problem with Audionics Space & Image Composer

Hi there

I've a problem with my Space & Image Composer. One of the output volume IC's is defect. Now I can only hear all channels correctly if I adjust to max. output volume. Otherwise one channel have heavy distortions.

The IC is labeled as a LM1853N. It is a 14 pin package and was produced in 1977 by National Semiconductors. I've already ask National for more information but they can't tell me anything about the LM1853N.

I badly need a datasheet and/or equivalent for LM1853N!

Thanks in advance for all help!

I will see what I can find out for you. Pray it isn't one of the Tate chips.

The Quadfather

Bob Popham is the one to talk to about getting an Audionics Composer repaired. I don't know how to get in touch with him, though I should, since I have a composer. Does anyone know how to get in touch with Bob Popham?

The Quadfather

Mr Bob Pophams home page is www.rjpc.com there you can find a 'contact/info' button on the left side. Under that link is a page where you can write him ([email protected]).
I've already did this 2 1/2 weeks ago but no answer till this day.

The LM1853N is definively for the volume control because the logic works very well whichever output volume is adjusted. The seperation is like the TATE seperation. But if the volume level is not set to "normal" you can hear extreamly distortions in one channel.

You can find the both IC's direct behind the back-front-balance knob. I've also interchanged both LM1853N. The result is once the front right channel have problems and the other way the left back channel have problems.

PS: sorry for my german-english

I am going to try and look that up when I get back to the TV studio. Hang in there.

The Quadfather

no answer till this day from Mr. Bob Popham...

I hate to be the bearer of bad news but the output chips in the s & i composer are propriatory Tate chips, there is no replacement for them except from anouther Tate. The possibly good news is that if you were getting any thing from them they arn't bad or you would get nothing. I think the problem may be elsewhere in the unit.

Dave

Sorry Dave, but the two LM1853N and the LM1852N inside the S&I Composer are not a part of the Tate Logic. These IC's are 'only' the drivers for the output balance (stage balance) and/or the output level control.
I know how a damaged OPA(Operational Amplifier) sounds and it seems that the LM1853N is such one - certainly a custom-made product for Audionics.

The LM1853N was manufactured by National Semiconductors but not the Tate chips!

Those three chips "are" the des curcuit and NS made those custom for the Tate. Most of time when they go, they are just dead. The basic sq decoding is done before those chips and the signal then sent to the des curcuit where the Tate magic happens. If you are getting garbage to those chips then garbage is all you will get after the des. Those three chips are not listed because they are made of unabtainium (hehe). All the other chips in the Tate are replacable.

Dave

Did you try cleaning the pins?

Dave

of course, the pins are very clean!

Generally the act of removing the chip from it's socket and returning it to the socket will clean the pins enough to bring the unit to life if that is the problem. A bad capacitor can allow a dc voltage to be applied where it shouldn't be and cause distortion. If a dc voltage, even a small one, is applied in such a manner to the input of an op amp chip, the chip will amplify the voltage, driving it's output near one of the supply voltages with the result being that any signal that drives the output voltage to swing beyond the supply voltage will be clipped at the supply voltage. It will appear that the chip is bad, but it really isn't. It is just trying to do what it is incapable of doing. This condition as well as others can be seen on an oscilloscope. (I'm sure all of y'all have a Tektronix scope on your home electronic workbench, right?) Anyway, if you do have one, it is a great aid to troubleshooting. Of course, the problem is that you have to know what you are looking at. Oh well, then there's that thing about two years of tech school. Oh well, You might be better off just sending it to Bob Popham. I couldn't find a chip that was a direct cross. I did find one with a similar number, but without a pinout on the original chip, you would be risking a lot to try it. If it isn't one of the Tate chips, you might find one like that, but even the non tate chips are rare. I wrote Audionics and asked them to release the schematics to the composer, it isn't as if they were going to produce more of them, there is no longer any need for secrecy even if there ever was in the beginning. (most manufacturers release their schematics as a matter of policy) Even that wouldn't reveal the Tate secrets. Maybe if we all at once Emailed Audionics (Fosgate) they would respond to one of us. They didn't respond to me. I would like to be able to fix some minor problems I have with mine. I don't dare poke around in it without a roadmap for fear of really screwing it up. Is there anyone that has a Composer that is already unrepairable, that could be used for disection in order to get a schematic, I would be willing to take on the project. I would be willing to do it on mine, but you have to remove all the chip sockets and other components, so the traces under them can be seen, and the risk in that is rather higher than I would want to invest in a working Composer. So, y'all bombard Audionics with requests for Composer schematics, even if you don't own a Composer, (you might find one later) and if it works, later we'll do it again for the Tate II.

The Quadfather

I have to write bob popham again...

No answer from bob popham... no chance to get through him

Is it necessary to readjust the Logic if I replace all the old electrolytic condensers?
If so, is there anybody who know how to readjust the S&IC Logic?

Bob Popham is a little tough to get ahold of at times, but he does a super job, and actually was involved with the creation of the Composer at Audionics. I emailed him to fix my Tate, got one reply, and then couldn't get any more replies. I ended up calling him and leaving messages, either on his machine or with his receptionist. I did finally get through to him in person, got a price for the overhaul and mailed it out. It took about 3 months to get the Tate working properly, it had a funky problem that required more stuff being replaced than he thought, but the orinal repair price stayed the same. Bob actually called me from Colorado a couple of times in response to messages I left. Bottom line is that he does a fantastic job, he is an honorable guy of the first order, his services are in much demand for all manner of stuff that he can do, but he still takes time to keep these old gems running. I can't imagine that it's all that profitable for him, but he has a love for these units. Thanks go out to Tab Patterson for finding him and posting the link on his website. There's certainly no one I could find in this area (Central NJ) that even knew what a Tate was, much less was able to repair it.

Unfortunately, re-capping your S&IC at this point will not resolve your problem. As you've already determined that it is a failure of the 1853 chip itself by switching it with the rear channel 1853 and confirming that the problem moved with the IC, recapping will be just a waste of effort. You'll still have a bad chip. Your only possible remedy is another S&IC or TATE II that has a good IC in it.
As far as I've heard in the past, neither Bob Popham or Jim Fosgate himself has any of these ICs left now. I have restored/repaired about a dozen TATE IIs and 5 S&ICs now. I have figured out how to bypass the 1853, but the results were equivalent to a "non-logic" decoder...totally unacceptable for what these units can and should produce.
Just hope this serves as a warning to all of you running TATE IIs and/or S&ICs.......if you're using them now...restore them ASAP!!!! Once those ICs fail.....your ultimate SQ decoder is finished.
And, just for a shameless plug......it doesn't take me 3 months to do either of them now. Turn around time is 2-3 weeks.

QuadBob

www.innovasic.com/ This is a site I ran into sometime ago that remanufactures discontinued IC's. Mabey somebody in the group that has electronic knowledge and good persuasive skills could contact them and see what they are willing to do. Mabey this would help promote a future for the tate/variomatrix decoders.

Dan

Ok, this is freakin me out. The last response was from me, not calimali02. How did that happen?8o 8o

> www.innovasic.com/ This is a site I ran into sometime ago that remanufactures discontinued IC's. Mabey somebody in the group that has electronic knowledge and good persuasive skills could contact them and see what they are willing to do. Mabey this would help promote a future for the tate/variomatrix decoders.

Hey, Great find Dan!! If they don't laugh us out over the small quantity we need, or start talking big $$$ this might be a solution.

I'll make contact with them and get the facts, at least on their website they do show a quantity of "1-100", and our TATE DES chips are probably relatively simple in comparison to the microprocessors that they remanufacture.

I'll also need to contact Jim Fosgate to try and get the original "datasheet" for the ICs......at this point I would hope he doesn't feel the need to be as secretive as they were in the past regarding the service literature/information..... everyone's buying Dolby ProLogic II anyway right??

I'll update here and via email if you contact me.

QuadBob

Hooray!!!!!

Quad Bob is back in town!!!!

Still grooving on my KGB FM Homegroan albums and the van proudly displays the OB sticker!!!!''

Thanks!!!!!!