Restoring a Supreme Model 562 Audolyzer
The model 562 Audolyzer was advertised by Supreme as a dynamic RF and AF signal tracer and radio analyzer. It contains a 5-band tuned radio frequency (TRF) receiver with built-in speaker. The receiver is integrated with a built-in vacuum tube voltmeter (VTVM) and an ohmmeter. It looks like the model 562 was manufactured from around 1939 to the mid-forties before being replaced by a newer model.
From what I've read online the earliest units had a gray face plate in an oak case, a #80 rectifier tube, did not have the ohmmeter, and used a bias battery in the first audio amplifier. Later units are said to have a black metal cabinet and face plate, the audio circuit was modified to eliminate the bias battery, the rectifier was changed to a 5Y3 and, of course, it had the ohmmeter. I've even seen photos of a black face in an oak cabinet. This particular Audolyzer has the gray face in an oak case and the #80 rectifier like the original units, but also has the ohmmeter and the rest of the circuit matches the schematic for later versions which eliminate the bias battery. One of the schematics I found online is dated 1946 and says it is for units S/N 2100 and up and shows a 5Y3 rectifier. This Audolyzer is S/N 2443 but still has a #80 rectifier. Doesn't make sense. Supreme must have made a lot of incremental changes over the years.
From what I've read online the earliest units had a gray face plate in an oak case, a #80 rectifier tube, did not have the ohmmeter, and used a bias battery in the first audio amplifier. Later units are said to have a black metal cabinet and face plate, the audio circuit was modified to eliminate the bias battery, the rectifier was changed to a 5Y3 and, of course, it had the ohmmeter. I've even seen photos of a black face in an oak cabinet. This particular Audolyzer has the gray face in an oak case and the #80 rectifier like the original units, but also has the ohmmeter and the rest of the circuit matches the schematic for later versions which eliminate the bias battery. One of the schematics I found online is dated 1946 and says it is for units S/N 2100 and up and shows a 5Y3 rectifier. This Audolyzer is S/N 2443 but still has a #80 rectifier. Doesn't make sense. Supreme must have made a lot of incremental changes over the years.
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The chassis removed from the wood case. The case is falling apart at the joints and needs reglued and refinished.
It is complete inside, but obviously has been worked on, looks like at least a couple of times. The older repair work was mostly well done, but later someone else was trying to troubleshoot it, snipping leads and tack soldering components back. Just wiggling some of the resistors and capacitors was enough to break the leads free. Real poor work, but it made it easier to remove the old components. The paint is literally falling off the front panel and there are rusty areas on the chassis. The chassis can probably be touched up but the front panel will have to be recreated from scratch. |
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The chassis is dirty but not too bad a shape except for the rusty patches. At least the paint is not falling off the chassis like it is on the front panel. There was a battery for the ohmmeter on the left side where it's rusted. The metal strap that held the battery is also a rusty mess.
The chassis is actually painted the same gray wrinkle finish as the front panel, something I don't often see. A little better quality than just a bare metal chassis. The tube complement, starting with the glass tubes, from front to back, are a 6J5, a 6V6 and the #80 rectifier. On the metal tube side the first two are 6SG7 and then a 6SQ7. The schematic shows two 6SK7 tubes but the 6SG7 is a valid substitute. |
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Under the chassis is clean but there's a lot of paper and electrolytic capacitors to replace. I counted 18 paper caps in all plus 5 electrolytics. The shielded box contains the band coils and trimmer caps for the receiver plus several of the paper caps and resistors.
All the resistors need checked and since they are the older "roundy" style it's a good bet some will need replaced. The input and output jacks are oddball Motorola-style antenna jacks as used on automotive radios. I noticed in an Audolyzer manual photo of a later metal-cased unit that two jacks on the right were changed to 1/4" phone jacks. I may do the same. Only the probe jack was still the antenna-style jack on that unit and since the Audolyzer uses a single dedicated probe, I can leave this one in place. |
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The front panel removed from the unit. Every time I touch it more paint falls off. I want to scan it before I loose too much paint so I can recreate the dials and lettering on my computer. I hope to be able to print decals to relabel it.
The top left corner is bent, apparently from having been dropped. The oak cabinet corner isn't damaged so it must have been out of the case when it happened. It will get straightened when the panel is repainted because if I do it now more paint and lettering will fall off. |
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The top of the chassis cleaned up nicely and I found an off-the-shelf spray paint that was a close color match to the original gray finish. The rusty spots were treated with naval jelly, then paint was sprayed into a cup and brushed on. The touched up spots were dry brushed into the existing finish and it came out much better than expected.
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Inside the the shielded compartment are the band coils and trimmer capacitors for the TRF receiver. There's also three paper capacitors to change and several resistors to check. Only two of the resistors were found to be out of spec. Both are 1500-ohms on the schematic but were actually 1600-ohm resistors in this unit. They can be seen at the center in each half of the box.
The TRF receiver has two RF stages, a detector and then two AF stages. It tunes from 95Kc to 14.5Mc which covers all the common IF frequencies. It also has an antenna input coax in the rear to use it as a radio. The antenna is connected to the receiver RF input when the PROBE SELECTOR is in the AF OUT position. The radio's audio output from the first audio amp is then routed to the test probe and also on to the 6V6 audio amplifier driving the speaker and AF OUT jack. The output of the probe can be used as an input source to test audio circuits. |
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I removed the variable capacitor and cleaned it with a product called Super Clean. It came out almost as shiny and clean as new. It's a degreaser so a coat of WD-40 was applied after cleaning to protect the metal.
The RF Multiplier switch has two paper caps to replace. The hardest part was just getting the cover off. |
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The speaker was rusty and needed painted. It says it's made in England and if the schematic is correct it is not original. The schematic shows a speaker with a field coil, not a permanent magnet. The output transformer was hanging by just a single screw from it and looking under the chassis revealed the wires from the 6V6 to the transformer had been cut and spliced. So it's not original either. It must have been changed a long time ago though, because the spaghetti tubing on the splices was dry rotted. The field coil is labeled as 1000-ohms on the schematic and had been replaced in the power supply by two 2000-ohm power resistors in parallel.
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The oak cabinet joints were reglued and then it was sanded, stained and coated with clear enamel. The original handles were missing and replaced with "screen door" handles from a hardware store. The metal back panel was also missing and a new one was cut from a decorative metal panel and grommet holes were added for the power cord and antenna coax cable. Not an exact match for an original back but close enough. It buttons up the rear nicely and still allows for good ventilation.
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I found an old probe in a junk box and converted it for use with the Audolyzer. I replaced the original internal resistor with a 100KΩ, and changed the connector to a Motorola-type. The probe end is a two-piece affair, it must have originally had interchangeable tips but the others are long lost. It uses the same antenna-style connectors to plug the two halves together, so a wrap of yellow tape was added to keep the tip from being unplugged.
One of the advertised advantages of the Audolyzer was that just a single probe was used for troubleshooting a radio all the way from antenna coil to voice coil. You don't have different probes for RF, AF or the VTVM. But using the probe with the VTVM is optional, a set of regular test leads connected to the meter jacks can also be used, while using the main probe for a different function at the same time (with meter in EXT. VOLTS position). Ohms measurements are also made using the test leads connected to the meter jacks. |
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The front panel was stripped and repainted in a black wrinkle finish. It still needs recolored gray to match the chassis, and relabeled. I like the black face and am torn between recoloring it and just leaving it as it is.
I've found a couple of fonts that are pretty close to the Supreme lettering so now I can recreate the dials and print them on water slide decal paper. |
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I also found a couple of products called Microsol and Microset to "melt" the decals onto the finish of the panel so they will almost be part of it. Then they'll be coated with matte spray. Now all I need is the time to do it.
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I decided on recoloring the front to match the chassis. Recoloring was done by spraying a coat of gray paint over the black wrinkle finish and then quickly rolling it with a paint roller to remove excess paint.
The wrinkle paint is VHT brand and available at auto stores. VHT also makes gray wrinkle paint but it was not available locally. |
more to come...
Page created 12/7/2019
Last updated 1/21/2020
Last updated 1/21/2020
