my National RX-7200 88-108 MHz FM and 120VAC modifications/repairs

What can I say? It's an amazing one, great design and sound, especially comparing to my childhood tiny RQ-4050FD...
Both original 76-90 Mhz and 100 VAC are quite disappointing.
FM due to the fact that it only picks 2-3 stations from the bottom of the US band around 88-90 Mhz.
100 VAC is simply a disaster area - RX-7200 is made to work off 12-15 Volts DC as noted on the back.
When plugged into Florida's 120 VAC outlet (outputting about 125V) the internal transformer outputs 17.5 VAC as a result!
After the rectifier bridge is sends pretty much fatal 22.5(!!!) Volts DC to the main board which would kill the 33-years old beauty quite fast. It can run off DC adapter, but most of recent adapters are switch mode not linear, so they would cause extra interference plus it's large external non-OEM piece.
I took care of both issues so now it has full coverage on 88-108 Mhz with correctly displayed frequency and normal power voltage. What else can be done? Full re-belting is done, pinch roller replacement is pending roller arrival.
Dead indicators lamp might be replaced with the warm white LEDs tomorrow but this is mostly cosmetics.
Will replace power filter cap alone with a few dry ones in but I'm against the total recapping.

BTW is someone needs FM conversion or 120-220 VAC power PM me - there is no need to ship the whole boat, just a few blocks.

Wow, nice job!!!

RX-7200 is so cool..

Super nice work! Can you give some details? This would be a great asset for those who have Japanese spec boomers.

Thank you! What kind of details you'd like to see?
The work is more complex than rebelting or plain replacement of all electrolytic capacitors, so I'd refrain from step-by-step guide since the results might be quite disappointing due many factors. Not to mention that it might even not being possible for another models. Even this one was a "die hard" due to schematics absence. I've been doing these mods for over 10 years now mostly on car radios. Plus I worked in consumer electronics repairs since early 90-s.
As I noted above all RX-7200 owners can PM me so I can help them out while I have time and parts.

Best of Panasonic classics.
It is amazing that the display had 3rd digit for 100+, though it was mostly a Japan only model, if I am not wrong!

Nice work getting it switched. Curious to know how you got the FM range to change....?

100% Japan model the only reason they have the first "1" is because of AM indication.
It was made before 1990-s when decontenting and penny-saving policy started.
It took a couple of days to figure that out
In a good company alone with RQ-4050FD - 1.5 months of collecting.

Well done - especially having the tuner "re-tuned".

Speaking of warm white LEDs strip - I gave it a try tonight and I don't like the results...
3-LED strip is about 2" long and there is simply no space to conviniently lay it out against the edge of light carrying acrylic sheet where the OEM lamp was. Also since the LED consumes only 3.5 mA off the 9V light supply when the switch is turned off it dims VERY slowly - must be a cap somewhere in the circuitry.
I think I'll go authentic filament lamp. It only consumes 35 mA off 12 V source.

You can cut the strips into individual chips and recreate the circuit with wires soldered.
I didn't have the problem of slow dimming on my RX-7000. It works just like filament lamp or even better, if not infinitely better .
Pl. see the thread: https://boomboxery.com/forum/index.php/topic/17082-national-panasonic-rx-7000-cool-white-led-illuminated/?hl=rx-7000

I can only fit one LED into the space ao I'd have to come up with new current limiting resistor. 7000 circuitry might be different without cap need to look at service manual.

Ok tonight I made it absolutely perfect - took the display to a full extend!
I added the hundredth (.X0/.X5) Megahertz display segment so we have a fully-blown display so tuning makes sense now (you know the exact frequency you tune into).
Not practical in the US where we use only odd frequencies, but correct indication alone with being very very sweet looking

thats a terrific piece of work to improve a great box

I agree, certainly my most favored box by far. With retuned tuner, it'll be a forever keeper.

I have people PM-ing me about who made this mod - it was done by me, no external resources or people were involved.

Sweet - with full FM and 120 VAC!

how come that last digit is dimmer than the rest?

We have snake eyes in the club
Fixed!
I also noted that the power transformer runs 24/7 even though they use a mechanical switch for power.

I never showed the new transformer

That looks like the old transformer.