VDO Tachometer- Bulb holder for the instrument lights

[Ian_Edwards]

One of the bulb holders has a broken contact which is preventing the new LED from lighting up.

The instrument is a VDO tachometer from 2007, part number 02 012 195.

The holes in the PCB are approximately 8.75mm in diameter, the hole isn’t perfectly round, and the small diameter of original bulb holder is around 8.35mm, the flange being around 12.2mm. In the VDO parts list it is describe as “lamp socket ( push in Wedge type)”

I’m having great difficulty sourcing a new bulb holder, with the smaller diameter than the standard T10 holder.

I've bought 2 sets of bulb holders of the Internet and they are both too big, obviously designed for a 10mm fitting.

Dose anyone know of a stockist of wedge bulb holders of the size I’m looking for?

I've tried a good number of the classic car companies who advertise on the web, but drawn a blank so far.

 

[vas]

I have them on my dash, fiddly small things, hopefully all work. Wouldn't it be easier to find a way to restore contact? new wire soldered on, superglue bits, etc?
I know it would be difficult to replace bulb, but these bulbs seem to be fine for 600-700h of engine use (from experience)

cheers

V.

 

[pvb]

Is this the one?

VDO Lamp Holder T5 Wedge Base Bulb - W2x4.6d Ocean Line 85 mm

 

[vas]

must be it, my instruments are also OceanLine 85mm, but it's not really cheap at 8euro for a tiny bit of plastic!

 

[Ian_Edwards]

Thanks pvb, I didn't think of looking for T5, I tried T8, because it an 8mm clearance hole, but that doesn't exist, I thought T5 would be too small.
8 Euros is expensive, but I guess it's all about the cost of handling, which is more or less independent of the wholesale cost of a small item.

Now I know it's a T5, I'll have another search and see if I find the same item at a lower price.

I broke the original messing about trying to fit a red LED, one side worked OK but I made a mess of the other side.

 

[PaulRainbow]

Local scrapyard would have a million of these, they are not unique to VDO, easrch Ebay for "instrument bulb holder", or similar. Be warned though, there are a few variations, make sure the contacts and locating lugs are the same.

 

[Mistroma]

Local scrapyard would have a million of these, they are not unique to VDO, easrch Ebay for "instrument bulb holder", or similar. Be warned though, there are a few variations, make sure the contacts and locating lugs are the same.

I thought scrapyard as well but last time I went to one must have been more than 30 years ago.

Should be plenty on eBay, probably under T5 286 Bulb holder . I think that they might come it 2 sizes or shapes and one is 10mm. Not certain about the last part but think the ones on my VDO tacho were 10mm. I bought a whole boxful of red bulbs on eBay for buttons but didn't need holders.

These look very much like the ones in my VDO:
10 x 286 Car Dashboard PCB Instrument Panel Bulb & Holder 286T T5 12v 1.2w B8.5D | eBay

 

[Ian_Edwards]

Update:
I followed the VDO webshop link, and the total cost for 2 items, including VAT and delivery was a staggering € 37.20!

I found what appears exactly the same bulb holder at Classic Car LEDs Ltd - classiccarleds.co.uk for £3.20, for 4 bulb holders, including VAT and delivery.

I'm not exactly sure they will fit, but at £3.20, it's worth a go.

This must be one of the highest mark-up for the "Marine Tag" I've ever seen.

 

[Mistroma]

Update:
I followed the VDO webshop link, and the total cost for 2 items, including VAT and delivery was a staggering € 37.20!

I found what appears exactly the same bulb holder at Classic Car LEDs Ltd - classiccarleds.co.uk for £3.20, for 4 bulb holders, including VAT and delivery.

I'm not exactly sure they will fit, but at £3.20, it's worth a go.

This must be one of the highest mark-up for the "Marine Tag" I've ever seen.

That is stupidly expensive and really insulting to their customers. Clearly saying "we think you are really gullible".

The holders on my VDO looked exactly like the ones I used to have on cars many years ago. I really doubt they'd make one-off specials for such a common object. The ones in my eBay link looked identical to the ones in your picture and there were plenty of people selling them in a variety of pack sizes. I expect the Classic Car ones will be fine. Remember to post confirmation if they do fit as it might help someone else later.

It might be worth ordering some 12v 1.2w T5 red bulbs at the same time. They were dirt cheap when I bought them and I bought a box. I've given away more than I have used, many people I meet seem to have non-functional VDO tacho. lights. Prices seem to be higher now but postage might be free if you are adding a few to an existing order.

 

[Boater Sam]

1990s and 2000s Citroen and Peugeot instrument/speedo clusters are full of these bulb holders. Incidentally they are not LEDs but filament bulbs.

 

[Ian_Edwards]

Yes, I'll post an update when they arrive and whether they fit or not.
I'm quite confident they will, I had an email from Classic Cars confirming that they should fit.
What I found confusing when search on the web, was that there are a wide variety of holders which look much the same, and the T5 and T10 holders are easily confused when the websites don't publish any dimensions and the photographs are low resolution. Others have a slightly different style of locking mechanism for the twist lock system, this is especially true if your not quite sure of the detail of what you are looking for, i.e. no part number, and only a vague idea of the technical description..
I managed to damage the original holder, trying to fit a Red LED, which should have an operational life time of many thousands of hours, and should solve the problem of incandescent bulbs popping every 300hrs or so.
There is no back light for the LCD on these Tacho's light from the two instrument lights is "piped" to the LCD via two curved perspex light guide, so if the bulbs go out, you can't see the hours recorded by the tacho, but the LCD may well be working OK.

 

[Boater Sam]

Understood but are the LEDs 12v ones? Or do you need a ballast resistor? They are polarity conscious.

 

[Daverw]

My land rover dash has these, when a few failed a couple of years ago I took out the holder and soldered led with resister onto the small contact pads with led hot glued into the small hole, it’s worked with no issues for last 3 years

 

[Ian_Edwards]

Understood but are the LEDs 12v ones? Or do you need a ballast resistor? They are polarity conscious.

They are 12 volt, no need for external components, they just slot into the holders..
Classic Cars LED sell them and there are plenty available on ebay, you just have to make sure that they aren't too long, if they are. they'll interfere with the perspex light guides.
They are polarity sensitive, but if they don't work, just take them out and rotate by 180 degrees and refit, that effectively reveres the supply.

 

[vas]

if you go the LED route, will dimming dash lighting still work?
doubt it, just asking as I started the otherway round, just wanting to be able to dim the lighting for night passages - and slightly stuck with lack of powerful potentiometers and need to design a full circuit for it...

 

[Daverw]

we found it easier to have second light circuit to switch between as led light fittings don’t seem to have access to electronics to mod

 

[Ian_Edwards]

The bulb holder arrived from Classic Card LED, and they fit and work, so that's one part of the repair complete.
The Yanmar manual shows the power for the light connected to the power for the instrument in the vessel loom, so there's no ability to dim the instrument lights. That doesn't bother me, the instrument panel is low down next to the starboard wheel, it's also recessed behind a perspex screen, so it might illuminate my feet, but that's all.
I've alo successfully fitted a new LCD for the hours counter.
I'd now like to test and calibrate the tacho' I have a waveform generator, so I can feed it with appropriate pulses.
To enable me to do this I need details of the connections on the back of the tacho, and information on the number of pulses per rev I'll get from the alternator.
I don't have wiring diagram or and installation manual for the VDO tacho, and I've been unable to find one for the specific version I have:
VDO tachometer from 2007, part number 02 012 195, 12 volt version.
There are numerous installation guides and diagrams on the web for VDO tacho's, but I can find one for this version. Most of the diagrams I've seen show pin 8 as the input from the alternator, but in this version pin 8 isn't connected, there's not even a spade terminal soldered onto the PCB. Only pins 1 to 5 have spade terminals.
Al little bit of detective work, shows that pin 5 is ground and pin 1 powers the lights, but I currently have no idea what the other 3 pins do.
I emailed the VDO help centre last week requesting this info', but haven't received a reply, I don't know if this a Covid-19 effect or they are just not interested.
Has anyone got access to any connection information for a this Tacho?

 

[vas]

I'd now like to test and calibrate the tacho' I have a waveform generator, so I can feed it with appropriate pulses.
To enable me to do this I need details of the connections on the back of the tacho, and information on the number of pulses per rev I'll get from the alternator.
I don't have wiring diagram or and installation manual for the VDO tacho, and I've been unable to find one for the specific version I have:
VDO tachometer from 2007, part number 02 012 195, 12 volt version.
There are numerous installation guides and diagrams on the web for VDO tacho's, but I can find one for this version. Most of the diagrams I've seen show pin 8 as the input from the alternator, but in this version pin 8 isn't connected, there's not even a spade terminal soldered onto the PCB. Only pins 1 to 5 have spade terminals.
Al little bit of detective work, shows that pin 5 is ground and pin 1 powers the lights, but I currently have no idea what the other 3 pins do.
I emailed the VDO help centre last week requesting this info', but haven't received a reply, I don't know if this a Covid-19 effect or they are just not interested.
Has anyone got access to any connection information for a this Tacho?

VDO manuals and serials are a bit of a mess, took me way to long trying to find the right wiring diagram, never found it, just used common sense and figured out which one was the signal. Anyway only had GND, V+ and this other cable...
FWIW, the "right" manual was completely wrong.

assuming tacho was working before, I wonder why you want to calibrate it (other than not having anything else to do stuck at home )

V.

 

[Ian_Edwards]

I live in hope that I'll get sailing this year, getting the Tacho sorted,will be one less job to do when I eventually get work on and launch the boat. If I had access to the boat I'd simply plug it in, measure the diameters of the crankshaft and alternator pulleys, work out the ratios, then knowing than it's a 12 pole alternator, I'd be able to calibrate it.
When I started looking for the information, I assumed that VDO being a well known brand, it would be easy to find an installation manual or wiring diagram, they have sold a lot of these units and companies will have had wiring diagrams and installation manuals to enable them to be incorporated into their products.
As you rightly say, VDO's documentation is a mess, the documents which come up in Google searches, don't apply. It seems like the core of the Tacho is similar to several other instruments which have been sold into the marine and avionics industries, so I see lots of similarities. There also seem to be a succession of version, starting with pure analog, through microprocessors version, to more sophisticated version with multifunction displays, but no systematic catalogue of manuals.
I'll most like start to work back from the chips on the board, identifying pins from the chips specs' and then working back to the connector using a multimeter.
We're in lockdown, so I have time to do that, but it shouldn't be necessary.

 

[Ian_Edwards]

Update:
I've reverse engineered the PCB in the tacho to the extent that I've identified all the semiconductor and now have copies of the data sheets. This allowed me to trace back to the connectors on the back of the tacho and identify the function of each pin.

VDO tachometer pin connections
Part number 02 012 195
Pin Colour Function
1 Red/Black +12V for instrument lights
2 Red +12V for tacho
3 Black -12V ground for tacho electronics
4 Orange tacho input from alternator
5 Black -12V ground for lights

The wire colours are taken from the Yanmar circuit diagram, because I don't have access the the boat, so they should be checked.
The separate power and earth for the instrument lights and the tacho, provide the ability to dim the lights, however on the Yanmar 4JH4E these two circuits are in parallel in the wiring harness, so the instrument lights can't be dimmed without modifying the wiring harness.

The components on the board are:
LM 7805 a Standard 5 volt regulator, which takes 12 voltsr from pin 2 and is protected from reverse polarity by a diode in series
LM 2903 a dual comparator which is used to convert the signal from the alternator into a TTL logic signal.
A custom philips microprocessor, which I think is based on the 8XC51_8XC52 series, and probably has a custom mask. The processor has built in timers, which I guess are used to time the pulse from the alternator in some way. I can trace the timer inputs to the comparator, but don't understand much more than that. This chip is more than likely irreplaceable.
SN74AC240 an octal buffer, designed to drive memory chip.
PCF8582c_2 which is an EEPROM, a memory chip which I guess is used to store the engine hours.

I then built a test harness and powered it up, initially the instrument lights came on, but the LCD didn't power up. I'd already change the LCD, however with a little bit of checking and inspection it looked like the electrolytic capacitor in the voltage regulator circuit was faulty. I replaced the capacitor and the LCD now works and shows the engine hours.


The red LEDs were purchased from Classic Cars LED who also supplied the new lamp holder, no connection, just that they were very helpful and reasonably priced. The LED's takes just a few mamps, the original incandescents took 600 mamps.

I still have to calibrate the tacho, but I'm hoping that the guys from Electromaax in Canada will get back to me with the diameters of the crankshaft and alternator pulleys of the serpentine belt conversion which goes with the 140 amp alternator I installed. That will allow me to calculate the pulse per rev from the alternator and, with luck, calibrate the taco. But as they say, that's for another day.