Rheem Roberts Reel to Reel Model 1725 Restoration

[jcrubin]

While visiting my mother I came across her tape recorder that she got when she was in high school and decided that I would restore it as a side project.  The challenge will be that I will have no tools or test equipment with me, I will only be able to order parts and steal what I can from my brother to do the job.

     The project will start with a complete disassembly and inspection.  There is many years of dust and the unit is a maze to disassemble.  Joining to assist in the project is my mother to provide commentary as well as Mason and Sadie to help with quality control.

     Inspection shows which caps will need to be swapped from the unit, an order goes our as soon as possible, also I bought some QD contact cleaner and lube from home depot.  All of the pots and switches get treated.  Silver polish was used to clean the headphone jacks.

    Each tube will be removed and carefully cleaned.  Then the chassis will have the dust removed, finally the tube sockets and tube contacts get cleaned with contact cleaner.  Date codes bring this recorder to around 1966.

     The mechanical portion of the recorder is cleaned and then completely re-lubricated.  Sadie inspects everything and determines my work to be satisfactory.  In the mean time, an empty reel, and a 'blank MP3'  arrives for mason to inspect, also new rubber real holders were ordered.

     All of the outer components were cleaned to remove grime, that includes the metal and tolex.  It came out surprisingly nice.  Mason approved.

      The capacitor swap was much fun with a tiny hobby radio shack soldering iron, but I got by.  eventually all of the old caps were replaced, albeit, slowly.  With that Assembly started in the reverse ensuring not to damage anything with the metal clips.   Also the tape heads were serviced.

     Smoke test was good for about 2 minutes until the 2uf cap exploded.   It is non polarized........   I put the old one back in and will have to replace it.  I know the old one will not last long.

     With the rest of reassembly done, testing begins with some simple recording.  Also the tape will be played through so that it can be tensioned.

     Finally the big demo presentation is done as the tape is moved into the living room on the shelf reserved for this unit.

[ciccio]

     Smoke test was good for about 2 minutes until the 2uf cap exploded.   It is non polarized........   I put the old one back in and will have to replace it.  I know the old one will not last long.

 

The old 2 uF capacitor is a film type, used to drive the motor (it actually creates a second phase from the single phase mains ac) and have it rotate in the correct direction.
You cannot replace it with an electoliythic capacitor, even with a non polarized one. When 60 Hz ac current will flow in it it wiil smoke or explode or go into flames...
You must search for a correct replacement, but I think the old one wiil work.. They last for a lifetime.
Best regards

[Richard Crowley]

It is safe to assume that any capacitor attached to or connected to a mains-powered AC motor must be a mains-rated, non-polar cap.  You are lucky your electrolytic failure wasn't more dramatic and traumatic.

You (or your mom) are extraordinarily lucky that all the rubber parts of the transport are still in working order. Many machines even newer than that vintage have rubber parts that have hardened, softened, turned to goo, or simply crumbled away.  There is a cottage industry of guys rebuilding rubber parts (typically pinch rollers) for R2R tape restorations.

[Richard Crowley]

The ideal way to leave a tape "packed" for good longevity is not to unwind slowly and rewind rapidly. It is rather the opposite.  It is the "play-speed" wind that leaves a nice, evenly-tensioned, and physically leveled "tape pack".  That is why many pro tapes are stored "tails-out".  Where you put the reel on the "take-up" side, first rewind it, and then play it so that the slow play-speed packs the tape back on the reel nice and even.

[james_s]

I don't think I've ever had one of those small motor run capacitors fail, why did you decide to replace it?

[jcrubin]

Because it failed.   I have the correct cap and will be replacing it next month.  It was leaking out the bottom and getting hot.

James?  Wow long time...

[james_s]

Oh, well yeah, leaking is certainly a good sign that it's bad

There are two types of capacitors I'd look at here. One would be an oil filled motor run capacitor, and the other a dry film capacitor. 2uF is about the point where the price is probably similar for either one.

[jcrubin]

I have a 2uf film rated to 630v