pioneer SX-440 Tuner Board Germanium diode

[jackson]

Howdy all-
I am restoring a Pioneer SX-440- nice little unit. All complete except for a question on the tuner board regarding the Germanium diode pictured in attachment.
The board has W35-027A marked- it is not the same as the service manual schematic and my searches have not found any info for a board of that number.
Any info/assistance is appreciated- Thanks Jackson

 

[sregor]

That looks more like a germanium diode.
I printed to PDF a copy of the schematics which was included in a pioneer schematic collection (volume 3) The website I got it from is no longer available.

 

[zebulon1]

If in the AM circuit it could be the detector diode a 1N60.
Why are you asking?

 

[jackson]

That looks more like a germanium diode.
I printed to PDF a copy of the schematics which were included in a pioneer schematic collection (volume 3) The website I got it from is no longer available.

Correct- I just wrote the wrong thing- thanks

 

[jackson]

If in the AM circuit it could be the detector diode a 1N60.
Why are you asking?

Just recapped unit and replaced a bad transistor on the board in question. It functions now and brings in stations, but diode seems to go in and out- you can tap it and it works again- do not want to sell the unit until I am sure it functions 100% Thanks Jackson

 

[larryderouin]

Check for a cold solder joint or a trace fracture to both ends of the diode 1st. Repair as necessary.

 

[BPW]

Hello-reviving this post as it relates closely to an issue im working through. My sx440 has this same 35-027 tuner board discussed above, that does not apoear to have a parts list in either the 440 manual or the schematics shared above by sregor. The board appears to have been previously reworked and i’d like to audit the capacitor values against the stock config. Schematics above are ok for mf values- but lack voltages. Curious if anyone has been able to uncover a components list for this 35-027 board.

 

[zebulon1]

Those older manuals don't have a itemized parts list.
Maybe someone has a list they developed like you are asking for but I would look at each cap and make a list from there.
Now the highest voltage a cap in the tuner would encounter, is 13v's. Some will be less. Finding any through-hole, less than 25 volts is near impossible.

 

[Watthour]

Those older manuals don't have a itemized parts list...

It never hurts to ask. I just happens that I have something which might help alleviate that. The original is 13Mb, and too large to upload through AK. I compressed it to 4Mb and the site server still didn't like it ("The uploaded file is too large.") That's why I keep posting cleaned schematics in the Digital Docs forum.

You can find it here:

www.wwdsltd.com/files/PioneerSX-440OwnersManualCompressed.pdf

 

[BPW]

Thanks for the share watthour. That 440 user manual was my starting point and the exact type of info needed. Unfortunately, the tuner board detailed within is the w35-007, so the w35-027 remains elusive! From a quick visual study of the board drawing versus my physical part, the boards do appear to be very different from a layout perspective.

On a separate note, I begin swapping out the output transistors, and that seems to have solved 50% of the issue. Left side speker output works fine on both channels A&B. Right side outputs are not working on either and I’ve blown two output fuses so far.