• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Bell Pacemaker 2221b recap

oldman55

oldman55

Well-Known Member
Not much to do on this unit as most caps are ceramic and don't believe they ever go bad.
The first cap on the PS is a 40uf off of a 6CA4 rectifier. I don't know the limits on the tube and was going to put a 47uf in the old paper cap along with a 22uf (spec 20uf).
Rectifier has 360vac and schematic shows 150ma off of cathode.
Also, any suggestions on improvements that can be done to this old thing?
Thanks
Oldman
 
Last edited:
Register to hide this ad
Now that I have stuffed all the ecaps in the power supply, all that are left in the unit, including coupling, are ceramic disc. Surely some good polypropylene film caps would make a sonic difference.
Since space is so limited and the caps are difficult to get to, I would prefer to leave them if that were not the case. Anybody have experience with ceramic coupling caps?
 
oldman55 said:
View attachment 1502765
View attachment 1502766
Click to expand...
I've never seen ceramic coupled stages. Are you sure they are ceramic coupled? What are the two transformers either side of the filter cap for.... are those the output transformers? It is a nice clean layout, sure is tightly packed. I'm sure someone with more knowledge will answer about the ceramics and any improvements changing to a different type. It's just that I've never seen them used to couple audio stages.
 
Yep, those are the OPTs. Never had a 6V6 either.
Think the op coupling caps are .1 uf. If I do change out to film caps I was wondering if I should go ahead and tweak the values while I'm at it if there is a better one.
Obviously, my first choice is to leave them alone but this unit is planned to be sound compared against a much later model (and better built) 7189 amp.
My money will not be on this Bell regardless.
 
Electrically ceramic caps tend to hold up a long time, I just don't personally think they sound good. There are assorted technical reasons about why they're not very good too.
 
I think max input cap on the 6ca4 is 50uf so 47 will be fine. You’d likely extend the tubes life by sticking to 33 or 40, if you can get one. Switching from ceramic to film would be a good improvement, but I would stick to the values that are in there. Do you have a schematic? Maybe post it if you do, someone smarter than me can see if bigger coupling caps would be beneficial.
Other improvements. Maybe check for out of tolerance resistors. Check voltages. Line voltage is much higher than it was when that thing was new, if you keep the heaters within spec you’d make all the tubes last longer also.
 
RUmad said:
Do you have a schematic? Maybe post it if you do, someone smarter than me can see if bigger coupling caps would be beneficial.
Click to expand...

Cannot upload high enough resolution through AK (anyone know how to do so?) so here is a link to schematic:
https://www.dropbox.com/sh/l27ww4pi5464sea/AADaBIqoepxIE8UjEpC9EDMEa?dl=0

As far as sound quality, I have wagered someone who thinks that in a blind test that this unit will outperform a Sansui AU 70 (which I havent even started yet). Procrastinating.
spaghetti.jpg
 
Last edited:
oldman55 said:
Cannot upload high enough resolution through AK (anyone know how to do so?) so here is a link to schematic:
https://www.dropbox.com/sh/l27ww4pi5464sea/AADaBIqoepxIE8UjEpC9EDMEa?dl=0

As far as sound quality, I have wagered someone who thinks that in a blind test that this unit will outperform a Sansui AU 70 (which I havent even started yet). Procrastinating.
View attachment 1503078
Click to expand...
Hmmmm. maybe the work force that wired up your Bell, migrated to Japan and worked for Sansui?
I noticed that my Bell Carillon 6060, like yours, also has wiring that looks like "an explosion at the Spaghetti factory". Probably why i have not rebuilt it to this day. Although, i had bought the unit when i was very inexperienced and probably was unsure about what to change out with it.
 
I have a Bell/TRW 2440 integrated (a couple of years newer than your model) that originally had ceramic disk 0.02uf (labeled 20000mmf) coupling caps on the 7189 output tubes. It had a very faint red plating going on with one tube on the left channel. I almost couldn't see the red plating, except in a dark room.

Changing out the coupling cap with a new one fixed it - so I replaced all 4 caps on both channels, with Sprague orange drops in this case. Point is - the ceramic disks can go bad and leak.
 
primosounds said:
Hmmmm. Probably why i have not rebuilt it to this day. Although, i had bought the unit when i was very inexperienced and probably was unsure about what to change out with it.
Click to expand...
I'm still inexperienced and thought that I was ready to take it on. The PS caps were an easy drill-out and stuff. Coupling caps are on the pins with mainly no leads. Labelled .01HD So guess I will have to order some .01uf as there are 12 of them.
caps on pins.jpg
 
oldman55 said:
I'm still inexperienced and thought that I was ready to take it on. The PS caps were an easy drill-out and stuff. Coupling caps are on the pins with mainly no leads. Labelled .01HD So guess I will have to order some .01uf as there are 12 of them.
Click to expand...
Working on my 6060 is not an issue just motivation. I have Altec 19 speakers which only require a 5 watt SE amp to drive me from the room. I suppose i should release the Bell back into the wild.
 
oldman55 said:
Cannot upload high enough resolution through AK (anyone know how to do so?) so here is a link to schematic:
https://www.dropbox.com/sh/l27ww4pi5464sea/AADaBIqoepxIE8UjEpC9EDMEa?dl=0

As far as sound quality, I have wagered someone who thinks that in a blind test that this unit will outperform a Sansui AU 70 (which I havent even started yet). Procrastinating.
View attachment 1503078
Click to expand...

Yea, ha!! Looks like Sansui in that pic. Still, that Bell is almost as dense. I had one of those Bell’s in my hand last week - but I didn’t pull the trigger because after I looked inside . . . It was so dense.
 
Some equipment is just unbelievably dense inside. The Japanese stuff seems to be right up there with "bowl of spaghetti" as the design model used. or maybe "bowl of ramen" is more appropriate.
 
I should never have gotten into this deal but it may make the Sansui seem easy. Voltages not right, hope new rectifier remedies (original test OK, just a little low on emissions).
 
I have had this particular amp since I was a teen. No major problems - just replaced tubes and electrolytic capacitors as needed. Pre-amp is surprisingly quiet, I have used it to convert vinyl to CD's through my PC. Sounds great through a pair of Realistic Nova 15 speakers. Less maintenance than my Sherwood S-9900.
 
You must log in or register to reply here.
Back
Top Bottom