Confused with capacitor color bands

Frequently asked questions on capacitor types, ratings, brands, use and abuse.
User avatar
dai h.
Solder Soldier
Information
Posts: 242
Joined: 24 Nov 2007, 18:42
Has thanked: 46 times
Been thanked: 12 times

Post by dai h. »

sounds about right.

re: the tolerances, (if you look to the right of the above pic at the caps with some silver bands (C7&C10--330pF and 470pF, respectively), at least one must be a tolerance band (i.e. silver = 10%), but there are two of them and I'm not sure which is which.

edit:

IIRC Mouser used to have some of these (tried looking for a datasheet but no luck). Unfortunately, I don't remember the maker, which makes it more difficult to look for a datasheet. Tech 21 Sansamp (the original) also had (one? two?) of those (47nF) I think around the same time as well (early 90s or so).

User avatar
Lucifer
Cap Cooler
Information
Posts: 671
Joined: 06 Apr 2011, 12:59
my favorite amplifier: Vyse BBQ Blue
Location: Dorset, UK
Has thanked: 89 times
Been thanked: 72 times

Post by Lucifer »

As per my previous post, black in the fourth band signifies 20% tolerance.

The fifth band is maximum working voltage: Red = 250v; Yellow = 400v, therefore, a GREY band would suggest 800v (grey = 8 in the normal colour scheme, therefore 8 x 100v = 800v).

Hope this helps.
”Sex is great - but you can’t beat the real thing !” - The Wanker’s Handbook

User avatar
dai h.
Solder Soldier
Information
Posts: 242
Joined: 24 Nov 2007, 18:42
Has thanked: 46 times
Been thanked: 12 times

Post by dai h. »

I seriously doubt those are 800V rating.

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

Sorry, but I insist in my option... those are old design caps so, the first band -yellow in this case- is NOT the first digit value: is just a temperature coefficient... then you have the first and second digit, then you have the multiplier factor and then you have the tolerance.
Attachments
CAP SLICE.jpg
CAP SLICE.jpg (46.87 KiB) Viewed 4738 times
CAP CHART.jpg
CAP CHART.jpg (55.39 KiB) Viewed 4738 times

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 985 times
Been thanked: 305 times

Post by Intripped »

In the Guv'nor
viewtopic.php?uid=12425&f=1&t=25590&start=0#p246578
There are some 5 bands caps like those and, if the schem is correct (does it come directly from the factory?) then the first 3 bands indicate the value.
Really confusing anyway.

User avatar
sinner
Old Solderhand
Information
Posts: 4709
Joined: 06 Nov 2008, 17:16
Location: ...no more
Has thanked: 1031 times
Been thanked: 908 times

Post by sinner »

Duckman wrote:Sorry, but I insist in my option... those are old design caps so, the first band -yellow in this case- is NOT the first digit value: is just a temperature coefficient... then you have the first and second digit, then you have the multiplier factor and then you have the tolerance.
Yeah, I've seen that method too but look

Example

Brown/black/red/silver/silver. If you take 3 first band as a value and another two for cap spec it will give you 1nF (as per factory schematic). Method described by you in this case isn't relevant

User avatar
dai h.
Solder Soldier
Information
Posts: 242
Joined: 24 Nov 2007, 18:42
Has thanked: 46 times
Been thanked: 12 times

Post by dai h. »

(I will repeat what I said previously)

for *old* caps, yes the chart can make sense, but for those (relatively) newer ones, no.

I mean look at the schematics:

(go down to around the middle, where you see "The 25th Anniversaries") :

http://www.drtube.com/en/library/schema ... ll-schemas

the values and temp. coefficient, voltage ratings you would get going by the old chart wouldn't make sense.

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

Then no :blackeye

User avatar
alex28m
Information
Posts: 5
Joined: 13 Feb 2016, 21:30
my favorite amplifier: JTM45
Completed builds: various commercial
Location: Pacific
Has thanked: 4 times
Been thanked: 4 times

Post by alex28m »

Hi,

The capacitors used by Marshall in their PCBs up until the late 90's were predecessors to CTC's CA-Series axial ceramic. They were used because they were mounted by insertion machines and were relatively cheap. The dielectric used was Ceramic NPO (Black-band) or Y5P (Silver-band) - light green body. The CA-Series example here is only a 50V DC rated part (this was the only electronic datasheet I could find on the Internet), there was a higher voltage rated part used that was about the size of a 1/4W metal film resistor like the old Philips MFR25; I can't recall that part number or details of.
I understand that the last supplier in the UK was Anglia Components Limited in Cambridgeshire - I don''t know if you can still get them.

Attached is an excerpt from the CTC CA-Series Datasheet that will help you decode the colour code used on the body.
Panasonic and Taiyo Yuden made similar products and were also used.

If you need to replace these capacitors, replace them with another good quality NPO ceramic (Y5P was used because it was cheaper and readily available), I can suggest AVX. If use an alternate capacitor dielectric, like MKP or MKT, you'll change the sound characteristics of the circuit. Quite some testing and listening went into the prototypes to get the "Marshall Sound" from the circuit.

Regards,

Alex.
Attachments
CTC CA-Series Axial Ceramic.png
Last edited by alex28m on 19 Jun 2016, 08:34, edited 2 times in total.

User avatar
alex28m
Information
Posts: 5
Joined: 13 Feb 2016, 21:30
my favorite amplifier: JTM45
Completed builds: various commercial
Location: Pacific
Has thanked: 4 times
Been thanked: 4 times

Post by alex28m »

Here's the Panasonic ECB Series part, also a 50V DC part too.
Attachments
Panasonic ECB Capacitor.pdf.png

User avatar
alex28m
Information
Posts: 5
Joined: 13 Feb 2016, 21:30
my favorite amplifier: JTM45
Completed builds: various commercial
Location: Pacific
Has thanked: 4 times
Been thanked: 4 times

Post by alex28m »

Following is the Panasonic datasheet for their leaded axial ceramic capacitors. You'll notice the dielectric varies depending on the capacitance - keep that in mind if you're wanting to keep your repairs true to the original sound of the amplifier's circuit.

The NPO types weren't always available in the larger values and you ended using one of the Y5* dielectric variants that were temperature dependent and became significantly microphonic as the capacitance got larger. Nonetheless, the ac transfer characteristics, and their non-linearity at small signal levels was often something you wanted to give a "characteristic sound" to a circuit.
(If you want to know more about capacitor sound, read Cyril Bateman's Capacitor Sound articles that appeared in Wireless World: I saw these have been published here:
https://linearaudio.nl/cyril-batemans-c ... d-articles

A lot of the film capacitor types give a "clean" sound or in the words of my old boss, "...those capacitors sound too bloody Hi-Fi and were not making any of that..." - the ceramics were used for good reason in most cases

Alex.
Attachments
Panasonic ECB leaded axial ceramics.pdf
(672.5 KiB) Downloaded 181 times

Post Reply