1983 Suzuki GS 1100 ESD Tach

[reddirtrider]

using the Suzuki manual standard changing range upper limit of 15.5V I get about 3.3 watts (10.5V drop). I guess that explains it's size.

Jim

True enough, but for power dissipation we use average power, not instantaneous. Voltage ratings are different, they go with instantaneous.

My wife just returned. I'll try to make time for this tonight. My fingers are sore from sanding rims, so it will be a welcome change.

 

[posplayr]

15.5v

15.5v

True enough, but for power dissipation we use average power, not instantaneous. Voltage ratings are different, they go with instantaneous.

Is the upper limit at 4000 RPM so in one hour of riding at 4000 I'm sure you will reach thermal equilibrium or run away which ever applies.

 

[reddirtrider]

Well, I ganged seven 220 ohm 1/2 watt resistors together and gave it a try (radio shack is all we have within 40 minutes driving time) and the voltage reading was 2 volts. Unfortunately, I think there is something else wrong as the makeshift resistor was very hot to the touch. When I say very hot, I mean burning hot.

I didn't expect to dig into this right now with the rest of the bike still in pieces, so I'm not prepared to do much else as my bench space is gone. I'm rigging this up on the seat of the ATV and using its' battery.

If all else fails it wouldn't be difficult to design a circuit that does the conversion necessary to drive this tach. The unknowns at this moment are what is the input and what is the necessary output for any given input. Since I don't have a running bike, it's hard to determine either.

Sorry for the bad news, but such is life. This bike has given me problems every step of the way. If it wasn't my sons' I'd seriously think of parting it out.

 

[reddirtrider]

Is the upper limit at 4000 RPM so in one hour of riding at 4000 I'm sure you will reach thermal equilibrium or run away which ever applies.

If we ever figure out what the components are on this board we can work the numbers. Right now we're ****in' in the wind. Frustrating my friend.

 

[posplayr]

Red

Red

Regardless of the components on the board, Power ratings should be based on the steady state maximum voltage available from the charging system.

The manual states that 15.5V is an acceptability state maximum at 4000 RPM (you brought up the terms instantaneous which do not apply to these numbers).

Considering there are plenty of GS's running around Even above this (one recently at 18.5V ).

Any power calculation should at least use 15.5v if not something higher like 16.5v to provide some margin. Otherwise with certainty if the R/R were to stop regulating the Tach components will soon go into thermal overload and fry.

Using a upper voltage like 16.5V for thermal calculation is a good idea and I know that now and that is NOT"****in' in the wind".

Pos

 

[Nicholaschase29]

I have a good working GS 700E at home. I can get you whatever readings you need from that board. If you let me know what numbers you need so we can proceed I'll have them for you by next week. Thanks guys.

 

[posplayr]

A couple of things to check:

1.) what is the sensitivity of the tach movement (how much current to get to full scale).
2.) how much restsiance does the movment have.

You can answer these two questions by measureing the resistance and then applying a (1.5v battery) small voltage to the movement and reading the deflection.

current = Volts/measured resistance
sensitivity = %deflection/current

Is the tach input directly from the coil (-)?

3.) What voltage do you measure at the input (+) side of the movement (it an be disconnected).

If I remember your diode is hosed so you need a new 5 volt zener for 3.)

4.) If the bike is running what is the supply voltage (+12v) coming in? At idel at 4000 RPM.

Pos

 

[reddirtrider]

Using a upper voltage like 16.5V for thermal calculation is a good idea and I know that now and that is NOT"****in' in the wind".

Pos

Actually, since we don't know what the zener voltage is - it is. Anyway, I've been to a customers the last few days and I'll be on the road the next week.

I agree we must use the maximum sustained input voltage. I just wasn't aware what it was. What I was looking at was reverse engineering Suzuki's system. In other words, what input voltage did they use if this is indeed a 5v zener. It wasn't 16.5v based on that resistor.

Without more info, we may as well design a new system. It would be far easier.

 

[Nicholaschase29]

GOOD NEWS!!!

I replaced the original zener diode with a 5.1V 5 Watt zener diode. I now have response from the needle.

Here is a video of what is happening.

It seems like the needle responds slowly, and that it registers less than the actual RPM.

My theory:

The diode is really a ~12? V diode, the 5 V diode supplies about half the voltage to the needle, so it has about half the current, and reads half the rpm.

Looking at the video again it looks like it is closer to the actual RPM than I originally thought. Could someone who has one of these bikes please tell me what speed you're traveling in 2nd gear at 6000 RPM? I'll take mine out and see if it is close. Thanks

Let me know what you think.

http://s464.photobucket.com/albums/rr10/zacharyalan09/?action=view&current=tach-1.flv

 

[Guest]

Sounds great but your tach isn't even close.

 

[Nicholaschase29]

bump

bump

bump................

 

[TheCafeKid]

Nicolas, I got your pm. I would be happy to give you readings but unfortunately, mine seems to be just as untrustworthy as yours...Ive even replaced the board with one out of a set of gauges that i had laying around, its a BIT more accurate, but up in the higher RPMs i still think its lying. I have geared down a tooth on my rear sprocket for better cruise RPM and its STILL saying that im turning anywhere between 5-6K in 5th at 70ish mph...i know that its prolly close, but it fluctuates, and up to a 1000rpm at times so i think its still full of it. I plan on sending my board to PosPlayr as he has agreed to take a look at it and see what he thinks. I will let you know if anything pans out with that. I will still get some readings however, and bounce them off of you and perhaps between the two of us we can see exactly how far off this thing truely is...

TCK

 

[posplayr]

Josh

Josh

Send me the whole tach not just the board. I can then run a calibration to see how much it is off. I plan on driving it with a square wave signal generator to simulate the primary signal and can then measure the sensitivity and readout accuracy of the guage.

You have to have this if you ever want to design a new PCB.

Jim

 

[Nicholaschase29]

Well that is good news. I'm glad you guys are looking into it. I think I've gone about as far as I can on my own. Let me know what you find.

 

[posplayr]

Well that is good news. I'm glad you guys are looking into it. I think I've gone about as far as I can on my own. Let me know what you find.

http://www.thegsresources.com/_forum/showpost.php?p=995900&postcount=47

can you answer any of this?

 

[Nicholaschase29]

A couple of things to check:

1.) what is the sensitivity of the tach movement (how much current to get to full scale).
2.) how much restsiance does the movment have.

You can answer these two questions by measureing the resistance and then applying a (1.5v battery) small voltage to the movement and reading the deflection.

current = Volts/measured resistance
sensitivity = %deflection/current

Is the tach input directly from the coil (-)?

3.) What voltage do you measure at the input (+) side of the movement (it an be disconnected).

If I remember your diode is hosed so you need a new 5 volt zener for 3.)

4.) If the bike is running what is the supply voltage (+12v) coming in? At idel at 4000 RPM.

Pos

1) I'm not sure, although 1.62 V (measured AA battery voltage) reads 9500 RPM's.

2) I didn't check.

The tach input is directly from the 2/3 coil. It is the same wire to coil ground.

3) I didn't check.

4) With my old R/R it was at 15 and climbing when I shut it off. With the R/R I replaced it with it is at 12.2 and my battery doesn't charge. It was laying around, I thought it was good but I guess I was wrong.

Sorry I forgot to check those when I had everything apart. I was so excited to get my new diode in and watch the needle move I forgot to take the measurements. I'm sure I'll have it apart again though and will let you know what I read.

It just looks so nice closed up, I'm afraid if I take it apart it'll never get put back together.

 

[reddirtrider]

GOOD NEWS!!!

I replaced the original zener diode with a 5.1V 5 Watt zener diode. I now have response from the needle.

Here is a video of what is happening.

It seems like the needle responds slowly, and that it registers less than the actual RPM.

My theory:

The diode is really a ~12? V diode, the 5 V diode supplies about half the voltage to the needle, so it has about half the current, and reads half the rpm.

Looking at the video again it looks like it is closer to the actual RPM than I originally thought. Could someone who has one of these bikes please tell me what speed you're traveling in 2nd gear at 6000 RPM? I'll take mine out and see if it is close. Thanks

Let me know what you think.

http://s464.photobucket.com/albums/rr10/zacharyalan09/?action=view&current=tach-1.flv

I'm on the road visiting customers so here's another guess. The zener may not be a 5v unit. It could be 12v and is used just to proivide a stable 12v reference since we cannot rely on that from the R/R.

Give it a shot and see what happens.

Sorry for not having any real answers, just suggestions, but there's not much to go on.

 

[posplayr]

Nicholaschase29

Nicholaschase29

Well hopefully the unit Josh is sending is functional so I can do some measurements. I'll compare to your numbers.

I was just curious,; It sounds like you probably fried the unit due to over voltage though given +15V and climbing .

Jim

 

[reddirtrider]

Anybody found out the zener voltage on this yet? The zener on my unit is definetly bad and I'm going to head to an electroics store tomorrow if I have time. I doubt it's a 5v unit as I originally thought. Possibly a 10v or 12v reference?

Anyway, if no one knows yet, I'll get an assortment and do some testing.

 

[posplayr]

I doubt it's a 5v unit as I originally thought

why is that?