Soundtracs CM4400

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 I’ve got a Soundtracs CM4400 1980’s vintage audio mixer to repair. The problem the 2k x8 eprom has gone flaky and I’ve not had much luck finding the hex file so i can burn a new one. Anyone out there know about these units ( especially the UK based ones) and know where i can source the eprom hex file?

 

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I repair vintage audio equipment for a hobby so I will reach out to a few clients and see if any either have one of those beauties, or knows someone who would let me copy the eprom.

 

Might take some time, how fast do you need this?

 

And what is an eprom doing in an anaglogue board?

 

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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jgmdesign wrote:
And what is an eprom doing in an anaglogue board?

The internal routing via the microprocessor is great for submixing into the groups.

 

FF = PI > S.E.T

 

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ki0bk wrote:

jgmdesign wrote:
And what is an eprom doing in an anaglogue board?

The internal routing via the microprocessor is great for submixing into the groups.

 

IT would appear that there are photos of the board with, and without a screen.  The one I pulled does not have the screen.

 

Thanks for the clarification.

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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 Thanks Jims,

 

the board in question has a z80, some ram and a handful of TTL to manage the routing. Something the AVR would handle with ease. How fast do I need this? Yesterday of course! We all know with this old stuff that performing the impossible takes a little longer!  

 

It has a serial port that you could supposedly hook up to a Commodore64. Advanced stuff in the 80’s.

 

People seem to go mad over this old analog stuff - it was cheap-n-cheerful for its time and is no better today. But it is ANALOG!

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I'll take an analog audio system over this digital crap any day of the week.

 

Far superior,  but just my opinion

 

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Without wanting to get into the whys and wherefores of an analogue vs digital audio debate: the significant thing about digital audio is that it can pass through equipment in the digital domain completely unchanged.

 

When it goes in and when it comes out it's analogue; what matters in both cases is how good the analogue input and output stages are.

 

Neil

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These guys might have some things to help:

 

https://www.youtube.com/watch?v=...

 

https://gearspace.com/board/so-m...

 

http://www.studiosystems.co.uk/soundtracs/range.php

 

one other issue that steve helped me out with was the understanding of the consoles computer. i had one engineer friend say that if the computer went the whole console was dead.

TIM: Well the patch system would die , but there is a BYPASS slider switch actually on the Z80 processor board , slide this and all channels and tape monitors 17>24 will route to mix ….

my understanding now is that the computer was just for automation and is not an integral component in it's operation (still waiting to hear back from steve to confirm this). if it's like any of the 80's SSL's i've used, the console can function without the computer. i really do appreciate your help. I'mreally getting excited about making this console work. i hope to hear back from you. hope all is well.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Candyman - been down that path. “ never had a z80 or eprom die in 30 years” was the response. I can tell you the eprom is very suspect. Heated it, froze it - it reads different garbage each time. Short of seeing the little blue flash in the old 2708, this is the deadest eprom i’ve seen for a while. Might be worth posting on eeevblog - hopefully someone has the binary or hex image of the eprom.

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 Heated it, froze it -

I assume you pulled out & thoroughly cleaned all sockets and the chip pins of the Z80, EPROM and any other chips...they can build up a nice layer of intermittency.

 

Also, hitting the solder joints with a hot iron can get rid of many wrinkles in your PCB. 

 

 

 “ never had a z80 or eprom die in 30 years” was the response.  ....well, then one of them should then be able to send you a valid hex file...maybe offer to send them some of your latest vocal tracks in return.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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I could clean the sockets ad infinitum, but that won’t fix a dodgy eprom will it? The poor thing is suffering chip rot rather than bit-rot.

 

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avrcandies wrote:
they can build up a nice layer of intermittency.
Use of Stabilant 22A TM on PLCC Packages & Sockets via Application Notes | Stabilant

 

"Dare to be naïve." - Buckminster Fuller

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Kartman wrote:
The problem the 2k x8 eprom has gone flaky

Is this one of those EPROMs with a sun roof? 

I have seen these where the data will change when light hits them, so cover the window with a sticker and see if that helps, they work best in the dark!

Jim

 

 

FF = PI > S.E.T

 

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I have a Russian 2764 eprom that is light sensitive as you describe! The eprom in question is a TI 2516 with quartz window with a sticker on it. The issue seems to be the logic levels are not correct.

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Question:

If you had the code for the chip, would re-burning the old chip make it work good as new?

i.e., has it just forgotten it's 1's and 0's, but when re-burned the memory cells are good as new?

Or is there other aging that takes place within the memory cell architecture that irreversibly ages?

 

2nd question:

The 2716/2516 were "5V" chips, (25V for programming), IIRC.

Many 5V systems ran at 5.2 V.

Many of the chips, "back then", I think, had a 5.25 V Vmax.

So does putting the chip in an external testbed and very carefully powering it @ 5.30 V impact one's ability to correctly read the cells?

 

JC

Last Edited: Tue. Nov 9, 2021 - 05:47 PM
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I began my EMS work back in the 1970's, that's been a while!

My first VHF Police/Fire/EMS receiver had tubes!.

That was followed by a VHF/UHF scanner that was all transistors.

One had to buy a separate, (expensive) crystal for each frequency that one wanted to listen to.

(And it had to be the correct type of crystal, 3rd overtone, etc., etc.... )

 

One of the earliest microcontroller based scanners was made by Regency, and is shown above.

It had many features, and was a leading edge product at the time.

Unfortunately, being a very early microcontroller project, the designers didn't get the clock / alarm clock feature right.

The clock lost time, several minutes / day, and the loss was, (I think), proportional to the number of radio transmissions received.

(Today even a Tiny uC running an ISR would trivially solve that problem!).

 

In any event, I worked at the local hospital during college and put some money towards college, and some money towards this radio.

I then used it for many, many years!

 

Until it got dementia, and started having memory failure problems.

Its eeprom died, and wasn't, unfortunately, replaceable.

 

 

Now for even more info that you didn't ask for:

Back in the day Paramedics used an orange boxed BioPhone to talk to Medical Control at the hospital ER.

IIRC, (gosh, my memory is as bad as the faulty eeproms we are talking about!), the Biophones used 8, 400 MHz, paired channels, (perhaps later increased to 10 paired channels).

A 400 MHz transceiver was pretty leading edge at the time.

The Medic could transmit a 1 lead EKG signal by plugging the analog output from the EKG Monitor/Defibrillator into the input on the Biophone.

The EKG signal modulated an audio signal, 2 KHz baseline, or whatever it was, which was then transmitted to the ER instead of voice.

In the ER the receiver used a frequency - to - voltage converter and then displayed the patient's EKG on an (old fashioned) slow decay CRT display.

One could also just listen to the tones and know right away if the patient's heart rate was about normal, or way too slow, or way too fast.

A steady-state tone was never a good thing!

 

And what does this story have to do with a uC Forum you ask?

Well, it was also the days of early LEDs.

One of my earlier, somewhat challenging at the time, projects was to build an interface for the Regency Scanner that adjusted the audio signal amplitude, and then did the F-to-V conversion, and then lit up a column of vertically stacked LEDs.

As the patient's EKG signal changed, the tone changed, and one could watch the LED column bounce up and down with the EKG signal.

It was analogous to having a single vertical column output, likes today's persistence of vision toys, with which to "see" the EKG, without having a (complex) CRT display.

It was just a toy for fun, but was one of my first projects integrating medicine and electronics.

 

Ah, the memories.

All from a Thread on a fried eeprom!

 

JC 

 

Edit:

And to think that these days it would be weekend project to decode the ADC'd audio signal and display the EKG on a GLCD/ OLED !

 

JC

 

 

 

 

 

Last Edited: Tue. Nov 9, 2021 - 05:44 PM
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That's a cool history!  It's what keeps electronics folks going towards the future.   Keep your wire-wrap guns humming. 

It is crazy to see how far things have progressed, yet many of the problems remain the same. 

 

In any event, I worked at the local hospital during college and put some money towards college, and some money towards this radio.

I then used it for many, many years!

 At first, I thought you meant the yellow "bio" radio...I thought Yeah, it looks used!!

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Tue. Nov 9, 2021 - 08:48 PM
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On another sideways note... in a broadcast environment, there are usually loads of crosspoint routers. Traditionally, a sound desk worked with analogue audio from and to such a router, so it could get the inputs required and its output could be sent where required. When I last bought a sound mixer, probably in the late nineties or early 2000s, they basically cost about ten grand an inch... the wider they were, the more expensive.

 

I recall the 'doh' moments when someone realised that if instead of crosspoints you put 64x64 multipliers in, you could build a sound mixer in software... you could even have multiple sound mixers in the same bit of hardware. Suddenly digital sound and automation got cheap! (In broadcasting terms, of course...)

 

Neil

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Wow that looks like the radio Gage and Desoto used on TV!   It seems to be missing the antenna that you had to insert before using.....

 

 

FF = PI > S.E.T

 

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Doc, i suspect the chip has major issues as the logic levels are not correct. So reprogramming it would not solve the problem. Apart from the stored charge leaking away, there’s many other mechanisms that cause ics to fail with age - electromigration, contaminants - external and internal, bond wire failure and so on.

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Ahhh, the thot plickens! Got some bin files but the one that looks useful expects another eprom :( how do I know this? I disassembled it and spotted a number of external calls. There was another file that had the pcb number as part of the filename and it looked like the extra eprom. Tried and no dice. Found the 6116 ram chip was dud - I’ve had a few of these die over the years. Nevertheless, still no luck with it. Next trick might be to write some diag code and burn an eprom to make sure there’s no more hardware evils.

 

it doesn’t want to succumb easily.......

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Kartman wrote:

Ahhh, the thot plickens! Got some bin files but the one that looks useful expects another eprom :( how do I know this? I disassembled it and spotted a number of external calls. There was another file that had the pcb number as part of the filename and it looked like the extra eprom. Tried and no dice. Found the 6116 ram chip was dud - I’ve had a few of these die over the years. Nevertheless, still no luck with it. Next trick might be to write some diag code and burn an eprom to make sure there’s no more hardware evils.

 

it doesn’t want to succumb easily.......

 

Australia already made the channel for repair.It looks the first gathered for repair all the electronics.yes

 

www.tokopedia.com/madagang .Buy and Donated cheap electronics and manuscripts.