Repair Triplett 930PL Meter?

Here's some more info:

I opened the case and visually inspected the replaceable parts. There are two resistors that seem like they may be faulty. One especially is bulging at one end. The manual states only the resistance value of these resistors as 2.5 ohms and 25.12 ohms. It does not say what type they are or any other specification value. Any ideas on the type, power, % etc.? It looks like a pretty easy replacement using the existing leads, but I need to identify what parts to order.

A bulging resistor? That's a new one... Can you take pictures of the parts?

Some old meters require the battery to bias the AC rectifier. The original AVO 7 is this way. Pretty standard type VOM, but the AC voltage readings are wrong if no 1.5 volt battery is in place.

Mark Z.

Well ... maybe 'bulge' was a poor word choice. However, there does appear to be damage at one end of a resistor. Not sure if a binary will be allowed here, but I shrunk a picture down to 56K to show the damaged part.

I don't think that's the case here as the meter has been working fine without the batteries for quite a while now. I'm pretty sure there is a damaged resistor and am trying to post a photo here of same.

Here's a shot of the full meter back.

Looks a bit burnt, I'd say. As a guess, it's probably about 2-3 watts. Since it's likely to be fairly important as far as accuracy of the meter is concerned, the closer the better. Perhaps .1% if you can find them. For the wattage go with the highest that will fit in the meter (within reason, of course)

Richard, the resistors that you've mentioned are in the DC Current circuit; not even involved in the AC Voltmeter circuit. It's to be expected that a 40 year-old multimeter will have some inaccuracies due to inevitable changes in component values. If you don't have a good digital multimeter to measure the resistors, maybe you could borrow one from a friend or neighbor. The resistors (R1 through R6) and the rectifier in the AC Voltage circuit should be under scrutiny, especially the rectifier. Check the values of the resistors. If they are pretty close (they are 1% resistors), then the rectifier is the most likely suspect, and it might be difficult to find a direct replacement. I don't see the picture that you posted (this isn't a binaries group), but if you'll repost the image to a binaries group such as alt.binaries.schematics.electronic, I'm sure more people can see it. I used to work in a calibration lab that serviced Simpson, Triplett and Weston meters and multimeters. I don't remember specifically what the rectifier looks like, but it's possible that I might have one or two in my junque box that I can send if the resistors prove to be OK.

Cheers!!

Didn't get through on Supernews; here is an inline image as a test of binary filtering (cut and paste and decode with 'uudecode':

begin 700 test.jpg M_]C_X``02D9)1@`!`0$`8`!@``#_VP!#``,"`@,"`@,#`P,$`P,$!0@%!00$ M!0H'!P8(#`H,#`L*"PL-#A(0#0X1#@L+$!80$1,4%145#`\\7&!84&!(4%13_ MVP!#`0,$!`4$!0D%!0D4#0L-%!04%!04%!04%!04%!04%!04%!04%!04%!04 M%!04%!04%!04%!04%!04%!04%!04%!3_P``1"`#'`*4#`2(``A$!`Q$!_\\0` M&P`!``,!`0$!``````````````+C)#0V M0E)RDZ'P_]H`#`,!``(1`Q$`/P#5,``````````````````````````````` M`````````````````````````````````````````````````!'_`!"W35+& MP%DNY*)*Z*M4>V:G4(,GEIU9&E6BDD>BB,CT[D9"0!%7%C]UC, MG^&5G_A>`&:GMD9\\^+-3_):/_"#VR,^?%FI_DM'_`(0B$!D7NKCOA6?1/T`U M7^(0['XDO>V1GSXLU/\\`):/_``@]LC/GQ9J?Y+1_X0B$`]UCTSID++]?R3!OFZW[H:I,6DO052(42.IE3ZYQ. M_5V6]Q'R&OG:Z:=M-3&>(NMZ+#[99@_`4'_95!.Z%Q^)Q&+4*LVU9F4^4S53 M0>B-7I8K`86-.HIQ5UOLWMY30@``:`=0@``````````````````````(JXL? MNL9D_P`,K/\\`PO"51%7%C]UC,G^&5G_A>`&.P``PP^J8````76]%A]LLP?@* M#_LJ@I2+K>BP^V68/P%!_P!E4%DU?_?EU,Q7RO?PO/\\`OAWFA```T\\Z+```` M```````````````````15Q8_=8S)_AE9_P"%X2J/)5J3!K]*FTRIPH]1ILUE M^S^8[4^_G]&_>_I&.P#8GV3L(?!O'_`.EX/[0>R=A# MX-X__2\\']H/1CY[[/YA[^?T;][^D8["ZWHL/MEF#\\!0?]E4%L_9.PA\\&\\?\\` MZ7@_M#JK%Q/8^+^N]3;-M^TNNV=7X%2V(74;-VSF**O56(DJ/YUYM"$]B/3_:B2PVMVC:\\LE>E.E\\JZ MFOK66#27*UF=MT6]^V8"H?"QQS1UIMY6_=O0[.K\\"JC$WI]^[9S.4M6W=L7IKIKM5I[C` M'5@````Y]K(5JOR;;CM7-1W)%RLKDT-I$]HU55I+9.K23:DK-2-2)* MB/W'J.@``````````````'DA5:#49,^/$FQY4B`\\4:8TRZE:HSIMH=)MPB/5 M"C;=;7M/0]KB#]RB,P/6``````````````*5>E'Q/8_LG9-O;U-M_P!61([ MH5O

Hi Dave:

Unfortunately, BellSouth, in their infinite wisdom, is blocking the binary groups. Upon inspecting the meter, it's very clear that one resistor is damaged. What I initially described as a bulge seems to be a burned section at one end of the resistior. In the manual it's designated as R8 with a value of 2.5 ohms. The Triplett part number is listed as 15-2869. I thought itwould be relatively easy to locate such a replacement but that doesn't seem to be the case (plus I'm a

Along the lines you suggested re: what circuit is the resistor associated with, I looked at the schematic and R8 is part of the DC MA circuit. Resistors R1 through R6 all look OK. I'll try to borrow a multimeter in the next few days to check them more thoroughly and report back here.

Richard, the resistors in the DC Current ranges are 1% units at 1 watt or greater. The current shunts in multimerters are usually wirewound, so the resistor you found at Digikey will work fine. R8 is the current shunt for the 100ma range. Those part numbers in the manual are Triplett part numbers, and are meaningful only to Triplett (now owned and known as Jewell Instruments, LLC). If you need anything non-standard for your meter, you might try to find a service shop or cal lab that services Triplett instruments. They are likely to have those parts. Also, you could email Triplett at snipped-for-privacy@jewellinstruments.com and ask for a quote on the parts. The 630 is quite old, and some parts might not be available.

Cheers

Create a free account at