| Author | Message | ||
     whunter Experienced User Username: whunter Post Number: 6 Registered: 10-2003 |
Hello Everyone Here is a simple diode test DIY. Statments: It is not possible to test diodes in circuit; diodes must be isolated from the circuit to be tested. The most basic description of a diode: a one way electrical valve. Here is a simple test procedure I use: Two alligator clip jumper wires, a crayon, a permanent marker, a note pad and pen, a small plastic or rubber mat, a five amp Maxi fuse, a car battery and a test light are needed. Take all diodes and mark one terminal on each with the crayon. You may want to number mark each diode also. #1. Connect one jumper to battery ground and connect the other end to one leg of a 5 amp Maxi fuse. #2. Connect the test light clip to the other leg of Maxi fuse. #3. Connect the other jumper to battery +12 terminal and the other end to the selected diode on the crayon marked end, lay the connected diode on the plastic or rubber mat. #4. Touch the probe end of test light to the unconnected end of diode, if it lights, make a note, if it does not light, make a note. #5. Remove jumper wire from crayon end of diode and attach to unmarked end of diode, lay the connected diode on the plastic or rubber mat. #6. Touch the probe end of test light to the unconnected end of diode, if it lights, make a note, if it does not light, make a note. Diagnostic chart for this test:  "Bad diode" Light comes on with diode attached in both directions. "Bad diode" No Light with diode attached in either direction.  "Good diode" Light with diode attached in only one direction. _________________ whunter RROC, Lake Michigan, Motor and Ohio region. ASE Master Mechanic Bloomfield Eurotech 45671 Woodward Avenue Pontiac, MI 48341 Work Phone 248-334-6400 Fax 248-334-2363 asemastermechanic@juno.com | ||
| Richard Treacy Prolific User Username: richard_treacy Post Number: 65 Registered: 4-2003 |
Diodes cost only a few cents each, so don't even bother testing them. Just replace them and see if the problem is solved I suggest. | ||
| whunter Experienced User Username: whunter Post Number: 9 Registered: 10-2003 |
Hello Richard Who is your supplier? Last month I purchased one diode from RR&B dealer $2.48 USD. The next time you replace all of your diodes I would be happy to have them. I have tried radioshack, they have changed stock, now have only the smallest/lightest diodes. If anyone knows of an alternative diode, I would be most interested to hear from you! Until then; I plan to test diodes. whunter RROC, Lake Michigan, Motor and Ohio region. ASE Master Mechanic Bloomfield Eurotech 45671 Woodward Avenue Pontiac, MI 48341 Work Phone 248-334-6400 Fax 248-334-2363 asemastermechanic@juno.com | ||
| Richard Treacy Prolific User Username: richard_treacy Post Number: 66 Registered: 4-2003 |
Tandy / Radio Shack have now given up on small components altogether I believe. However, the major electrical wholesalers sell diodes still at maximum US30c as a service to their trade customers. For example, Distrelec in Zurich where I live, or George Brown in Canberra Australia sell them. 1N4001 - 1N4004 power diodes are a good un-heatsinked device. Just about any power diode will do the job, and for heavy duty a diode such as a DS17-044 will go fine with a heat sink. If you need some I'll post you some free of charge. The trouble is that they are so cheap that practically no retailer will bother to sell them, and for Crewe they are just a logistical nightmare, hence the price. RT. | ||
| William H. Trovinger II Prolific User Username: bill_trovinger Post Number: 39 Registered: 8-2003 |
W Hunter; Any electrical supplier that carries NTE. We have a couple in Milwaukee but I am sure there are a few in Detroit. If memory is right I paid about 80 or 90 cents each for them this summer. Regards, Bill | ||
| whunter Frequent User Username: whunter Post Number: 13 Registered: 10-2003 |
Hello "Richard Treacy and William H. Trovinger II", I would like to thank you for helping me on this problem. My plan is to contact suppliers Monday and locate/order 50 new diodes. At the cost you describe, it would be foolish to test them. Thank you. whunter RROC, Lake Michigan, Motor and Ohio region. ASE Master Mechanic Bloomfield Eurotech 45671 Woodward Avenue Pontiac, MI 48341 Work Phone 248-334-6400 Fax 248-334-2363 asemastermechanic@juno.com | ||
| Richard Treacy Prolific User Username: richard_treacy Post Number: 67 Registered: 4-2003 |
The other semiconductor which ages is the transistor in the coolant level amplifier. If you ever have the top roll / dashboard cover off (a much easier job than it sounds by the way), the amplifier is on a small card located at the middle top. Replacement is straightforward with a soldering iron. From memory it is an NPN transistor, and I used a BD139 power transistor with no heat sink. If by chance it was a PNP, a BD138 will do, but I am reasonably certain it is an NPN. These transistors are used prolifically in industry and cost about US$0.70. If your coolant level indicator is malfunctioning (always on or not operative alike) this is the fix, but a precautionary replacment of the transistor while the top roll is off for any reason will save you heartache some day. RT. | ||
| David Gore Moderator Username: david_gore Post Number: 133 Registered: 4-2003 |
Thanks Richard, I have this problem to attend to - coolant warning light does not come on when test button is used - replaced bulb last time dash was out and then presumed header tank sensor was faulty so postponed tear down until coolant was due for replacement. Now I have to take the fascia off again - no problem as I will go looking for relays at the same time and do some preventative replacement. WHunter, while you are talking to the components supplier; get a price on the 12V MES [minature edison screw] bulbs used to illuminate the switch box and wiper switch - these will be many orders of magnitude less than the Crewe Spares price. Also, if you have customers complaining about the dim panel lights in Shadows; replace the standard 2W push-in bulbs with 5W bulbs; you will be able to see the needles at night!!! | ||
| whunter Frequent User Username: whunter Post Number: 17 Registered: 10-2003 |
Ouch, to late on this, got them from CREWE, found them the next week at Lionel train hobby shop $0.020 each. RE: price on the 12V MES [minature edison screw] bulbs used to illuminate the switch box and wiper switch - these will be many orders of magnitude less than the Crewe Spares price. Thank you. whunter Thank you, have customer complaint on this now. RE: dim panel lights in Shadows; replace the standard 2W push-in bulbs with 5W bulbs; you will be able to see the needles at night!!! | ||
| Richard Treacy Prolific User Username: richard_treacy Post Number: 68 Registered: 4-2003 |
Hallo there, Great news. It seems that my estimate of 30c was even too high by 50% ! (I assume they cost 20c each and not 2c as you stated). Now you see why I don't bother testing them in-situ. However my Fluke multimeter has a diode test function so I check the new ones first to be sure before soldering them in, and the old diodes also for interest after removal. Which diode type did you select (1N4001 etc) ? Actually it doesn't really matter which type as just about any power diode will do, and 13.8V doesn't stretch any type at all, but I am interested. RT. | ||
| Bob UK Unregistered guest Posted From: 172.185.217.126 |
When I was at University they used to buy semiconductors by the truck load and something like a 1N4001 would cost 10pence for a 100. For us students to play with and then throw away. There is an enormous profit made on electronics. the cost of the components in an ECU is very small compared to it,s selling price. My VCR cost £39.99 new A VCR has lots of semiconductors in it which the manufacturer brought at very low cost in bulk to sell the VCR at £40 | ||
| Bill Coburn Prolific User Username: bill_coburn Post Number: 67 Registered: 4-2003 |
David I have just gone through the preventative bit with the dash lights on the Spur. The three MES bulbs around the switch box were all out but I found the bottom two were simply loose in their sockets and the top one the feed wire was detached. Having paid AUD7.50 each for the replacement bulbs (which I didn't need) I got very excited to see MES bulbs for a nominal price in Dick Smith's. Closer examination revealed that they were 12 volt and not 14 (or 13.8 I think)volt and apparently wont do the job. For the record soldering the feed wire onto a terminal inserted through a plastic holder was an exercise in microsurgery. I finally succeeded by pushing the bottom terminal of the socket out of the plastic when it was hot, soldering the wire to it and refitting the assembly. Unorthodox but it works! And lastly after the session at Goulburn, Al Kinloch told me that he went and bought a fistfull of diodes and fitted them to the fuze box of his Shadow. He tells me the heater/air conditioning system is now working for the first time in twenty years! | ||
| David Gore Moderator Username: david_gore Post Number: 147 Registered: 4-2003 |
Bill, I have been using the Dick Smith MES bulbs for 4 years without any problems - don't forget these bulbs are the same rating as your other bulbs [eg stop/tail/markers] which is a nominal 12V. Good news re Alistair's experience - he was amazed when we ran the diode test using the multimeter on his car to find two failed diodes and 2 dodgy ones. Just don't forget JV's advice about finding unlisted diodes in the wiring harness as well as the published ones. | ||
| Bill Coburn Prolific User Username: bill_coburn Post Number: 71 Registered: 4-2003 |
Well on the dealer's advice I have not tried the local MES items but I will. Why does the factory use 13.8V bulbs??? | ||
| Bill Coburn Prolific User Username: bill_coburn Post Number: 72 Registered: 4-2003 |
Well on the dealer's advice I have not tried the local MES items but I will. Why does the factory use 13.8V bulbs??? | ||
| Richard Treacy Prolific User Username: richard_treacy Post Number: 73 Registered: 4-2003 |
Bill, Don't hesitate with MES bulbs. Afterall, the worst they can do is fail. All automotive "12V" bulbs are in fact rated for at least 13.8V. 13.8V is the normal operating voltage of any nominally "12V" lead-acid battery. On charge, 14.5 is common. | ||
| Bill Coburn Prolific User Username: bill_coburn Post Number: 75 Registered: 4-2003 |
I had better beef up the fire extinguisher. Seriously someone ought to sic the Consumer mob onto these people. The other little racket appears to be the short 10 amp fuses used in Shadows. The items from the Factory are clearly made by HM on a Sunday judging by their price. The local 10 amp item is cheaper than confetti - but a fuze - how do I know etc? | ||
| William H. Trovinger II Grand Master Username: bill_trovinger Post Number: 120 Registered: 8-2003 |
OK; Trying to convert all my dash lamps to LED as they are brighter and run cooler than standard bulbs. On the MES have located source for E10 Miniature screw base and wondering if these look correct, really do not want to open the dash to check them out in advance. Will try and upload picture of them. Thanks, Bill  | ||
| David Gore Moderator Username: david_gore Post Number: 266 Registered: 4-2003 |
Hi Bill, could you please give us the dimensions of the bulb as they cannot be read from the picture however at first glance they should be suitable - only thing to be checked is the height of the LED above the bulb holder - this needs to be the same or less than that of the MES bulb. Another point to consider is the sideways dispersion of light from the LED - this needs to be as high as possible for gauge illumination whereas it doesn't matter for warning lights. | ||
| William H. Trovinger II Grand Master Username: bill_trovinger Post Number: 122 Registered: 8-2003 |
David; Will try emailing you better copy of the drawing. Thanks, Bill |
