National/Panasonic RX-5350 problems.

[Tinman]

First off, I completely recapped this and verified the capacitance value on every one before installion.
Yesterday, after partial reassembling, I tested it out and came up with several problems.

1. The right meter seems to work fine but the left meter only works if I turn the rec. mode switch on or turn the left rec. level knob up.
When turning the knob up, the meter actually starts working little by little until the knob is all the way up.
2. When I turn the meter switch to tuning/battery, the tuning meter doesn't move at all while tuning into different stations (FM & AM).
The power meter points up like it should on AC.
3. Amb/stereo/mono switch:
The stereo and ambience modes aren't working for FM radio except very, very faintly.
Mono seems to be working fine for FM.
The Amb, stereo and mono modes work for both the cassette player and aux in (all three modes also work while on AM).
4. The TPS switch doesn't stay locked when pressed however the search function works while in play, both ff and rev.
It basically feels like a momentary switch, I push it in and it pops right back out.
I'd appreciate it if somebody could verify if the button is supposed to lock in when pressed.

I've gone over all boards with a magnifying glass and haven't found any noticeable problems.
I normally wouldn't be asking for help so soon after finding problems but the service manual I have is for the Panasonic 5350.
That and the fact that the print is hard to make out, even viewing it on my desktop, is making it difficult to troubleshoot.
Is there a National/Panasonic 5350 service manual available in English?
Any help would be appreciated.

 

[stynger007]

Good day, problem 1, sounds like a record slider / switch cleaning issue, would clean all switches well with deoxit; number 2, is the FM stereo light locking on when in tuning mode? Maybe a weak signal or again, switch cleaning, 3 cleaning switches , 4 yes it is a momentary button..

 

[Tinman]

I've worked on dusty and dirty boxes but this one looked like it had a heavy layer of soot all over the boards.
It was really filthy so initially I cleaned all pots and switches with CRC electronics cleaner.
The following day I used Deoxit D5 then I finished the next day with F5.
They're probably as clean as I can possibly get them from the exterior.
I've been contemplating removing all of the switches and manually cleaning them which is what I'll probably do tomorrow.

No, the stereo light isn't coming on when in stereo or ambience modes.
Like I said, I can hear the stations but they're very faint with no light.
In mono, it's pulling in a lot of stations very clearly so I'm thinking the stereo light would come on if it was working in st/amb modes.

I'm confused what the TPS button actually does being a momentary switch.
The only thing I can think of is while it's searching fwd or rev, the button can shut the search off so the tape can remain playing.
Is that correct?

 

[Tinman]

I removed and cleaned all 5 switches and the record bar.
That got the left music meter working.
It was several hours of work but now I can rule those 6 switches out for the remaining problems.
I also took the TPS button apart and cleaned it.
The only thing it does when pressed is turn the search light out while it's running so either it's not working or it's useless.

 

[Superduper]

Are you talking about the TPS Program or TPS on/off switch? The on/off switch latches. The program switch is momentary.

 

[Tinman]

Are you talking about the TPS Program or TPS on/off switch? The on/off switch latches. The program switch is momentary.

This is a National/Panasonic, it only has the single on/off button and single led.
Mine doesn't latch.

 

[Superduper]

So, this is the Japanese version then? That being the case, it's no wonder that the service manual (if you have it) is in Japanese only. Nowhere else is the japanese model sold except in Japan, so it's almost a certainty that any service publication is going to be Japan only. As for the switch, I did do a google search and found a high(er) resolution image good enough to be able to determine that the single TPS button you refer to should be the latching type. The legend (on/off) is exactly the same as on the lower button of the Panasonic RX-5350 which latches. So there is something wrong with your switch.

 

[Tinman]

No, it's not the Japanese version but the only service manuals I can find for the Nat/Pan version seem to be in Japanese.
I have the Panasonic service manual from the library here so there are added circuits (Dolby, mixing and 3 TPS search) that mine doesn't have which is making it more difficult for me to trace for my stereo & ambience problem.
Again, stereo and ambience work in AM, cassette, and aux in modes but not FM (only mono works for FM).
When I had the TPS switch apart, it did have the locking setup in it but cycled right past it and returned to the up position.
I'm not really sure what the button is supposed to do but my TPS does work in fwd and rev while it's in play mode.

 

[blu_fuz]

Send me your email, I will send you the PDF of the 5350 service manual. It won't upload in this post, file too large.

 

[blu_fuz]

Or try this link:

Panasonic RX-5350 Service Manual

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

 

[Tinman]

Another problem solved, the tuning meter is now working.
It was one of the printed resistors on the tuner board, R19.
I installed a 2.2k jumper in it's place.
In my pic, you can also see the TPS board.
I'm assuming the tuner boards are the same between the three brands so this was pretty easy to find.
The stereo/ambience is going to be tougher.

 

[Tinman]

Or try this link:

Panasonic RX-5350 Service Manual

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

Thanks but I believe that's the Panasonic version I already have.
The Panasonic has extra components in the circuits that the Nat/Pan doesn't have namely Dolby and mixing.
That's what's making it tough for me to trace.

 

[Tinman]

Ok, I just changed out the ba1320 ic401 (which is ic403 in the Panasonic version).
I believe I gained the tuning meter staying on when in stereo and ambience modes but there's still no sound or music meters in either mode.
The last thing I can think of is changing out the ba6133 ic which I believe is the "ambience chip" although I don't know if that has anything to do with stereo mode.
I'd appreciate any help on this, I'm pretty much out of ideas.

 

[Tinman]

Nobody?
Nothing?
Not even a guess as to why the stereo and ambience modes might not be working?

 

[Josh9994]

I would think it may need the tuner alignment done.

 

[BoomboxLover48]

Check for cracks on the PC board. I inspect with a magnifying glass and trace with a DMM. Certain areas of the board are in stress and can develop hairline cracks. I had that issue with my Panasonic.

 

[Tinman]

Check for cracks on the PC board. I inspect with a magnifying glass and trace with a DMM. Certain areas of the board are in stress and can develop hairline cracks. I had that issue with my Panasonic.

I did read and do that but I'll give it another going over, it's possible I missed something.
Thanks.

 

[BoomboxLover48]

Some resistors are wired/buried in the tracks. I was lucky to find the PC break that caused the VU meter malfunction.

 

[Tinman]

Some resistors are wired/buried in the tracks. I was lucky to find the PC break that caused the VU meter malfunction.

I've looked but haven't seen those types on the main board.
It seems like it's a resistor or other component problem because the channels are there in stereo and amb modes, they're just extremely faint and the tuner led doesn't light.
I'll have to look closer.
If I had the actual service manual for this version, it'd make it so much easier.

 

[Superduper]

Why do you say that your National is not a Japanese model? Is the FM tuner range 76-108? Regardless, this model has lots of issues with the PCB's degrading over time. There are a lot of printed traces that included resistors printed directly onto the PCB. They probably did this in carbon layers built up until they arrived at the desired resistance value. These tend to degrade over time. Modern double sided boards do not have this problem because they employ all copper traces on both sides, but this is an early attempt, and these were not expected to survive 45 years later. Essentially any or ALL of the traces on the component side can deteriorate. You will need to check them one by one, and YES it is a tedious task, and NO, there is no easy way around it. You can fix this with basically a DMM, without a scope but it is time consuming. I would suggest you focus on the area around the MPX IC since that is where your issues appear to be but an issue can manifest everywhere. The service manual does have voltage specs for the semiconductors. Do a Voltage, Resistance check throughout the area and chart it. Make sure settings prescribed is in the correct position as voltage will change depending upon the mode and settings. Then compare to the specs in the service manual. Additionally, where there are printed traces connecting between 2 points, this will not be obvious in the schematic which will just show a line like normal. The best thing to do is to test for resistance between those 2 points directly at the solder pad. If there is a 220R resistor in between 2 points, it should read 220 from those 2 solder pads. If there is no resistor, it should read near 0. If there readings are off, you will need to jump those 2 solder pads with a wire, or a resistor if the resistance has drifted far from specs (after cutting the printed connection to sever it and prevent parallel resistance). All of this is described in the 2 threads below, I will not rehash scores of hours of work and typing. BTW, you will also have to check the switches S3 and S5, make sure to test for proper operation with DMM directly at the pins.

Fixing a legend.....

I bought this Panasonic RX-5350 knowing there was some kind of issues with it, but didn't know exactly what. After getting it here, overall the condition is good. Needs a cleaning/detail and is missing the battery door. The problem is after testing it out, the capacitors might be dried up...

boomboxery.com

The Saga Continues (blu_fuz 5350)

Ok, I'm starting a new thread since the old one just got too long, and as this thread only will include the fixes without the 200 encouragement posts, it might be more helpful for folks needing to fix a similar type of issue. This regards the tuner to Joe's (Blu_Fuz) RX-5350 repair thread...

boomboxery.com