: RCA Orthophonic Console SHF-5 need help  ( 701 )

thermofin

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RCA Orthophonic Console SHF-5 need help
« : March 29, 2021, 01:41:47 PM »
I recently bought an RCA Orthophonic console model SHF-5 that is in very good shape but needed to be refurbished. I recapped the amp and restored the changer but I'm having an issue getting the console to operate. There are 4 RCA jacks on the amp, Tuner, Phono, Tape and Stereo. The only jack that produces sound is the stereo jack that has no volume or tone control and the sound is approximately half volume or so. There is likely a simple solution but I have no idea what it would be. Any help diagnosing a fix would be appreciated. My skill level is limited!
I have swapped tubes but there is still a possibility the 6CG7 tubes may be questionable, but I'm fairly confident the 6V6 tubes are good. There are 2 - 470pF and a 220pF caps that have not been replaced.
Thanks

TC Chris

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RCA Orthophonic Console SHF-5 need help
« #1 : March 29, 2021, 06:24:43 PM »
I'm going to let people with RCA experience get into details, but some photos of the input jacks might help. 

Chris Campbell

Motorola Minion

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RCA Orthophonic Console SHF-5 need help
« #2 : March 29, 2021, 06:50:46 PM »
Ill pull a sams schematic and see if I can offer something. Still working on an SHF-1 for a customer, so maybe.
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Dave

thermofin

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RCA Orthophonic Console SHF-5 need help
« #3 : March 30, 2021, 06:56:45 AM »
I have the schematic but can't seem to attach a PDF or jpg. Any guidance on attaching docs?

Bill

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RCA Orthophonic Console SHF-5 need help
« #4 : March 30, 2021, 08:12:08 AM »
For some reason the attaching part of the forum is not working.  If you can copy and paste a link to your post/thread that seems to work ok. 

Bill

thermofin

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RCA Orthophonic Console SHF-5 need help
« #5 : March 30, 2021, 04:50:01 PM »

This is the first time I have shared a link so I hope this works.

This is for the Schematic:

https://docs.google.com/document/d/1JQa6O7r50nmJRzafzE99SCuEsGyUS-rGpQw20vrg4JU/edit?usp=sharing

This is the picture of the RCA jacks:

https://docs.google.com/document/d/1sJMr5PZ76MDQ9z382MNLGdYQVHkd62Ybwp4_7Dsd07A/edit?usp=sharing


TC Chris

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RCA Orthophonic Console SHF-5 need help
« #6 : March 30, 2021, 08:26:18 PM »
The phono and tuner inputs should work with volume control. The "stereo" input bypasses the preamp and volume control (I think). Those wafer switch diagrams make my head spin.  But if you used that input, it would explain why there was no volume control effect.  Try the tuner RCA jack or the other tuner jack (the two-pin one).

Chris Campbell

TJ

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RCA Orthophonic Console SHF-5 need help
« #7 : March 31, 2021, 06:37:45 AM »
My guess is that the stereo input was used for when there was an extension speaker and a second amp for stereo with a stereo input section.  But most inputs were not stereo so you needed a way to have the mono signal through both amps when those inputs were selected.  So mono inputs would would split a signal through the stereo input to have the audio coming out of both speakers, stereo inputs would leave the signal alone and the signal would just pass through. 

A lot of times the preamp was external so this was all done at the preamp, but since the preamp and the amp were one unit, they needed a way to combine the signal when needed. 
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thermofin

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RCA Orthophonic Console SHF-5 need help
« #8 : March 31, 2021, 11:39:41 AM »
I have read where the stereo jack was used for the purpose of adding in another component. I have connected the changer to the other 3 jacks - tuner, phono and tape but no sound except through the stereo jack.
The 2 pin is a power supply for an aux component. I guess it is for an AM/FM receiver. It will also power the changer.
I don't have the knowledge or equipment to trouble shoot various components, but maybe the problem could be more obvious to some of you.
I'll try any recommendations.

Thanks

TC Chris

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RCA Orthophonic Console SHF-5 need help
« #9 : March 31, 2021, 06:22:47 PM »
I have read where the stereo jack was used for the purpose of adding in another component. I have connected the changer to the other 3 jacks - tuner, phono and tape but no sound except through the stereo jack.

Look at the schematic--those three inputs are routed through the two halves of the first 6CG7 preamp tube, a dual triode.  If there is no sound through them, something is wrong in those two stages of the preamp.  Try wiggling the tube in its base.  No lick? Try touching a screwdriver to pins 2 and 7 (grids) to see if you get clicking or hum (be careful-- count accurately--pins 1 and 6 are the plates with 80V).  Or maybe check the voltages on the various pins as shown on the schematic.  If AOK, test the tube.

Let's wait and see if others have other ideas.

Chris Campbell

thermofin

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RCA Orthophonic Console SHF-5 need help
« #10 : April 07, 2021, 06:56:53 PM »
Chris, Sorry for the delay getting back. I was waiting for another set of 6CG7 tubes to test. I installed these tubes and no change so it doesn't appear to be a tube issue. I'm not very good with schematics but I will try the 2 and 7 pins and see what happens. Just to be sure, I'm connecting these 2 pins and should get a clicking  or hum? Any other suggestions since the tubes don't appear to be the issue?

Thanks,

Guy

TC Chris

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RCA Orthophonic Console SHF-5 need help
« #11 : April 07, 2021, 09:27:15 PM »
Chris, Sorry for the delay getting back. I was waiting for another set of 6CG7 tubes to test. I installed these tubes and no change so it doesn't appear to be a tube issue. I'm not very good with schematics but I will try the 2 and 7 pins and see what happens. Just to be sure, I'm connecting these 2 pins and should get a clicking  or hum? Any other suggestions since the tubes don't appear to be the issue?

No, DO NOT CONNECT THE PINS. Just touch a screwdriver to each one alone and see if you get a click or hum. 

Chris

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RCA Orthophonic Console SHF-5 need help
« #12 : April 08, 2021, 02:27:35 PM »
After you posted the schematic, I understood it was different than and SHC-4 I just picked up.

Chris recommends the screwdriver test to confirm an audio signal on the input grids pins 2 and 7 of the 6CG7s, which otherwise are at 0 volts so you can touch them to impart some stray AC to confirm its passing INTO that tube . If you measure pin 1 and pin 6 for plate DC, it should give a second clue after screw-driver hum test.

Looking at the schematic, stereo "input" goes via wafer to a sample of the speaker output, normally fed via RC network into pin 3 - cathode of V2, also used to possibly connect an amplified speaker? In other positions of the wafer switch, the tuner input which is not labeled on the schematic, is connected to that stereo "input"

RCA brochures are varied, covering certain "mark" levels of quality and hard to pin down, but may show the accessory intend for a model like yours.
Tubes - Magical - Tubes

Dave

thermofin

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RCA Orthophonic Console SHF-5 need help
« #13 : April 10, 2021, 03:45:20 PM »
I ran the test on pins 2 and 7 and got the hum on 7 but nothing on 2.

Below is a scan of a page in the instruction booklet for connecting to the stereo jack. I am under the impression that at the time tape decks were available for a stereo application but not for records.

https://docs.google.com/document/d/10RYf_FO2wdyLJytPlbAHOW2-OjtELvk_j_1lmIoVQSc/edit?usp=sharing

firedome

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RCA Orthophonic Console SHF-5 need help
« #14 : April 11, 2021, 02:01:25 PM »
Stereo tape decks preceded stereo RP carts by about 4-5 years so they were the only alternative at the time
 for serious HiFi buffs to enjoy 2-channel sound.
Happy Motoring! from Roger in NY