Radiobar Company of America 510 Schematic

Radiobar Company of America 510

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Product Information:
Model:510
Manufacturer:Radiobar Company of America
Description:w/ '46s

Schematic Pages

PNG: Page 1 Rider Manual Volume 4
PNG: Page 2 Rider Manual Volume 4

Schematics Content

Page 1:

Model 510 Without Rear Fuse and Cover 146 Power Tubes

Model 510 With Rear Fuse and Cover 59 Power Tubes

Page 2:

SERVICE DATA (All Models) All models have automatic volume control of the diode type, controlling the first detector as well as the high frequency amplifier tubes. This A.V.C. makes it impossible to service and rebalance without a meter of the type to be described. This meter will work on any make or type of A.V.C., provided care is used. It can not be damaged by improper connection of the leads.
PARTS RROUIRED ROR VACUUM TURE VOLT METER

USING VACUUM TUBE VOLT METER The cathode clip is connected to the cathodes of the tubes controlled by the A.V.C. The bass clip is connected to the A.V. bus in front of the isolating resistor.
Adjast rheostat shunt until meter shows full scale reading.
All balancing is done with maximum peak indicated by the meter swing toward O. Sensitivity of various receivers can be checked by the swing of meter from a kaowa station. Short Wave fading can be seen by tuning in the station with meter connected to set.
REBALANCING Do not rebalance a set until you are sure it requires it. 99 per cent of the sets do not need it. We do not find one case in one hundred that really should be rebalanced.
INTERMEDIATES Connect a 262 K.C. oscillator to the first detector grid (No. 57 tube next to the dial) leaving grid cap in place. Remove oscillator tube (No. 56). Ser dial at 100. Hook up vacuum tube volt meter as described and care fully adjust 6 varitor screws for maximum gain (minimum reading of meter). Don't flat top any stages. Have all shields in place. Keep volume control at lowest level.
CONDENSER GANG Set dial at 100 when gang is at maximum position and tighten dial set screws. Tune in a station (or use an oscillator) to a known frequency signal around 1400 K.C. Carefully adjust oscillator section of gang until frequency is correct on dial.
If the intermediates are balanced on 262 K.C., the dial will now track within 5 K.C. over the entire dial. Adjust first detector section for maximum gain and follow by adjusting band pass trimmers.
Don't bend any condenser plates unless absolutely necessary.
OVERLOADING - OR POOR QUALITY AT LOW VOLUME The chief cause of this trouble is too long an antenna. A powerful local station will cause the R.F. tubes to block. Check this by disconnecting the antenna on the station causing the trouble. If too close to a powerful station, installing a switch in the aerial circuit helps this. In rare cases the set seems to overload and the A.V.C. works too quickly on all stations.
Check the following:
Disconnect 5 meg. resistor from A.V.C. base a tie point. Have all tubes cold. Use high voltage, high resistance obmmeter capable of reading 25 megohms and test from ground to A.V.C. bass for leakage. After condensers have charged, no leakage should be shown. This must read around 100 megohms to ground If slight leakage is observed, disconnect bypass condensers from buss until defective one is found. Sometimes moisture is found on coil terminals. Scrape this clear.
NOISY OPERATION (Not Static) A defective 82 tube will cause a sharp 60 cycle R.F. pickup. This is most prominent on low frequency. Replace with a good tube.
In many cases it is found that the noise cannot be eliminated by servicing the receiver. Noise may enter over the light lines or via the antenna. The only way to check the source is to turn off one after another all electrical apparatus in the vicinity of the set. There is no freak or trick antenna that will eliminate natural static.
GENERAL All resistors, bypass condensers and filter units are marked. Voltages are shown at tube socket on diagram. 99 per cent of trouble in a chassis is caused by defective tubes, check them carefully.
ENT AUTOMATIC VOLUME CONTROL (10 tube models only). Adjust tuning dial to greatest noise level between stations with right hand trimmer switch turned to extreme left. Then close switch by turning trimmer to extreme right; adjust screw driver control just below point that eliminates all noise.