IFR 1200 service monitor checksum error repaired - Page 1
Forum section: electronics / repair

author: Radio Tech
author_rank: Frequent Contributor
timestamp: June 21, 2014, 10:26:24 pm
content: I have gotten many emails and PM's from a post a put on the site some time ago about my service monitor issue. Seems others have had this issue also. Funny thing is no one was able to come up with what was causing it.On boot up it gives a checksum error followed by memory reset. Also the spectrum would not behave like it should and would drop well below the bottom of the CRT. For over a year I checked around and never could find the info to fix these issues.Over the past few days while looking over the service manual I found that board number 17 was the CPU unit. On this unit was a 3 volt coin battery. Could this have been the problem the whole time?Yes.For all those that asked...Please excuse my crude video in my redneck country boy way.https://www.youtube.com/watch?v=S7U9EGVQwPM&feature=youtu.be

author: SeanB
author_rank: Super Contributor
timestamp: June 22, 2014, 07:51:04 am
content: Did you use a CR or a BR battery? There is a difference between them in that the BR is a high reliability version.http://www.panasonic.com/industrial/batteries-oem/oem/primary-coin-cylindrical/br-cr.aspx

author: Fraser
author_rank: Super Contributor
timestamp: June 22, 2014, 10:26:15 am
content: I own the communications monitor variant of your unit, the IFR 1200R. I have maintained several of these over the years and should warn of another, more serious issue that may occur at this late stage in the units life.The EPROM's suffer age related corruption, rendering the unit inoperative. I have seen three suffer from this problem and that was almost 10 years ago ! The EPROM's should be backed up or duplicates made. I reprogrammed the corrupted EPROM's using another units EPROM's as a known good 'Master'. The original EPROM's work just fine after having been erased with UV and re-programmed, so they were not faulty.EPROM programmers are pretty cheap these days so I recommend the investment and backing up of any critical EPROM's in elderly equipment as they are operating well beyond their expected life and could corrupt at any time.Aurora

author: Radio Tech
author_rank: Frequent Contributor
timestamp: June 22, 2014, 11:33:15 am
content: Quote from: SeanB on June 22, 2014, 07:51:04 amFor now I used a CR. I have no 3 volt BR types atm. But as easy as it is to replace now no worries.Quote from: Aurora on June 22, 2014, 10:26:15 amI agree with that. And is what I used to do some time ago until my last Windows 3.1 machine bit the dust. I still have the programmer and card but no machinr to run it. I really need to invest in another one. I posted about this a year ago here:https://www.eevblog.com/forum/microcontrollers/new-programmer-to-replace-old-one/msg269406/#msg269406

author: SeanB
author_rank: Super Contributor
timestamp: June 22, 2014, 11:44:24 am
content: Buy the Minipro that has been discussed before here. It does a lot of programmable memory devices. It is cheap and easy to use.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: June 22, 2014, 12:08:37 pm
content: Quote from: SeanB on June 22, 2014, 11:44:24 amThis one?http://www.amazon.com/Signstek-Universal-MiniPro-Programmer-Support/dp/B00K756PB6

author: SeanB
author_rank: Super Contributor
timestamp: June 22, 2014, 12:32:59 pm
content: Yes, cheaper direct from China, but if you want it tomorrow then use Amazon prime if you have it. I got my one through Frankie, and it came with a whole set of adaptors for various SMD devices as well.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: June 22, 2014, 12:57:49 pm
content: http://www.ebay.com/itm/MiniPRO-USB-Universal-Programmer-TL866CS-support12000-chip-include-6PCS-adapter-/320947942396#ht_14926wt_940Not Frankie but I see what you mean. The amazon one has no adaptors.Got to get me one of these. I loved my old ModMac programmer but is is so outdated.There are several old CB and Ham radios I work on that use these EPROMS that need replacing. Was going to go the "PIC" route. What everyone was telling me to do. But I know the old stuff and yet to learn the PIC stuff although I do have the programmers (PicKit2).I just been putting things off too long.And thanks for the recomendations BTW.

author: KY5Q
author_rank: Newbie
timestamp: September 21, 2017, 08:30:34 pm
content: Regarding the IFR-1200. I just acquired one. I replaced the battery on the CPU card (the CPU card is the one with the 8031 style processor, not the 80188). I still have the check-sum error. When I power it up, it says "Checksum Error" then "Memory RESET" and waits for me to do something. I can enter a frequency and it seems to work otherwise. I read something about the EEPROMs failing after years of age, so I am willing to update the firmware, if I could find the firmware. Suggestions?

author: voltz
author_rank: Frequent Contributor
timestamp: September 23, 2017, 11:33:12 am
content: Hi,Check that the 3v3 battery voltage is in fact reaching the RAM chip pin. The schematic will show you exactly which pin. There may be a fault in the battery supply circuit (its a diode).It doesn't sound like an EPROM fault to me, but if you wanted to try that then you will need a firmware version less then v3 (like 2.5 for example). They changed the firmware for the newer 80188 from v3 onward. Not easy to locate on the net, but versions are out there. Means physically burning new eproms and changing them on the board.Hope that helps.

author: Fraser
author_rank: Super Contributor
timestamp: September 23, 2017, 02:31:17 pm
content: Having thought about this I concur, the EPROM faults that I had did not produce the checksum error. The unit just refused to boot.As suggested I would check for sufficient voltage on the SRAM chip. Sadly there is also the possibility of a failed SRAM chip in this age of equipment. It is also worth checking any addresss and data buffers that serve the SRAM that could cause a data error on the SRAM read side. I do not have my schematics to hand so cannot suggest more. It would be interesting if you are able to remove the SRAM IC and boot the unit with then SRAM missing. If you get the same error, I suggests an SRAM related issue.Fraser

author: try2fix
author_rank: Contributor
timestamp: June 17, 2019, 07:01:55 pm
content: Hi, hope you can help, I did that But.................I burnt eproms from a working IFR1200 , put the new eproms in & the cpu card is now bricked- I put the old eproms back in with no change, I took from another IFR1200 a good working CPU card and put in the eproms and it is bricked now --- are there some kind of blanking program that has to be run before changing the eproms ? -- I removed the batt and discharged the caps to try to clear and still no go - the display is blank when the cpu card is not working, all you will get is @@@@@@@@@@@@@@@@@@ flash when you power down the unit - I put a good CPU card in and the unit works great --but now I have a few dead IFR1200s as I have Bricked there cpu card - any one got any answers please, Thanks