OKI I661

[rdelius]

Bought on Ebay for $19.95. A copy of a german W28 set but the dial is based on a British one.I dont think I will be repairing this unless I get lucky and find parts The induction coil is fried, along with the dial cable.Not much luck with finding  working pre-war Japanese sets.
Robby

[LarryInMichigan]

Robby,

How were the induction coil and dial cable fried?  Did someone perhaps try to turn the phone into a lamp?  I would be curious to see the back side of the dial.  I have some British and Australian GPO dials, and it would be interesting to see how similar this one is.

Larry

[rdelius]

I think a lightning strike or a high voltage got it. Coil got hot enough to catch the paper covering on fire.Rec capsule ,capacitor and ringer coils are fine.Note the finger stop clamps to the number disc instead of the frame.Finger wheel is sheet brass plated nickel instead of heavy copper.Dial frame is steel instead of brass
Robby

[LarryInMichigan]

Thank you.  Aside from the interesting finger stop contraption, the dial does look alot like a British GPO.

I wouldn't suppose that Steve Hilsz has any spare Oki induction coils for sale.  It looks like the bakelite is in decent shape though, so some after some sanding and repainting of the metal, it should at least look good. Of course, if nobody's looking, you could slip a mini network into it   Are the transmitter and receiver good?

Larry

[rdelius]

Rec good, Tx has tabs that clip under the screws.If I wanted to use this set I would use a more modern tx capsule. No mini network for me in here.W28 parts not common here. Have plenty of the British dials and a couple of the Japanese copies in my stash. The threads an the Japanese dials are different, The number card holder is larger than the British one, even the later ones.
Robby

[GG]

Very interesting, good catch there! 

If the phone took a lightning strike, even at long range (miles down the wire from where the lightning struck), it would be more likely to show "explosive" damage rather than fire damage; for example the ringer capacitor might have blown out or the coil might have simply gotten an open. 

Fire damage is more likely from lower voltages than lightning, sustained over a longer period than a brief transient pulse.  One possibility is contact between the AC mains and the phone line.  This wouldn't blow the ringer capacitor.  It would result in a continuous ring, and when answered, the voltage would pass through the induction coil and could very well cause the wire to heat up enough to cause a fire.  In that case you would also see blackening and possibly some slight pitting or melting of the hookswitch contacts. 

There's a slim possibility, worth checking out, that the fried coil is actually good but what caused it to malfunction was loss of solder between one of the fine wires in the coil and one of the connecting lugs where it joins up with baseplate wiring; this as a result of the heat of the fire. 

Is it my imagination or do the dial pulse contacts appear to be darkened?  If the pulse contacts also showed signs of pitting or melting, but the off-normal contacts didn't, that would be consistent with the AC mains hypothesis, and no attempt to dial the phone during or after the abnormal voltage & fire. 

Rather than use a mini-network, you could go for the RC network, especially if it can be done from the terminal screws.  I'd suggest keeping the transmitter; that's a unique configuration and it probably sounds better than a cellphone. 

I have a postwar NEC of roughly similar style but all bakelite (the corners of the base resemble an SC 1243), in which the capacitor had blown in a manner that suggested it was leaking nasty chemicals: I replaced the capacitor with an ordinary electronic component capacitor (0.5 uF, 200 volts) and it works fine.

[dsk]

I'll guess about any German  induction coil will fit. The wiring diagrams for German phones has not changed much from 1928 to the 70ies.

If this is Japanese an original one would be more difficult to get. On the other hand about any induction coil should do the job.

I may have some W- 48 coils.

Are the ringer coils OK. (W28 used to have 2 coils of 300 ohms)

dsk

[rdelius]

The coil is charred,hopeless. The cable to the dial had 2 wires vaporise. The dial pulse assy metal has darkened, have not checked to see if it is still springy. I have replacement British and Japanese contact assys .I would use another coil if it fit, need to check my junk boxes.300 ohm ringer coils are good. No date codes on the parts on this set unlike my Fusi copy of a W28
Robby
Should post some photos of my Japanese "candlestick" soon.

[migette]

Nice find, sure these w28 lookalikes don't turn up that often. The bell coils look OK but may well be o/cct, as GG suggests the problem could well be on the solder tags. Had the same problem on a Galion where the coil was intermittent and checking the continuity while applying tip of soldering to each tag and commoning tags with solder to flux the old solder suddenly the meter flicks across and sorted. This does not always work but its worth trying as another make of coil probably will not fit or the threads different   sods law. The induction coil, no good, more scope here to fit one that goes in the space even if a bit of araldite is used, the connections complete trial and error. The principle the same with these to give a small sidetone and match the transmitter to line. Lastly the dial is based on the British slipping cam design which was superseded by the Trigger Dial which was brought in to prevent back dialing when used with a coin box to prevent free calls being obtained. Hope these notes may help good luck with your phone and let us know how you get on   Peter

[rdelius]

The induction coil got hot enough to burn the paper wrappings off. All other parts are good. The dial is a very close copy of a British one but parts such as screws and nuts have different threads.I have other Japanese sets with similar dials except my Fusi copy of a W28 has a copy of a German dial
Will post photos of my Japanese candlestick soon
Robby

[GG]

Pardon the brief digression but...

Migette, I never heard that the reason the trigger dial existed was to prevent people making free calls at payphones.  The version I've heard is that it was designed to be inherently more reliable than the slipping cam mechanism.  Where'd you hear that item about payphones?

Back to Rdelius' Japanese W28...

Dial wires vaporized (that suggests lightning), dial pulse contacts compromised, induction coil hot enough to catch the wrapping on fire... all's I can say is, that's a lot of stuff to restore; it will probably never be perfect, but it could be very acceptable.  When my refurb stack gets backed up I tend to get just a wee bit lazy and do the ones first that'll be easiest, just to make space on the bench. 

[migette]

Hi re slipping cam dials, I remember back in the early days when still in late teens and attending a course  by the GPO that all its apprentices attended (1960's) being given this info of the reason why the sc dial was superceded was to do with back dialing it and getting free calls from the old AB type call boxes.These boxes allowed calls to be made free to operator by dialing 100 or emergency 999 by an arrangement of axillary dial spring sets which only worked when 1 0 or 9 was dialled, thus allowing a call to be made without putting money in the box. If a call to the operator was made for a trunk call she could inform how much money was needed to be put in the box and this caused a bell to be struck in the box which the operator would hear and know if the correct money had been put in the box. Our bible at that time was a book by Atkinson as I remember in 2 vols......

Getting back to the dial, there was a way to get the other digits by either tapping the hs rest or winding the dial backwards to cause pulsing. Does anyone else know about this as it was a very long time ago.

I well remember one of the open days that the GPO put on where the public were allowed to visit the exchange (central office) and I showed a young lady around who wanted to know how the automatic system started and I told her about a certain undertaker who was losing trade to a competitor whose wife was an operator and diverting business to her husband. From tophats to the system we had today was through a certain gent from  Kansas A B  Srowger. Later that day I was accused of making it all up as a Cock and Bull story, fortunately my manager confirmed I had told a true story. Hope these anecdotes help   Peter