3
\$\begingroup\$

I'm new to StackExchange. I am trying to repair a Yamaha digital radio tuner model TX540 made in early 1990s. I don't have a schematic.

I have been desoldering components and checking them with a DMM or ESR meter (for the capacitors). There are a number of small resistors, all marked the same, that read OL on the DMM. Initially I thought the first one I checked was open, but another 3 are showing the same.

The resistors are only small and the colour banding is Brown Black Orange Grey Brown. I checked this on a dissecting microscope, although the grey band could be silver. If grey is correct, then that indicates a 10 GΩ resistor. That seems ridiculously large for a small resistor in a domestic radio tuner. I'm assuming the resistors are OK, but outside the range of my DMM which is a Brymen BM257. I have also checked with another DMM, with the same outcome.

I'd appreciate any thoughts anyone might have on this.

\$\endgroup\$
4
  • \$\begingroup\$ Have you replaced the battery on the meter? Is it ac powered? I've never heard of that brand...please give us a link to the manufacturer's datasheet for the meter. \$\endgroup\$ Commented Mar 13, 2019 at 0:27
  • \$\begingroup\$ @ElliotAlderson Brymen is a reputable brand, if not one of the top brands. They're the OEM that makes the meters sold under brands like Greenlee and Extech; they also sell direct to consumers in Asia and Oceania, I believe. \$\endgroup\$
    – Hearth
    Commented Mar 13, 2019 at 0:33
  • \$\begingroup\$ Could you be reading them backwards? (a common problem with 5-band 1% resistors). 180k seems more reasonable than 10Gig. \$\endgroup\$
    – glen_geek
    Commented Mar 13, 2019 at 0:40
  • \$\begingroup\$ radiomuseum.org/r/yamaha_natural_sound_amfm_stere_9.html \$\endgroup\$
    – jsotola
    Commented Mar 13, 2019 at 1:51

2 Answers 2

4
\$\begingroup\$

They're probably 10nF (103) axial lead tubular ceramic capacitors. 10% 100V I think would be the tolerance and voltage rating.

Certain Japanese companies (eg. Taiyo Yuden) made ceramic caps like that with color bands. For what it's worth the bodies tended to be light green or flesh color.

Here are a couple that I designed in, back in that era (1nF and 10nF):

enter image description here

Aside from the oddball color (the green is similar to some axial-lead inductors), they have a bit less of an hourglass figure compared to carbon film resistors.

\$\endgroup\$
6
  • 1
    \$\begingroup\$ Hi Spehro, I think you may be on the money here. The body is flesh coloured and it looks very much like the one circled on the right but with a brown band on bottom. I'll check on capacitor meter and confirm one way or another. They certainly look like resistors. Glenn \$\endgroup\$ Commented Mar 13, 2019 at 4:23
  • \$\begingroup\$ Sphero, assuming they are capacitors, are they polarised and if so which is the positive end? Glenn \$\endgroup\$ Commented Mar 13, 2019 at 4:26
  • \$\begingroup\$ @GlennEdwards 1 or 10 nF capacitors are usually not polarised. \$\endgroup\$
    – Uwe
    Commented Mar 13, 2019 at 11:15
  • \$\begingroup\$ No they are not polarized. \$\endgroup\$ Commented Mar 13, 2019 at 12:10
  • 1
    \$\begingroup\$ Hi Spehro, they are indeed capacitors. Some slightly outside tolerance so I shall replace. Many thanks. \$\endgroup\$ Commented Mar 13, 2019 at 22:24
1
\$\begingroup\$

If you are talking about axial lead tubular ceramic capacitors that look like resistors, I replaced the ones I damaged (on removing) on a Yamaha tuner with "typical" ceramic caps of similar value (brown bag types). No problems encountered.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.