Greetings Allan and Norm. thanks for moderating this great forum and special thanks to Hal and Meade my mentors from another thread Motorola 610-T Restoration.

viewtopic.php?f=1&t=191632

I have two Motorola 610-T radios. The first one (if you look back at the above link) arrived in pretty poor shape but was complete with the tuner and power unit. My good friend and fellow truck forum member from Australia spotted this one a NOS 610-T never installed, still in the box unit on eBay. Although I was well into the restoration of Radio and Power Unit#1, I couldn't resist even though I knew it was missing the power unit. I was not sorry when I opened the UPS package.




Wow I can actually see the colors of the wires!

Thanks,

Hank

This thread is not about the NOS 610-T Tuner. It's about its OUS ("Old Used Stock") Power Unit which I call Power Unit #2. I might mention a little history or "Lessons Learned" about its even more neglected predessor power unit #1.



Unfortunately, it looks like "Two Tooth Timmy the Tow Truck Driver" got to this radio before I did and for lack of a simple screwdriver blade and a little TLC, cracked the phenolic connector.

Finding phenolic board without having to buy a square foot ($) proved to be near impossible. Forced into a second choice I could only find styrene board in a model shop. Although it turned out o.k., and bench tested just fine, I would still like to find some phenolic board as I’ve gotten pretty good (even with the crumby drill press I used) but phenolic would be a better choice of material.

Thanks for your interest,

Hank

After a through cleanup, restoration Plans for Power Unit #2 (pending review and approval) are as follows:

1. Replace all Capacitors. (including the 3-section Electrolytic)

2. Install new solid state vibrator.

3. Replace all Resistors stepping up one wattage rating for non stressed existing resistors and stepping up two wattage ratings where component design has proven through time and normal operation to be underdesigned like R16 and R17 shown here: (Hal, you'll like this!)


(I think I now know what a leaking cap and a burnt out resistor looks like)

4. Rebuild 4-pin Power Plug and solder new audio plug onto existing shielded cable. The wires contained within the loom and going back into the chassis seem to be in good shape, existing to remain.

5. Provide new speaker wires.

My main challenge for power unit #1 and #2 are with "How to Replace the 3-Section Electrolytic" Although I am just learning, it's starting to look a little simplier and I know if I do all I can to read/review various articles I have found and ask the right questions on AR, I'll be allright.

Thanks,

Hank

I would recommend installing separate electrolytic capacitors on terminal strips under the chassis. Lots of room under that power supply chassis and also several holes to bolt up the terminal strips. The radial caps sitting on top of the chassis in the picture in your earlier thread would be one way to do it (mounted on phenolic boards or even some spare tube sockets). Simply disconnect the existing filter cans and leave them in place (for appearance if nothing else). Any wiring to the can mounting (ground) lugs can be left in place, and is also a good place to ground the new filter caps.

The 20 mfd for the 6AQ5 output tube cathode will be rather small and could be soldered directly to the tube socket.

Meade and Hal,

Thanks for being in there for me. I bought all the resistors and capacitors for Power Unit #2 today. Following Hals observation (hey where is Hal?) and the obvious overheating of R16 and R17 in both Power Unit # 1 and #2, I stepped up the wattage for all resistors as mentioned in the post above. Hal please double check me on this.

I plan on removing and installing all the resistors and capacitors tomorrow with the exception of the Electrolytic. I purchased both radials and axial capacitors in 33mf 350V and 2mf 25V. I was a little surprised that the axial capacitors are much larger than the radials (especially the 33mf 350V)



I like your idea of terminal strips as this seems very manageable and easily accomplished providing I can figure out which wire goes to what capacitor. In light of my novice (at best) ability, I intend to try to get a grasp on the schematic, take a bunch of photos, then before removing, carefully tag where each wire attached to C21 and finally make some sort of schematic and physical mock-up for your approval before soldering anything.

I apologize for being so inept and really appreciate both of you helping me,

Thank you,

Hank

Please bear with me on answering your posts; I’m having computer problems the last two days. I have to wait till my computer guru (son) gets off work to bail me out.

It’s easy to figure out where the wires belong. On the 3-section can, each section is marked as to mfd and voltage. Notice the symbols that follow each voltage on the can. After one of the 33mfd at 350VDC markings there is a small square---after the other 33 mfd there is a triangle----after the 20mfd at 25VDC it is plain, no mark. These same symbols (square, triangle, plain) are also on the under-side of the can, right next to the solder lugs on the phenolic wafer---may be hard to see, but they are there. Those symbols correspond to the ones on the schematic, shown just above the diagram for C21. I’m sure you’ll find it easy to trace out the circuit.

Making a mock-up of the capacitor/terminal strip layout is good practice. Moving things around for the simplest component and wire routing makes a better job of it.

4/28/2011

Replaced all capacitors and resistors with the exception of resistors attached to C21.



Power Unit #2 was much easier to work on than Power Unit #1 partly due to lessons learned and actual hands on experience. All capacitors With the exception of the cracked power cord plate, the wire loom was in much better shape and did not require replacement.

This time I was able to avoid disturbing any of the pool solder connections by coiling capacitor leads and soldering directly to the wire remaining by clipping out the old capacitor close to the body (an old trick I’m sure you already know)



Once the repair of the cracked Power Cord connector plate (see post date Apr Thu 26, 2012 8:24 pm) is complete, (unless advised otherwise) I am considering mounting the tubes, solid state vibrator and bench testing the unit.

Hal hope you notice that I was able to replace R16 and R17 (56 mfd 1/2w) with (56 mfd 2w). It was obvious in both units by looking at them that 1/2w was under designed. Taking your advice, each resistor was stepped up a notch. It seems to be practice.

The early part of next week will be a planning stage for replacing the Electrolytic and I’ll be busy with understanding the schematic, sketching a solution and mocking up the results for comment before soldering anything (Meade hope your son is able to fix your computer)

Thanks,

Hank

This post will be edited to show a progression of sketches and used as a dialog (with your help) to produce a final schematic leading to a mock-up of the decomissioning of actual installation. There's only four wires involved so I guess it's not rocket science to you but it's new territory to me so I appreciate your indulgence.




Does this cropped area of the schematic show enough of the circuit or should I provide one showing a larger area?


Does it look like I have the square, triangle and dash correct?

The truck is 6V pos Ground. Does that mean all the positive ends of the 3 new capacitors should be grounded to the radio chassis?



Rather "A failure to read schematics"

(To be continued, but some input re polarization would help at this point).
O.K. Polarization now corrected to reflect Negative Ground

Please stay tuned, Thanks,

Hank

Power Unit #3 just showed up on eBay and was a "Buy it Now" it was advertised as a speaker but well you guys know... it's not. Why do I need a 3rd power unit if I only intend to complete one radio:

1. I prefer the metal case in lieu of the cardboard. (It appears that trucks were equipped cardboard and cars had the metal case)
2. Of all three of the units this one looks like it is in excellent shape.
3. It would really be nice if this unit was in working condition. If only I could confirm that both tuner units were working properly before starting to rebuild C21 Electrolytic (which I will do) and that the solid state vibrator is working properly.



Still waiting for feedback about C21, but in the meantime keeping busy.

Thanks,

Hank

All three electrolytic caps (C-21) should have the negative ends grounded, as in most conventional power supplies. Only the vibrator (if solid state) is polarity sensitive.

Your layout looks great so far—just turn those caps around!

AAAAAHH! Another "Cool Hand Luke" fan!

Meade so glad you are back!

It can’t be that simple really? Do you mean that all I have to do is to solder the wires that go to the 30 mfd square, the 30 mfd triangle and the 20 mfd to the positive lead of the electrolytic capacitor and the negative lead of each to ground? Theoretically that’s it?

Tomorrow I’ll work on finalizing the schematic then pending approval will do a physical mock-up without soldering anything.

Thank you so much,

Hank

Pretty simple really. Be sure to disconnect the wires and resistor from C-21 positive terminals and move them to your new electrolytic cap positive terminals. Any wires on the ground (negative) mounting terminals of C-21 can and should remain (This is a good place to ground the negative terminals of the new caps also).

I will be away from the computer most of today.

That's no problem I've got plenty to do. Oddly enough the guy that I purchased Power Unit #2 threw in an unexpected radio that is really trash but has salvageable parts like tube sockets. I still like that idea of using tube sockets to mount the 2 30 mfd cans, so will have fun stripping the unit down to the chassis. Power Unit #3 should be arriving today so that'll take a little of my time too in general cleanup and some bead blasting of the metal housings in preparation for painting.



One thing I'm realizing is "You can always do a little better than you actually did"

Will edit this post later...

Hank

Meade this is a good point to comment. Hopefully I am on target

Thanks,

Hank

To follow: Physical Mock-up using 2-salvaged tube sockets (20mf 25v) to be soldered to existing 6AQ5 socket

Not sure I should do this but I think it can't hurt to try:

Power unit #3 is not the same as Power Unit #1 & #2. Although the chassis is identical, and it looks like some of the parts are the same (will have to go deeper into it) the circuity is different. Power Unit 1&2 has 1 6AQ5 and a 6x4 Rectifier. Power Unit #3 has a 6x4 Recifier 2-6AQ5 tubes and a 6AT6. The 6AT6 is only found on the tuners.



What I'm thinking about doing is removing the electrolytic from Unit #3 (the ratings are a match) and installing it in Unit #1. I realize it might be a waste of time as ultimately I need to replace the older style 3 section electrolytic with three separate new ones.


Thanks once again.

Hank

Hank,

Referring to the image of wire placements, I believe you meant that wire #4 goes to the 6AQ5, not the 6X4. Should go to pin 2 of the 6AQ5, with resistor R19 (270 Ω).
The vibrators will interchange between power unit 1,2, and 3. Although there many versions of 6 volt vibrators, they are the same in this case. For solid state vibrators there are different versions of 6 volt types also.

What I’m seeing on this thread so far is that you have at least one tuner and three different power units, one of which is original for a 53 Dodge truck (the Mopar 610T). I would suggest picking one of the power units and sticking to it till you get a working radio. Moving the electrolytic cans around is as you say, a waste of time, unless you just want the experience of doing it.

If it were my radio, I would use terminal strip/s to mount the new electrolytic caps. Much easier and convenient to replace if/when a cap goes bad.

Maybe a little history on some Motorola radios of this type is in order:

Power unit #1: Part of Mopar 610T, with cardboard cover (Made by Motorola).
Power unit #2: Motorola from an unknown radio model, but essentially the same as the Mopar 610T unit (steel cover versus cardboard). Experience tells me that it is probably part of Motorola’s aftermarket line and is probably known as their chassis P6-2 for a 6-tube plus rectifier radio.

Power unit #3: Motorola also from an unknown model, but was probably part of Motorola’s aftermarket line, and probably known as chassis P8-2 (push-pull audio) for an 8-tube plus rectifier radio.

A typical Motorola radio using P6-2 or P8-2 is their aftermarket radio for 51-52 Chevrolet. A customer could order a Motorola aftermarket radio for his 51 Chevy in 4 different versions:
Model CT-2A (push-button tuner) with P6-2 power/audio unit.
Model CT-2A (push-button tuner) with P8-2 power/audio unit.
Model CT-2M (manual tune tuner) with P6-2 power/audio unit.
Model CT-2M (manual tune tuner) with P8-2 power/audio unit.

Either tuner could be combined with either power/audio unit and vice versa.

Send me an email or a PM and I’ll scan the schematics for P6-2 and P8-2 power/audio units for you.

Meade,
Thank you for your review and comments. Somehow I got flipped upside-down and backwards. You are correct, wire 4 does go to 6AQ5, with resistor R19 (270 Ω). (Incidentally, where did you find that “Ω” ohm symbol? Are there any other electrical symbols or is there a font out there that has schematic symbols?

Thanks to you I think I’m clear on how to handle the 3 new electrolytics , am no longer terrified and feel ready to proceed with confidence with a physical mockup. I will not solder until you tell me I really have it down. I’m hoping to do this tomorrow.

I brought the two Vibrators I have (one from the 610-T and one from the P-82) to my local electronics store. Often I will notice older shoppers (I know I’m one but don’t admit that to myself). Today I asked one gentleman if he knew anything about tube radios. “Too much, I’m afraid” was his reply. I showed Bob the two mechanical vibrators. The can of one was opened (by me) to burnish the contacts. As Bob slid the mechanism out he said “These things never go bad” he then added “Except for the coil.” I wanted to know if I could use the vibrator from the P-82 in the 610-T chassis. The numbers do not match, but Bob told me and it makes sense that the vibrator itself has no current rating and only produces AC current based on the amount of current that is input. I also know that the solid state vibrators specify voltage (12v or 6v) and have a “P” or “N” worked into their part number. I think that Bob told me the mechanical vibrators are neither Positive or Negative (and that kind-of makes sense to me) since they produce alternating current.

When I test the vibrators (on the lagere pins) results seem to vary but they seem to initially jump to 18. or 16. then begin a downward cycle and settle in at 4. or 5.

I’d like to understand why Power Unit #1 and the NOS 610-T worked for 15 minutes or so back a couple of weeks ago. Was it the solid state vibrator my friend gave me that failed, or more than likely once things got warmed up a 60 year old component (wax capacitor or the electrolytic ) was the most likely cause of failure. Hopefully things will be different once the 3 new electrolytics are installed.

I'm not sure if ultimately want to use solid state vibrators if by installing the new electrolytics and the radio works as it should. Are there good and bad solid state vibrators on the market and how would I know the difference?

Made some progress on the 2 metal housings. It took about 5 minutes to bead blast them yesterday in preparation for Rust-Oleum Black Hammered finish. I think they’ll turn out real nice. The housings are stamped P-62 (Unit #2) and P-82 (Unit#3).



Your knowledge is quite overwhelming. I would like very much if you would be so kind as to send schematics for both units. My email is hankstruck@verizon.net. I’m very happy to know that “Either tuner could be combined with either power/audio unit and vice versa,” although I don’t understand how the P-82 unit can have 2 more tubes than the P-62 and still work. I guess it ‘s my lack of knoiwledge. I noticed this book (shown below) on Amazon the other day and would like to know if you have a favorite book that will help me have a deeper understanding.

Thank you,

Hank

Email sent.

The Ω symbol is "Alt" plus "2,3,4" on a windows machine.

Although most of my time went into Power Unit #1 installing all new capacitors (including abandonment of the 3-section electrolytic and installing 3 separate caps) replacing all the resistors, the old eBay field find has not yet been brought into working condition. This is due to the most recent discovery that both the power and output transformer need to be replaced. That’s the bad news first.

The good news is that Power Unit #2 is working flawlessly thanks to the magic of Meade, who not unlike “Doc” with sparks flying, was able to re-energize the “Flux-Capacitor” (3-section).





I'm very grateful for Meade sharing the time, knowledge and patience for walking me through this project and bring it to a successful completion. Many thanks to ARF and it's forum members.

Hank