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OER Tach or Tic Toc Tach Schematic anyone?

Redtunnel

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I bought the Ebay special Tic Toc Tach. Ad said clock works tach doesn't. They were truthful, the board is roasted, OER does not sell replacement boards. Have searched the internet but come up empty, anyone else had a problem with one and taken it apart? check the picture.
No picture of the other side of the board but traces around the big grey resistor? and the red wire are pretty much missing. Thanks in advance.

part numbers on the circuit board 1277441 and 1277447 these are the same part numbers for the OER Mopar ralley Tach and tic toc tach
tach board.jpg
 
I don't know if these will help you, but these are the ones I took before I tore mine apart.

20181209_153306.jpg 20181209_153319.jpg 20181209_153329.jpg 20181209_154737.jpg 20181209_154843.jpg
 
I don't know if these will help you, but these are the ones I took before I tore mine apart.

View attachment 806084 View attachment 806085 View attachment 806086 View attachment 806088 View attachment 806090
thanks Bob is yours an original? i have called some of the repair shops from the forum and i think any of their boards work on the originals but since this is after market they wont commit to it, that's why i was looking for a schematic to try and repair this one
 
thanks Bob is yours an original? i have called some of the repair shops from the forum and i think any of their boards work on the originals but since this is after market they wont commit to it, that's why i was looking for a schematic to try and repair this one
 
Gentlemen,
I concur wholeheartedly with using Real Time Engineering's tach board. They have both the initial design and for a few $$ more, get the one that can bench calibrated if you want. Both work very well. The installation instructions are written wery well and are easy to understand. BTW.... their instrument panel voltage regulators are the best and most reliable. DO NOT EVEN MESS AROUND WITH "Fixing" the old board....its not worth it in my opinion. After all, who will know its not the original numbers matching, you cannot see it anyway. The new design is far more accurate and reliable..... Just my opinion of course.
Now if i can find someone that supplies a replacement for the origional mechanical clock like one what has a quartz movement.....I can upgrade both at the same time.
Bob Renton
 
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I appreciate the replies and suggestions, if this was an original tic toc tach i would upgrade to the RTE board, it is an OER tach so the boards are not compatible. see the pictures of the board i am trying to find a schematic for. i tried to get a good picture of the front and back of the board, there is almost nothing on the board but some components are not labeled and other are too scorched to read. thanks to all who replied.
 
Red,
A tach (any tach) is nothing more than a a voltmeter that is displaying RMS (Root Mean Square) or average of a string of incoming voltage pulses, generated by the ignition coils primary winding. As these pulses come closer together, as the engine RPM's increase, the AVERAGE voltage will increase resulting a higher reading on the tach's scale. The components on the board help shape the pulse train, dampen any noise pulses, and limit the max voltage applied to the board.
If I were to GUESS as to the cause of the failure, because of the scorching and apparent burning, it is due to operation on a capacitive discharge ignition system, perhaps MSD or something similar. A CD ignition system furnishes the coil's primary an extremely high voltage pulse, in the neighborhood of 500+ volts DC, allowing the coil to produce an extremely high voltage, maybe 40,000 volts, to the plugs. At lower RPM's the control box can generate several of these high volrage pulses per cylinder, which is claimed to make more power.
What type of ignition system are you using? Is it stock Mopar or something similar? Perhaps you should inquire if any "tach adapter" is required to operate a factory installed tach. Call RT Engineering to see if their design is compatible with your system OR replace your ignition system with something more compatible with your tach (once you get it repaired). This is just my opinion of course. I'm sure the MSD boys will have their own opinions.
Bob Renton
 
One additional thought...
IF the OER (Original Equipment Restorations) tach has duplicated the origional Mopar (Borg-Warner) tach's MOVEMENT with the stationary permanent magnet and the moving magnet powered by the electronic board's output, and IF the moving coils resistance is the same, the tach will or should work with the RT Engineering's board.....yes..?? Can you measure the moving coil's resistance to be sure ?
Bob Renton
 
Red,
I found this link to a universal tach board.....it sort of resembles your old one..... Follow the link....no guarantees this will work with your tach....nothing ventured....
www.dinoplex.org/tachoconversion
Its listed as a universal board that can accommodate most modern ignition systems including points....
Bob Renton
 
One additional thought...
IF the OER (Original Equipment Restorations) tach has duplicated the origional Mopar (Borg-Warner) tach's MOVEMENT with the stationary permanent magnet and the moving magnet powered by the electronic board's output, and IF the moving coils resistance is the same, the tach will or should work with the RT Engineering's board.....yes..?? Can you measure the moving coil's resistance to be sure ?
Bob Renton
I bought the tach not working off eBay hoping for something I could fix. I run an old accel dual point in the car . I looked down inside the tech body at the coils, all the coil connections attach to the board through the 4 brass rings in the center of the board, 2 appear to be ground. The ground? 2 posts measure 100.6 ohms between them. The plus? 2 posts meaures 138.1 ohms between them. Not sure how to meaure the winding? On the shaft that is attached to the needle.
 
Hey did you find the replacement Circuit board. I just pulled mine out and I have the exact same. Mine is blown the exact spot yours is. Any luck finding a replacement?
 
Hey, sorry to post on an old topic, but it shows up on google search so Its still relevant.

The OER Tach on my Brothers 68 Charger fired. His car has a stock Mopar electronic ignition system with the little orange box on the firewall, so I'm not sure why it failed. I was able to fix it though so I thought I would share what I learned.

The board uses a CS8190 Tach/Speedo Driver. Here is the data sheet:
https://www.onsemi.com/pdf/datasheet/cs8190-d.pdf



The circuit differs slightly from the one in the data sheet so I also drew this crappy circuit diagram for the melted area. I drew it looking from the back, where the solder is. Its not complete, nor a conventional diagram, but it got the job done for me.
1083756-9108d259503572175603d45920ade5a0.jpg

Here is my shopping list:
1 X 223 Film Cap
1 X 104 Film Cap (I don't know the original value because the letters were burn off of the cap. This value is based off the diagram in the data sheet)
1 X 10 Ohm 2W Resistor
2 X 10k Ohm 1/4W Resistor
2 X 1n4007 Rectifier Diode
1 X 50V 0.5W Zener Diode (This is for over voltage protection. You could probably use a lower value but I just based it on the diagram in the data sheet and don't know the original value. Use your own judgment here as I'm not a electronics expert. I used a 51V SK51A as it was the only thing my local electronics supplier had in stock that was close.)

The copper tracks were completely destroyed on mine so I made a new Auxiliary board and wired it in with jumper wires. Hopefully you're not so unlucky, but if you are, its still salvageable! The red wire goes directly to the pin on the IC.
1083754-3640cbee21cc5dbbdfbc6eee841fb5a8.jpg

I also designed and 3d printed a little plastic case and taped it on the gauge to keep everything from moving around. I'm sure a big wad of tape would have been just as effective.
1083753-36415dd078444f693300d9ed4021ee6f.jpg

The tach works again! I Hope This Helps! If you have any questions let me know.

IMG_20210821_142834311.jpg IMG_20210821_142857958.jpg IMG_20210821_142903668.jpg IMG_20210821_163914673.jpg
 
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