Grunow - Model 654 | Bias Cell Replacement w/ a Mini Solar Panel Cell

The receiver playing after recapping and replacing all out of tolerance resistors in addition to using a 1.0V Mini Solar Panel Cell to replace the old defective Bias Cell for the 6Q7G tube.
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New lead dress on both I.F. Transformers and tackling a few capacitors and resistors along the way.
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In the second episode, replacing a few capacitors and resistors before discovering the I.F. Transformers lead dress issue that needs to corrected.
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In the first episode, preparing to restore this beautiful Grunow (General Household Utilities Co.), Model 654, Chassis 6N from 1937. The cabinet is very unique being a Table Upright; looks like a mini console covering two bands, i.e., the BC (550-1750) kHz and SW (2000-7000) kHz. The I.F. Frequency is 465 kHz.
The schematic: Riders 8-19, 20.
The receiver tube complement:
6K7G - RF Amplifier
6A8G - 1st Detector/Oscillator
6K7G - I.F. Amplifier
6Q7G - 2nd Detector/A.V.C. & Audio Amplifier
6F6G - Power Output
80 - Full-Wave Rectifier
The playlist for the series:
studio.kzbin.infoP...
LC (Front-End) AM Broadcast Tester - One Chip AM Radio Circuit
studio.kzbin.infoZG_E...
Thanks for watching and subscribing to my channel on vintage radio repair and other related circuits.
#restoreoldradios

[@hestheMaster]

Never thought of doing that with a solar cell. You are darn clever Don.

[@RestoreOldRadios]

Thank you Steve. Kinda popped in my head when I was moving some Arduino… stuff around. Best, Don

[@matambale]

The solar cell solution is brilliant; bias looks rock-steady! I know how that feels - an absolutely pristine speaker that's not properly centered. You have to get to a point where you accept that it's not actually pristine, precisely because it's not centered.

[@RestoreOldRadios]

Thank you. Best, Don

[@tectalabyss]

Hello my friend. That's one cool work around for the Basis cell. Smart very Smart . As always I liked and shared. All my very best to you and yours.

[@RestoreOldRadios]

Many thanks Bobby. Happy July 4th! Best, Don

[@tectalabyss]

@@RestoreOldRadios You and yours also Don.

[@Radio478]

Your videos keeps us all going, thank you from England

[@RestoreOldRadios]

Thank you, I appreciate your kind words. Best, Don

[@bradnailer2440]

Great solution. I have a Rogers Majestic, that's been waiting for you to solve this problem. I think it has two 1 volt bias cells. Thank you, sir.

[@RestoreOldRadios]

Glad it helps out. I would love to hear back from you if and when you give this a try. Best, Don

[@josephmagedanz4070]

Interesting workarounds...thanks for sharing!

[@RestoreOldRadios]

You're welcome! Thanks for watching and reaching out. Best, Don

[@W1RMD]

Great looking mods! I never would have though to use a solar cell.

[@RestoreOldRadios]

Appreciate it Ryan. I know it’s not period correct, but serves its purpose. Best, Don

[@W1RMD]

@@RestoreOldRadios Take care and have a great 4th.

[@RestoreOldRadios]

@@W1RMD You too.

[@johnblystone8781]

Don. As you were explaining the problem with the speaker, I was wondering if lightly spraying both sides of the cone with water and adding some temporary shims would move the center the needed distance (perhaps 1/32" or so") after it was allowed to dry? Just a thought.

[@z95m]

I seem to remember a video where Don did that by spraying the cone with alcohol and it corrected the problem.

[@RestoreOldRadios]

You are correct. Best, Don

[@RestoreOldRadios]

Since the rub was so significant, I decided to remove the old cardboard gasket and detach the cone from the frame. I just posted the video. I’ll keep your recommendation in mind when the next one shows up. Thanks again. Best, Don