Racal Dana 5002 ROM images

[dxl]

Hi,

i just got a Racal Dana 5002 wideband Voltage meter.  There are a few issues with it:

- The Battery leaked and left a real mess.
- The famous Schaffner Linefilter in there of course blew 1 minute after I plugged it in.
- The 4x 2732 EPROMs in there seem to lost their content

Does anyone have a image of these ROMs? Unfortunately can't search on the ko4bb website, it always redirects me to the start page...

Thanks,
dxl

[garrettm]

I have a 5002 with date code 1991 (IIRC) and an IC programmer to read the ROMs. It might be a few days before I get around to doing it, and if I forget just send me a PM to remind me.

I've fixed four of these units I got in an auction lot. Had to replace the crappy RIFA film caps across the power switch contacts and the lithium 3V battery and everything was good to go for me except the newer one from 1991 had a bad power switch that I had to replace and the oldest one had a bad 74LS09 that affected the front panel buttons. I think the AC input filter is a bigger issue for you guys in Europe with 240VAC mains. Here, 120VAC doesn't seem to be enough to cause the line filter to blow up.

One systemic issue with these units is the crest-factor measurement's peak detector circuit overshoots based on signal rise time. To test, use a variable symmetry triangle wave (which mathematically has identical CF regardless of symmetry value, the proof is fairly simple to work out) and transition from equilateral 50% symmetry to a "ramp" (sharp rising or falling edge) and the CF goes bonkers. The peak detector circuit needs dampening to prevent overshoot. I was going to work on a fix for this but got sidetracked before I could get around to it.

An additional trimmer and fixed resistor can be added to replace R24 (100kohm) to fine tune the offset. My unit was off 2 or 3 counts from zero which annoyed me enough to look for a fix.

Follow the attached instructions for clearing the battery error (Er01). These units require a good read of the manual to unlock the full potential as some measurements are "special functions" and are not discrete buttons on the front panel.

[garrettm]

Here's a PDF of the Teledyne ADC and a photo of the resistor (R24) I pulled to fix the zero offset.

[dxl]

Hi garettm,

thanks! Another eevblog member sent me already two sets of ROM images (one is RevA, the other is unknown). I burned a new set of EPROMs, but still nothing on the display. I see the processor address + data lines toggling, which is good. Have to do additional debugging, but it was already late after burning PROMs yesterday.

[wn1fju]

Have you reconnected the battery and made sure that all of the traces in the battery circuit are OK?  When I first got my 5002, all I saw was a blank LCD display and no LEDs lit except for the power LED.  The battery was dead and after I replaced it, the unit worked flawlessly.  Just a thought...

[dxl]

There's a lot of corrosion going on, so there are no traces to the battery any more...

I had two replace to resistors in the 15v regulator, because they where open due to the leaked battery. So i'm assuming that the 15v regulator put out way to much voltage, and the analog stuff might be broken as well.

It did powerup correctly once this morning, and was alternating between a ~500mV and Er01 Display. I guess the Er01 means battery empty. However, connecting a new battery didn't help. I'm now connecting a Logic Analyzer to trace what the microcontroller is doing.

[dxl]

There seems to be some logic that disable CS for the RAM chips when power is going away. Maybe there's something wrong, i'll check later.

[dxl]

Checked, see R/W and CS toggling at the RAM. Guess i have to trace the uC with the Logic Analyzer. Attached is a photo of the battery area after cleaning - can't get the PCB to look any better.

[dxl]

Stupid me... I used 27128A instead of 2732 EPROMs, because i don't have any 2732. But on IC16, i didn't really solder the 4 additional pins to Vcc as it should be. Almost invisible the gap, but after soldering it again, it looks better now :-)

It says now  'Er 01', although i have a 3V battery connected. The manual says 'Er 01' which means 'non volatile memory corrupted'. Should that go away by itself, or do i need to do a calibration?

[F64098]

Press 97.1 Shift SF and the error will vanish.

Best regards

Frank

[dxl]

Thanks, that worked - now need to repair the analog part, and then it's hopefully working.

[dxl]

There's a Pickering 80-1-A-5/5D Reed relais in the input section switching the 60dB attenuator. The coil seems to be open - so need to look for a replacement.

[timeandfrequency]

Hello dxl,

[..]
Does anyone have a image of these ROMs? Unfortunately can't search on the ko4bb website, it always redirects me to the start page...

I encountered the same behaviour on the KO4BB site and tried to fiddle a little bit the URL, but could not succeed
I just sent a email to KO4BB so that he gets informed about the issue.

[dxl]

Looks better now 

Now waiting for the postman to bring a new battery, power switch, and line filter.

[timeandfrequency]

Hello dxl,

[..]
Does anyone have a image of these ROMs? Unfortunately can't search on the ko4bb website, it always redirects me to the start page...

I encountered the same behaviour on the KO4BB site and tried to fiddle a little bit the URL, but could not succeed
I just sent a email to KO4BB so that he gets informed about the issue.

The issue is still present but there's now a workaround available 
@Xyphro identified the issue and @eliocor devised a small Tampermonkey script that allows seamless navigation on KO4BB's site. Many thanks to them.