OM617A Tach Amp - Page 8 - PeachParts Mercedes-Benz Forum

Mark Rapier · #**106** 12-13-2012, 08:01 PM

Quote:

Originally Posted by Doktor Bert

I'm ready to order one!!!!!

Looks like you can go directly to his website and order it there:

Product - Tachometer Amplifier

Doktor Bert · #**107** 12-14-2012, 12:26 PM

Cool, Man!!!!! Thanks!@!!!

Doktor Bert · #**108** 12-16-2012, 02:47 PM

One question, is there a way to install the original cover so it isn't exposed????

techguy512 · #**109** 12-16-2012, 05:08 PM

Quote:

Originally Posted by Doktor Bert

One question, is there a way to install the original cover so it isn't exposed????

Yes....pull the old guts out of the top cover gently with a pair of pliers. It's a friction fit. Once the module is out the cover is empty and screws on the base, covering the new module.

TnBob · #**110** 12-17-2012, 04:52 AM

The cover comes off much like a tooth coming out when you were 10. Takes only a real bit of pull and it pops right off.

Ol' Yeller · #**111** 06-12-2013, 08:02 AM

Quote:

Originally Posted by beermc00

I want everyone to know that if your car uses this style of Tach Amp, Techguy's (Bob's) replacement will probably fix your tachometer. He sent me instructions on how to do a few easy electrical tests with a multi-meter before I bought it because I was sure that my 1983 300D was going to need other parts to get the tach working again. Reason being, I attempted the trick of putting a washer shim on top of the old amp and that blew my #8 fuse and then the amp and the plug it goes into smelled like burning electrical wires...not good.

After my car passed the three preliminary tests Techguy emailed to me, I bought his part and installed it in less time than it takes me to check my oil and the tachometer now works perfectly...plus that self-test, sweep thing it does while you are waiting for the glow plugs is pretty cool.

Thanks for reading!

Hi Bob,

Are you still selling these? I've sent a couple of emails to your website.

Thanks!

- Neil

Doktor Bert · #**112** 06-12-2013, 09:59 AM

Just saving up for one....

Derekwh · #**113** 07-26-2014, 12:20 PM

Quote:

Originally Posted by techguy512

After struggling with my tachometer for over a year, and trying all the tricks including contact cleaning
and cigarette butts, I decided that if I wanted a functioning tach I would need to take matters into
my own hands and tackle the project of designing a cost effective replacement Tach Amp.

The results of the project are shown below in photos.

1) Tach Amp installed in the connector socket on the left front fender
2) Cover (minus the old electronics module) being replaced on the connector socket

This tach amp should be compatible with the following vehicles equipped with the OM617A
engine built between 1978 and 1984:

W116 Chassis 300SD 1978-1980
W126 Chassis 300SD 1981-1983/1984 (it's unclear exactly when the tach amp was phased out)
W123 Chassis 300D/CD 1982-1984
W123 Chassis 300TD 1981-1984

My minimum order quantity on PC boards was 40pcs, so I have about 35 left, and I want to offer
them to anyone that is tired of having no tach. Cost is $42 with $4 S&H.

I have attached the User Guide (with photos stripped out to reduce file size) for anyone interested in
learning more about the operation of the Tach Amp.

During this project I learned a ton about the operation of the tach in these vehicles, as well as how
to troubleshoot tach problems. If anyone has any questions, just fire away....

I just put one of these in my '82 CD. The tach works perfectly now. I'd forgotten what a luxury it is to have a tach that works correctly and doesn't bounce all over the place and only worked when it felt like it.

kvt1949 · #**114** 09-11-2014, 09:24 PM

Hi ! I have a 1985 300 D turbo, but the engine is 1983. It have no place for RPM sensor on the back of the engine. Can I use the front sensor close to the pulley ?( I add the green & black wire ) . Of course I will buy from you the electronic part you have for sale .How can I test the signal from the cable? Cris , 8054559477. My email is coco_4449 @ yahoo.com. How can I order ?

PlaneCrazy · #**115** 05-23-2016, 07:39 AM

Techguy's web site is down. Is he still around? People have been asking.

DrLou · #**116** 05-23-2016, 09:40 AM

Yeah, it looks like he neglected to renew his domain...
Think I could use one of his Amps!

kuene · #**117** 05-23-2016, 12:29 PM

(echo)

i would love to buy one too...

79Mercy · #**118** 08-22-2016, 10:19 PM

Anyone have an email or some type on contact information for tech guy, would like to buy a tach amp if he still has any. Thanks

math · #**119** 02-19-2019, 03:19 AM

I too would like one of these, even if it's a file with the PCB plans and a parts list, or a schematic.

I've kind of decided to make one for myself and if it works, i'll be happy to offer it to others.

cornemuse · #**120** 02-19-2019, 11:54 AM

Over the years, I have gathered 7-8 tach amps from the local 'pick n pull' yard. 1st time was $1, last one was $3 (or so). Still have 1 or 2 somewhere in the garage, , , , (gave some away to cohorts, needed to replace a few)

'Plan ahead'