1989 CRT / Radio issue

First, let me apologize for posting this here but I suspect that the real experts on this issue are here instead of the Riviera Forum. Yesterday I bought a 1989 Riviera. When test driving the car a couple of weeks ago, the radio worked and initially the CRT worked. I used the CRT to turn the radio off during the test drive. Shortly after that, the CRT display disappeared. It then came back on intermittently.

I have removed the CRT and reinstalled it. I have also unplugged and replugged the cables to the related component inside the console near the accelerator pedal. While I have not driven it much yet, as I was working on a few other cosmetic issues last night, the CRT display now appears to be working consistently.

All or most of the buttons on the CRT appear to work correctly but the radio now does not seem to work. The volume up and down buttons on the radio screen do not respond or beep and the tuning buttons seem to have some limited ability to respond as well. The preset stations appear to work, but I have not been able to tune to other stations, which does not really matter much for now as the radio does not make any noise at all. The cassette tape eject button opens the cassette door.

My prior experience with these systems was with a 1986 back when my repair source was taking it back to the dealer to be repaired under warranty. I have not yet obtained a factory service manual for this car, since I just bought it yesterday. Any suggestions about what I should check on the radio issue? It is not critical, but I don't really want to wait if there is something that I might be able to tinker with on my new purchase.

Is the cdm (radio brain) unplugged? Sound as if it is, or the communication (e&c) wire is open, final option bad cdm. They are pretty easy to get a bold of.

Forgot one other option. Power to the radio both acc and battery.

Well, since the cassette deck does eject, you have eliminated a faulty ground (G102) as a point of failure. The radio and cassette deck share a dedicated ground wire to G102. FYI, the radio display on the CRT is largely a product of the CRT controller rather than actual communications with the radio. Before I found the faulty ground (G102) on my Reatta, my radio was intermittent to non-existent, BUT the CRT displayed virtually everything radio related just as though the radio was alive and well.

I would try reinserting all the connectors on the radio module itself (located in console driver's side just forward of the console storage). You can easily get to it by removing the shifter assembly and then the console bezel comes off with the removal of screws beneath the shifter assembly and another set just to the side of the cigarette lighter. There is a plastic bracket that holds the radio module in place. There are 2 plastic screws that lock the bracket to the metal frame of the console. Once that bracket is removed, the radio will lift up and out. There are connectors on the top as well as the forward end of the radio.

No need to apologize, this forum will tackle pretty much anything.

We'll let you peek at the FSM if you sign up here:

http://reatta.net/docs.html

Don't tell the other Riviera owners it's the same FSM as ours. :cool:

As to the CRT, check and clean the common ground posts under the hood.

http://reattaowner.com/roj/component/content/article/62-electrical-system/other-electrical/224-ground-terminals-junction-box-location

Need good power, (at least 11 volts) and good grounds to keep the electronics happy.

As to the radio, wonder if the radio is getting power as well. Presets are in the CRTC so they don't tell anything about the radio operating. Does the power antenna go up and down with the radio turning on and off? If you turn the volume all the way up, do you hear any amplifier noise in any mode?

Just have to determine if there is a connection issue to the radio or you need another one.

Sounds like 2014 is off to a good start for you!

Mathew you have so far received excellent advice. I had a similar situation, thought it was the radio module, went to Gibson's [my local you pull] and grabbed another one. Cleaned the contacts, plugged in the "new" unit and all is good. Maybe I had bad/dirty plugs, but figured that with the module being so old I had to replace it.

Thanks to all.

Daniel, All the fuses seem to be good so I don't think that it is a power problem.

drtidmore, That gives me some stuff to check. I thought that was probably where the "radio" was located, but I had not taken the time to figure out how to access it.

McReatta, I registered there last night, because I figured that FSM access would help until I actually buy a printed version, but have not yet gotten any response. The power antenna is another issue. Not having seen the FSM manual, and since it did work on the test drive, I am going on the assumption that the radio should work even if the antenna will not go up and down. The antenna is stuck in the up position and if you plug in the connector on the antenna that the previous owner had unplugged, it gets warm but the antenna still does not work. I was going to check out the antenna problem after I get the radio actually working.

Daves89, my local pick and pull does not have any Reattas or Rivieras at the moment, but I will probably pull some extras the next time they get one.

There is a possibility that the touch screen grid, which is a separate part from the CRT, could be failing.

Have you tried switching to the climate screen and using the controls in the same section of the touch screen to make climate changes? If that area of the touch screen will not change the heat/ac functions then the problem is with the touch screen and not the radio control module.

Matthew,

Pull the power antenna and send to Barney Eaton as he does an excellent and affordable rebuild on those units. The issue with these antennas is usually the plastic cable that runs the mast up and down. There can be issues with the relay, the motor, or the gearing, but usually just the cable. Barney replaces the old cable with a plastic incased steel cable and makes sure that the antenna works properly. Should last a LONG time.

The antenna would NOT explain why you are getting NO hiss, noise, nada from the radio. That will require more troubleshooting along the lines already mentioned.

Should your issue be a genuine failure of the radio module, don't despair, there are plenty out there at affordable prices. It is worth noting that virtually all these units are showing various signs of failure, typically distortion. There are instructions over on Ronnie's ROJ site for replacing the most common cause of distortion for those inclined to tackle such projects.

As removing and replacing your CRT as well as the connectors at the CRTC seemed to correct your intermittent CRT, that is a good sign that moisture may have been involved leading to contact corrosion. It is certainly an easy enough exercise to pull the radio and ensure that those contacts are clean.

There is a possibility that the touch screen grid, which is a separate part from the CRT, could be failing.

Or as I discovered with a spare CRT I purchased, bad contacts where the touch screen portion connects into the CRT. When I first plugged the spare CRT into the car, the touch screen was totally unresponsive. Knowing how robust that touch screen has proven over the years, I carefully removed the side mounted touch controller connections and reseated all the connectors and that fixed the issue. Been running that spare CRT for a couple of months now while my original one is being rebuilt by Eddy Voland (BTW, Eddy is back and has his ebay site back up).

Ronnie,

The touch screen appears to work correctly on climate control, so it appears to be something in the radio components and/or connectors for that. As soon as I can take a look at the FSM, I expect this problem to get easier to solve. Many years ago, I worked in a car stereo/cb radio/general electronics store. Most of what I did was car stereo installation and minor repairs, so I will actually enjoy working on this, although the installation/removal work was easier when I was in my 20's instead of my 50's.

drtidmore,

It has been about 30 years since I was working on similar antennas so if I can't figure the antenna out with a cursory glance, I expect that I will contact Barney about rebuilding it.

It looks like I will need to contact Barney about the antenna. The plastic cable is broken. I suspect the radio module is just dead. Wow, that was fun removing and re-installing. They certainly wedged that thing in there didn't they.

Matt,

They certainly wedged that thing in there didn't they.

I'm sure it looked good on paper.

John F.

... I suspect the radio module is just dead. Wow, that was fun removing and re-installing. They certainly wedged that thing in there didn't they.

The CDM (radio) box can be interchanged with a number of other GM cars of the era. Since you have a local Pick-N-Pull type yard, look for vehicles from '88 to '95 or so. There are three basic types of boxes:

* built in amplifiers, 5-band equalizer

* built in amplifiers, bass/treble

* Bose line level output, bass/treble

You can visually tell the CDMs with built in amplifiers from the Bose versions by presence or lack of cooling fins on the side of the module. I don't (yet) know of a way to visually tell the difference between the 5-band EQ and bass/treble version of the amplified CDM box. Just have to visually see the control head from the car/truck it came from, look up the part number, or simply try it. The Reatta CRT will support either version.

In some cars, such as W-body cars like the Regal, and C/K trucks, the CDM box will be remotely mounted away from the control head. In many others, the CDM box is plugged into the top of a more conventional looking control head. Look for the 5-band equalizer option though. And if AM is important to you, look for 1990 or later to get expanded band (1630-1710 khz) coverage and AM Stereo. Most, if not all, bass/treble versions of the non-Bose CDM box do not support AM Stereo.

I have also noticed reduced parts counts on the circuit boards as the years progress. I have a '89 Bose CDM that has 5 internal circuit boards with loads of electrolytic capacitors to go bad. Compare to a '95 Bose CDM which has a single board, a few chips, and only a few capacitors. So obviously the later the CDM the more likely it will be to work right.

Forgot to mention that since you have a Riviera, there is a possibility that your car has the Bose option. In that case, I would definitely recommend a CDM box from a '92-'95 Cadillac that has the Bose option. The CDM boxes in those cars are remotely mounted in the trunk - either on the back wall behind the rear seat or next to the antenna. Very easy to pull.

Some vehicles that are often overlooked that should have the same radio: 1988-94 GM and Chevy pickups

Some vehicles that are often overlooked that should have the same radio: 1988-94 GM and Chevy pickups

Right - the C/K (e.g., 1500 and 2500) pickups, Suburbans, and Yukons. I don't think the smaller S-10/Blazer/Sonoma trucks/SUVs have radios with separate CDM modules.

Right - the C/K (e.g., 1500 and 2500) pickups, Suburbans, and Yukons. I don't think the smaller S-10/Blazer/Sonoma trucks/SUVs have radios with separate CDM modules.

wws944,

Thanks for the additional information. I remember reading that the 95 Regal has the same radio module. I wonder if any other years are also the same. I see that my local pick and pull has a 94 Regal and a 96 Regal listed on their online inventory. They also have a few Chevy pickups of the right era listed so there are some others that I can check. The radio is # 16072780, so from my limited online research, I don't think it is the Bose one.

Ronnie,

I now have access to the FSM through reatta.net. Between the reading on your reattaowner.com and the FSM and other data on reatta.net I think I will figure this out soon. With the FSM diagnostic checklists, I can now troubleshoot it easily. Thanks for all of the help.

wws944,

Thanks for the additional information. I remember reading that the 95 Regal has the same radio module. I wonder if any other years are also the same. I see that my local pick and pull has a 94 Regal and a 96 Regal listed on their online inventory. They also have a few Chevy pickups of the right era listed so there are some others that I can check. The radio is # 16072780, so from my limited online research, I don't think it is the Bose one...

That part number is a 5-band EQ amplified box. So not a Bose.

The '94 Regal should be fine - especially if it has 5-band EQ controls next to the cassette deck (or the rare CD player). The '96 will not have what you want.

Thanks. They also have a dozen 88-94 Chevy trucks so I think the odds are pretty good that I will find what I need there.

Before you through in the towel on your current CDM, refer to the FSM and verify that you have +12 (both switched and unswitched wires) as well as ground. Verify the +12 voltages using both the ground wire in the connector as well as the console frame just in case somehow the ground wire to the radio aft of the splice with the cassette deck might be bad. Since the cassette deck does eject, that at least indicates that the ground (G102) out by the battery is still intact all the way to the cassette deck.

Last night the CRT decided that it was time to go out again and frustrate my efforts to see if the removal/re-installation of the radio module made any difference. After reading the FSM Computer System Diagnosis section I was thinking that it sure would be nice to have a J 34914 CRT Tester. I just could not resist this:

http://www.ebay.com/itm/370918634786?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Mine should be here Monday. He still has one more for sale if anybody else is interested.

From what Eddy has told me, the main reason for complete CRT failure is overheating of several circuit board traces which over time lead to cold solder joints. This issue was corrected in a running design change that can be incorporated in previous versions (Eddy does such on all rebuilds not already incorporating those changes). The lower section display distortion is deteriorating electrolytic capacitors and occasionally one of the weaker ICs in the circuit (he replaces all of these during rebuild). He also reflows all the solder joints on the circuit board as a precaution against future failures.

I considered getting one of these testers, but in the end, all it can do is prove that the CRT/touch screen is operational or not. GM did not allow any field repairs (depot only) of the this system, so using the tester was an exercise to determine if the unit required wholesale replacement. I concluded for purposes of maintaining an operational CRT system, investing in spares (CRT and CRTC) and having my CRTs rebuilt seemed the most appropriate approach to the issue. The CTRC (CRT Controller module) has proven extremely reliable over the years but it never hurts to have a spare CRTC on hand to verify that issues with the CRT are NOT related to the CRTC as well as having a replacement unit available.

Even with rebuilt CRT spares on hand, it is a matter of time before the cathode ray tubes in these units reach eventual end of life. Eddy tells me that NOS of the tubes have completely dried up (Zenith was the manufacturer). These display tubes have proven extremely robust and reliable over all these years, but nothing has an indefinite lifespan, especially in high heat electronics. The interface between the INTEL 8088 based CRTC and the CRT module has never been reverse engineered, but since the CRT module handles all the scan/sweep circuitry, the interface between the CRTC and the CRT is likely very similar to what was in use in PCs of the early 1980s, so it is not outside of technical feasibility to come up with an LCD based replacement for the display section while maintaining the existing touch screen section. The cost and effort to do this is another matter completely and there is NO way for it to ever be economically feasible for such to be mass produced given the extremely limited user base for such. Regardless, those of us wishing to maintain our CRT systems long term are faced with the inevitability of such an effort at some point.

The FSM describes its function as "it is used to isolate faults in the CRT, CRTC, and wiring". I figured it was worth $99 to me to make it simple to check all of the components following the FSM troubleshooting charts. If it just diagnosed the CRT, I would agree that having a known good spare CRT would probably be sufficient. From reading the FSM, it sounds like having the additional capability to test the CRT, test the CRTC and to test to identify faults in the wiring would make it worth having.

Couple of things to add here. The tester tool is useful to have for ease of testing without taking the dash apart. It also does a rudimentary test of the crtc as well. If you can get one cheap and are planning on long term or multiple Reatta ownership it is good to have.

NOS crts are available (tube only, not complete unit) from ebay through an account held by Rex service in Chicago. I purchased a couple I have not used yet, keeping them for future use. Changing out the tube is no easy task though.

An LCD could perhaps be adapted. The video interface is plain VGA 320x200 monochrome probably at 72hz refresh rate. The physical connectors are all proprietary however. Also difficult to find an LCD panel of the right size at 4:3 aspect ratio.

KDirk

Ok, you convinced me that the tester is worth having, so I bought the other one that was on ebay. I am going to check into the NOS tubes from Rex as I would like to have a couple of spare tubes for my two CRTs.

Update on Rex Service. They don't have anything listed on eBay at the moment, but I did find their web page and have emailed them. Hopefully they still have some NOS or a suitable new stock replacement to offer.

David-

http://www.ebay.com/itm/160986853743

Keep in mind that this is a bare tube. The deflection yoke will have to be installed and you will have to manually tweak the geometry correction with yoke magnets (this will be different for every tube as each has unique errors that need to be "fixed"). So, it is not a typical DIY project. Also not exactly cheap.

KDirk

I am old EE educated at the cusp of the vacuum tube to solid state transition, so I have a foot in both the past and the present. Thanks for the info. It has been years since I installed a new CRT in anything, but I have done it and am aware of the process.

Guess that CRT/CRTC tester that I just purchased will come in handy should I have to replace the CRT (i.e. aligning the deflection yoke using the pattern displayed by the tester).

They certainly do LIKE their NOS tubes, but then again, they are NOS and while there may be suitable new stock replacements out there for less money, it would be a crap shoot finding such.

Thanks again for the info

Well the CRT Tester arrived earlier than expected. While I don't think the CRT is the reason for the radio not working, the radio will have to wait for the CRT repair. Most of the time, the CRT tube will just not light up. Every now and then the tube lights up and the test pattern looks great.

I just purchased a CRT rebuild from Eddie Voland on Ebay. I am about to box up the CRT and drop it off at the Post Office. While I am at it, I guess I will go ahead and get the radio antenna in the mail to Barney Eaton.

Success. I got the antenna back from Barney a while back and I got the CRT back from Eddy today. With the CRT reinstalled, the radio issue seems to have gone away. It is working fine now.

Just a little update. I just sold the 1989 Riviera so I no longer have any need for the J 34914 CRT Tester. If anybody is interested in a CRT Tester I would be happy to sell it for $100 plus shipping here before I put it on eBay.

Matt,

I already have one but, to those out there that are interested, that's a good price.

John F.