Any members here that are capable of installing an AUX jack into a factory radio ?? It's a factory 80's radio I need the AUX jack installed into - but not your "typical" Delco deck.

 

On most older radios, it's generally fairly simple in there. You only have to find a source of sound signal (cassette reading head, radio to amp, or even straight at the volume pot) and add a jack, preferably switchable.

 

send 84TA a PM, he can install it for you.

 

They make a transfer switch that plugs into the antenna port on the radio and has an aux out. You simply mount the switch whereever you like and then by flipping it you change between aux and radio input.

 

Reminds me of the way we installed FM converters in our old AM radios back in the 70's.

 

I've already got an FM modulated CD changer plugged into the Antenna port of my factory radio,.... I was hoping that I'd be able to find someone able to modify the original radio and place the AUX on the face itself.

The deck I need this mod for is a Berlinetta radio.

I know it can be done with the cassette deck/EQ version of that radio because I referred someone to Ron in OH (red88tagta )and he installed the an AUX jack for him. Ron had done a lot of radio work for me in the past - including adding an AUX jack to my GTA deck - so I contacted him again about a month ago to install the same set-up for me in my Berlinetta radio and he was going to do it - but suddenly backed out the day I was about to drop off the radio with the post office ( & after I put a ridiculous amount of time/effort into testing/preparing my stuff to be sure he would be working with the best parts possible.)

If it's GOT to be the cassette version of the radio - so be it. However; I've created a custom Berlinetta radio without cassette but WITH EQ and hope that the AUX jack installation will be possible in my custom built unit. ( all factory parts ) That way I can do away with the cassettes and the CD changer all together.

Custom 84-85 radio on the LEFT and 86 style on the RIGHT.



As many of you probably already know - this is a 2-piece system with the receiver mounted inside the center console.

I'm not good with a soldering Iron and doubt I'd be able to figure out how to install the jack myself so I'm hoping to find someone with the ability to do this at a reasonable price.


Thanx GASPEDDLER ! I'll PM him and will include a link to this thread so he knows what I'm looking for.

If anyone else has anything to add - please do !!

P.S. from what I've read online tapping into the cassette wiring isn't a good idea because they muted the "HIGH" frequencies to help eliminate tape "hiss".

 

As mentioned, there are a few ways of doing this, some better than others due to the quality of signal and other factors. IMO, with the knowledge you have you should be able to handle it yourself or at least try it on a more typical (aka less valuable) receiver beforehand. Either way, knowing the method used would be useful even if you have it done.

EDIT: Lol, disregard most of that, I didn't see your most recent post. FWIW, soldering isn't difficult if you have the right equipment and knowledge, it can appear difficult without it.

 

Off the top of my head, I'm wondering if the equalized signal is going back through the connector between the two? Seems like the tuner and EQ would be in the top section and IIRC, the amp is in the bottom part where the speaker outputs are. So access to the pre-amp signal may be relatively easy?

 

I'm certain that the EQ signals are handled by the in-console 'Receiver'.

Obviously; control is performed by the buttons on the swiveling 'Head'..... but the Receiver itself ( or AMP ) is specific to a EQ or non-EQ deck. Meaning that if you plug a EQ 'Head' into a non-EQ Receiver the only EQ adjustments that work properly are the highest and lowest frequency. ( AKA: Bass and Treble )

I also know that all Balance and FADE are controlled by the Receiver/AMP too. Those circuits often fail causing 1 or more of the 4 speaker channels to go dead. A radio Tech I use to have work on my radios some 10-15 years ago used to re-solder all those connections for me 'just in case' when I had him rebuild/service the cassettes decks for me. ( wish that guy was still around ! )

FYI: The circuit boards in the "Head" of 84-85 radios are not the same as the 86 units. I do not know if the Receivers are different internally, but as the pic above shows,.... they obviously have a different external head-to-receiver mating plug.

P.S. I do have a couple problematic Berlinetta radios that could be used as guinea pigs.

 

Oh, I didn't know that the lower ends (receivers) differed based on the EQ option. I have a lower unit that I can look at, but the upper part looks like I'll need a special nut driver to remove the screws at the neck. I'm not really too interested in taking the time to pull it apart anyway. That said, it is really heavy in comparison. With my limited knowledge of automotive radio equipment it looks like the lower part includes a tuner and the output transistors that are on a daughter board. There is another daughter board and what looks like an eprom chip on the main board which I have no idea what it's there for. Do you happen to have any schematics on these?

The idea that the balance/fade control are in the lower receiver section is intriguing. I say this because controlling those functions remotely by the upper section would normally require more wiring for each button unless they were using a more advanced serial comm type of interface (which isn't likely at the time it was produced, but this eprom makes me wonder). The weight of the upper part in comparison to the lower makes me think that more of the processing is in the upper part.

A very common reason for the channels to go dead as you described is due to the output transistors. Some of the reasons for failure include; that they are an output/interface and subject to outside hazards, they heat up, speaker ohm mismatch, and require a heat sink where the thermal compound can dry out. So those are a few factors which can lead to failure over time. It is also common for them to fail even if one of the speaker leads happen to touch ground. I know this because I fixed a radio in an '85 Blazer when I started out in electronics some 15-20 years ago.

Yes, I noticed the different plugs. Very strange considering it's short production run.

If you're new to soldering I would even grab something random out of a junkyard before touching the Berlinetta radios. Once you get to where you can apply/transfer the heat quickly you'll have more confidence, then I would move on to the Berlinetta radios re-flowing the solder as your old tech used to do. Then go back to the standard radio and try removing and replacing through hole capacitors, transistors, and chips. It is mostly easy work once you get the hang of it, but it is time consuming, ...and to pay someone else can become prohibited. The basic idea is to quickly transfer the heat to the connection and then flow the solder into it. Some factors like the wattage/power, condition of the iron tip, condition of the solder, type and amount of flux and solder used etc., can make a huge difference. If any of those are holding things up, it could take more time to get the solder to flow, and when that happens the board can start to heat up creating a frustrating situation and possible damage. (Hence the reason to work on throw away stuff at first.) On another note, the thing with some of this GM radio equipment is that you typically have to commit to taking the whole thing apart and laying it out on a bench to work on them, but once they're open they are pretty basic and easy to work with. If you have any questions on soldering don't hesitate to send me a PM. You have a lot of talent otherwise and it's a shame if this is something that would be holding you back imo.

 

Thanx for sharing your knowledge,........ Every little bit helps !

Sadly; I don't have the internal schematics. I did about 10 years ago but they were loaned out and never returned.

There is actually very little to the top 1/2 of the radio. I've opened up at least a couple dozen of them over time and it's pretty easy once you've done it. About 85% of the weight of the "head" is the cassette deck. There is just 2 circuit boards inside the Head itself and the non-cassette units are very light.

IIRC those little nuts holding the bottom of the post mounted "neck' are 3/16ths,.... it's actually much quicker/easier to just use needle-nose pliers to remove them because it's REAL tough to get a socket in that tight spot. ( 86 units used torx screws for those holes. )

If I knew what I was looking at once I had the Head and Receiver disassembled I'd be a lot more willing to screw around in there. But I don't know the difference between a capacitor, transistor, or resistor and even if I could ID that stuff,.... I don't know how to tell if those things are working or failed. I wish I did - I've got a lot of non-functional parts that I'd fix if I knew what I was doing !!

 

You're welcome! I'm more than happy to be able to pass along what I can.

That is a disappointment about the schematics and especially due to how you lost them. It would have really helped, even if it is with my own curiosity about that eprom.

Interesting about the upper half not having much inside.
Ok, I was thinking about needle nosed pliers since the head of the screws are butted up against the sides on mine. Makes me wonder how they assembled the thing in the first place. I didn't want to scratch it up either. Seems like a long time ago I had one opened but I don't know where that unit is.

Well, I don't know radios that well either. My studies ended up being digital (computer related) but I still dabble into other equipment now and then. Hence my previous thread on the dimming mirrors and that (like this) was simply out of curiosity.
Lol, one thing I will tell you is that you don't want to turn any of the little screws inside of the little metal boxes on the lower half. Simplistic explanation is that they are variable resistors used to tune the radio circuits. Lets just say I wrecked a few AM radios as a kid.

Finding (completely) failed components is relatively easy, knowing if they are the cause or the symptom is something else. Visually they might be burned, broken/split open, bubbled, or cracked.
Capacitors (electrolytic) actually have scores on the top that split open to help release pressure when they fail and/or become old. By now the insides are typically dried out and it's a good idea to replace them if possible. They do have a polarity like a battery does so if you ever replace one make sure you note that before removing. Or if it isn't indicated on the board, you can check another unit as a reference.
example:

From here.
http://www.instructables.com/id/Repa...blown-capacit/

Power transistors are typically attached to thick metal to help dissipate heat. They are also right at the outputs for the speakers and very easy to find.
In general, the difference is that a trained/knowledgeable technician will find out why a circuit failed and then repair accordingly, and non (or poor) technician will just replace the bad parts that they can see/measure and hope for the best. The latter really need to make sure they wear safety glasses when they power up their repairs.
Actually you should wear them on any power and also when soldering.

One thing very common with electronics of this type and age are cold solder joints -and that doesn't require any knowledge of individual components. It's a simple matter of the solder connection cracking over time. Probably even more prevalent due to the many heat cycles, vibrations and bumps from being in a vehicle. The repair involves re-flowing the solder to secure the connection. You know when people used to smack the side of a radio or TV? That's similar to what is happening. The connections at the end of the internal cables could also be a cause of poor conductivity due to light corrosion on the surfaces. I think they make a spray or paste you can apply if it's really bad (probably dielectric), but oftentimes separating and re-plugging them in is all you need to do.

Most electronics like this has separate areas such as; the power section, the output section/amplifier, tuner, and tape to name a few. So say if a unit was dead (and you metered for shorts beforehand, and maybe looked at any nearby capacitors), you would hook it up and start metering at the power section to see if the rest of the unit is getting power. Schematics would even help with simple things like checking the internal power circuits that would be at say 12v, 5v, or 3v etc. Sometimes you can find this printed on the board as well. Or, if a speaker output is bad; then you go from that end and work your way back either visually, or with a meter. Knowing this should make it easier to troubleshoot and also digest things a little at a time.

One thing people try, is replacing a good board into a bad unit (and also in this case, swapping upper and lower halves). Be careful doing this because if there is a short in one part, it can cause your good part to fail as well. Then bring what used to be two good parts back together, power it up, and now you have a collection of junk! On a side note, we had one new guy set up to perform relatively simple fixes on a two board system. Apparently he told the hiring personal that he knew what he was doing. Well, he did not- and he had some fifteen boards piled up before we put a stop to it. He was very fast at what he did, and it didn't help either that he was powering up equipment with screws from disassembly underneath as well.

One non-technical way of helping to avoid this is to meter out the inputs and outputs on a good unit and then write them down. This was a common failure on computer parallel ports, especially equipment that didn't have strong buffers. So as a preventative measure we would check the parallel port and if it was off we replaced the buffer chip. This may or may not work with these radios but would certainly tell if you had a strong short to ground on something you just picked up that you don't know anything about. The process a simple matter of setting a meter to ohms and connecting the black lead to ground and the other on each input or output (power off if you didn't know). The readings may vary from unit to unit, but should be within a certain range. It doesn't really tell you what is wrong since you are typically measuring many circuits at once, but also doesn't take much knowledge or skill to perform obviously.

Well, that's some basic, non-technical information that may help when you look into one of these again. I guess I wandered off of the soldering topic, and can try to elaborate on that later on if interested.