The BOSE Prototype that Never Made It

[@bobgrob4]

Mark, we need a part 2. It can't end this way!! It can't end this way, Mark! Bwaaaaah! You can do it, Mark!! Have him leave it with you.

[@straxx99]

I was hoping for a part 2 or more, it's fascinating with prototypes like this.

[@DJSubAir]

Thankfully we got a part two!

[@szyszka8303]

Memory chip with firmware was wiped out, there is nothing that Mark can do!

[@_MasterLink_]

@@szyszka8303 Actually that's not true because there is a part 2 from 4 months back. The radio simply needed a BCM (Body Control Module). See that "Theft Lock" label on the bezel? Yep. ;) It needed that BCM, and they got it booting, DCC working too, but the Minidisc needed some help. Check out his video from 4 months back.

[@DRDCC]

Thanks Mark for a great day and all your efforts trying to make this work for the DCC Museum.

[@tullgutten]

Try powering it up again, think it was just missing the ignition power to turn on after the ribbon was put in the right way 😅

[@bigbadbith8422]

I still have my Philips DCC😊

[@Petertronic]

@@tullgutten I'm sure they thought of that

[@tullgutten]

@@Petertronic shit happens. Sometimes the most obvious thing can be forgotten

[@Bretware904]

@@tullgutten How do you think the chips were passing data....because it was on

[@maligi62]

Mark you are a real man. Because you have patience and only with a smile on your face. Success! I enjoy following your work.

[@jeremythejetplane4712]

Hey Mark, a couple of comments on this. In my experience the 8v rail is very common in car stereos; it's often used for the tuner and audio processing (e.g. volume/tone) sections. The display driver IC is an Oki MSC7170 - also a common part in car audio. It includes button inputs so also often handles the button matrix as well. Datasheets are readily available if you search for the full part number. I thought this was a very interesting job to take on, thanks for posting the video even if it didn't work out!

[@fretlessfender]

That was just a pleasant surprise to see Ralf pop up in your video! I am a member of the DCC forum and a massive fan of you Mark... so seeing you both together was someting else!

[@Yorumcu63]

Mark You have great videos. You have excellent knowledge and experience.Congratulations. You wrote on your website that you were busy for several months due to repair requests. You can ask your customers "Do you want a video to be taken during the repair?" If the customer says "I want", you can ask for an extra fee. You are already very patient and work very professionally in repair. Your customers will also see how much effort is put into them. In addition, these videos are also useful in youtube videos. Regards *Translated with google translate

[@eddieMurphy11111]

enjoyed the video again i am just trying to remember everything i was taught before my stroke so a wonderful video thank you

[@silberware]

A Theftlock feature is probably looking for an unlock code. This was popular in the 90s, discouraging theft by rendering the unit useless if disconnected from power without knowing an individually assigned code which is entered thru the preset buttons to reenable functionality. The Nakamichi TD1200 was one of the first products to use this scheme.

[@XMguy]

I hope for a part 2. I want to see this working. Great video.

[@rafi3412]

Great to see you 2 guys together. Greetings from Poland

[@sparkybruce]

Your PSU is current limiting which might be causing it to crash during power up. If you swap over to the 25V 4A config on the PSU you can run it with a 12V @4A current limit to see if that helps.

[@trevorwhalley7466]

Dear Mark. I don’t use telegram, this video about BOSE, and your previous one on B&O, shows that both are quality goods, its really. nice that you invited a guest, gave hospitality, and admitted ( understandably) components you don’t know of beat you, your magnetic personality does you well, keep making the vids, they are so interesting and entertaining.Trevor

[@Big_ol_bass]

We need more videos Mark, absolutely love them!

[@brianp7022]

Wow imagine having that unit in your car back in the 90s …looks like it was mega expensive!

[@shantrannyduck]

a toy of utter beauty

[@Jawst]

As an ex mechanic, I just wanted to let you know... With all older car stereo, you always need three wires to make them work!! 2 wires for power. + , - , and ignition ( not illumination) When you get in your car and turn on the ignition, the radio comes on! On older VW's, the ignition feed is actually turned on by a small door covering the Keyhole on the ignition barrel!

[@pacadet]

These GM headunits get a command to power on via the Class 2 "comfort and entertainment" bus. Without that command, it'll remain dead. It needs to physically go into a car or build some crazy off-board harness with a proper BCM.

[@ewoutbuhler5217]

Excellent little mystery we have here. Two heros, Mark and Ralf. Thanks for this video, it was worth a shot!

[@Marcel1984nl]

Great work, I'm speechless after this video! I know those old car stereos can give you a headache. You don't give up easily and that's a good thing. You really did your best to find defects to fix it.

[@t0nito]

I know it's a stupid basic question but it wasn't shown in the video, did you redo the battery + ignition connection? Because I was under the impression you left the battery wire only to see if there was still current draw.

[@dervwfahrer]

I am quiet shure he will know how a Car Stereo works with Permanent 12V and Switched 12V.

[@t0nito]

@@dervwfahrer I think so too, but he could have forgotten, who knows?

[@Bretware904]

It was on and passing data

[@TheAnimystro]

@@Bretware904 yeah but that could have been standby behaviour.

[@Jawst]

This was my thought exactly! If he did wire up with the ignition feed he would have showed it but instead he showed wiring up with the illumination feed

[@Robjud-u2x]

Did you connect the ignition feed back up to it after finding out that the ribbon cable was plugged in upside down for the display? Car radios generally wont turn at all unless they are getting an ignition feed.

[@frank40m999]

Never heard of a DCC? In my new car in 1996 I just had a Radio/DCC player, with many pre-recorded tapes and my own tapes recorded at home. All Phillips…

[@Capturing-Memories]

What a gem! A MD changer and a dcc combo? wow. I hope you guys manage to get it going in the future, I want to see the MD changer in action.

[@v12alpine]

Make sure you reconnected the red (key switch) power wire after you corrected the front panel ribbon. The radio won't do anything without both yellow (constant) and red (switched) inputs. I'm sure it's nothing that simple though and you already figured that much. Ribbon was probably upside down from previous trouble shooting attempt. I'd focus on that burnt transistor, maybe the transistor is good (or not) but whatever it's powering and possibly what feeds it isn't good for sure.

[@myopinion69420]

this. I would not be entirely surprised if it was just a matter of that ribbon being flipped. shorting something to ground that should not be to draw the 7w. then having removed the switch wire, once fixed it was just using the bare minimum power to keep the clock/settings memory going.

[@mountain177]

Im sitting here thinking about security, and how radios of that era started needing a security code punched in to unlock the radio so it could work.

[@envisionelectronics]

I worked at a shop that repaired a lot of Delco units. I hated them with a passion bc we often didn’t have schematics. I got really good at repairing anything without the service information and many times was stumped by Delco. The parts are all OEM marked.

[@stephensams709]

Exactly and their soldering was notoriously terrible. I can't count the number of Delco electronic products that I have repaired just by repairing the solder joints.

[@alexmikhael5061]

@@stephensams709 the US NAVY 3M micro minicomp certified me in the late 80s..... RIBBON CABLE and SURFACE MOUNTS were BARELY comming into the equipment, but the amounts of ''sketchy'' solder joints that are out there, its a wonder the TRONS don't let out more smoke!!! (Aviation Electronics Tech I was.... worked on IFF, radios, ...a missle avoidance system... many MANY M A N Y PRC90s !!! ....sigh... anyhow... lol yea... I look at peeps showing RADIO WORK on their bench and I shudder sometimes cuz the BRAND NEW RADIOS they are puttin ''kits'' into and watnot to tune them up or WUTEVER and I see radios *I* would have REFLOWED the joints in HALF the radio just cuz... well LESS GRIMILINS I LET BACK OUT INTO THE HANDS OF THE PEEPS THE LESS GRIMILINS I WILL BE CHASING LATER!!! or something like that... and the peeps that use 2x to 25x the amount of WATTAGE they need to properly flo the solder, is like WOW.... DID YOU USE A WELLER 250w SOLDER GUN TO SOLDER THIS?!?!?!??!?!? ...well it was just the POWER WIRE!! ...sigh... nevermind... flashback ;)

[@rkan2]

From RoHS with love.

[@Watcher3223]

@@rkan2 RoHS would not have been a consideration with General Motors Delco units from the 1990s. And because it's GM, that's why you have problems with Delco. They weren't known for the finest craftsmanship. The "Mark of Excellence" was a running gag. And it's also easy to understand why it was so hard to get service information on Delco products; GM would rather you take your car with a faulty Delco device to the dealership to deal with rather than have their devices fixed by an independent shop.

[@Vchat20]

The theftlock writing on the front plus being Delco is a dead giveaway that this was likely a GM component here in the states. The power draw may be a red herring as GM vehicles even back around this era passed all the bings and bongs from things like lights being left on, key in the ignition with door open, etc. through the headunit so the amp circuit was probably legitimately active for this purpose. I was going to make a comment about possibly needing some digital 'ignition' signal to turn on but I'm not 100% sure if they used this methodology back then. It's more common now however with CAN bus based vehicles. EDIT: Doing some more research bears out the last point. Looks like GM vehicles of this vintage didn't have a traditional voltage based ignition signal but was all data based. So this unit is likely looking for a digital signal from the vehicle telling it the ignition is on. GM-LAN is the protocol used so that may help if you want to try to rig up something to fool it.

[@Pressbutan]

100% a very close copy of what Cadillac was using in the Seville and DeVille around this era, late 90s/early 2000s. It might be looking for a CAN signal or some control unit that lives in the trunk. GM loves doing that shit

[@thijsvanexel]

Bedankt

[@graemeyetts3465]

You can just tell his love for electronics. He's like a benevolent electronics surgeon ❤

[@MichaelCowden]

That Bose stuff is weird and complicated. Mix it with automotive technology and Delco and a prototype and mixed-vendor integrations, and you’ve got a recipe for failure. The GM vehicles I’ve owned all had entertainment system problems. The one I had with a Bose was so problematic and strange with unobtanium parts, I replaced it with an Alpine system that sounded better and worked right. Good effort and another great video, Mark. Thank you for sharing! EDIT - another thought is the front panel says it has TheftLock. There could be some code required on one of the back panel inputs that matches an internal key to convince the proprietary controllers to power on. GM used to do it with resistors embedded in the ignition keys, but I don’t know if that resistor value is directly connected to the radio or whether it triggered the car’s BCM to send a “security good” signal out to the entertainment system. If you dig in any further, this might be a route to explore and research further.

[@williamjones4483]

That "Theft Lock" feature is something unique to General Motors vehicles. The VIN has to be coded in by the dealer if I'm not mistaken in order for the radio to function properly. Ex., if the radio was removed (stolen) from a GM vehicle and was installed in another it will not work. BTW, I've got an '04 GMC pickup with the original Bose system and it still works great. I've tried TWO Kenwood aftermarket receivers and both of them quite working after a time.

[@Bananerocs]

​@@williamjones4483yeah bose is garbage

[@uxwbill]

I'm not sure what would make it weird and complicated. The Delco/Bose systems just use a separate power amplifier to drive the speakers, rather than the one in the radio. Perhaps in earlier systems there are actual differences in the radio head. I have not worked on any of those. In the later ones, up to at least 2007 or so, it's just bits in an EEPROM that are set according to what sound system is going in the finished vehicle. GM calls these calibrations and they can be changed with a Tech II. (The later radios contain a fully functional audio power amplifier and can therefore be programmed to work with either "regular" or Bose speakers.) There are different generations of TheftLock. The earliest systems let the end user set their own desired code. Later versions picked up the VIN (or a portion thereof) over the CAN bus, and if there was a mismatch or no communication, the radio would lock out or simply refuse to turn on. I believe there are some weaknesses in the VIN based TheftLock system that could be used to work around it. Just power one of the radios on the bench, and it won't turn on beyond the clock display. (You can press a sequence of keys to make the radio turn on and run for a short time, which is probably a diagnostic routine.) However, if you put it in a vehicle where the VIN mismatches and turn the ignition key "on" (not to run), you can use the radio normally. When you turn the key to RUN and the BCM wakes up, the radio will lock out when its firmware realizes there is a VIN mismatch. I suspect the CAN bus line to the radio is held at a constant high or low signal before the BCM wakes up, as opposed to simply floating.

[@DrFiero]

It would still power up though, and display "Locked" on the front panel.

[@H0kieJoe]

Sounds like you're unlucky. I've owned 7 GM vehicles over many years and none of them had faulty radios. AC Delco made fantastic radio's.

[@drububu69]

You always make my day when you publish a new repair! (Even when it doesn’t get repaired 😅)

[@JonDoe-zi3mh]

Awesome. I'm a big fan of your channel and found your video just three minutes after posting. Gonna enjoy watching it!

[@super-gerald]

That's the first time I've ever seen one device with both MD and DCC together! This is a very special machine!

[@CommodoreFan64]

Same, and with that combo, I'm not surprised it never came out with how CD players took off in cars in the 90's.

[@RWL2012]

​@@CommodoreFan64it might be CD changer compatible?

[@LeWernerSens]

Thank you for letting me be in your world.

[@michaelcarey]

Great video Mark! It was very interesting to see competing digital music formats in the one unit, especially considering the history of Sony and Philips with the development of the Compact Disc. This Bose unit reminds me of those short lived combo HD-DVD/BD players that were made by LG and Samsung 🙂

[@dangerousbrian6388]

I actually have the exact model myself.. Not sure where it is at the moment??? It was fitted in the hi spec Caddillac STS cars from approx 1996 to 2000 I think? DAC cassettes sounded amazing... Much higher bit rate that HQ CDs.. Keep up the good work..

[@tbonky]

Thanks for bringing this piece of tech Raif! Thanks for being real Mark.

[@TheAnimystro]

did you try powering it on with all three supplies through the connector once you had the front panel on correctly? It might be that it needs all power supplies to turn on, but without the front panel it goes into some sort of panic mode, or unintended behaviour which means it tries to boot without all power supplies. Fun video Mark!

[@sdungworth]

I Love your channel it's very interesting when you take things apart and explain what everything is thanks very much Mr kind regards Simon from the UK!

[@Slartibartfas042]

The 5V you were searching for was pulled down from something. As you found the 5V line totally at the other side of the main board on most upper left pin of an IC I bet it was a pull-up line, being sourced from an 5V regulator that controls the voltage for all digital stuff. Left upper corner very often is VCC for digital IC's. And with that in mind you can be sure that there has to be some power mosfet to switch on and off the power supply of the high power stages (AMP, Cassette mechanics, receivers and so on). But of course - that would be a project going totally beyond economical repair. What came into my eyes right at the beginning - maybe the device locked by the anti-theft control? IIRC "Blaupunkt" and "Becker" car stereos were locking up the controller (for ever?) if wrong code was keyed in to often. ... but there were rumours that one could re-enable this locked devices with almost no effort... 😉

[@D.Hozzie]

Mark have you stopped posting? Have you another place that you post on? You are missed! Hope all is well.

[@Sweepthepuppet.]

Mark iam in absolute awe of you you are an absolute genius i am currently watching all your videos honestly you have the patience of a saint incredible and very interesting

[@randallstewart1224]

My exposure to Bose car stereo equipment was that it came as factory installation in my 2003 Acura. When I was shopping for the car, my friend was so impressed with it that he only sat in a car and listened to the stereo while we were at the dealership. Acura claimed that the speakers and head unit were fine-tuned to the resonances of the car for best performance, and I had no reason to not believe it. The Bose head had a 6 disk CD changer, which I didn't use that much, and which eventually failed mechanically to cycle CDs. I looked into getting it repaired, but it seemed that this was the weakness in these units, and a repair would cost as much or more than buying a new unit. In the end, I replaced it with a better Kenwood unit which had no CD changer, but added a backup camera. I kept the Bose speakers. Anyone who pays extra for a "name brand" of audio equipment in their new car is drinking too much dealership Kool-Aid. They all come out of the same Chinese factory.

[@cthawes]

Be good to see this working again. It looks very similar to one I had in my JDM RHD Cadillac Seville but it was CD and MD not the tape player

[@tolgahancoban7591]

Mark, it was quite enjoyable for me to watch this video. your method was good. This job doesn't always turn out well.

[@MattTester]

I've never seen something that doesn't silently work doing so much! I just bought a non-prototype car radio that was arguably a failure about 9 years ago, the Sony XSP-N1BT. It's designed around the idea of using your phone as the display, still works and the app still works, for now.

[@Jesselovespinball]

Awesome video Mark ! That was a really cool unit ! I’ve also never heard of the compact cassette, never even knew it existed! Great to see the guts of it all!

[@LeWernerSens]

We need more Mark. Pls =)

[@tomo-zb2tk]

I bet it needs battery positive and key positive to turn on.

[@1ralton1]

The 11 pin chip bolted to the back which appeared to be quite warm is a quad requlator chip L4946B, datasheet available

[@JacGoudsmit]

Ralf and I will look into this further at the DCC Museum. I didn't know that the MD player was a changer! After you flipped the flex cable and powered it on, you could see that it powered itself up, then down again, so it's probably communicating with the front panel. That's great news! You also showed that when you plugged the inverter board back into the motherboard, the front panel was getting AC for the heaters and a high voltage for the VFD cathode. When you soldered the VFD back in place, it still didn't light up?

[@DRDCC]

After the VFD was back in place and all cables connected correctly…. It still did not start and light up.

[@DominicClifton]

You can use a conductive metal brush connected to the multimeter probe to find the other end of a trace. You then just lightly brush the board until you it beeps. much quicker then prodding everything with a pointy probe tip.

[@ashleycox432]

I fixed a similar Bose radio once which did have faulty ribbons. Ended up replacing some of them by just hardwiring boards together. I hadn't seen a broken one until then, but they do fail.

[@teslastellar]

This was an interesting video Mark 👍 Thanks ❤

[@marcse7en]

Love the intro music, played on a 78 RPM wind-up gramophone with a great big horn attached to it! 👍🤣 "Wind It Mark"

[@grabo454]

This was absolutely amazing! There were probably 50 different silicon faults with this thing, these are American Delco units. They are far from perfect but a feat of engineering. The reason you didn't have a nut driver is becaise some of those cap screws are fractional metric! Wild shit.

[@samuelfielder]

I thought, at 11:37, you measured 5v on pin 4 of the motherboard connector into which the power switch board plugs. Later, you found no 5v on the power switch board itself. Does that not indicate a discontinuity between the motherboard connector and the power switch board? Either in the connector itself, or on the power switch board traces.

[@craiglemon5026]

Bad luck, Mark and Ralf (@DRDCC). I really didn't think many repairs are beyond Mark, but sadly this was one. 😢 Hopefully, one day someone can shed some more light on this MD/DCC/automotive rarity! 🤞

[@eaglevision993]

My father had a Cadillac Seville STS that was a re-import from Japan. It had this exact radio with the MD Player.

[@samwellfoden]

I have a pioneer prototype car head unit brand new from the 80’s! Recently started using it with external speakers as a media centre for my cassette tapes

[@tullgutten]

🫣 I where screaming innside myself after you flipped the ribbon. You NEED power on both incoming supply cables to turn it on. One is always on for memory while one is for ignition to allow it to turn on. I think you fixed it but didn't know it needed both powers (every car radio is like this)

[@leokearns1221]

Had a Phillips DCC machine and was fantastic sound

[@ANTandTEC]

Ribbon cable fitted incorrectly on a prototype is feasible. I did not see the two power connections remade after the ribbon was turned over 😮 The mini disc magazine changer looked very cool 😎

[@proluxelectronics7419]

Nice explanation Mark, and a methodical approach. I do a lot of blind fault-finding and find using a brass rubbing pen refill on the end of a probe is a great time saver for continuity tracing.

[@chasewilliams3949]

Given that it's from 1995 and made by Delco, this may well be part of the GM impact prototype, which was the prototype for the GM EV1. Seeing as the EV1/Impact was using completely new and futuristic drivetrain, it would make sense to have all the latest audio gear in there too. The connector on the back also looks similar to the one used on the EV1. You could well have a piece of EV prehistory on your hands!

[@CatalinaSkybird]

Here's my theory: I highly doubt that this is from the Impact, and definitely not the EV1. If you look at the EV1s interior, it actually has an Oldsmobile head unit. What this radio looks like, is something that would have gone in a 1998-04 Cadillac Seville. Being that this is a prototype made in 1995, the timing would roughly line up.

[@DrFiero]

@@CatalinaSkybird - I was going to say something about a caddy as well. My fully loaded '99 Seville STS (that I bought from the original owner) didn't have that head unit, nor was there a mention of it in the owners manual (which showed all the options). My '01 doesn't show it either. 🤷‍♂

[@groovedodger]

The DDC system was fantastic sound quality on par with DAT but 18bit I've still got loads of tapes and a recorder (Phillips DCC 730)

[@danoconnor618]

savage video mark. well done

[@outfield1988]

Great video as always

[@SnepperStepTV]

There's a very similar unit that came in the 2000 Cadillac DeVille with regular cassette and minidisc, usually with a CD changer connected from the glovebox. I had to look into this digital cassette thing, like the audio version of miniDV tape, that's pretty cool! Despite the fact I'm glad cassettes stuck around, this format being more widespread would be really cool- i'm a firm believer that formats needn't war because they all have specific niches each other cannot fill and they should all exist alongside one another regardless of technology.

[@sdungworth]

I Love using Mini Discs. 👍 I would love to have this in my Mini

[@marktubeie07]

Fantastic exploration Mark - there is something about prototypes that is fascinating. Nice try...!

[@LockdownElectronics]

Excellent as always!

[@davidv1289]

Great effort! I recently found your channel and have been watching your past videos - fantastic work. As one of your other commenters suggested, did you try applying the main and standby 12 volts, wait a bit and then apply the "ignition" 12 volts? That may explain the dead power switch. Regards, David

[@KnottingleyGuns]

I had a handheld data cassette recorder in the 1990’s which we used for recording outdoor events for BFBS radio

[@raygunpyle]

Only in a parallel universe would I ever imagine a HiFi that includes both DCC and MD in one unit.....to have a automobile head unit though? That's as alien as can be!!! Are we sure this is from planet earth? Either way, loved the video!!!! I would love a part 2 even if its not a happy ending. Hopefully the proper documents and resources get discovered.

[@ncooper8438]

Given the complexity and number of interconnecting modules the unit could need all modules connected to actually function due to mutually-dependent circuits. The lsi chips dont help either. Very difficult to repair that unit without circuit diagrams etc. or donor modules. Would suggest removing and reinserting the socketed integrated circuits to refresh the connections.

[@jdekong3945]

Well done Mark, I wouldn`t have touched it, looks a bloody nightmare

[@xeroidkid]

Mark watching you chase through that board without a diagram is a lot of experienced guess work on your behalf. I suppose having Ralph by your side during fault finding wouldn’t be of help because you need to concentrate your thoughts. I did wonder if you connected the ignition connector back up again. The unit would allow you to put tapes in without the ignition on but wouldn’t play them (obvious) the memory connector may be helpful, it could be associated with playback. I did wonder if supplying a separate 5volts to the on off/switch may produce a result or give you more clues. I suspect this unit will haunt you as to what could be done to find fault, it’s obviously been tampered with because the flat cable was transposed upside down, which wouldn’t help. Has Ralph left the unit with you, so you could pick it up again if you get any spare time? Good luck with that one Mark.

[@Fireship1]

Love old OEM car audio gear. Would have loved to have seen this unit brought back to life. You gave it a good try though!

[@mohindersembi7647]

Hi Mark very interesting video i had the same unit very very long time ago as i bought it from one person in Germany 🇩🇪 he was working in usa army base in Germany and other hi-fi units very high end ones and i have miss placed the the until as i move to 6 different houses 🏘 and i am sure you will fix it waiting for part 2

[@tanjem]

Thumbs up for the work.. The power button is kind of a puzzle ...

[@TheFlyingBusman]

Right off the bat I’m thinking it has probably been destined for a Mazda or Honda. Definitely an interesting piece of kit.

[@ecurepair]

The build inside Looked more typical of a GM unit to me.

[@JIMISPIER]

That was an excellent example of a graceful loss. I hope to get there eventually.. lol

[@tareq7922]

Oh man! I'd love to see it working

[@ctrlzyx2]

Time for an immediate follow up addressing the power on signal. Agree with others. Units typically get constant +12 v and ground at all times. Will not power on without ignition on at +12 v. Three wires.

[@vwestlife]

If this was made for the U.S. market, then it would have another rare feature: Motorola C-Quam AM Stereo!

[@electrickal1]

MAAARRRKKK!!!!!!!! This is only the beginning my friend, ya gotta get that sucker makin music.

[@white93z34]

Being for a Cadillac and of the vintage it is it may require GM Class II serial data to power up, not sure how to generate those signals outside of a car. I know around this time GM was moving in that direction and being a prototype made in 1995 and the shape that it is it looks to me like it would have been destined for the 98-04 Seville which in the UK and Japan did have Mini-Disc options - I've never seen a US market car with the Mini Disc option. I'm just a random person on the internet but I do have the car that this would most likely power up in. Very neat obscure piece of history. To have a MD/DCC AND the optional 6 cd changer you would have been king of the digital music world.

[@JWP33]

Like others have said both constant 12+ on yellow and switched 12+ on red for the ignition. But I think that gm’s use a negative trigger for illumination. It looks like you instead had 12+ connected. This may have damaged the front panel illumination. (Probably done by the previous troubleshooting attempt) Should be able to leave the illumination wire disconnected to simulate the headlight off position triggering the brightest display setting.

[@rogerlundstrom6926]

.. I wouldn't know anything about that specific unit, but.. I have a couple of thoughts when it comes to various things I have come across (with work primarily on various types of computers/processors).. AND I try to extrapolate that into how car stereos work. The thing is....(For a car stereo)... There is one power that is turned completely off when the stereo isn't used, and another one that is only supposed to give maintenance power for the clock and settings. . The problem is that we want a stereo to come on IMMEDIATELY when we press the power on. All processors take a while to start up and get moving. Often it even has to go through some form of boot process, load things from a slow RO M to a faster ram, detect what peripherals are available and so on.. I would assume that this boot process happen when the ~maintenance~ power goes on (That is how I would design it).. because.. IF I mount a stereo into a car, That will get power already when I put in the cord. Then I could assume the boot process to be done when I press the other button. This would mean that after a power-cycle it WOULD use some power because it isn't in "standby" mode, BUT it would go to standby mode AFTER the boot-process and then only provide power to the ram-modules to keep those active.. Possibly even keep ONE of those processors up and running (the one that uses the least power? and possibly have a frequency divider so it runs at a slower speed to make it even MORE efficient), and then that processor may literally be the only thing that notices the power-button in the first place.. I have no reason to say that I know this is how it works, but.. It is a very decent functionality design and there have been embedded computers who have worked that way. That is why (when dealing with unknown hardware)..I always try to make sure that the power comes on the way- and in the order- that the device SHOULD expect. One thing is that I have noticed a lot of "soft on" styled devices actually require you to hold in the power button for a while for it to try to come on.. (I'd say usually less than one second, but I tend to hold in 3-5 seconds on an unknown device just to be sure).. There are some form of capacitor or something that kind of have to get charged to hold the power in the on position.. In some devices this is actually a good thing IF there is a lot of movements around so you may press the button just accidentally while brushing against it, so I THINK there are some devices twhere they intentionally added a delay just because ythere are good reasons to NOT want it to start up accidentally, but that feels like a bad reasoning for a car-stereo, though we often DO have our fingers close to it, and may f.ex. press some button accidentally while shifting gears or searching for something WHILE keeping our eyes on the road.. So when you FIRST tried this one.. I got almost anxious because I couldn't tell you to do a real.. clear.. press.. whenever I press a start-button and nothing happen, I press it again, and hold it in until something happen- at most five seconds. (A few times during the part I watched you seemed to press the front buttons to see if something happened.. which I find to be rather foolish since you didn't even seem to try the actual.. POW#ER button before doing so.... ..)

[@grave8digger8]

Good Luck Mark :)

[@alper1978]

I think display controller ic dead about wrong way connected. 50v line might kill the controller ic.

[@johnnyelectron]

If I'm not mistaken, Delco, OR FoMoCo also made a prototype DAT player for vehicle use.

[@jdtseventyfour]

wow what an intriguing device, hopefully one day it will be awakened from its slumber!!

[@beflabbergasted325]

In car head units the amp chip is usually the one that causes a lot of issues when it blows up. Did you check it?

[@carlmannion708]

Great to see a car stereo on the bench

[@paddle_shift]

Nothing worse than seeing the Mend it Mark timeline coming towards the end and not getting "stay tuned to part 2". 😢 I do think the on off issue is somehow related to the ignition key on sequence. Most cars in the US specially in those days would not turn on unless the ignition was on the "on" position or the "engine start" position.

[@scaleop4]

we need a part2!

[@daShare]

The +5V rail (that the switch pull-up connects to) seems to be gone once the front board in plugged in? Not as simple as a shorted IC or SMD cap on the front board?

[@Dan-oo1rj]

Ask this guy for help: www.youtube.com/@DanielRakowiecki He was fixing tablets, laptops, stage power amplifiers, ships (yes), video cameras, DSLR lenses, industrial automation electronics, car control modules, old computers like C64 (?) for the museum and many more.

[@Herbsy11]

The Radio was made for the Cadillac Seville STS/SLS from 1998 😍

[@gtretroworld]

I quite fancied a DCC bitd but had a feeling it was going to flop,never seen anything like this.Good to see a collaboration though and a good try Mark👍

[@Lackooo84]

Still no part 2? UPDATE: Oh nvm, I just see it on the guest guy's channel, he uploaded it 5 days ago lol...