Vintage Audio

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This is my old Voice of Music model 1465-2 AM-FM stereo tuner. All vaccuum tubes. I remember using it to listen to 60's rock on WKTK-FM in Baltimore when I was a teen.

Wilcox-Gay Recordio 4F10

I tried to sell a Wilcox-Gay Recordio model 4F10 at the NEARC Westford show this past winter. I had rescued it from the town dump. It was clearly someone's prized possession, as it had all its accessories, an original service manual, and a telephone pickup coil in its original box. But old mono reel to reel tape recorders aren't very interesting to most collectors, so no one was buying.

Wilcox-Gay Recordio 4F10

One fellow wanted me to open it up and sell him the tubes from it. I finally gave in and pulled the tubes; he did score a single Ampex Bugle Boy 12AX7, but had hoped to get two. The second 12AX7 didn't have any notable markings.

I put a "free, take me" sign on the remains, and some young fellow did eventually do that. I regret selling off the tubes; I should have just given the whole works away. But then it probably would have been scavanged for tubes anyway and dumped.

Anyway, I did make a scan of the Wilcox-Gay Recordio 4B10 and 4F10 Service Manual. It's also linked from my Liberated Manual list in the nav-bar to the left of the page.

I also made a gray-scale scan of the manual. It's much bigger, but the photos are better. I should have tried a 600 dpi black and white scan with descreening; that probably would have been the best compromise between file size and quality.

V-M Model 168 StereoVoice Auxiliary Speaker with Amplifier

Some fellow on the Antique Radio Forum was recently asking for service information on a Voice of Music model 722 tape recorder. My dad had one, and I fondly remember spending many hours investigating it as a small boy. 

I recently came across my dad's old owner's manual for the Model 168 Auxiliary Speaker. The model 722 stereo tape recorder only had one speaker and one amplifier channel built-in; the model 168 Auxiliary Speaker provided the amplifier and speaker for the other stereo channel. So, I'm posting a scan of the Model 168 Auxiliary Speaker Owner's Manual for the ARF'er and anyone else who's interested. Click the preceding link or the image below to download the PDF file.

V-M 168 Manual

Nikko NR-719

I sold my old Technic SA-200 receiver that I had been using as my bench receiver. I brought it along to the NEARC Westford show mostly in case someone wanted to audition the restored Voice of Music speakers and tuner I was trying to sell, so I didn't really want to sell it. I priced it higher than I thought it was worth, but someone liked the looks of it and bought it.

So, I dug into the pile and brought out a Nikko NR-719. It mostly worked as-is on FM. Deoxit on the controls along with vigorous exercising of them cleaned up the noisy contacts and potentiometers. I put a little Deoxit on the tuning capacitor contact points, too. The AM section was dead and the signal strength and tuning meters didn't move. And, of course, the pilot lights were soldered in and every one was burnt out.

I couldn't find a service manual for the NR-719, but HiFi Engine had a service manual for the NR-819. I suppose the power amplifier and power supply sections are different, but the RF and preamp sections of the NR-819 manual seem to match my NR-719.

The unit had a little rust on the bottom cover and a little less corrosion on the top cover and some of the internal structure. It also came with a few dead insects inside. It may have been stored outside in a covered location.

I cleaned up the rust on the bottom cover with a wire wheel in a hand-drill and coated it with Krylon clear spray to protect it. The rest of the corrosion was minor enough that I just let it go; it's only a workbench receiver, after all.

I next tackled the meters. The service manual says to release the spring wire clamps from the read of the meter and just pull it out. Mine were held in by hard-to-see clear tape in addition to the wire clamps. I had to pry them out a little with a screwdriver to stretch the tape a little, then get in to cut it with an X-Acto knife. When I put them back in, they seem to be secure enough with just the wire spring, but if I were to ship it, I'd want to replace the tape to prevent the meters from being jarred loose.

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Here the meters are removed from the front panel. The meter bezel is molded into the clear plastic front cover for the tuning scale, so the needle and movement are exposed when they are removed. So be careful, and only do this in a clean environment so crud doesn't get into the movement.

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I unsoldered the meters, put my DMM on a high resistance range, and put the probes on the meter lugs. The meter moved but stuck returning to zero. 

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I played with the needles on both meters; they were both sticky. 

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I examined the movements carefully but I couldn't see any crud that would rub against the armature. 

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I guessed that the moist storage environment corroded the bearings. So, I started backing out the pivot screws. It took about three-quarters of a turn before the meters would reliably return to the zero point. The signal meter zero was a little off, but the zero adjustment had been sealed with black lacquer and I couldn't get it to budge with the limited amount of force that I felt comfortable applying to it.

I reassembled the meters and resoldered them and they are now working nicely on FM.

I started investigating the AM section. I could get a signal if I cranked my signal generator output level all the way up, but below about 50 millivolts the receiver abruptly cut off. I checked the ceramic filter with a scope; there was a strong signal coming in, but nothing coming out. I at first suspected that the filter was bad, but then I measured the IF frequency by plugging my counter into the vertical output of my scope - the IF was set at 530 kHz! So nothing was going to get through the 455 kHz ceramic filter. Someone had golden screwdrivered the alignment. 

I started following the alignment instructions in the service manual (with a little extra bit of interpretation, as the manual would have you use a sweeper to do the alignment). I got a big clue there: the adjustment on the second IF did very little. After I got the local oscillator on the right frequency so that I was getting a signal through the ceramic filter, I started looking at the second IF. 

The AM receiver uses a Hitachi HA1197 chip, so the second IF is a little strange - it's a series-resonant LC circuit. Examining the signal with a scope, I saw a strong signal coming in but only a small signal after the LC circuit, and diddling the core didn't make much difference. The IF can had a few extra pins; the Nikko schematic didn't show them, but the data sheet for the HA1197 did. Assuming the can matched the Hitachi data sheet, I measured the coil resistance as 6 ohms, so probably good, and the capacitor measured about 13 kOhms. Aha! The cap appears to have shorted, so the circuit can't be tuned to resonance, and the series resistance of the short is high enough to greatly attenuate the signal.

I still have to test this theory and see if I can repair the second IF can by replacing the capacitor. I also still have to test out the phono preamp.

Update:

Yes, replacing the capacitor in the second IF can fixed the problem.

Yamaha CR-620 Receiver

I have a 1970's-vintage Yamaha CR-620 receiver that I'm trying to restore. I found a manual for the CR-620 on HiFi Engine. Electrically it seems to be working fine, aside from some noisy switches and potentiometers. A little Deoxit fixed that up. 

Mechanically, someone removed the tuning pulley and tuning shaft and gear from the tuning capacitor. 

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Side View

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Top View

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Three-quarter view

So I'm searching for replacement parts: the tuning pulley and dial cord spring, the tuning shaft, and the gear.

Here's a view of the top of the RF section:

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View of entire RF section

The manual says that the same parts are used in the Yamaha CR-620, CR-820, CR-1020, and CR-2020. The pulley part number is 320000-CB07926. The dial spring is 320000-AA08053. The tuning cap and associated parts seem to be part of the RF board assembly and don't have separate part numbers.

I've found some on eBay at prices too high for me. I'm hoping someone has one of the aforementioned Yamaha receivers in their boneyard and will swap or sell the parts to me at an affordable price.

I'm also working on a Nikko NR-719 of similar vintage to the Yamaha and noticed that the NR-719 tuning cap looked very similar to the Yamaha CR-620's tuning cap. I suppose the design was a common one among many of the Japanese manufacturers at the time, so perhaps I can find a substitute from a different brand.


Voice of Music Model 1465-2 AM-FM Stereo Tuner restoration

I started work on restoring my V-M 1465-2 AM-FM Stereo tuner while waiting for parts to complete my V-M 307 restoration.

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The bezel got a bit banged-up on the move from my parent's home in Towson, Maryland. 

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I first pulled all the tubes and cleaned the crud off the chassis with isopropyl alcohol and a toothbrush.

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A look at the chassis shows that Voice of Music used pretty high-quality components for the early 1960's: carbon film resistors, polystyrene capacitors, and ceramic disks. There were a couple of paper bypass caps.

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Is this a film cap or a paper cap? I'll have to test it and see if it leaks, then dissect it.

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The blue electrolytic looks to be well sealed. I wonder if it is still good? (Update: it's working fine. It's made by Ducati, in Italy. Still, I'll replace it as a precaution.)

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I do need to re-stuff the main electrolytic can.

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I used a couple of short pieces of 1x2 and some small C-clamps to improvise a chassis stand.

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Getting the can electrolytic out was a bear. One of the tabs was soldered to the steel chassis and I simply could not get things hot ehough to suck out all the solder. I ended up breaking off that tab.

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I restuffed it using 12 mm diameter radial electrolytics from Mouser.

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I replaced the paper bypass caps with modern film caps.

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I needed to get out my Weller 8200 soldering gun to work on the soldered connections to the steel chassis. I also tried a modern Weller D550 with the set-screws rather than tip-nuts, but my old 8200 seemed to deliver more heat. Too bad Apex or Cooper ruined a good product by cheapening the design.

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I'll have to leave the one electrolytic bypass cap in for now, until my next Mouser order.

Update:

I cleaned the tube sockets and pins, applied some DeOxIt to the tube pins and the socket fingers, left it alone for a while, then cleaned up the residue and plugged in the tubes. The tuner mostly works fine and is much more sensitive than my Technics SA-200 shop receiver. It still had one problem that I remember it had back in the early 1970's - the stereo indicator light didn't work.

I had a poor copy of the schematic from the owner's manual (which I seem to have misplaced; I can't find it now that I need it), and so I was able to track down the fault.

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This coil (L6 on the schematic) is part of a 19 kHz L/C filter that amplifies the pilot tone and applies it to a neon lamp which is the stereo indicator light. It had gone open. Fortunately it failed at one of the ends and I was able to splice in a small section of 30 gauge wire-wrap wire to fix it. Yay!

One of the #1847 pilot lamps failed while I was troubleshooting the stereo indicator problem, so now I need to order some replacement lamps.

My parts order from Mouser arrived, so now I can replace the blue Ducati-made electrolytic.

Next up: restoring a VHF-capable signal generator so I can align the tuner.

Cabinet restoration

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As I mentioned at the beginning, the front panel was dented in the upper left ...

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... and the bezel was dented in the upper right.

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I was successful in removing the dent in the upper left, but less so with fixing the dented bezel. I cleaned up the front panel and the knobs with Gojo, as well as the rest of the cabinet.

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Here's some photos of the finished product.

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Dual 1219 Repair

I purchased a new Dual 1219 turntable back in my youth. During my college years, I learned about UPS shipping and insurance when I shipped it home one summer. It arrived with the dust cover smashed, the plinth broken apart, and worst of all, the head-shell broken off the tone arm. My fault for not packing it correctly, and of course UPS wouldn't pay up on the insurance.

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I repaired it using super-glue, and it served for light duty for years with occasional re-gluing.

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But eventually the glue residue became too thick for further repair. I managed to find a replacement headshell (although it's plastic rather than the original cast magnesium). I'm not sure where I bought it; probably from Garage 'A Records.

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I managed to remove the headshell mounting tab from the tone arm without removing the tone arm from the turntable, but I'm sure it's going to need to be removed to install the new headshell and thread the new wire harness into the arm. 

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I tried to get Audio Lab down in Harvard Square to do the work, but their tech didn't want to attempt it. I downloaded a copy of the manual from the Vinyl Engine, and the instructions for removing the tone arm don't look too difficult.

The lubricants are all gunked up, of course, but the turntable runs its single-play cycle except that the friction plate doesn't move the tone arm. I guess I'm missing the steuerpimpel (guide white). I haven't tried the changer cycle yet; I do have both the 33 1/3 RPM and 45 RPM changer spindles, but I figure I'll wait until I re-lube it before fiddling with the changer cycle.

Anyone have any advice on removing the tone arm and replacing the head-shell, or on cleaning and re-lubricating the works?


© Steve Byan 2011-2016