Grundig R25 capacitor replacement

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jogunast
Messaggi: 51
Iscritto il: mar 11 feb 2020, 18:05

Grundig R25 capacitor replacement

Messaggio: # 11928Messaggio jogunast
ven 15 mag 2020, 13:36

Hello. Im new to the forum but long time grundig fan from Croatia and i have collected almost everything Massimo reccomended on the main site.

I have few Recievers; R20 and R35 that work flawlessly and R25 that needs few minutes of warm up and has slight channel imbalance.

I decided to make complete refresh of capacitors in R25 and make it my daily worhorse for pc/dac use. However i cant seem to find suitable replacement for axial frako and blue nsf (470uf 25v and 2x220uf 40v). Only ones i found are from Kemet and Vishay.

Would those be a suitable or is there a better choice?

Thanks

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M.Ambrosini
Site Admin
Messaggi: 3558
Iscritto il: ven 9 feb 2018, 7:10
LocalitĂ : Ravenna
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Re: Grundig R25 capacitor replacement

Messaggio: # 11934Messaggio M.Ambrosini
sab 16 mag 2020, 7:16

Hi,jogunast (your name?)
I don't advice to change Frako capacitors or also tantalium capacitors...chango only if defective.
The slight channel imbalance its probably due to potenziometer problem (volume, balance or tone potenziometer) or to any switch contact problem...capacitors are not responsible for this problem.
Massimo

jogunast
Messaggi: 51
Iscritto il: mar 11 feb 2020, 18:05

Re: Grundig R25 capacitor replacement

Messaggio: # 11947Messaggio jogunast
dom 17 mag 2020, 14:21

Massimo thank you for reply. I'll try to use contact spray on pots. I'll follow you advice to keep frako inside for now and replace other elkos because receiver takes more than 30s until it starts to get some sound. I dont mind taking the risk with this one (i have >10 amps and recievers in good working condition)

Unlike other grundig devices, i guess there's less chance to mess up cci since capacitors can be changed while circuit board is still on chasis.
If i remember corectly from other posts, 70% of sound is coming from chassis implementation and 30% from circuit itself. (v7000 and v1700 are different but sound almost the same)

Even if it loses some of that 30% it will still sound good for PC/DAC use 🙂

jogunast
Messaggi: 51
Iscritto il: mar 11 feb 2020, 18:05

Re: Grundig R25 capacitor replacement

Messaggio: # 13217Messaggio jogunast
mar 1 dic 2020, 22:17

I finnaly got the time to do the refresh.
For the all small value capacitors I used elna silmic II, axial frakos were replaced with F&T A series, filter capacitors with Nichicon KS and 1000uf 40v and 100uf 100v were replaced with Frolyt ERY.
I worked with circuit on plastic chassis, only removed the metal case.

I dont know where the problem was but Frakos had weird powdery substance on them and non of them looked good.

After turning amp on there was no warming up till the sound came, no weird noises, balance is perfect now.

I don't know if got lucky with capacitor choice but sound retained typical Grundig signature.
Bass has come to life, details have better separation and sound stage sounds full bodied and there is even more space. Keep in mind that there was no burning in time so I expect even better sound after 50h.

My device had some issues otherwise i wouldn't touch it. However I couldn't be happier with the end result.

jogunast
Messaggi: 51
Iscritto il: mar 11 feb 2020, 18:05

Re: Grundig R25 capacitor replacement

Messaggio: # 13220Messaggio jogunast
gio 3 dic 2020, 16:45

After initial 20h of burn in time sound has begun to settle down. Everything feels more mellow and clear, soundstage is becoming relaxed and is being pushed further behind the speakers making the illusion that room boundaries no longer exist. Bass is not overwhelming anymore. Initialy warm, tube like nature of amplifier was accentuated maybe a bit too much, now it feels more linear with nice texture to it..

I didn't notice any loss of sound quality compared to my other recievers, only slight gain in body, depth and precission comparing it to it's previous state.
Its important to note that reciever was abused by previous owner(s) to the point that the even red fm bulb doesnt work.

jogunast
Messaggi: 51
Iscritto il: mar 11 feb 2020, 18:05

Re: Grundig R25 capacitor replacement

Messaggio: # 13263Messaggio jogunast
gio 10 dic 2020, 12:17

Last post from me.. Actually it was a R20, not R25 as I wrongly written before. But never mind.
Restauration is now complete. I used chinese T5 and T10 LED's from aliexpress.. you can get 40 pieces for 3eur.. unlike expensive ebay kits for receivers with weak halogen yellowish bulbs.
LED has brighter light and has cooler white than halogen bulbs which makes for a spectacular look. You only need to watch for +/- otherwise LED's wont shine. Here are some pictures.
P.S These T5's fit in on off switches on many amplifiers, and as backlight on receivers like R7200, R7150..
I may conclude that R20 after >100h of burn in has become one of best sounding and looking devices in my collection :)
Allegati
R20.jpg
t10 t5.jpg
t5 t10.jpg
t5 t10.jpg
R20.jpg

Filippo
Messaggi: 3359
Iscritto il: mar 6 mar 2018, 21:49
LocalitĂ : Salerno

Re: Grundig R25 capacitor replacement

Messaggio: # 13266Messaggio Filippo
gio 10 dic 2020, 15:07

Very nice, congratulations.

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