Recapping WSR and MRA

[andylevine]

Finally getting around to re-capping the amplifier and selection receiver for my rookie 100B project.  Selection receiver went swimmingly and I'm carefully making my way through the amp. The amp was upgraded from the B amp to one from a C, an MRA3-L6.  Some day I'll make it correct, but for now this will do.  I bought recap kits from Vern Tisdale moons ago when I first bought the box.  
 
Question:  What do most people do with the big can capacitors, like the one on selection receiver between the relays, or the 3 on the MRA3??  Do you just wire in the tiny new ones underneath, leaving the can for the visual aesthetic?? Totally remove the can and wire the new tiny one one in the hole??  If you leave the can, do you do anything with the innards?  I'm sure many of you find exact replacements instead??

Any assistance appreciated, pictures welcome as well.

Thanks
Andy

[Ron Rich]

Hi Andy,
For my purposes, I just add the newer ones under the cans--just be 1000% sure they are all grounded to the same ground, buss bar.
I have heard of some people digging out the cans, but have never done so--
As for a MRA-3 or higher in a model B--it won't work right, unless you ground pin 3 on the mute plug socket--- Ron Rich

[robnyc]

I always remove the old components. Old cans often start to leak causing a rust streak down the front of the chassis. The only disused parts I sometimes leave are tube sockets after I rework the circuit to eliminate that specific tube.

"Re-stuffing" is IMO, ridiculous.

RobNYC

[andylevine]

Thanks for the advice... can always depend on straight up answers here. Great that there are those willing to share their valuable experience. Ron, I had read about MRA-3 and the B and the muting switch....sure enough, at one point whomever was maintaining this box for all those years did attach ground to pin 3..... but I found it flapping it in the wind! Will reattach when I get to that section of the recap.

[Ron Rich]

Hi Andy,
I have never caught an old can leaking, after it was removed from service--I always look for any signs of leakage, and remove any that show even a trace of it--then cover the hole with a plate, or screen. I think if I were to eliminate a tube socket, I would also cover that hole/socket ? Ron Rich

[robnyc]

Nov 29, 2017 12:53:19 GMT andylevine said:

Thanks for the advice... can always depend on straight up answers here. Great that there are those willing to share their valuable experience. Ron, I had read about MRA-3 and the B and the muting switch....sure enough, at one point whomever was maintaining this box for all those years did attach ground to pin 3..... but I found it flapping it in the wind! Will reattach when I get to that section of the recap.

I do not see the point of grounding pin 3 -outside of testing/experimenting.  Keeping the pin 3 grounded at all times fully enables the AGC but prevents the squelch voltage from being applied during scan & handling. This means that each record will start at full gain and, depending on what cart, stylus type and record loudness, some records will blast for a few seconds while the AGC voltage builds up and gets control.

You might as well just remove the SK7 and SL7. At least then you'll have consistent gain although with varying levels and possible distortion on "loud" records.

I bought one of the old 'upgrade" boxes that added AGC to the older Seeburg amps at the Philly show in 1989 and after rebuilding installed it on a "B" amp. Problem was, no extra contacts for the squelch. My solution was a small 5 volt relay with diode, 10mfd cap and resistor. The components allowed the use of the 6 vac heater supply to power the DC relay which whose coil was connected to the mute contacts.  The mute was now also operated via a separate set of contacts on the relay. It was placed inside the chassis of the amp.

RobNYC

[Ron Rich]

Rob,
Well, first of all,the model B mechanism had no "squelch" contact on it--It was part of the add-on kit. The add on's I have rebuilt had a new mute/squelch socket on them ? They work fine if directions/schematic for the later style, are followed. Ron Rich

[robnyc]

Well Ron, when one is fishing an ancient part out of a box of junk, it is kind of 'rude" to expect that the extra blades, two longer nuts and instructions will be included.

I did find the original instruction sheet in the reams of dumpster-bound items as Tenth Ave collapsed in the late 80's.

RobNYC

[Ron Rich]

Hi Rob,
Ifin one plans to sell it--I find it inconsiderate NOT to have all the parts needed to make the item work. I make up the extra two leaf switches and purchase the longer screws, if necessary--
I guess that's why I don't make a habit of "selling" partz--The only thing I sell on ePay ( and on his forum !) is the Seeburg SMC, Gen 2, Micro-computer replacement board I build and TEST-- Ron Rich

[andylevine]

Nov 29, 2017 23:01:11 GMT robnyc said:

Problem was, no extra contacts for the squelch. My solution was a small 5 volt relay with diode, 10mfd cap and resistor. The components allowed the use of the 6 vac heater supply to power the DC relay which whose coil was connected to the mute contact

Interesting, Rob....  I had read in Harold Hagens 'Dr. Know It All, Vol. 1'  a similar solution in which he used a 24VAC relay hooked in to the reject switch in the selection receiver.  He did this as it is only active when the record is playing. The relay then can be connected to pins 1&3 of the mute switch on the amp.  I had thought about doing this, but didn't like the idea of having to wire between the two units as there appears to be no simple way, short of drilling a hole through the side walls or just draping a wire over the edges of each unit. yuck. 

Have any pictures or additional specs of your solution?? Resistor size? Relay part number??  I'm a newbie at this and dont want to screw it up. 

Thanks
Andy