Does anyone have a RGS with a rev counter that actually works?

1200ts

1200ts

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USA - Riverside CA
My RGS has always had the usual problems with the rev counter. Needle jumping around and being mostly useless. Today is has decided that 0 revs is actually 2K revs as that is where the needle sits with the motor off. It has never done this before.

For those who had a RGS when they were new, did the rev counter actually work or was it just as bad back then?

My RGS had the Bosch ignition when I first purchased it and for the past twenty has had a IIS ignition. The rev counter has worked equally bad with both.

I have been told that the gauges are from a Lancia? If looking for parts, what year and model Lancia had these gauges?
 
Mine worked for 3 years........ I got the bike with 22K now has 40K, but has just recently thrown a wobbly!

I do like what KSOLOM? has done with his Tac and Speedo 👌
 
My rev counter works ok, not rock solid but good enough. Sachse ignition seemed to help a bit over the original.
However I had a problem a couple of years ago with the needle alternately sticking and waving about uselessly. Closer inspection found that the metal counterweight under the short end of the needle had dropped out and was rubbing on the face. An extremely careful application of a fraction of a drop of superglue fixed it and hasn’t given any trouble since 👍
 
Hello Bruce, the oem tacho chip is obsolete well and truly, ended up striping out all the oem through hole components from the thin original pcb substrate and fitting National LM2917 ( now TI ), which may or may not be still available as DIP8, you can get adapter mini pcb smd to dip through hole, for little money on ebay.

A few extra passive components on the remaining cleared pads will have you with a much more accurate tacho drive for the meter movement. A tiny dab of Rocol Kilopoise ( just checked, its no longer available though there are substitutes ( * )) damper fluid will alleviate the rapid road based gyrations of the movement needle, just did the lower bearing pivot as it has a brass disk and adjust screw for easy access. Made this mod to at least 6-10 customers RGS display, with your background it wont take long to modify the original pcb inside the tacho module. If i find my notes will forward them to you, though its been 20 years perhaps since have done this modify and service on the Tacho. HTH j

( * ) seems only one of the variants of KIlopoise is no longer available, the formula i have is the tube born grease type. Somewhat like toothpaste in texture and dispense form.
 
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Hello John,

Since your ignition has a rev limiter, the tach not working correctly has never been an issue. But it is getting worse and is time to fix it.

I just had to dig out my old National Semiconductor data book from 20 years ago and see that the LM2917 is a frequency to voltage converter. It looks like it will be relatively simple to make it work. I should not say this as I have not yet looked inside the gauge assembly and have no idea what the Italians did to make the tach work.

I will put a scope on the tach wire tomorrow to see what the signal looks like to drive the LM2917. Then need to build a circuit with a 555 to replicate the tach signal for testing.

Now as for my original question. Is there anyone out there who bought a RGS when they were new? Did the tach work correctly? I have never seen on that did.

Bruce
 
Ok Bruce all noted, iis tach drive is a 12V signal, though not used for the oem chip which is a scaled -300V flyback signal from the ignition coil primary. If you do modify the oem tacho pcb for a low voltage LM2917 then you remove the oem Dark Green/Grey connection at the coil primary ( ignition coil three ) connect to the iis Mauve colour wire that is adjacent at the coils, easy as. this connect the iis tacho drive signal out ( 0-12V ).

Forgot to mention that detail last message, easy to config the LM2917 as a low volts input sense, and the iis does the rest. No need for test 555, the iis outputs tacho drive in test position "F" on the curve switch. Not sure if your iis has the tachometric stepping test 1000 to 10,000rpm or only the 1000rpm output signal. Hope that helps. j

*** Figure 21 in the TI data sheet application notes is the basic circuit i used, flicked the 300V voltage divider and used a nominal series resistor from the iis to the input of the LM2917 Pin 1 to scale at 0-12V drive signal, ( you will adapt the DIP14 to the DIP8 package from figure 21 ). Not as complex as it seems Bruce, says me, a smile here.

Not sure how anyone would know if the tacho was accurate over its working life, worse i saw was one that under read by 1500rpm at upper reves. The owner kept banging the rev limiter and said the iis was "cutting out" prior to iis he as reving the daylights out of his RGS at easy 1500rpm over redline, or around 9500rpm give of take tacho inertia lag.... madness, 120 motor can take a beating it seems...

 
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Don't want to steel the thread but a quick question.....does the standard RGS rev counter function with the Ignitec ignition at all, unstable or otherwise, if connected?
 
1200ts said:
Hello John,

Since your ignition has a rev limiter, the tach not working correctly has never been an issue. But it is getting worse and is time to fix it.

I just had to dig out my old National Semiconductor data book from 20 years ago and see that the LM2917 is a frequency to voltage converter. It looks like it will be relatively simple to make it work. I should not say this as I have not yet looked inside the gauge assembly and have no idea what the Italians did to make the tach work.

I will put a scope on the tach wire tomorrow to see what the signal looks like to drive the LM2917. Then need to build a circuit with a 555 to replicate the tach signal for testing.

Now as for my original question. Is there anyone out there who bought a RGS when they were new? Did the tach work correctly? I have never seen on that did.

Bruce
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I bought mine used in the late 80’s and never had any issues with the tach. It was always smooth and steady, last time I rode it before putting it into storage and beginning our travels it was just fine.
 
Dick Buthker in Holland has devised a replacement (reliable and accurate) RGS tacho that retains the original dial.
I'll see if I can find the details.
 
hooksey said:
All very well with this tech talk,........Im well outta my depth with a fix for an electronic Tac.
Is someone in the know prepared to put their hand up, that has sufficient time, to spend fixing these Tacs ?
Name ya price........should be plenty RG owners lining up!

Or do we just junk them ?
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Like many tasks, matter of batching to make it worthwhile, once the bench is setup and a run of the task or modification is processed then it becomes sort of cost effective. Then the peripheral aspects come into play, postage.. imagine the cost and trepidation in sending a whole RGS pod through the mail or courier system twice. It arrives with new issues from the handling ( assume worst case ) after modification, no fun dealing with the peripheral issues and detracts from the original idea to update the tacho. Alas it becomes all too difficult as you/me age. Rather sit in the sun, plodding away on my resonator guitar. There are others as mentioned offering solutions, better or worse, cost to be of this era not 25 years ago costing. Had to be asked Hooksey, you did that and have one persons perspective. J
 
I had a very ugly dash on my Corsa with the wavy needles and all that and bought an entire NOS RGS dash from Wolfgang for very reasonable money at the time (maybe 5-8 years ago). Alas I think they're all gone now. The new one works more or less perfectly... for now.

I think I had been speaking to Wolfgang about other things and casually asked how to fix RGS dashes when he said "just buy a new one from me". But prior to that option opening up I was figuring on retrofitting the guts from a new aftermarket speedo/tach in behind the original face etc. It has been done and documented on this forum before if you go searching. There is also the option of making a new dash face and just fitting aftermarket round instruments in their entirety (as on the recent RGS dyno video) which no doubt works well but loses something of the uniqueness of the RGS concept.
 
iis_iis said:
Like many tasks, matter of batching to make it worthwhile, once the bench is setup and a run of the task or modification is processed then it becomes sort of cost effective. Then the peripheral aspects come into play, postage.. imagine the cost and trepidation in sending a whole RGS pod through the mail or courier system twice. It arrives with new issues from the handling ( assume worst case ) after modification, no fun dealing with the peripheral issues and detracts from the original idea to update the tacho. Alas it becomes all too difficult as you/me age. Rather sit in the sun, plodding away on my resonator guitar. There are others as mentioned offering solutions, better or worse, cost to be of this era not 25 years ago costing. Had to be asked Hooksey, you did that and have one persons perspective. J
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Good on you John........smelling the roses!
Your contribution to Lav owners world wide, with your Ignitions puts you at the top of the tree as far as keeping these ole bangers on the road Bravo(y)
But i've got plenty of ridin left in the tank and id like a working tac , well aware of documented fixes by others. We need a specialist to poke his head up...........just like you did all those years ago :)
 
When I bought my RGS 23 years ago, I soon bought a new dash for it to replace it when the rev counter would fail, or when passing the 100.000 km. At 100.000, well 103.500 actually, the rev counter still worked fine, but the faces had faded.
Apart from the pretty sight, the biggest difference is that the old speedo exaggerated some 10%, whereas the NOS one is pretty accurate.

Oh yes, started off with standard ignition, mounted a DMC2 later, where it needed the additional device to make the rev counter function properly.

Marnix
 

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I have no issues wih mine, it is working since I own the RGS in 2006. I use a DMC 2 and the RGS had about 130000 km done, 70 with me.
 
Shortly after recieving my RGS, with 38000km on the clock, I replaced the shagged instrument pod for a NOS item. The old one had been butchered, with some sort of electronic tach that was totally out of whack and the whole assembly in a generally appalling condition. As a precaution, the damping weights on the tach needle got a blob of super glue and the front fairing mount silentbloc was swapped for a solid alloy bar. The "new" odo has now just passed 70000km, the tach still works as it should, with no sign of anything giving up. The dials and needles have faded a bit over the past 20-odd years, there also no signs of vibration-induced issues. DMC II/32 system with the appropriate feed filter.

Only real complaint I could think of is that the speedo is more than just a little optimistic, always a 10-15km/h more than shown on the Garmin.

piet
 
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sfcpiet said:
Shortly after recieving my RGS, with 38000km on the clock, I replaced the shagged instrument pod for a NOS item. The old one had been butchered, with some sort of electronic tach that was totally out of whack and the whole assembly in a generally appalling condition. As a precaution, the damping weights on the tach needle got a blob of super glue and the front fairing mount silentbloc was swapped for a solid alloy bar. The "new" odo has now just passed 70000km, the tach still works as it should, with no sign of anything giving up. The dials and needles have faded a bit over the past 20-odd years, there also no signs of vibration-induced issues. DMC II/32 system with the appropriate feed filter.

Only real complaint I could think of is that the speedo is more than just a little optimistic, always a 10-15km/h more than shown on the Garmin.

piet
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Can you still supply NOS instrument pods, Piet?
 
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