Can anyone fix a Lexicon RV-8 for audiodon?

I did some hunting on that chip. It looks like it MIGHT be a chip that gets reloaded on power-up rather than having the code programmed into nonvolatile memory. Not sure of that.

On second read of part of the data sheet, the chip is rated for up to 100 R/W cycles of the internal memory so it may be a factory programmed part that Lattice programmed for Lexicon. That may be what the number on it means. The data is supposed to be stable for 20 years but all bets are off when power supplies go bad.

Here is a link to a data sheet on a similar chip. It may be the same thing but this one is a GAL 16V8D P/N rather than 16V8R.

The RV-8 is an insanely complex system. The clocks alone are really hard to understand and I used to do this stuff for a living.
 
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Erik, if the output of that chip is low, that could be due to a bad chip on the sending end or something else pulling it down further down the circuit. If the chip is really warm, something may be pulling too much current out of one or more of its 8 outputs.

Probably the only way to isolate the problem is to disconnect that digital output from whatever it feeds. Note that it may need a pull-up resistor to have a proper output if the output driver has an open collector config.
 
I am going to go down the path of replacing the chip. With out a connection to the processor, the voltage is fine. When I connect it to the processor, the voltage drops. I will need the bin file to reprogram the chip or another chip to copy and reprogram another chip. I don't trust that this chip is good with the heat that it is putting out.
 
I replaced the chip and it looks like it needs to be programmed. Luckily, I put in a socket so that I can remove and insert it easily. I had to move a cap in order to do so. Let me know if you know of one RV-8 to be sold for parts pricing!
Thanks,
Erik
 
Hi Erik, I hope the new chip works. I couldn't tell you how to program it. My plan for Don's unit is to keep it and slowly hack away on it as I have time to do that. That won't start til May, at least, and I expect it to be a long term project. I won't be getting rid of it so it won't be your parts unit for the forseeable future.

I'm thinking that I might try to get clever and emulate the functions of any bad chips or signals I find by using an external microcontroller to try to recreate the I/O signals of the bad chip(s). An Arduino might work or it might not be fast enough. Perhaps a Raspberry Pi would be better. I haven't really looked into any of that so far.

Sorry to not be of more help.
 
With your unit showing the same symptoms, I believe that we have the same issues and may need the same fixes. The more eyes and minds out there, the better our potential for a solution. It looks like Lattice Semiconductor has the development tools posted online. We may be able to recreate the program for the chip using the description of the functions from the service manual.
 
I borrowed a chip burner and was unable to read a program from my old chip. So either I am in search for a donor or I am going to try to create a replacement program. In reading the service manual, I can sketch out the logic except for the clock divider. There are several published examples of clock dividers that I will attempt!
 
I am planning to program a replacement chip with the below code. I would love it if someone would check my work with the description in the service manual of the U44 functions. Let me know!

Module LexiconRV8U44



Q1 PIN istype 'reg_D';

Clock,Preset PIN;



LexiconRV8U44 DEVICE 'G16V8'



Title 'ABEL Program for Lexicon RV-8, U44 Chip as described by the service manual functions'



Declarations

"Inputs

DISP_CTRL PIN 2

CPUCS3/ PIN 3

CPUWRL/ PIN 4

CPUWRH/ PIN 5

CPURD/ PIN 6

CPUADDR3 PIN 7

CPUADDR2 PIN 8

CPUADDR1 PIN 9

CLK12500B PIN 1



"Outputs

CPUCLKI PIN 12

RESREGDECL PIN 13

RESREGDECH PIN 14

DISP_RS PIN 15

DISP_RW PIN 16

DISP_E PIN 17

U43!G PIN 18

U43DIR PIN 19





Equations

"Clock Divider-Flip Flop method

Q1.CLK = CLK12500B;

Q1.AR = Preset;

CPUCLKI := !Q1.fb ;





"Decode Strobes for External Registers

RESREGDECL = CPUCS3/ & CPUWRL/ & !CPUADDR3 & !CPUADDR2 & !CPUADDR1

RESREGDECH = CPUCS3/ & CPUWRH/ & !CPUADDR3 & !CPUADDR2 & !CPUADDR1





"Address Decode control interface to the VFD

!DISP_RS = CPUCS3/ & !CPUADDR3 & !CPUADDR2 & CPUADDR1

DISP_RW = CPUCS3/ & CPURD/ & !CPUADDR3 & !CPUADDR2 & CPUADDR1 # !CPUADDR3 & CPUADDR2 & !CPUADDR1

DISP_E = CPUCS3/ & !CPUADDR3 & !CPUADDR2 & CPUADDR1 & !CPUADDR3 & CPUADDR2 & !CPUADDR1





"U43 Controls

U43!G = !CPUADDR3 & CPUADDR2 & CPUADDR1 # CPUADDR3 & !CPUADDR2 & CPUADDR1

U43DIR = DISP_CTRL


Test_Vectors



End LexiconRV8U44
 
Hi Erik,

I haven't touched it in months and am not sure when, if ever, I will get to it. I'm working on other projects for my AK friend with ALS who owns the Lexicon. Unfortunately, he can no longer use his AV system any longer. I replaced the Lexicon with a Pioneer AVR and that is working fine for the rest of his family.

As I mentioned here a while back, my conversation with an authorized Lexicon repair center and tech has lead me to believe that there are likely to be multiple damaged boards and chips in the unit. No spare boards are available. The tech said that it's a write-off. I realize that may not true if either or both of us can track down whatever problems our units have but that's a very low priority for me. My assumption at this point is that the Lexicon is a goner.

At some point and if I have lots of spare time (hah!), I'll dig back into it but that's off on the horizon somewhere. I'm sorry I'm of no help to you.
 
HAPPY ENDING! I found a Lexicon RV-8 that was being parted out and grabbed the control board for $50. I put it in and I am back in business! Thanks for all of the support. If you are interested in the remaining parts, you can find them with a search in eBay.
 
Wow! Good for you. Nice work!

That makes me wonder if the control board may be all that's wrong with the unit of Don's I have here. I've been doing other things to help him out and haven't had a chance to even think about the Lexicon.
 
Hey guys, just wondering if you had seen this information (service manual). You probably have, but in case you have not here is the link:
https://www.harmanluxuryaudio.com/brandsupport/downloads/C/RV8_SVC_r0.pdf

Best of luck with your efforts!

How the heck did you come up with that link? Looks like it directly accesses Harman's Distributor/Dealer/SalesRep support library which normally requires a verified account to get into. I'd LOVE to be able to pull some of the JBL service manuals for the Synthesis line. Any suggestion?
 
It was nothing nefarious, just some next level Google-fu trying to figure out how to program an MX500 remote to work with my RV-8 as I lost my remote. Lexicon wants nearly $500 for a replacement remote. If anyone here would be willing to help me out in any way to use an original RV-8 to use the learning function of the MX500 replacement I would be willing to jump through hoops to avoid spending $500 for a remote.

Anyhow good luck to you in your search and sorry I don't have any specific advice!
 
Thanks for the link. I had found that manual a while back. It's a monster as is the RV-8 itself. Don's may or may not ever come back to life.

I will see if I have the remote for his unit. I will keep it in case I'm able to get his going at some point but maybe there is some way to push the buttons and read the output so you can recreate them on your MX500.

Looks like you can use an Arduino or Raspberry Pi processor and an IR detector to receive and record IR codes sent from a remote. You can also use that setup to emulate an IR remote if you add an IR diode.
http://www.instructables.com/id/How-To-Useemulate-remotes-with-Arduino-and-Raspber/
https://learn.adafruit.com/using-an-infrared-library/hardware-needed
https://www.packtpub.com/mapt/book/...lding-an-arduino-infrared-recorder-and-remote

Did you see this description of RV-8 codes?
https://www.manualslib.com/manual/3...ions-Protocol-Definition-Rev-1-7.html?page=41
 
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