Calbest help

sorenj07 · 11th December 2006, 03:37 AM

the can-shaped things are most likely capacitors, and the circled things look like wirewound resistors.

whitelabrat · 11th December 2006, 03:39 AM

Ok. I'm about to reveal how much of a noob I am. I'm a bit stumped by a couple parts on my Calbest tube amp, but I don't know what they are. Any ideas? My multimeter just gave up the ghost (and it was new!) so I put an order for a new one from Mouser. I'm hoping to bring this old girl up to speed, but I'll have to do some reverse engineering. Can't find schematics for this one.

Big photos! Yikes! Scroll down to the Calbest.

http://mysite.verizon.net/oldamps/

whitelabrat · 11th December 2006, 01:28 PM

Resistors. Interesting. Thanks for the post!

Once I get a working multimeter I'll have to measure the values and hunt down replacements.

And yes I'll have to discharge those big caps too using a 20K 5w wire wound resistor.

whitelabrat · 27th February 2007, 07:18 PM

Can anyone confirm the rating on this cap? My guess puts it at 4.2uF 400V +-20%

Svein_B · 27th February 2007, 08:23 PM

My guess would be 470 Kohm resistor. 5%.

(colors are a bit difficult to see, so it could be 4.7 M, but that would not be a likely value)

Svein.

frank754 · 27th February 2007, 08:33 PM

It's an old tubular paper capacitor, probably should replace these guys, being so old, but sometimes they are still OK.
Opinion wise, some say "replace these immediately", very undependable due to age.

For your question though, the color codes are exactly the same as resisitors.

470K pf, which would make it a .47 uF

The 4th band (black) would make it 20% tolerance (orange is 30%, silver is 10%)

And the last band, yellow, would make it rated at 400VDC

As for your pic, reverse it 180 degrees, so that the last (separated yellow band) is at the right, then you can look at it from left to right.

SY · 27th February 2007, 08:34 PM

No, that's a cap. 47 are the significant figures, but I can't make out the multiplier number. Very, very unlikely to be 4u7, but 0u47 or 0u047 are entirely possible.

frank754 · 27th February 2007, 08:41 PM

Thie third band also looks yellow to me, so I would stick with .47 20% 400vdc
I don't think these went up to over 1uF

whitelabrat · 1st March 2007, 05:16 PM

Thanks much. I've ordered a replacement part. I suppose I can verify the value with a multimeter that measures capacitance. That probably a very high voltage spot so care will be taken!

I've just picked up a quartet of EL84's too. Now I have to figure out how to set the bias. There are two pots that look like they're for the job. I just need to figure out how to take measurements.

I'm looking to do a lot of modification to this amp. For now just making this oldie safe and sound is my goal. There is just about zero information about this Calbest out there, so if anyone out there has one, please let me know!

whitelabrat · 5th March 2007, 02:21 AM

Took a closer look and the band that appeared to be yellow is in fact orange.

The multimeter says about 31nF

11th December 2006, 03:39 AM	#2
whitelabrat diyAudio Member Join Date: Dec 2006 Location: Maryland	Calbest help Ok. I'm about to reveal how much of a noob I am. I'm a bit stumped by a couple parts on my Calbest tube amp, but I don't know what they are. Any ideas? My multimeter just gave up the ghost (and it was new!) so I put an order for a new one from Mouser. I'm hoping to bring this old girl up to speed, but I'll have to do some reverse engineering. Can't find schematics for this one. Big photos! Yikes! Scroll down to the Calbest. http://mysite.verizon.net/oldamps/

27th February 2007, 08:34 PM	#7
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	No, that's a cap. 47 are the significant figures, but I can't make out the multiplier number. Very, very unlikely to be 4u7, but 0u47 or 0u047 are entirely possible. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

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11th December 2006, 03:37 AM	#1
sorenj07 diyAudio Member Join Date: May 2006	the can-shaped things are most likely capacitors, and the circled things look like wirewound resistors.

11th December 2006, 01:28 PM	#3
whitelabrat diyAudio Member Join Date: Dec 2006 Location: Maryland	Resistors. Interesting. Thanks for the post! Once I get a working multimeter I'll have to measure the values and hunt down replacements. And yes I'll have to discharge those big caps too using a 20K 5w wire wound resistor.

27th February 2007, 08:23 PM	#5
Svein_B diyAudio Member Join Date: Oct 2005	My guess would be 470 Kohm resistor. 5%. (colors are a bit difficult to see, so it could be 4.7 M, but that would not be a likely value) Svein.

27th February 2007, 08:33 PM	#6
frank754 diyAudio Member Join Date: Jan 2007	It's an old tubular paper capacitor, probably should replace these guys, being so old, but sometimes they are still OK. Opinion wise, some say "replace these immediately", very undependable due to age. For your question though, the color codes are exactly the same as resisitors. 470K pf, which would make it a .47 uF The 4th band (black) would make it 20% tolerance (orange is 30%, silver is 10%) And the last band, yellow, would make it rated at 400VDC As for your pic, reverse it 180 degrees, so that the last (separated yellow band) is at the right, then you can look at it from left to right.

27th February 2007, 08:41 PM	#8
frank754 diyAudio Member Join Date: Jan 2007	Thie third band also looks yellow to me, so I would stick with .47 20% 400vdc I don't think these went up to over 1uF

1st March 2007, 05:16 PM	#9
whitelabrat diyAudio Member Join Date: Dec 2006 Location: Maryland	Thanks much. I've ordered a replacement part. I suppose I can verify the value with a multimeter that measures capacitance. That probably a very high voltage spot so care will be taken! I've just picked up a quartet of EL84's too. Now I have to figure out how to set the bias. There are two pots that look like they're for the job. I just need to figure out how to take measurements. I'm looking to do a lot of modification to this amp. For now just making this oldie safe and sound is my goal. There is just about zero information about this Calbest out there, so if anyone out there has one, please let me know!

5th March 2007, 02:21 AM	#10
whitelabrat diyAudio Member Join Date: Dec 2006 Location: Maryland	Took a closer look and the band that appeared to be yellow is in fact orange. The multimeter says about 31nF

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