1996 LS400 AUDIO UPGRADE OPTIONS

[Howplum]

Having done a bit more digging on the internet I came across this post on a US forum:

https://us.lexusownersclub.com/forums/topic/35241-hooked-ipod-to-stock-stereo/

The post I particularly like is the last one by Kevin in 2017 where he has wired the auxiliary wires direct to the radio PCB in such a way that the AM button becomes the auxiliary selector. However, whilst I can use a soldering iron, I would appreciate any observations from those amongst you who know more about electronics than I do.

It's a little difficult to see exactly how/what he has soldered to the TUL and TUR connections, but am I correct in assuming they would be the respective wires going to the centre posts on the female RCA phono plugs I plan to use, the negative (outer) wires being soldered to the chassis?

 

 

 

 

 

 

[runsgrateasanut]

That's interesting.  From memory the Tape deck etc is all "caged" and so will require careful cutting to "open it up" or  am I wrong here?  Been a long time since I took my unit out.

I'll watch this thread with interest.

[Howplum]

Stuart, I don't think the cassette assembly needs to be touched, although the phrase "Remove the upper AM/FM circuit board from the radio" might be economically worded! We'll see.

I have got some bulbs on order, which is another issue, together with some female RCA phono connectors, so once they arrive later in the week I'll dismantle the radio (again!) and let you know how I get on. I'll take a few pictures along the way.

This is very much uncharted waters for me, although I dismantled the instrument cluster more times than I can remember.

[cruisermark]

The aux input has definatey been done:

Factory Radio Service aux-in on 2000 LS400 - Page 3 - ClubLexus - Lexus Forum Discussion

It also mentions some sort of isolator to get rid of hiss

[Howplum]

Thanks for that link Mark, very interesting. It looks as though there is more than one way to achieve the same result, i.e. a hard wired 3.5mm input, especially for an expert.

I see that ground loop isolators are plentiful and cheap, but first things first, to see if my unit can be modified successfully.

[cruisermark]

a how to here - but you do lose AM setting:

How To: Build and Hardwire an Auxillary Input to OEM Stereo - Page 52 - ClubLexus - Lexus Forum Discussion

[Howplum]

Thanks again Mark, but that's the post number 766 by "Kebin"  I referred to in my post yesterday. What appeals to me is that it looks like a fairly straightforward and is also on a non-US spec. car, so hopefully mine will look the same when I open it up. Who listens to AM anyway? If it works then the OCD in me would like to re-letter the AM button, but perhaps that's a step too far!

Some of the (US) alternatives mentioned seem fairly complicated and occasionally unsuccessful.

[runsgrateasanut]

That "mod" seems to be on a Nakashimi model given the final photo of the rear. 

My '93 Pioneer I found that the Cage could not be opened in my bid to replace the "Rubber Band"  which I assume is the cause of my Tape Deck not working.  Can you get to your Tape Deck "band" in the later model, Howard?

[Howplum]

All will be revealed in due course. Watch this space.

[Howplum]

I dismantled the radio this afternoon so here are some pictures:

This is the standard Pioneer audio unit fitted to my 1996 model. The two waveband buttons (top left) are different to those shown in the post by "kebin", but hopefully this won't make any difference to the modification. The display is starting to deteriorate, but I'll live with that for the time being.

This is after removing the top cover, which is held on by just a few screws.

 

Next I removed the front fascia, which is held on by two screws and two clips on each side. The power/volume knob has to be removed first. Strictly speaking this doesn't need removing before removing the upper PCB, but I have three of the micro bulbs to replace.

Next I removed the upper PCB, which has no physical attachments other than the black multipin connector on the right, so a firm upward tug will release it. Hopefully reassembly will be equally straightforward.

Turning the PCB over I was relieved to find that the TUL, TUR, AML and AMR connections were exactly as per "kebin"'s post, so it's looking promising so far. However, I didn't realise they would be so small - they looked bigger in the pictures! I have marked them with a red pen.

That's it for the moment. I'm waiting for a magnifying glass on a stand to arrive to that I can do some soldering.

Stuart, on the tape player I can see the drive belt and in theory it should be replaceable, given the attention to detail so far, but without delving deeper I cannot say for sure. Mine works so I'm leaving it well alone!

 

 

 

 

[Howplum]

I made up a lead from a couple of lengths of speaker wire with female RCA phono sockets on one end. Red is right and black is white.

Then I drilled a hole in the casing in such a way that the upper cover could be removed without disturbing the leads.

Then I soldered the other ends of the red leads to the TUR and TUL connections. The two black leads I attached to a chassis tab, although they were reluctant to stay in place at first. Not pretty, but hopefully effective.

At the same time I replaced the three micro bulbs in the fascia, which was REALLY fiddly, although I have covered this in a separate topic.

All back together again.

However, the problem I have now is that having reinstalled the complete audio and climate control assembly back in the car the audio unit does not power up, which is very frustrating. Either there is something I have missed or I have damaged a vital component somehow.  Any ideas anyone?

 

[Howplum]

Is it possible there's a security code? The unit has been out of the car for several days.

[steve2006]

A security code wouldn’t prevent the unit powering up.

I would start by checking the associated fuses for the audio system.

Although unlikely the cables you have soldered in may be shorting out on the PCB, screened cables may also be a better option to minimise interference.

[cruisermark]

I would concure with Steve

I remember unplugging the amplifier on my 430 and it blew the fuse and I never thought of the fuse and drove around for months without music lol

[Howplum]

Thanks. I do a few checks when I have time.

[runsgrateasanut]

A couple of possibly useless thoughts. If the 1996 Car had a seperate Amplifier (not in a 1993)  and CD Player in the Glove Box does the Cartridge eject? Power I believe comes from the Radio?  Second thought, was the Antenna plugged in as I imagine this is an essential earth?

[runsgrateasanut]

What sort of Cable is that Kevin has used? Reminds me of ancient House wiring.  Stupin Q. you did have Battery connected and ignition set to ACC.  Sometimes we (or I) do forget the most basic things.  Coming back from Abroad many years ago my 500SEC wouldn't start and I called out the on site Battery charger guy.  Only whe he arrived did I remember I had one of those push in Immobiliser plugs. Doh! 

[Howplum]

The cable was twin core speaker wire, but is much too thick for the job, in my humble opinion. I have some silicone (or maybe it's rubber) covered wire which is much thinner and more flexible, so I'll make up a new connection once I get the unit working.

[Howplum]

I checked the connections and confirmed the unit was receiving power, both switched and unswitched, so the problem isn't the fuses.

So, I dismantled the radio, yet again, but a bit further this time, and discovered this leaking electrolytic capacitor on the lower main circuit board:

 

I can only assume it's an  unfortunate coincidence, since it's nowhere near where I was soldering.

The other minor issue I noticed was two of the prongs that connect the lower board to the upper board were slightly bent, so perhaps they weren't making proper contact. They were easily straightened, but obviously great care is need on reassembly.

It's out with the soldering iron again!

[cruisermark]

you leave us in suspense . . . . 😅

[steve2006]

If you’re referring to the white stuff around the capacitor that’s glue not electrolyte leakage so it’s fine.

[Howplum]

I assumed it was leaking so have removed it and ordered a replacement. Bu**er. 

So perhaps it was the two bent prongs, but since the fascia is connected to the lower PCB, which is where the power comes in, I have no other idea for the apparent complete loss of power. 

[Howplum]

As a diversion I came across this option for installing a replacement double din unit:

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/857222-1995-1997-ls400-aftermarket-radio-install-utilizing-stock-amplifier-for-pioneer-radio.html

It's American, so the wiring will be different colours, but hopefully the pin numbers will be the same. Obviously, the CD multi-changer becomes redundant and is subject to finding a housing adapter to fit, which might be a challenge because most seem to be for pre 1994 models. Ideally a single din would suffice, but finding a housing might be be even more challenging.

[runsgrateasanut]

I have a spare DIN Mount Radio Provision with pocket.  Ref is 99-8156 This is single DIN and for a Lexus 1990-1994. Possibly will fit the space but maybe not. Check for other part references. Nearly all are imported from the States.

[Howplum]

Thanks for the offer Stuart, I will bear it in mind.

In the meantime, it occurred to me it might (hopefully) be something simple, starting with the on/off switch. One push of the button should presumably close the circuit, turning the unit on, the next push opening the circuit, thus turning it off.  This is the back of the POWER-VOL assembly in situ:

And these are the connection markings:

I assumed the middle three connections related exclusively to volume control, so by default the two outer ones are for the power supply.

Using the resistance facility of my digital multimeter on the prongs, with the assembly installed, it looks as though the circuit between the two outer connections is permanently open (no resistance reading). It is only closed (resistance reading 0.00) when the button is held in, which doesn't seem right. Also, there is no click indicating that the internal switch is locked in place, which I'm sure there used to be/should be.

Am I barking up the wrong tree?