Simpson 260 Episode 2 Resistance is Futile
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- Опубликовано: 28 авг 2024
- There should be resistance, but there is not.
I know there are sources of precision wire-wound resistors, and I will see if I want to pay for them. But for my purposes, this meter now works perfectly.
Good job on the restoration of the Simpson 260👍
Love my 260. Buddy of mine got it at a yard sale and gave it to me.
I have not viewed "Episode 1", yet can offer a couple thoughts as I watch this one:
- There is no such thing as a "Simpson 260 schematic". The 260 has been produced for a LONG time in quite a few versions, or 'Series'. There are significant variations in the circuits of the various series, and Simpson's drafting department was often not clear about which series a particular schematic goes with, and this can be very confusing.
- I my own experience restoring various 260's, including the original/earliest version, I found MANY mistakes on the Simpson schematics. I know that within each Series/version Simpson made changes during the production runs, and my guess is that they also had versions of the schematics that would match all the variations, but I have never found a positive way to definitively match a Simpson schematic with a specific example of a 260; Simpson seems to have been less than professional in their documentation, otherwise they would have included serial number ranges or something on each schematic version/revision, or some equivalent scheme.
- I have seen Simpson 260 schematics that, for example, identify resistors in the M Ohms as the same value without the 'M', e.g. a 2.4M resistor would be shown as a 2.4 Ohm resistor on the schematic, and clearly that would be a mistake and not due to some incremental variation.
Hi,
Liked seeing this video very much. I too have “refurbished” a few analogue meters in past years. When I say “refurbished” I do so loosely. First of all I never had any standards equipment, so accuracy, or “factory accuracy” could not not be achieved on all ranges. Also, achieving resistor accuracy was often a time consuming effort. Having selected, and measured the value of several resistors to arrange in parallel, and/or series to make a specified value of one resistor never makes a decent looking job. For example, one of my AVO (model 8, mark 3) meters works exceptionally well, and its outward appearance looks virtually new, but internally it looks hideous with several resistors made up from loads of resistors that are both in parallel and series arrangement.
I own four AVO model 8, mark 3 analogue meters: they were once used in industrial factories by technicians, and engineers. That model of meter is often quoted on most British radio and television circuit diagrams as being the meter used to clarify amperes, voltages, and ohms - hence the brand name AVO.
All the best, Phil
Thanks, Phil. The idea of creating the exact resistance required seemed unreasonable to me, and not required. There are a couple of firms that make custom wire-wounds, but the cost is prohibitive.
@@fibberscloset498So if one wants to restore one of these it will be very expensive due to the cost of the precision resistors?
I have two 260 series five and they more than likely need repair. The price of those precision resistors is holding me back
I think that's accurate. You can have them made, but is it worth the cost? @@SDsailor7
@@fibberscloset498 Only if I could afford it.
Very interesting and informative video. Thank you very much.
Thanks, Phil. If I were doing any lab-standard work, I would invest in custom resistors. But, I work in the realm of +/- 20% and that’s close enough for me. Thanks for watching. Martin
Why is there heat shrink around the resistors?
Good question, and one I don't have a good answer for. It was obviously done for a reason, but I can't think of a good one.