Diodes will give a different reading depending on the CURRENT supplied by the meter, and the knee curve charactoristics of the particular diode. (see mfr spec sheet). The resultant reading is a function of the diode. Jim McVey McVey Alltronix 327 Broadway Newburgh N.Y. 12550 Factory authorized service for over 20 major brands. 845 561 8383 ----- Original Message ----- From: "walter wood" <wwood_38478@xxxxxxxxx> To: <techassist@xxxxxxxxxxxxx> Sent: Friday, August 27, 2004 11:03 AM Subject: [TechAssist] Re: Diode testing > I've seen that happen in circuit, but never out of > circuit. > Maybe someone smarter than me can explain it. > Walter > --- Wayne Vanaman <Wayne@xxxxxxxxxxxxxxxxxxxxx> > wrote: > > > Wendsday I pull CR4401 pn 242907 from an RCA 169 > > chassis, and it > > measured -1.2 volts on the diode check setting > > with a fluke 77 series 3. > > Minus volts out of circuit on a > > diode? What the heck? Changed the battery in > > the meter, same thing. > > Changed the diode and the set worked. > > > > How the heck do you get minus volts? That means > > that > > there was some sort of capacitance/pn junction > > problem with that diode. > > > > Minus ohms. > > > > Wayne Vanaman > > Omega Electronics > > 6904 W Fairfield Dr > > Pensacola, Fl. 32506-3310 > > > > Wayne@xxxxxxxxxxxxxxxxxxxxx > > WWW.PensacolaTVRepair.Com > > > > 850-456-5995 voice > > 850-458-6369 fax > > > > > > ----- Original Message ----- > > From: "walter wood" <wwood_38478@xxxxxxxxx> > > To: <techassist@xxxxxxxxxxxxx> > > Sent: Thursday, August 26, 2004 9:24 PM > > Subject: [TechAssist] Re: Diode testing > > > > > > > It seems to depend on the meter, as to what the > > > diode check position will read. > > > I have a Micronta(inexpensive radio shack) that > > > reads 820 t0 840 consistantly on good diodes. > > > I have two Fluke meters, ond old (series 73) > > but > > > great, and an expensive Model 83 series three. > > > They both consistantly read 460 on the diode > > scale. > > > I think you diodes are leaky. > > > You have enough evidence that I would certainly > > > replace them. > > > Check the new ones out of circuit before > > installing > > > them, and if weird make a note of it. > > > There are some odd ball things out there. > > > i've got a large spiral notebook full of such > > > measurments. > > > ALWAYS, use the same meter though, for > > comparaison, > > > or note the results with the different ones. > > > Another thing I like to do is take resistance > > > measurements on key components, such as > > convergence > > > ic's, regulators, outputs etc. on common > > products, > > > on a set that is working correctly. > > > I note this, and it helps more often than not. > > > SAMS used to provide this. > > > HTH > > > Walter > > > --- Paul <dntwntv@xxxxxxxxxxxxx> wrote: > > > > > > > When checking diodes for leakage, what range > > on > > > > the ohm meter do you use and is there an > > > > acceptable amount? Sounds like electronics > > 101 > > > > but I have a couple of diodes that are flat > > case > > > > diodes mounted on a heat sink. They read 160 > > > > front to back on the diode check. No reading > > back > > > > to front. However they read 20k on the ohms > > > > scale. If heated this reading goes down to 2 > > or 3 > > > > K. I normally set my meter on 100k ohm for > > > > leakage. I thought they must be leaking. But > > > > wondered if there are some big diodes that > > test > > > > this way normally? Someone said that 10X the > > back > > > > to front was normal. These are in the > > secondary > > > > of a SMPS + & -- 25v to convergence amps. > > > > > > > > Paul > > > > > > > > Paul ,B > > > > Central TV&Video > > > > 911W Grand Ave > > > > Grover Beach Ca. > > > > (805)481-8084 > > > > > > > > > > > > > > > > > > -------------------------------------------------------------------------- > > --- > > > > Lost Password: > > > > http://www.tech-assist.org and select "Login > > > > Problems?". > > > > Email Archives: > > > > //www.freelists.org/archives/techassist/ > > > > > > > > > > > > > ===== > > > Walter Wood > > > Future Tech Home Center > > > 2786 Hwy. 43 N. > > > Lawrenceburg Tn. 38464 > > > 931-829-3337 > > > Fax 931-829-4044 > > > mailto:wwood_38478@xxxxxxxxx > > > > > > > > > -------------------------------------------------------------------------- > > --- > > > Lost Password: > > > http://www.tech-assist.org and select "Login > > Problems?". > > > Email Archives: > > > //www.freelists.org/archives/techassist/ > > > > > > > > > > -------------------------------------------------------------------------- --- > > Lost Password: > > http://www.tech-assist.org and select "Login > > Problems?". > > Email Archives: > > //www.freelists.org/archives/techassist/ > > > > > ===== > Walter Wood > Future Tech Home Center > 2786 Hwy. 43 N. > Lawrenceburg Tn. 38464 > 931-829-3337 > Fax 931-829-4044 > mailto:wwood_38478@xxxxxxxxx > > -------------------------------------------------------------------------- --- > Lost Password: > http://www.tech-assist.org and select "Login Problems?". > Email Archives: > //www.freelists.org/archives/techassist/ ----------------------------------------------------------------------------- Lost Password: http://www.tech-assist.org and select "Login Problems?". 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