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RE: Eico HF-32 PEC Loudness Circuit

38.65.76.96

In Reply to: RE: Eico HF-32 PEC Loudness Circuit posted by strijw426 on March 25, 2015 at 13:42:06

Chip;

The loudness circuit you referenced does have some interesting data associated with it. However, I still wish to learn the internal values of the old parts for posterity and to help others in restoring one of these in the future. I am updating the schematic data in the service manual *.pdf file I have on the unit.

I have seen many volume controls with a single loudness tap, but this one is new to me since it has two taps. I may have to find another person with the same model and access to ohm meter and capacitance meter to check the internal parts values. I do not actually have an EICO HF-32 at this time to examine myself, otherwise I would have done so and measured the components without requesting assistance.

I am a member of the Fun With Tubes group on Yahoo, and they have some excellent data on practical tone control circuits.

Thanks for the reference and I have added that to my files.

Joe

Follow Ups:

RE: Eico HF-32 PEC Loudness Circuit - DAK 12:31:36 03/26/15 (2)
Hi Joe, I have a couple of hf32 I will check my units about what you need to know and get back to you. AFAIK, the treble and bass control PEC are the same for all of the EICO units. If you need to know the value of that PEC let me know and I can give you that info. cheers, Dak
- RE: Eico HF-32 PEC Loudness Circuit - strijw426 14:48:32 03/26/15 (1)
  DAK;
  
  It is not the treble and bass tone control PEC that is in question. I already have the information for the internal parts on it. The one I am inquiring about is shown on the schematic as PC2, and connects to the volume control, not the tone controls. The odd thing is that although it appears in the service manual on the schematic page, it is not shown in the parts list, but PC1 (the tone controls PEC) is listed along with its part number. It is almost as though the company did not want to acknowledge that the amplifier even had one in it or failed to completely document the product.
  
  I suspect that PC2 is a custom part manufactured for EICO by Centralab, Sprague or another company. Any alpha-numeric characters on the part would be good information to have. Please measure the internal resistor(s) in PC2 (ohmmeter) I would appreciate at least that much information. To do so you will have to disconnect its leads from the volume control. To measure any internal capacitor(s) you would have to have a capacitance meter.
  
  Another possibility is that EICO may have produced some HF-32 amplifiers that had discrete parts for the loudness circuit instead of the PC2. If so those parts and their values would be the ones I am looking for.
  
  Joe
  - External Measurements - Triode_Kingdom 15:48:50 03/26/15 (0)
    "Please measure the internal resistor(s) in PC2 (ohmmeter) I would appreciate at least that much information. To do so you will have to disconnect its leads from the volume control. To measure any internal capacitor(s) you would have to have a capacitance meter."
    
    That's likely to be a total waste of time. Even one series or parallel RC in the package will probably render results meaningless.
    --------------------------
    Buy Chinese. Bury freedom.

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