Malc

This is symptomatic of gradual failure. The backlights will work less and less often until they give up the ghost. Its only a pain at night but a big pain.

The problem is likely to be the failure of 1 or more resistors most probably due to dry joints. Benfur and I have been fixing MKIII issues and I currently have one on test. There being no useful info available for MKIII's. However, there are fixes available on tinterweb for MK's I, II and IV. You will have to Google them I'm afraid.

Apart from screw driver and the ability to remove the unit from the car, you will need a fine point soldering iron and either a bench-mounted magnifying glass or those special binocular-style glasses. You can't use a hand held because you cant solder and hold it and you cant see properly if someone holds it (the magnifier!!!) for you. The resistors in the MKIII are only a couple of mm long and imagine the same applies to other MK's.

The fix we've devised, involves removing the rogue resistors altogether and replaceing them on the underside of the main board and that definately needs a magnifying glass to follow the circuit in order to pick up the contact points for soldering.

[whysub]

This is symptomatic of gradual failure. The backlights will work less and less often until they give up the ghost. Its only a pain at night but a big pain.

The fix we've devised, involves removing the rogue resistors altogether and replaceing them on the underside of the main board and that definately needs a magnifying glass to follow the circuit in order to pick up the contact points for soldering.

Are you and Benfur going to offer this fix to us MkIII owners with this problem at some time soon? It's the one thing that drives me mental about my car, and MkIII radio's don't come up for sale that often, whichg seems to be the only fix for shaky handed solderers like myself!

I'm just glad there are owners like you that identify how to fix problems like this.

[Malc]

Thanks for your help with this guys................... so far ................. I had Chris Vince sort out my dash lights a couple of years back ..... he seems to be a whizz with the soldering iron I think.

Maybe I'll contact him to see what it's all about.... there's noway that I'm adept at doing this fix myself saidly.

ALSO the other day I noticed that one end of one dash needle ( the speedo ) is starting to blacken-up ........ guess it's the same age related problems ?

Penny for your thoughts please.

Thanks.

Malc

[SteveLS400]

Thanks for your help with this guys................... so far ................. I had Chris Vince sort out my dash lights a couple of years back ..... he seems to be a whizz with the soldering iron I think.

Maybe I'll contact him to see what it's all about.... there's noway that I'm adept at doing this fix myself saidly.

ALSO the other day I noticed that one end of one dash needle ( the speedo ) is starting to blacken-up ........ guess it's the same age related problems ?

Penny for your thoughts please.

Thanks.

Malc

Yup, same age related issue.

[SteveLS400]

This is symptomatic of gradual failure. The backlights will work less and less often until they give up the ghost. Its only a pain at night but a big pain.

The fix we've devised, involves removing the rogue resistors altogether and replaceing them on the underside of the main board and that definately needs a magnifying glass to follow the circuit in order to pick up the contact points for soldering.

Are you and Benfur going to offer this fix to us MkIII owners with this problem at some time soon? It's the one thing that drives me mental about my car, and MkIII radio's don't come up for sale that often, whichg seems to be the only fix for shaky handed solderers like myself!

I'm just glad there are owners like you that identify how to fix problems like this.

I'm hoping the fix is permanent - hence my testing it. Benfur's are all breakers so testing is difficult.

[whysub]

I'm hoping the fix is permanent - hence my testing it.

I look forward to hearing that your fix works permanantly.

Thanks for trying to devise a repair

[benfur]

I'm hoping the fix is permanent - hence my testing it.

I look forward to hearing that your fix works permanantly.

Thanks for trying to devise a repair

Hi

I will leave the final repair Formula to Steve

As to be quite honest my electronics repair is limited and your eye sight and a steady hand has to be Top notch for the soldering.

Steve has finally hit upon the problem area and I am hoping he can spell the repair out

in pretty basic Layman terms - Even for me !

As I break LS400s Some come in with partial back lighting or none at all or without the button illumination, so from my perspective it would be nice to repair these.

Anyhow I am sure with Steves help all will be revealed shortly

Maurice

stage-1@tiscali.co.uk

[steve2006]

Hi guys,

For the first time yesterday the radio backlights didn't appear until about 15 miles into my journey !

Radio / CD worked fine, just no lights. The car hadn't been used since Sunday tho' and I just wonder if it's going to be a recurring feature or if it's just damp or whatever coz it's not been used for 5 days.

It shoudn't be the bulbs coz they all sprung to life eventually.

Any thoughts ?

Thanks

Malc

This is symptomatic of gradual failure. The backlights will work less and less often until they give up the ghost. Its only a pain at night but a big pain.

The problem is likely to be the failure of 1 or more resistors most probably due to dry joints. Benfur and I have been fixing MKIII issues and I currently have one on test. There being no useful info available for MKIII's. However, there are fixes available on tinterweb for MK's I, II and IV. You will have to Google them I'm afraid.

Apart from screw driver and the ability to remove the unit from the car, you will need a fine point soldering iron and either a bench-mounted magnifying glass or those special binocular-style glasses. You can't use a hand held because you cant solder and hold it and you cant see properly if someone holds it (the magnifier!!!) for you. The resistors in the MKIII are only a couple of mm long and imagine the same applies to other MK's.

The fix we've devised, involves removing the rogue resistors altogether and replaceing them on the underside of the main board and that definately needs a magnifying glass to follow the circuit in order to pick up the contact points for soldering.

Are we talking surface mount/MELF resistors here and the delightful double sided print?

[SteveLS400]

Are we talking surface mount/MELF resistors here and the delightful double sided print?

Delightful is the word. The originals are chip type and so small its almost impossible to solder them because even the solder moves them on the pcb. They are slso mounted in the worst place possibe to get access and they are very close to the main voltage regulator which generates heat which in turn gradually weakens the solder on the chips. The pcb is highly complex and ridiculously fine in detail although the lower face is easier to work with. The fix is melf resitors to the underside.

I have pictures and have promised Maurice (Benfur) that I will write it up. I just want to make sure that the one in the car is fixed and not susceptible to any problem. The grief and aggro means you don't want to be doing it more than once. Trust me. I can remove the unit, strip it down, rebuild it and refit in my sleep Ive done it that often.

[whysub]

Delightful is the word. The originals are chip type and so small its almost impossible to solder them because even the solder moves them on the pcb. They are slso mounted in the worst place possibe to get access and they are very close to the main voltage regulator which generates heat which in turn gradually weakens the solder on the chips. The pcb is highly complex and ridiculously fine in detail although the lower face is easier to work with. The fix is melf resitors to the underside.

I have pictures and have promised Maurice (Benfur) that I will write it up. I just want to make sure that the one in the car is fixed and not susceptible to any problem. The grief and aggro means you don't want to be doing it more than once. Trust me. I can remove the unit, strip it down, rebuild it and refit in my sleep Ive done it that often.

I have no idea what a melf resistor is, let alone how to fit one. I really don't know how you work out why what goes wrong goes wrong, sut so grateful that you do.

I just wish I had a skill I could bring to the forum members.

[Malc]

Are we talking surface mount/MELF resistors here and the delightful double sided print?

Delightful is the word. The originals are chip type and so small its almost impossible to solder them because even the solder moves them on the pcb. They are slso mounted in the worst place possibe to get access and they are very close to the main voltage regulator which generates heat which in turn gradually weakens the solder on the chips. The pcb is highly complex and ridiculously fine in detail although the lower face is easier to work with. The fix is melf resitors to the underside.

I have pictures and have promised Maurice (Benfur) that I will write it up. I just want to make sure that the one in the car is fixed and not susceptible to any problem. The grief and aggro means you don't want to be doing it more than once. Trust me. I can remove the unit, strip it down, rebuild it and refit in my sleep Ive done it that often.

Steve hi,

Does that mean that you are very adept at fixing the radio backlight problem in my old lady when the time is right ?

If that is so then I would dearly love to pop over to you ( from Herne Bay in Kent ) via my nephew in Newmarket ( is that not too far ? ) one day. No rush tho' I guess, it's just the first time it's failed me !

Best wishes

Malc

[SteveLS400]

Steve hi,

Does that mean that you are very adept at fixing the radio backlight problem in my old lady when the time is right ?

If that is so then I would dearly love to pop over to you ( from Herne Bay in Kent ) via my nephew in Newmarket ( is that not too far ? ) one day. No rush tho' I guess, it's just the first time it's failed me !

Best wishes

Malc

I love to fix your old lady and the radio as well :winky: but it aint a 5 minute job and from where you are to me, Newmarket's about half way. Wait till I write it up.

[steve2006]

Just to show the size of components now involved in electronic equipment the picture below is a typical example of a power supply board from an LCD television,the coin is a 5 pence piece to give an idea of scale,the components marked R342 and R340 are the type involved in the backlight circuits,to replace these needs excellent eyesight,soldering skills and in some cases a microscope!

[whysub]

What 5 pence piece?

[SteveLS400]

You mean the half crown in the centre?

Thats about the size of it. The circuit is finer than human hair.

[Malc]

Wow, that is so fine ...... absolutely noway that I could ever possibly " fix " the problem personally ......... it would be oh so good to know of a kind soul who could achieve this for me when my time has come !!

Malc

[SteveLS400]

Wow, that is so fine ...... absolutely noway that I could ever possibly " fix " the problem personally ......... it would be oh so good to know of a kind soul who could achieve this for me when my time has come !!

Malc

Actually, you probably could. And I will write it up soon.

[Malc]

Update guys ........... strange, the past few days have been like summer here in Herne Bay Kent and wot do ya know !

Radio back lights have been as good as gold with all this heat .............. drying out seems to have helped them along ......... strange maybe !

Any thoughts please.

Thanks.

Malc

[Malc]

And again ............ this mini heatwave is maybe expanding the solder joints rather than shrinking them ...... the backlights have been as good as gold !

The cold weather, when the backlights vanished, maybe shrunk the joints ?

Heat and drying out or heat and metal ( solder ) expanding versus cold and NOT drying out and cold and metal shrinking !

Well, I don't know BUT it's keeping good and well so far touch wood.

Malc

[abs66]

I also have a problem on my radio back lights but also the LCD screen is unreadable too. I assume this is not fixable?

I'm not bad with a soldering iron but not sure I want to solder down to that small scale in case I buggered it up.

I away on holiday to sunny cornwall on saturday so I expect I will just chuck the Pure highway in for the trip and decide what to do when I get back.

The way I see it, i have three options:

1. Get a replacement original and risk it going duff again quite soon, lets face it they are getting on a bit now so all likely to have similar issues.

2. Repair Lights and LCD but what cost? Could be pricey compaired to....

3. Get an after market radio with Bluetooth but loose the sub.

Does anyone know what the sound quality is like if aftermarket root taken without the sub, I'm assuming a fairly easy install, double din adapter some kind of amp bypass etc.

Option 3 does give me the option of having a go at fixing the original radio which is very appealing to me as I like to tinker

Sorry if I went a little off topic a little, my bad.

[Malc]

Hi, there's another thread on here about the LCD stuff

Malc

[abs66]

Thanks Malc I will have a shufti unless you have a link to hand?