It is currently Mon Mar 16, 2020 10:18 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 8 posts ] 
Author Message
Post subject: 1968 AB 165 Bassman pots
Posted: Thu Feb 24, 2011 2:47 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Feb 13, 2011 6:16 pm
Posts: 5
I'm having trouble finding the right replacement pot for the 2 volume controls.
can anyone point me in the right direction? I also want to replace the input and speaker jacks. Not sure which one is best suited for this amp.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: 1968 AB 165 Bassman pots
Posted: Thu Feb 24, 2011 6:43 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26415
Location: Tombstone Territory
Steve at Angela Instruments or Tom of The Parts Guru should be able to help you out.

You want CTS solid-shaft 1 meg audio taper pots and Switchcraft jacks (self-shorting for the inputs).

Best of luck, HTH

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: 1968 AB 165 Bassman pots
Posted: Tue Mar 15, 2011 2:10 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Feb 13, 2011 6:16 pm
Posts: 5
Thanks, Arjay. I.m glad to see you help me as I've seen some of your other replies. I have a real bad buzz. I tried cleaning the pots and jacks but it didn't help. I think I may have grounding issue. I can remove the cable from the input and touch the faceplate and it really gets unhappy. Any ideas?

Thanks,
Jeff


Top
Profile
Post subject: Re: 1968 AB 165 Bassman pots
Posted: Tue Mar 15, 2011 2:35 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26415
Location: Tombstone Territory
Has the amp ever had the filter and biasing caps replaced?

If not, I recommend that they are -- as soon as possible. One symptom of aging-and-deteriorating caps is audible uncontrollable buzz. If allowed to progress, a dying cap often shorts to ground resulting in catastrophic (and expensive-to-repair) mayhem.

There are many how-to articles posted on the web about changing caps and other marginal components -- if you understand electronics and are familiar with tube-amp architecture you can easily perform the necessary "surgery" yourself. If not, I recommend you find a qualified amp tech locally and let him take a look-see to diagnose the exact problem(s). It's not altogether a rarity that these old amps need periodic servicing. But once repaired, they'll be good to go for a decade or more.

HTH

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: 1968 AB 165 Bassman pots
Posted: Thu Mar 31, 2011 5:50 am
Offline
Hobbyist
Hobbyist

Joined: Sun Feb 13, 2011 6:16 pm
Posts: 5
Thanks. I've found the caps and 2 of the filter caps are bad. One is mushrooming bad. Good call. I definitely appreciate the help. I'm having trouble finding a 50UF 50VDC cap to replace the bias cap at Angela. How much can I increase this cap. I see a 100UF 100VDC. The things I've read say not to increase more than 25% on the first number. I called and emailed Steve at Angela but haven't heard from him.

Jeff


Top
Profile
Post subject: Re: 1968 AB 165 Bassman pots
Posted: Thu Mar 31, 2011 9:40 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26415
Location: Tombstone Territory
A 100mfd/100VDC bias circuit cap should be fine. I had the same problem locating a 50/50 for my '67 Showman a while back and used an 100/100 instead without issue.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: 1968 AB 165 Bassman pots
Posted: Thu Apr 07, 2011 6:05 am
Offline
Hobbyist
Hobbyist

Joined: Sun Feb 13, 2011 6:16 pm
Posts: 5
Okay, I replaced all the filter caps and the bias cap on top. Now I have what seems to be about 20% of the volume and it sounds like I have a distortion pedal hooked up. Maybe I had the distortion sound before and couldn't hear it over the buzz, I'm not sure. There is a small quick buzz when I turn it on. Maybe a second long or so. I'm positive I soldered everything back correctly. I'm an AV installer so I'm familiar with soldering and paid careful attention to + and - leads. I'm afraid I'm gonna have to take it to the amp guy but I'd thought I'd lean on you a little more if you don't mind. I don't know if matters but the 100/100 cap I used for the bias cap was a smaller size than the 50/50 that came out of it. I figured the size wasn't as important as the capacitance. Any ideas?

Jeff


Top
Profile
Post subject: Re: 1968 AB 165 Bassman pots
Posted: Thu Apr 07, 2011 10:22 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26415
Location: Tombstone Territory
Many components today are physically smaller than their vintage counterparts, despite having equivalent specs. I doubt that the bias cap is your issue. It might be time to consult a pro on this one.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: