The Stovebolt.com Forums Home | FAQ | Forum | Swap Meet | Gallery | Tech Tips | Events | Features | Search | Hoo-Ya Shop
Big Thanks!

Big THANKS to

MONGO
for hosting
the weekend event.



Read all about it.


Stovebolt Site Search
'
Oh Lord, I just gotta find it....

A pdf guide to help you search the Site


Old Truck Calendars
Months of truck photos!
Nothing like an old truck calendar

Stovebolt Calendars

Check for details!


Who's Online Now
0 members (), 97 guests, and 3 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums60
Topics124,970
Posts1,008,598
Members45,105
Most Online1,229
Jan 21st, 2020
Image Posting Policy
Previous Thread
Next Thread
Print Thread
Page 2 of 2 1 2
Re: Gauge conversion
Tiny #1417061 Thu Jul 15 2021 02:34 PM
Joined: Mar 2010
Posts: 639
B
Curmudgeon
Well. since the forum wants to talk about Runtz, I'll bring this up. Some swear by the Runtz and some don't. Some get upset if you post negative against it. HandyAndy had two Runtz (absolutely not a clone) to fail. He was kind enough to send me one so I could investigate. In this order left to right in the picture. Capacitor, Diode, 3-pin Regulator and Capacitor. The design of the circuit is basic, not copyrighted and is used as an example in one of the manufacturer's spec sheets. The regulator chip had failed. The other components were good.

The 3-pin regulator is a Fairchild KA808R in a D-Pak configuration. All of the components are surface mount devices (basically, no leads). There is no heat sink for heat dissipation of the regulator chip. The circuit board had no evidence of burning or a burning smell of a component that had failed. Specs says the KA808R output is good for up to 1 amp at less than 15 watts. The circuit board was enclosed in a heat shrink tube (not watertight).

Four things that bugged me. One is, no heat sink (it can get hot inside an AD cab). Two, the Runtz is mounted on a threaded stud of the cluster gauge assembly. What would happen if the cowl vent was opened and you happened to come up on a rain storm? Would it fail if it got a little wet? Three, is 1 amp - 15 watts enough? Testing is required. And finally four, why use a 8 volt regulator when the system is 6 volts? The voltage drop across a diode is typically 0.6 volts.

Let the cat fight begin.

Attached Files
15.jpg (48.82 KB, 186 downloads)
Close-up.jpg (35.53 KB, 179 downloads)
Last edited by buoymaker; Thu Jul 15 2021 03:06 PM.
Re: Gauge conversion
Tiny #1417065 Thu Jul 15 2021 03:26 PM
Joined: Dec 2002
Posts: 4,241
Moderator - The Electrical Bay and Rocky Mountain Bolters
I bought my gauges from Bowtie Bits years ago.. already converted to 12 Volts.


Another quality post.


Real Trucks Rattle

HELP! The Paranoids are after me!
Re: Gauge conversion
Tiny #1417100 Thu Jul 15 2021 08:26 PM
Joined: Dec 2001
Posts: 15,562
'Bolter
Not sure about the cost anymore but D&M Restorations in Greenville S.C. has did several gauge projects for me over the years and they are still working to this day. Never one lick of problems and a couple are over 20 years, a couple of them just 5 years.
I'm just lucky they are only about 30 miles from my house.....


1937 Chevy Pickup [stovebolt.com]

1952 Chevy Panel [stovebolt.com]
52 Chevy Panel [photos.app.goo.gl]

Pictures in my Photobucket [s140.photobucket.com]

1950 Chevy Coupe
https://photos.websearch.com/share/...Nko1cUJCNFFMTVFEUnNRbjFhNTFPc1J4YWV4cmRB



I'd rather walk and carry a Chevy hub cap than ride in a Ferd.
I can explain it to you, but I can't understand it for you smile
Re: Gauge conversion
Tiny #1417110 Thu Jul 15 2021 09:03 PM
Joined: May 2005
Posts: 8,371
B
Sir Searchalot
I've joined in posts when members wanted to ask about Runtz. Examined how they are built and helped explain how they work and so on. That was because folks wanted to discuss Runtz. It's all in the search function.
Now we are discussing how they fail and all kinds of ways of reducing 12V to 6V. Worrying about the heat.
I try very hard to answer the question and stay with the poster.

Tiny, you specifically asked how to convert a gauge without using a resistor/reducer. You said you knew all about those components.
I did answer the question. You didn't want a reducer, you didn't want to buy a converted gauge, it seemed you wanted to know if others had converted their own.
Then you changed to saying you tried a Runtz, it failed and we are off to the races again.
Buoymaker said "Hey Guys".,,,,,,,trying to say what I'm saying now. Then he gave up and joined the crowd. If you have decided to use a reducer, and this goes for everyone else on these questions, why don't folks buy the $6 one from Classic Trucks? I would really like to know. This is a low tech issue. There is no worry about heat whatsoever. Everyone knows resistors create heat. Like the one on heater switches. If a rheostat is used, that is just a variable resistor. The one Classic sells for higher loads than a gas gauge has a heat sink.

Can we please stop talking about Runtz units and all the other clones. If the "reducer" at Classic trucks does not work, please advise. If it does work, buy it. Why would anyone want to build one for a gas gauge? The Classic one is probably an axial lead resistor, the others are solid state. Whatever. The Runtz style accuracy and built-in thermal overload is not needed. Spike protection is provide by direct wiring from battery and a fuse. Too much technical talk about a gas gauge.


Watch out for careful drivers!!!
I'm away on an ego trip. Will be back on Feb 30.
I'm not an Auto Mechanic, but I play one on TV.
I charge $0.02 for every opinion and I take Paypal.
Plan B is always better than plan A, by definition.
I used to think beer was bad for me, so I gave up thinking.
Sometimes no nonsense makes sense, in a sense.
You can't teach a new dog old tricks.
Honk if you're Amish


Re: Gauge conversion
Tiny #1417123 Thu Jul 15 2021 10:04 PM
Joined: Aug 2005
Posts: 9,360
Tiny Offline OP
Ex Hall Monitor
Bart, I don't understand. I mentioned the Runtz only in response to your post immediately above mine. You said they work, I said I tried one and it failed. Initially I did want a converted gauge because I didn't see a suitable alternative to the Runtz type resistor. I then thought about the buck converter I used on my heater and how one would probably work on the gas gauge so I mentioned that. Further consideration led me to think that using a buck would allow future restoration to stock if my son desires. How is that upsetting?


Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.
Re: Gauge conversion
Tiny #1417127 Thu Jul 15 2021 10:36 PM
Joined: May 2005
Posts: 8,371
B
Sir Searchalot
Tiny, you and I are friends. Don't want to injure that. Probably a mis interpretation by us both. As far as I can tell, you tried a Runtz before I posted. You did repeat that statement later on after I posted.

Regarding my statement, I see what you mean. Here is what I said:

"The Runtz or Runtz style or resistor does work".

I was trying to say that voltage reducers work. Any type a person wants to use. I was not saying that you can't get a bad one. The "resistor" method works and has worked for a 100 years. I don't know about the reliability of a Runtz brand. I don't know if the Classic one has good reliability. That's why I asked. But the concept works, that is what I meant. I got confused when we switched from converting a gauge...... to using a reducer so fast. Not upset. Just pointed that out. It was a major shift in the post in my view. Abandoning the convert question and then we concentrated on the Runtz brand and not the concept. Other types of reducers and etc. Whether a Runtz brand reducer is good or not, has been covered before. All manner of DIY and reducers have been covered before.
I was trying to explain that shift; and trying to separate several issues within the post. Not aimed at anyone. I understand you wanted to avoid the reducers because of bad vibes. The best remedy is not converting a gas gauge, it's using a reducer. Unless otherwise specified, I recommend the Classic Parts $6 job. Sorry for any remarks that seemed like disrespect.


Watch out for careful drivers!!!
I'm away on an ego trip. Will be back on Feb 30.
I'm not an Auto Mechanic, but I play one on TV.
I charge $0.02 for every opinion and I take Paypal.
Plan B is always better than plan A, by definition.
I used to think beer was bad for me, so I gave up thinking.
Sometimes no nonsense makes sense, in a sense.
You can't teach a new dog old tricks.
Honk if you're Amish


Re: Gauge conversion
Tiny #1417136 Thu Jul 15 2021 11:58 PM
Joined: Mar 2014
Posts: 2,525
J
'Bolter
I'll take the blame for mentioning the runtz thing. Honestly I brought it up because anytime somebody says they're interested in going from 12 volts to 6 volts, the runtz gets suggested and then a lot of people seem to step up and encourage the idea. In simple terms it isn't what I'd say is the best option. The failure rate for a product like that should be 1 in maybe 100,000 or 1 in 1,000,000...and it seems to me it is much greater.

What impresses me is simplicity, durability and as close as possible...a zero failure ratio. Same reason I would never suggest anybody purchase the Pertronix. Have you noticed? With the Pertronix failure is expected almost as much as if you had Charlie Manson pack your parachute.

When I get home, I'll study this and see if I can come up with another answer.


Jon

1952 1/2 ton with 1959 235
T5 with 3.07 rear end
Re: Gauge conversion
Tiny #1417142 Fri Jul 16 2021 12:47 AM
Joined: May 2005
Posts: 8,371
B
Sir Searchalot
Jon, you are not to blame for anything. There is no blame to give anyone.

In my opinion, the Runtz should be super reliable. It uses a purchased potted device used in aircraft, space, etc. They add a PC board for connection and solder it and sleeve it.
If the component is a National semiconductor or Texas Instrument or other well known maker, it should be super reliable. Many of these companies buy from China. Their parts would be spec certified and tested at production and retested at incoming.

The Runtz component could be a substandard non certified part. Those are available for non flight safety type, non critical type consumer products and cheaper priced. Now that Randy Runtz has passed away, I wonder if the family business is aware of the negative reputation that may be building and what they have to say. There are many complaints on the internet. There are possible other reasons: Electrostatic Discharge damage. EMF damage. If there really is a high failure rate, It can be anything from postal scanners to static in the air to Chinese dumping to low quantity buyers. Then of course user error. At any rate, it's easy to avoid this device. I feel sorry for the Family. It doesn't look like anyone is on top of this. Offering to replace with another bad part will actually kill the company faster. The only thing going for them is it's a household word for old vehicle conversions. Like Kleenex is to facial tissue, like coke is to beverage, like Jacuzzi is to hot tub..... The Runtz is a solid state voltage regulator. It must be properly grounded. This will provide ESD protection and is necessary for operation. The metal tab with a hole in it is a heat sink. The ground is a black wire.

I don't know if any of this applies but it's in our tip Section.

Also this is important Click [fifthaveinternetgarage.com]


Watch out for careful drivers!!!
I'm away on an ego trip. Will be back on Feb 30.
I'm not an Auto Mechanic, but I play one on TV.
I charge $0.02 for every opinion and I take Paypal.
Plan B is always better than plan A, by definition.
I used to think beer was bad for me, so I gave up thinking.
Sometimes no nonsense makes sense, in a sense.
You can't teach a new dog old tricks.
Honk if you're Amish


Re: Gauge conversion
Tiny #1417191 Fri Jul 16 2021 02:33 PM
Joined: Mar 2014
Posts: 2,525
J
'Bolter
What you and I and a few others here understand, Bart is anytime you "sacrifice" (for lack of a better word) 6 volts from 12 volts, it isn't as though you went to the grocer and selected 6 potatoes out of a display of 12 and just innocently purchased those. The 6 missing volts must basically be destroyed continuously whenever the circuit is made and that creates heat. Heat to many electronic components is instantly or rapidly fatal---depending almost entirely on the rating/quality of the component, how rapidly that heat builds up and how effectively it can be dissipated. In cases of poorly made discrete components or an incorrect application, the damage can be almost a guarantee...and that is what I expect is the root problem here. The runtz device (from my observation) seemed to have more than expected failures right from the start. Two years ago a neighbor reached out to me, complaining the ignition control module in his Ford had failed and kept failing no matter how many of them he installed. Turned out Ford had used an incorrect heat transfer material between the module and the heat sink. It formed a ridge of about 1.5mm, the newly designed module sat atop that ridge and unless you worked with acetone to remove that, the module could not dissipate heat fast enough to keep from burning itself out. As I said I'll give this some thought. Anyone who knows me already knows I would never connect my name to anything expected to fail. Look at the "alternate condenser." Months of study went into that...the selection of the capacitor, the German maker's corporate philosophy and history, the design and then after that several were sent to people to test and see if there were any reasons they didn't work so changes could be made. I imagine if (and I doubt I'll be around long enough) I sold 1000 of them that there would never be a single failure. It isn't something designed to be changed when points are changed and it was also designed to help keep points alive longer. I've mentioned the Vol-Ta-Drop. That was a very clever product. A single coil of special resistance wire divided into 2 lengths and put into a ceramic box. That's all it was. One length of the coil supplied voltage for the radio and the other length to other accessories. The company is gone now but back when I talked to them there had been no failures at all. They made the product for both 12 and 24 volts and converted into 6, 8 or 12 volts.

As I mentioned, simplicity, durability and a zero failure rate...and I don't see that in the Chinese condenser, the runtz device and some other things out there.

Our tip section needs attention, by the way.


Jon

1952 1/2 ton with 1959 235
T5 with 3.07 rear end
Re: Gauge conversion
Tiny #1417233 Sat Jul 17 2021 02:39 AM
Joined: Mar 2010
Posts: 639
B
Curmudgeon
Please let me point out something. The circuit board is professionally-made and uses surface mount components. A small business is not likely to have the equipment to make these. It is common practice for a engineer/designer to come up with a design on paper, make experimental models to "stress test" then farm out the final design to a company that has the capability to mass produce. During assembly, things can go wrong. Parts can be cracked, overheated and mispositioned for example. The parts purchased by the assembler may have defects. Now back to the small business. The first batch may work well and last a long time. Then a new batch made fails in a few months. This is when the tough part begins digging through what went wrong. Not unlike Takata Airbags. With the tragic personal loss, the small company may not be able to investigate...I really don't know. Also, these units are sold at low cost and probably little profit.

If you look at the picture of unit that failed unit, I don't seen anything obvious that looks damaged. The output of the regulator is not zero volts but a very low voltage which could mean one or more of the internal circuits of the chip have failed. These are my observations and opinions. What would help is for everyone that has a unit to fail, do a little checking and take pictures before throwing them in the trashcan. I would think the regulator chip can be removed and hand wire a new chip with a small heat sink. See what happens next.

Last edited by Rusty Rod; Fri Jul 30 2021 03:53 AM.
Page 2 of 2 1 2

Moderated by  Rusty Rod 

Link Copied to Clipboard
Home | FAQ | Forum | Swap Meet | Gallery | Tech Tips | Events | Features | Search | Hoo-Ya Shop
Powered by UBB.threads™ PHP Forum Software 7.7.4