Hello All,
This is chassis 8Y02 from the late 50s. The ribbon speakers don't seem to do anything. I see that they're stapled to the cabinet and riveted together. What goes wrong with these and how can they be put back together if they are taken apart?
The blond finish seems to be cracking off and the poninters are both snapped off. Does anyone know where I could get a replacement pointer knob? How can the blond grain be put back on. It looks like it's some sort of exteremely thin contact paper.

Thanks,

Dave

Ribbon speakers are typically like ribbon microphones. There is a ribbon of aluminum suspended between the poles of a magnet. A very low impedance transformers secondary feeds them. They respond only to the very light, fresh, and airy tonal qualities found in music. If your hearing is poor at those registers, you won't know if the speakers are running. It is possible that if you wire them to some bass source, you may see them vibrate. I don't know if they are typically isolated from bass or not when in actual use. Their sole purpose is high treble, so I strongly suspect that they are not normally fed bass. If your hearing is fine and you have some really clean records, you will be delited with what you hear when you get them working.

Thomas

Dave: Those speakers are only there to reproduce the higher frequencies. I have a Zenith with these, also, and it can be hard to hear them. You can remove the staples and look at one to see how they are put together. I don't think that I would try to take them apart because it appears that they would be easily damaged. Did you check the circuit they are connected to for any problems? Mark from Kalamazoo.

Heeey Sir David:

Just happened to read over this and caught the all important model number of its being a ZENITH Y832 rpt Y832 set and realized what you and others were referring to is actually its set of ELECTROSTATIC tweeters that it utilizes...with no thin
"ribbon" to be found therein in its construction.
It will only be a single tweeter on the cheaper model numbers , or a tandem set is incorporated in the sets top front corners on the Deee-luxe models.

Should be a garish yellow-green fiberglass and resin cast housing less than an inch in thickness and upwards to 4 in square dimensions. The units active
reproducer element being a micro thin film of aluminized mylar that is on front and set away from two plates that serve as the counterpoise electrodes. The front plate being perforated to permit the forward passage of the created sound.

Checking the schematic you will see that the wiring to each speaker is routed back to to the 35C5 plate circuitry where a .01 ufd cap extracts the high P/P
voltage from that plate circuits audio . That signal feeds to the taunt flat mylar sheet of the speakers construction, while the other plates, that it is
electrostatically deflecting from, is connected to a tandem parallel pair consisting of a 39K current limiting resistor and a .01 ufd bypass condenser to complete the AC signal to ground path.

As far as hearing it working , that would almost require ones ear against a units front and the engaging of intermittent connection action to evaluate
while listening to a sound source. It only produces the very highest frequency ..tinny..vocally sibilant sound structures.

An easier evaluation might actually be to lift one of the slip on leads to the large main speaker and make a connection to an ~4 ohm wire wound dummy load with clip leads so that the plate O/P transformer is properly load terminated and having that 6 in woofer dead.

Then you turn up the volume and evaluate the tweeters functionality.
I have never found any outright bad , but sometimes marginally challenged by the contamination 0f the units via close use/presence of cigareeet or seegar smokes carbon particulates entering and creating flashover. Same goes for inroom coal heating system
users.

As far as the cabinet if it is the blonde (Slimed Oak) or brown (MY-Hog Annie) they use a nominal quality of solid wood on the front framework, but the sides and tops are merely pressed resin cardboard with a microthin photographed and applied faux grained finish.

My usual situation is to sell the job of a thin re-veneering of the tops and sides .Usually leaning towards a Red Oak or Black walnut veneer finish. SINCE..overall that unit is one FINE performaing radio with its Full RF stage and dual...rpt.. dual IF's on
AM band as well as the generous woofer and those mentioned electrostatics ading the crisp highs to its sound.

In a system circuitry evaluation, I have shunted the AVC line feed to the frontal RF ,IF stages to ground at the left side of the 2.2 Meg (R17) feed resistor. (Thus, letting those stages run at full unbridled gain)
A measurement of the created AVC on the other side of that same resistor has revealed upwards of -60Vdc created AVC voltage on a strong local stations...now that spread threshold has the capability to create one FABULOUS performing AVC action on those units.

Thassit
73's de Edd

I am kinda taging along with this thread as I was looking for the audio output transformer for this same Zenith. It is a little strange in that the primary is 220 ohms with a 3 ohm tap. Does anyone know where I might find one of these?
I thank you alot.
Larry

:Heeey Sir David:
:
:Just happened to read over this and caught the all important model number of its being a ZENITH Y832 rpt Y832 set and realized what you and others were referring to is actually its set of ELECTROSTATIC tweeters that it utilizes...with no thin
:"ribbon" to be found therein in its construction.
:It will only be a single tweeter on the cheaper model numbers , or a tandem set is incorporated in the sets top front corners on the Deee-luxe models.
:
:Should be a garish yellow-green fiberglass and resin cast housing less than an inch in thickness and upwards to 4 in square dimensions. The units active
:reproducer element being a micro thin film of aluminized mylar that is on front and set away from two plates that serve as the counterpoise electrodes. The front plate being perforated to permit the forward passage of the created sound.
:
:Checking the schematic you will see that the wiring to each speaker is routed back to to the 35C5 plate circuitry where a .01 ufd cap extracts the high P/P
:voltage from that plate circuits audio . That signal feeds to the taunt flat mylar sheet of the speakers construction, while the other plates, that it is
:electrostatically deflecting from, is connected to a tandem parallel pair consisting of a 39K current limiting resistor and a .01 ufd bypass condenser to complete the AC signal to ground path.
:
:As far as hearing it working , that would almost require ones ear against a units front and the engaging of intermittent connection action to evaluate
:while listening to a sound source. It only produces the very highest frequency ..tinny..vocally sibilant sound structures.
:
:An easier evaluation might actually be to lift one of the slip on leads to the large main speaker and make a connection to an ~4 ohm wire wound dummy load with clip leads so that the plate O/P transformer is properly load terminated and having that 6 in woofer dead.
:
:Then you turn up the volume and evaluate the tweeters functionality.
:I have never found any outright bad , but sometimes marginally challenged by the contamination 0f the units via close use/presence of cigareeet or seegar smokes carbon particulates entering and creating flashover. Same goes for inroom coal heating system
:users.
:
:As far as the cabinet if it is the blonde (Slimed Oak) or brown (MY-Hog Annie) they use a nominal quality of solid wood on the front framework, but the sides and tops are merely pressed resin cardboard with a microthin photographed and applied faux grained finish.
:
:My usual situation is to sell the job of a thin re-veneering of the tops and sides .Usually leaning towards a Red Oak or Black walnut veneer finish. SINCE..overall that unit is one FINE performaing radio with its Full RF stage and dual...rpt.. dual IF's on
:AM band as well as the generous woofer and those mentioned electrostatics ading the crisp highs to its sound.
:
:In a system circuitry evaluation, I have shunted the AVC line feed to the frontal RF ,IF stages to ground at the left side of the 2.2 Meg (R17) feed resistor. (Thus, letting those stages run at full unbridled gain)
:A measurement of the created AVC on the other side of that same resistor has revealed upwards of -60Vdc created AVC voltage on a strong local stations...now that spread threshold has the capability to create one FABULOUS performing AVC action on those units.
:
:Thassit
:73's de Edd

Well, first-us, in olden times the manufacturers typically would reference the troubleshooting of transformers like that to something that the field servicers would have available. That being an ohmmeter, realizing that Joe Techamus was not going to have a lab quality impedance bridge at hand for an analytical inductance reading. Old tech schematics oft provide AC impedance- Z ALONG with like DC ohmic values for ROUGH estimations by the ohmmeter crew / set.

And does this mean that the original output transformer is missing, or that the unit is present and you have not yet depleted the very last chance effort. That meaning the pulling out of your magnifier and the fine # 0000 Swedish tweezers and a surgical peeling away of the outer covering of the windings and the core waxed paper and seeking out the micro- break in the # 42 wire of the primary winding, either at its start or finish, or hopefully where the taps joining is made at the taps lead wire. Then a tinning of that lead and forming a micro loop of 1 strand of Cu wire from tinned and fluxed up ( Testing your visual accuity and technical acumen, here !)AC line cord wire, letting the loop form across the tinned wires lead for a repair. Or if the open is at a transformers lead wire, that makes it easy to wrap one lead of the "1 strand of cu wire from tinned and fluxed up AC line cord wire" and then take the other end of that same wire strand and form a micro loop and insert that tinned "errant
floating lead" from the transformer into the loop and then reflow solder that loops blob. Then do a final check for continuity and mechanically protect that repaired area !.

Should that not pan out, might as well locate yourself a much easier to find 2.5 K primary to 3.2 - 4 ohm secondary output transformer.

Then consult the accompanying thumbnails of tech referencing. It shows the first generation of that chassis and its variation in the end with the chassis at the far right. They were always using the 35C5 but the output Z swung between the 2.5K <---> 3.5 k range. The idea / utilizaton of the tapped transformer unit was two fold, the bean counters were able to cut manuf cost a bit in the DC power supply filtering of the unit in the following manner. Preclude the necessity of a separate filter choke in the B+ supply by using the "free" inductance that could be acquired by the tapping into of the audio output transformer. They initially evaluated the degree of hum attributable as coming from the power supply and selected the tapped portion such that the two out of phase inductive elements of the transformer will be minumizing / cancelling out each other , the net result, minumal power supply hum, yet with less electrolytic filtering on the side....minumally cheeeper manuf costs.( x 10,000 units). Your
situation now is to install the new transformer and evaluate the units performance in the respect as to there EVEN being any objectional adjunct PS hum when the units volume is turned down to minumum. Checking their situation , you can see that their two tranfo situations had a variance of 80 ufd input filtering in the two different cases, but secondary filtering of 60 or 40 ufd used. You can vary in the same manner in stepping up the electrolytics capacitive values IF there EVEN IS a quiescent hum problem.

Tech Referencing:
http://img510.imageshack.us/img510/3284/thawzenoptsfn8.jpg

The Red boxes show the changes for utilizing a common output transformer, along with the wiring changes as red buss lines.

GO for it, lets get that magnificent specimen of a radio up and running.

73's de Edd

Well, first-us, in olden times the manufacturers typically would reference the troubleshooting of transformers like that to something that the field servicers would have available. That being an ohmmeter, realizing that Joe Techamus was not going to have a lab quality impedance bridge at hand for an analytical inductance reading. Old tech schematics oft provide AC impedance- Z ALONG with like DC ohmic values for ROUGH estimations by the ohmmeter crew / set.

And does this mean that the original output transformer is missing, or that the unit is present and you have not yet depleted the very last chance effort. That meaning the pulling out of your magnifier and the fine # 0000 Swedish tweezers and a surgical peeling away of the outer covering of the windings and the core waxed paper and seeking out the micro- break in the # 42 wire of the primary winding, either at its start or finish, or hopefully where the taps joining is made at the taps lead wire. Then a tinning of that lead and forming a micro loop of 1 strand of Cu wire from tinned and fluxed up ( Testing your visual accuity and technical acumen, here !)AC line cord wire, letting the loop form across the tinned wires lead for a repair. Or if the open is at a transformers lead wire, that makes it easy to wrap one lead of the "1 strand of cu wire from tinned and fluxed up AC line cord wire" and then take the other end of that same wire strand and form a micro loop and insert that tinned "errant
floating lead" from the transformer into the loop and then reflow solder that loops blob. Then do a final check for continuity and mechanically protect that repaired area !.

Should that not pan out, might as well locate yourself a much easier to find 2.5 K primary to 3.2 - 4 ohm secondary output transformer.

Then consult the accompanying thumbnails of tech referencing. It shows the first generation of that chassis and its variation in the end with the chassis at the far right. They were always using the 35C5 but the output Z swung between the 2.5K <---> 3.5 k range. The idea / utilizaton of the tapped transformer unit was two fold, the bean counters were able to cut manuf cost a bit in the DC power supply filtering of the unit in the following manner. Preclude the necessity of a separate filter choke in the B+ supply by using the "free" inductance that could be acquired by the tapping into of the audio output transformer. They initially evaluated the degree of hum attributable as coming from the power supply and selected the tapped portion such that the two out of phase inductive elements of the transformer will be minumizing / cancelling out each other , the net result, minumal power supply hum, yet with less electrolytic filtering on the side....minumally cheeeper manuf costs.( x 10,000 units). Your
situation now is to install the new transformer and evaluate the units performance in the respect as to there EVEN being any objectional adjunct PS hum when the units volume is turned down to minumum. Checking their situation , you can see that their two tranfo situations had a variance of 80 ufd input filtering in the two different cases, but secondary filtering of 60 or 40 ufd used. You can vary in the same manner in stepping up the electrolytics capacitive values IF there EVEN IS a quiescent hum problem.

Tech Referencing:
http://img510.imageshack.us/img510/3284/thawzenoptsfn8.jpg

The Red boxes show the changes for utilizing a common output transformer, along with the wiring changes as red buss lines.

GO for it, lets get that magnificent specimen of a radio up and running.

73's de Edd