: RCA SHF-1 original RP205 C 1  ( 602 )

Motorola Minion

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RCA SHF-1 original RP205 C 1
« : April 04, 2020, 07:36:42 PM »
Is there any information on this site about converting the mono tonearm in this unit to accept a stereo cart? I has a mono-wired metal tonearm

 I am told is the original type with removable head that used with the moving coil cart that WE will not be using. I plan to try a stereo cart like the one in my 1964 RCA, airplane stylus type ceramic.

I'm still working on the electronics in this huge console. Most of the 5% resistors are now 10% >:(, and I need to place another cap order too!
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Dave

TJ

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Re: RCA SHF-1 original RP205 C 1
« #1 : April 08, 2020, 11:14:50 AM »
Do you have any pictures of the underside of the tonearm? If it has the half-inch screw mount, that opens you up to quite a few replacement cartridges. You will need to wire the replacement cart for Mono output and you may have to get replacement wiring so that it has the correct ends for the cartridge.
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electra225

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Re: RCA SHF-1 original RP205 C 1
« #2 : April 08, 2020, 07:04:18 PM »
Gary Stork at VM Enthusiasts is the go-to guy for everything that has to do with a record player.  Tone arm pressure might be more for a mono cartridge than for a stereo, so that might be a consideration.
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Motorola Minion

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Re: RCA SHF-1 original RP205 C 1
« #3 : April 09, 2020, 11:38:12 AM »
Do you have any pictures of the underside of the tonearm? If it has the half-inch screw mount, that opens you up to quite a few replacement cartridges. You will need to wire the replacement cart for Mono output and you may have to get replacement wiring so that it has the correct ends for the cartridge.

It is the 1/2 inch mount. Ill get a pic but I figure if I run a separate ground wire, stereo carts of several kinds are possible. My main concern is finding a cart that has an output close to what the preamp needs.
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Dave

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Re: RCA SHF-1 original RP205 C 1
« #4 : April 09, 2020, 11:42:17 AM »
Gary Stork at VM Enthusiasts is the go-to guy for everything that has to do with a record player.  Tone arm pressure might be more for a mono cartridge than for a stereo, so that might be a consideration.

I will email him with my equipment photos of the arm. Im pretty sure I will send in the multiple rubber drive pulleys/shafts for a rebuild but they do look good for the age. It is a metal tone-arm so that is a concern, especially if the tracking force must be lower than 6 grams.
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Dave

electra225

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Re: RCA SHF-1 original RP205 C 1
« #5 : April 09, 2020, 12:32:22 PM »
Magnavox advertised tracking their stereo cartridges at "1/10th of an ounce" which would be 4 grams, nominal.  The lightest I ever got one to track and still trigger the changer mechanism was 3 grams.  I'd think 6 grams would not be too much, maybe even 8 would be okay, depending on the cartridge.  Gary would be much the better advisor on that than I would.  Good luck.
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firedome

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Re: RCA SHF-1 original RP205 C 1
« #6 : April 09, 2020, 03:42:18 PM »
Don't moving coil carts have very low output typically? IIRC that was the case with an Ortofon moving coil cart that was  mounted in an SME arm on a Thorens I picked up off local CL a few years ago. Hence needed more amplification in the preamp phono stage. Not sure about the RCA SHF-1, but I read somewhere that mods had to be made in order to use a different cart, which was mandatory as the oem cart had no replacement stylus available any longer.
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Motorola Minion

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Re: RCA SHF-1 original RP205 C 1
« #7 : April 16, 2020, 08:19:55 AM »
The single-channel preamp was gutted from the unit's preamp/tuner chassis. That is the thinking RCA used with some later stereo ceramic carts that had a tiny preamp built into to them.
There were two RCA jack cords run directly into the chassis, and this console was bought with a later Garrard (AT6?) installed.

This player is marked RP205 C1 and has the 4-pole motor, I found a parts player marked RP 205 C3 and IT has the alliance motor. Both units have a similar motor board and control speed via intermediate 4-turrets, which sometimes need rebuilt like the idler pulley, which is slightly smaller on the C3's assembly.

Apparently, this console had a few (in-home?) repairs on both amp chassis, evidenced by randomly replaced coupling caps, and baked/bypassed chassis-mounted "cand-ohm" cathode resistors with electrolytic in one of them. The power from one of those amps (almost identical) powers the tuner - preamp chassis.

Apologies for delays, now that I have both players open and cleaned, some pictures are long overdue.

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Dave