Need help for my Panasonic RX-5250LS

[5250ls]

Hello everyone!
Just cleaned this beauty found in a garage sell...
Everything is working fine including tape (original belt! Amazing...) but none of the rear entries are good (rca phono and din rec play)
I have cleaned all contacts (kff2) including that very long switch connected to the rec mechanism, resolder all input sockets, check all components (eyes only, very clean inside, no abuse seen, I think I'm the first to go inside)
-Phono input only make horrible scratch noises...
-Din input work but at a very low level, not even enough to excite the leds on vu meter...
Of course I have trying differents sources...
Every other functions working great, rec, vu meter, beautifull and powerfull sound, mics, dial lights...not even a bad noise in tape transport!
I'm in love with this unit and want to save it, especially because I was born on may 1981 and this was built in june 1981...almost the same
Oh I'm from France (please excuse my not perfect english) and glad to be accepted in this great forum!
Any help will be greatly apprecied...
Thank you so much in advance...

 

[hopey]

Nice box, not sure this has line level input have you tried pressing rec and play? Phono input is very low level.

 

[hopey]

It could be the function switch or the cap's on the op amp that's where I would start.

 

[5250ls]

Thanks for your reply!
Yes I have tried rec and play and fully tested the function switch...for the cap's they are all looking good, no blow or acid leaks but I have just only checked them visually and it can be not enough...they're almost all dark puple Matsushita...A friend of mine have a cap tester I will check in time.
What is the op amp? I can post all pictures of the inside if needed don't hesitate and again thank you for your help

 

[AE_Stereo]

Solid box.
What is written on the Phono input?

I have once bypassed the Phono amp circuit in a Sony micro system to feed Line-In.
I traced the Phono circuit to reach the output side going to the amplifier and tapped into the line at that point. Once it was tested to be working, I cut the continuity from Phono amp by making a scratch on the PCB.

 

[5250ls]

Nice idea!
Tomorrow i'll post picture of the inside circuitry to see if we can do the same thing on my unit...
Here is a picture of the back:

 

[AE_Stereo]

You can see the switch on the extreme left side marked PHONO/DIN. Means the set itself is equipped for Phono or Line-In through DIN. The Phono amp by-pass is already built-in.

Keep the switch in DIN IN. And it must allow Line-In through DIN port.
Since it is written REC/PLAY, it may work only for recording. If so, keep the selector switch to Phono and try with the Record+Play+Pause pressed at same time. Also the Record Level modes may have an effect on the audio level. So try changing the Rec mode switches and Record Level control pot.

Please post a clear photo of the front controls.

 

[5250ls]

Yes I have trying this, but I think it's where there is a problem, I explain:
-Din/jack cable adapter linked to my phone through earphone.
-rear switch on Din.
-front function switch on Din/phono.
-Result the sound is very very low, not even enough to excite the vu meter, (same with or without rec pressed or with manual or automatic level record)
-recording on a tape is also very very low in result.
-I have tried another source than my phone and the same thing.
-cleaned all contact and everything, all working perfect, radio, radio/front mics recording, auto/manual level, play and all, music settings, sound is beautifull...
All but none rear entries work well, phono making noise and Din is to low to use but at least stereo and well balanced...to see with phone and box at max volume is almost the same than radio or tape with volume level at 1/10. I have also tried another source than my phone and it was the same...here is picture of front:

 

[5250ls]

Also later today I'll redo a disassembly and post some step by step pictures, maybe it can help someone one day

 

[5250ls]

Removing front controls and cassette door (two screws)

 

[5250ls]

Removing the seven screws from the back, they're all the same, one in each angle, two in the middle and the last behind the battery cover...
As you can see I have already replace the foam on the battery cover.

 

[5250ls]

To remove the front panel, first lift the bottom and then release the top because there is clips on top...

 

[5250ls]

Here we are

 

[5250ls]

Unplugged speakers, just gently pull the plug, there is a lock on it but it is very smooth

 

[5250ls]

 

[5250ls]

Remove the dial to avoid scratch on it, to do just gently lift the needle

 

[5250ls]

Then remove the dial and replace the needle

 

[5250ls]

Lift the vu board and after check the path of tape deck cables release them, they are of the same style than the speakers one, five in total, motor, head, erase head and two for the differents switchs

 

[5250ls]

Remove the screw near the tape counter in order to release ground wire. Replace the screw after that (to avoid lost)

 

[5250ls]

Remove the four deck screws, one in each corner, all are the same screws (this is the same with all screws in the unit except antenna and it is great!
Then simply pull out tape deck...