guze

Collins 26j-1 maintenance and mods
« on: December 24, 2013, 02:58:37 PM »
Hi, i just got a collins 26j-1(actually a metron, it's the same)
 
 I got the manual and it says everything about it. I have some questions

 - should i replace the eletrolityc can capacitors?
 - should i change the input from 600ohm to 150ohm? (table3)
 - wich kind of selector does it need for the attack/release constant modification? (table2)

 - Does anynone does the mods and calibration in europe?
 
 Thanks

http://www.mediafire.com/view/0z4lp0lq30zaz5h/26J-1.pdf  link for the manual


pucho812

Re: Collins 26j-1 maintenance and mods
« Reply #1 on: December 24, 2013, 07:23:57 PM »
nice has 6386 tubes those will be expensive to replace. JJ makes new ones and they are pretty good and much cheaper then NOS versions.

Recap the unit if necessary, Does it hum? is it not working? Multican caps are expensive, if you can get away with it space wise use regular electrolytics vs the multican, it will be more economical and will function the same. There was a good thread at one point that showed the finer points of how to reuse the same multican casing but replacing the insides with regular electrolytic caps.

I wouldn't worry to much about strapping it to run at 150Ω, most modern gear can interface with 600Ω no problem.

 for the selection switch on table 2 you will need a double pole 7 position switch, but I doubt you will find a 7 position switch, they usually come in 6, 12, and 24. So you can either use a 6 position switch and not have all 7 positions or you can get a 12 position and not fill up all 12 positions.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

guze

Re: Collins 26j-1 maintenance and mods
« Reply #2 on: December 24, 2013, 08:39:44 PM »
It is working everything(except the on/off lamp), so the tubes should be ok for now(no distortion, "clean" signal), the 6386 will be the only one dificult/expensive to replace, i'll keep my eye for a nos , otherwise i'll just buy a JJ sooner oro later, but not necessary for now.

 It doesn't hum and the noise levels look ok, but the eletrolitycs should be replaced, right?

 The multican really are expensive, but i don't mind keeping it more "original" , i can't seem to find any 60uf+60uf , can i use a higher value with no problem?

 I don't mind using a 6 position, i can "loose" a slower setting

 thanks


pucho812

Re: Collins 26j-1 maintenance and mods
« Reply #3 on: December 25, 2013, 05:27:25 AM »
It is working everything(except the on/off lamp), so the tubes should be ok for now(no distortion, "clean" signal), the 6386 will be the only one dificult/expensive to replace, i'll keep my eye for a nos , otherwise i'll just buy a JJ sooner oro later, but not necessary for now.

 It doesn't hum and the noise levels look ok, but the eletrolitycs should be replaced, right?

 The multican really are expensive, but i don't mind keeping it more "original" , i can't seem to find any 60uf+60uf , can i use a higher value with no problem?

 I don't mind using a 6 position, i can "loose" a slower setting

 thanks

Only recap if necessary such as hum, not getting the right levels in power, something not functioning properly. Good luck finding a multican cap with the valued you need, they are not as common but you may check antique electronic supply, they may have it. Otherwise I would gut the the shell and rebuild the inside with regular electrolytics. Remember a can cap is nothing more the more then one cap and the negative side of each cap ties to the case and the positive side of  the cap comes out to the pins.   Would be easy enough to rebuild one if needed.

As for 6386's your NOS tubes will cost more to buy one of them then a pair of new jjs. I have 2 stereo compressors that have 6386 tubes in them, The JJ's sound quite pleasing so NOS is not even a consideration.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

dandeurloo

Re: Collins 26j-1 maintenance and mods
« Reply #4 on: June 29, 2015, 11:11:56 AM »
I just picked one of these up in great condition.  It sounds really great. I will probably try and adjust the release times with the switch mod.  The release is really long stock. 
PROFESSIONAL CHASSIS AND FRONT PANELS FOR DIY PROJECTS: WWW.COLLECTIVECASES.COM

Dan Deurloo
www.collectivecases.com
www.risendrums.com

guze

Re: Collins 26j-1 maintenance and mods
« Reply #5 on: February 10, 2019, 02:16:07 PM »
Hello aggain

I already did the full service and att/rel mod, everything works great and i love it. Been using it a lot.

It has a 15k limit frequency response, but i think it's probably in the circuit(broadcast filters)

Can anyone check if it can have a "flat" freq response to 20k

Thanks


EmRR

Re: Collins 26j-1 maintenance and mods
« Reply #6 on: February 10, 2019, 04:05:28 PM »

It has a 15k limit frequency response, but i think it's probably in the circuit(broadcast filters)

Can anyone check if it can have a "flat" freq response to 20k


There are no 'filters' other than the transformers themselves.   You could remove the input transformer secondary Zobel and see if you like response better without it. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

guze

Re: Collins 26j-1 maintenance and mods
« Reply #7 on: February 10, 2019, 05:57:55 PM »
And wich cap and resistor would that be?

EmRR

Re: Collins 26j-1 maintenance and mods
« Reply #8 on: February 10, 2019, 06:32:57 PM »
C1 / R5.  It will probably produce a peaking response bump at some high frequency once removed. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

guze

Re: Collins 26j-1 maintenance and mods
« Reply #9 on: February 11, 2019, 06:20:37 AM »
I know that old sta level and gates where also 15k band limit

Will it probably get a resonant peak near 20k or a "gentle" one?
 


pucho812

Re: Collins 26j-1 maintenance and mods
« Reply #10 on: February 11, 2019, 07:34:45 PM »
Hello aggain

I already did the full service and att/rel mod, everything works great and i love it. Been using it a lot.

It has a 15k limit frequency response, but i think it's probably in the circuit(broadcast filters)

Can anyone check if it can have a "flat" freq response to 20k

Thanks

What mod is that. do you have any information on it?
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

guze

Re: Collins 26j-1 maintenance and mods
« Reply #11 on: February 12, 2019, 06:53:06 PM »
it's in the manual in the link on the 1st post

pucho812

Re: Collins 26j-1 maintenance and mods
« Reply #12 on: February 12, 2019, 06:57:53 PM »
it's in the manual in the link on the 1st post

I see. Have you considered replacing the resistor with a pot?
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

buildafriend

Re: Collins 26j-1 maintenance and mods
« Reply #13 on: February 12, 2019, 09:33:42 PM »
There are no 'filters' other than the transformers themselves.   You could remove the input transformer secondary Zobel and see if you like response better without it.

 that's an expensive set of parts to change..

that said - maybe the sowter replacements are full band

EmRR

Re: Collins 26j-1 maintenance and mods
« Reply #14 on: February 12, 2019, 10:33:59 PM »
that's an expensive set of parts to change..

that said - maybe the sowter replacements are full band

No sane person has ever considered roll-off in a 1950's amplifier at 15K to be a problem.   Possibly only one who wishes to destroy the intrinsic value of the device, both the desired effect and the resale value. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde