Grundig Studio RPC-350 alignment procedure... - UK Vintage Radio Repair and Restoration Discussion Forum

ekjdm14 · 2nd Jul 2019, 12:00 pm

I've recently finished reassembly of my Grundig music centre, having gone through it and replaced any components out of spec (only a few electrolytics out of about a hundred!) but I'm less than satisfied with performance on UKW (FM) & feel it's an alignment issue.

Tune across a strong station and it comes in well and the stereo lamp lights briefly, but once I stop moving the dial stereo dips back out and the signal weakens. Also if I tune with AFC selected it doesn't "grab" the strongest signal like I'd expect.

I've had a quick search round & downloaded some service manuals from RM but I've reached the limit of my downloads and no alignment info...

Does anyone have the appropriate data they'd be willing to share please? This is a really nice system and sounds great, solidly built and looks amazing, just a shame the plastics are aging badly as there's a couple of broken gears, one that prevents the tape deck from rewinding and another that drove the tuning cap, though thankfully there's 7 permeability-tuned FM presets so I can still use that at least!

Thanks,

orbanp1 · 2nd Jul 2019, 10:10 pm

Hi Dan,

The elektrotanya web-site has the service manual, or parts of it, not the best quality, but it is usable:
https://elektrotanya.com/grundig_hif.../download.html
The schematics has some adjustment instructions.

There is also a guy who asked for help about the same radio on the DIYaudio forum, and posted some good quality scans of the schematics. You might contact him for the manual:
https://www.diyaudio.com/archive/blo...need-help.html

The radio is more or less conventional, and it uses ICs.
The FM-tuner section is a three transistor circuit with varicap diode tuning.
The FM-IF amplifier uses a TCA420 IC, the tuning voltage is produced by the TCA530 IC, including the AFC.
The switching of FM channels is done by the SA580 SAS590 ICs.

Look up the datasheets and it has application information in them, that is very helpful.

Hope this helps!

Regards, Peter

peter_sol · 3rd Jul 2019, 6:35 am

It is very unlikely to be alignment unless someone has deliberately messed with it.

ekjdm14 · 3rd Jul 2019, 12:43 pm

Ah thanks, I'll get a look at those links when i get a moment. I must remember that elektrotanya is a good resource, again never thought to look! I did think it strange that the alignment would be off but not having a decent service manual to refer to (just the parts of scans i managed to get from RMorg) couldn't really verify one way or another.

Hopefully it's something simple I've missed. Thanks to all for the replies, suggestions and links,

2nd Jul 2019, 12:00 pm	#1
ekjdm14 Banned Join Date: Feb 2019 Location: Congleton, Cheshire, UK. Posts: 609	Grundig Studio RPC-350 alignment procedure... I've recently finished reassembly of my Grundig music centre, having gone through it and replaced any components out of spec (only a few electrolytics out of about a hundred!) but I'm less than satisfied with performance on UKW (FM) & feel it's an alignment issue. Tune across a strong station and it comes in well and the stereo lamp lights briefly, but once I stop moving the dial stereo dips back out and the signal weakens. Also if I tune with AFC selected it doesn't "grab" the strongest signal like I'd expect. I've had a quick search round & downloaded some service manuals from RM but I've reached the limit of my downloads and no alignment info... Does anyone have the appropriate data they'd be willing to share please? This is a really nice system and sounds great, solidly built and looks amazing, just a shame the plastics are aging badly as there's a couple of broken gears, one that prevents the tape deck from rewinding and another that drove the tuning cap, though thankfully there's 7 permeability-tuned FM presets so I can still use that at least! Thanks,

2nd Jul 2019, 10:10 pm	#2
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: Grundig Studio RPC-350 alignment procedure... Hi Dan, The elektrotanya web-site has the service manual, or parts of it, not the best quality, but it is usable: https://elektrotanya.com/grundig_hif.../download.html The schematics has some adjustment instructions. There is also a guy who asked for help about the same radio on the DIYaudio forum, and posted some good quality scans of the schematics. You might contact him for the manual: https://www.diyaudio.com/archive/blo...need-help.html The radio is more or less conventional, and it uses ICs. The FM-tuner section is a three transistor circuit with varicap diode tuning. The FM-IF amplifier uses a TCA420 IC, the tuning voltage is produced by the TCA530 IC, including the AFC. The switching of FM channels is done by the SA580 SAS590 ICs. Look up the datasheets and it has application information in them, that is very helpful. Hope this helps! Regards, Peter

3rd Jul 2019, 6:35 am	#3
peter_sol Octode Join Date: Aug 2003 Location: Welwyn Garden City, Herts. UK. Posts: 1,906	Re: Grundig Studio RPC-350 alignment procedure... It is very unlikely to be alignment unless someone has deliberately messed with it.

3rd Jul 2019, 12:43 pm	#4
ekjdm14 Banned Join Date: Feb 2019 Location: Congleton, Cheshire, UK. Posts: 609	Re: Grundig Studio RPC-350 alignment procedure... Ah thanks, I'll get a look at those links when i get a moment. I must remember that elektrotanya is a good resource, again never thought to look! I did think it strange that the alignment would be off but not having a decent service manual to refer to (just the parts of scans i managed to get from RMorg) couldn't really verify one way or another. Hopefully it's something simple I've missed. Thanks to all for the replies, suggestions and links,