: RCA PVCR185  ( 1274 )

Motorola Minion

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RCA PVCR185
« : February 28, 2020, 04:17:53 PM »
I am not sure if I posted this one but I'm about 80% done with only the tuner chassis to do. After the modest 4VF439 experience, I was ready for even more fun with these 1961 models.

It is a 3-channel with a  3" cone tweeters, 5x7 mid-range speakers and a 15" center woofer. There is no reverb chassis but the P prefix stands for "provision", so it included a control knob. I thought it was equipped until I got it home at least :(

Before I did anything, I repaired the cabinet base which was water-loosened and added some solid cherry to make it stronger than new. Roger (Firedome) filled me in on making functional tenon joints. My neighbor helped with his jigsaw and it was a perfect fit. The grill cloth is perfect but the style overall is 60s tacky :-[ by modern standards.

One good thing about this console is that I have a smaller version, a VCR244 that never had work done-yet, same year - same chassis - same RP215 changer, to help keep me from making wiring mistakes. The build quality is very different though.

The dates give clues  ??? because it appears the -185 was built on a Saturday shift (day 6) after Thanksgiving in 1960, very sloppy around the controls and the multi-lead RC networks. The -244 looks very neat and was built on a Tuesday in August 1960.

 I recapped and replaced numerous crummy caps and resistors RCA seemed to love using. I have three new 6BQ5s and cannot wait to hear what this will do. driving a 15" woofer with a bass-optimized SE 6BQ5 output seems like a stretch, compared to Motorola 3-ch consoles.

Tubes - Magical - Tubes

Dave

Bill

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Re: RCA PVCR185
« #1 : February 28, 2020, 06:16:48 PM »
Your controls look just like mine Dave, but i have the French Provincial cabinet with the swing out speakers.  Mine is a VCR something?? :-[ :-[ that i can't remember right now.  It has all the hookups for reverb as well, but i don't have reverb.

Bill

TJ

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Re: RCA PVCR185
« #2 : February 29, 2020, 06:55:37 AM »
You could probably use this Hammond reverb unit as it is likely similar to what was originally installed:

https://www.ebay.com/itm/Vintage-Hammond-17-Reverb-Guitar-Organ-Reverberation-Unit-Type-IV/264573626157?hash=item3d99d1272d:g:CygAAOSwa~NeH2X1
My Consoles:
1962 Motorola SK112CW-FM, All original tubes
1958 Magnavox Continental - DIY Concert Grand!
1957 Magnavox Brittany - Amp 148 Magic!

Bill

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Re: RCA PVCR185
« #3 : February 29, 2020, 08:59:26 AM »
Thanks Trevor, I'll take a look.

Bill

firedome

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Re: RCA PVCR185
« #4 : February 29, 2020, 03:35:49 PM »
Looks great Dave - cheers for gettin' her mostly done!
Happy Motoring! from Roger in NY

Motorola Minion

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Re: RCA PVCR185
« #5 : March 04, 2020, 08:36:22 PM »
This is the first 3-channel RCA I have worked on, next is another "Victrola furniture" console 1VF507 with a  stereo PP-6BQ5 (RS-177) amp before I feel ready to tackle an SHF-1 that I don't own.

The other 3-channel RCA  VCR-244 I has a better-built chassis , a deja-vu of this one, but I'll let it sit for now. 

TJ- the reverb in this model may have had a tube "driver" stage in addition to the Hammond tank like our Motorola sets do, I need to check up on the reverb model number on the amp's tag. Motorola went all-in on reverb compared to any other mfr. 8)

The amp does have a reverb control, with a 2c shielded cable and that wacky RCA stereo plug, that just hangs unless you have the reverb unit to plug it in to.
Tubes - Magical - Tubes

Dave

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Re: RCA PVCR185
« #6 : March 05, 2020, 09:44:36 AM »
The tuner in this console already has all the resistors checked and replaced just 2 this time. I am tempted to leave alone several 100K with 10% tolerance band (silver) that measured between 108K and 113K.

The wax-paper caps were as awful as can be when I tested them. Shut down at less than 100v, barely opens the eye on my EICO 950 when looking for correct mfd. value. Routine replacements as always!

The three section electrolytic is up next, similar to any other AM-FM radio minus and amp stage.

This tuner, though simple and not stereo, has a 6E5 eye tube. Oops!  ???No it doesn't anymore, I used the 6E5 to restore a friend's Crosley Dynatrol 11  ::) but I have a plan for this tuner to use a 1629, the same eye tube my cap checker has. I also have about 6 NIB 1629's.

The 6E5 is a rare bird because the target gets dim. I put one of those dim ones in my Magnavox Berkeley's AM-SW receiver - the FM tuner has a bright 6E5. I can turn the FM off when no on FM but the AM SW is used at night, mostly so who needs a new/bright eye tube?
Tubes - Magical - Tubes

Dave

TC Chris

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Re: RCA PVCR185
« #7 : March 05, 2020, 08:39:37 PM »
The most important thing about an eye tube is just having some green glow to make the device look cool.  They don't actually serve a purpose in most radios since you can (and most of us do) tune by ear anyway.  The Emerson DS-436 I worked on recently uses a 6U5 eye and it's mostly for show.  I guess it would let deaf people tune in a station.

Chris Campbell

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Re: RCA PVCR185
« #8 : March 06, 2020, 10:45:39 AM »
The 1629 uses a standard octal base but needs 12.6 volts for its heater. The 6E5 has a 6-pin base like most other tubes pre-8pin octal, so it may be a lot of work if I cant find 6E5/6G5/6U5 that sort of works even if it is dim.

The plan for the different heater voltage is pretty easy though, if I change the 12AU6 to a 6AU6 then swap the heater wiring. This tuner has a power supply unlike most other console tuners. Like a Zenith that gets 120 vac - has its own transformer but the transformer secondary is 120 volts and lights all of the tube heaters in series, except for two tubes. In this case, the 6E5 and a 6BA6 heater are connected to a low tap on that 120 volt secondary.
Tubes - Magical - Tubes

Dave

TC Chris

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Re: RCA PVCR185
« #9 : March 06, 2020, 07:57:45 PM »
The 1629 uses a standard octal base but needs 12.6 volts for its heater.

What happens if you run it on 6V for the heater but full B+?  It would probably never burn out....

Chris Campbell

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Re: RCA PVCR185
« #10 : April 04, 2020, 07:29:11 PM »
Using this tuner on FM is really not that good. It may have an issue but the weak 6E5 can stay.
I have to do the speakers on this console but its at the shop, where I have not been this last 3 weeks. I have been so busy working from home, I started recapping the RCA SHF-1 amps and just starting on the preamp tuner chassis.
Tubes - Magical - Tubes

Dave

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Re: RCA PVCR185
« #11 : October 19, 2020, 11:44:37 AM »
This is an update to close the thread, I have successfully recapped the 3-channel amplifier and tuner.

The 15" woofer 5x7 oval mids and cone tweeters sound great despite the truly awful tuner. I just got a wheel for the RP-215 record changer, so I will cover that on the VCR244 model thread.

The tuner is a German-made type in a die cast enclosed sub-chassis, that Zenith and others used. It must have an issue but after disassembly, removing old flux, re-soldering etc, it made little difference. AM is ok but the lowest I can get FM is 89.5 with tuner string fully pulled out. Strong stations spread over too much of the dial, all but burying the weak ones, then AFC makes it even worse.
Tubes - Magical - Tubes

Dave

TC Chris

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Re: RCA PVCR185
« #12 : October 19, 2020, 08:09:53 PM »
Sounds like an alignment issue?  Assume you checked voltages on the tubes?

Chris Campbell

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Re: RCA PVCR185
« #13 : October 21, 2020, 02:47:38 PM »
If I encounter the same issue on the other near-identical RC-1192, that will guarantee I leave it be. The AM works good, FM is full-sounding though mono. But , if I want a weak station or one below 90 mc, where good music is found around here, no dice.

I suspect the oscillator circuit reaction to AFC, spreading a strong station over a 2 mhz of dial range, almost as if it cant be switched off. The circuit board is loaded with odd-looking ceramic caps and common resistors, no paper caps. I will look at this again on the other one, but using a socket extension to measure voltages may reveal something. Likely the issue is not external to the assembly.

The German parts all appeared to be physically intact. The mixer(conv) is the one triode section but the oscillator appears to be a diode, where afc voltage is controlled. It sure looks to be a similar one to my Motorola, and that works fantastic!
Tubes - Magical - Tubes

Dave

TC Chris

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Re: RCA PVCR185
« #14 : October 21, 2020, 07:11:26 PM »
OK, I'm not afraid to as a dumb question.  How do you make a diode oscillator?

Chris Campbell