After more than 10-15 years, you can be certain that the electrolytic capacitors in your amplifier will have aged, leaked, if not worse, and will not perform at their best, making your amplifier a worse performer.
Some of those capacitor are important because they provide an electrical power reserve when volume peaks are needed, some others are on the signal path, some are within the phono pre-amplifier.
A replacement of those capacitors (a recap) is something that is needed at that stage.
Theory
Here are the capacitors that will need changing on this amplifier, on the schematic diagram:
Here are the capacitors that will need changing on this amplifier, on the wiring diagram:
In order to visually help, here are a few shots of the real thing. The two main 8200 µF capacitors for the power supply are not shown here, but you can't miss them, they are the biggest things on the board!
Here is the list and description of the capacitors to change:
| Item | Number | Voltage (V) | Value (µF) | Diameter (mm) | Comments |
|---|---|---|---|---|---|
| 1. Power Supply | |||||
| C903 | 35 | 8200 | 30 | 10,000 µF 35-40V would be ok too | |
| C904 | 35 | 8200 | 30 | 10,000 µF 35-40V would be ok too | |
| C901 | 25 | 2200 | 16 | ||
| C902 | 25 | 2200 | 16 | ||
| 2. Amplification | |||||
| C605 | 100 | 10 | 6 | Something like Panasonic FC series | |
| C606 | 100 | 10 | 6 | Something like Panasonic FC series | |
| 3. Phono stage | |||||
| C405 | 10 | 4.7 | "Bead" | Something like Panasonic FC series, use 10 µF instead | |
| C406 | 10 | 4.7 | "Bead" | Something like Panasonic FC series, use 10 µF instead | |
| C417 | 50 | 10 | 6 | Something like Panasonic FC series | |
| C418 | 50 | 10 | 6 | Something like Panasonic FC series |
Here are suggestions for replacement, with references from RS Components:
| Item | Number | Description | Pack of | Diameter (mm) | RS Stock No | Manufacturer part # | Price | URL |
|---|---|---|---|---|---|---|---|---|
| 1. Power Supply | ||||||||
| C903 | Nichicon Aluminium Electrolytic Capacitor 10000μF 35 V 22mm Through Hole 5101-4 VY Series Lifetime 1000h +105°C | 1 | 22 | 739-5324 | UVY1V103MRD | £3.02 | http://uk.rs-online.com/web/p/aluminium-capacitors/7395324/ | |
| C904 | Nichicon Aluminium Electrolytic Capacitor 10000μF 35 V 22mm Through Hole 5101-4 VY Series Lifetime 1000h +105°C | 1 | 22 | 739-5324 | UVY1V103MRD | £3.02 | http://uk.rs-online.com/web/p/aluminium-capacitors/7395324/ | |
| C901 | Nichicon Aluminium Electrolytic Capacitor 2200μF 25 V dc 16mm Through Hole PW Series Lifetime 8000h +105°C | 5 | 16 | 715-2684 | UPW1E222MHD | £4.64 | http://uk.rs-online.com/web/p/aluminium-capacitors/7152684/ | |
| C902 | Same as above, in the pack of 5 | - | ||||||
| 2. Amplification | ||||||||
| C605 | Nichicon Aluminium Electrolytic Capacitor 10μF 100 V 5mm Through Hole JIS C 5101-1 VY Series Lifetime 1000h +105°C | 1 | 5 | 862-4190 | UVY2A100MDD | £0.24 | http://uk.rs-online.com/web/p/aluminium-capacitors/8624190/ | |
| C606 | Nichicon Aluminium Electrolytic Capacitor 10μF 100 V 5mm Through Hole JIS C 5101-1 VY Series Lifetime 1000h +105°C | 1 | 5 | 862-4190 | UVY2A100MDD | £0.24 | http://uk.rs-online.com/web/p/aluminium-capacitors/8624190/ | |
| 3. Phono stage | ||||||||
| C405 | Nichicon Aluminium Electrolytic Capacitor 10μF 50 V dc 5mm Through Hole PS Series Lifetime 2000h +105°C | 5 | 5 | 519-4289 | UPS1H100MDD | £0.93 | http://uk.rs-online.com/web/p/aluminium-capacitors/5194289/ | |
| C406 | Same as above, in the pack of 5 | - | ||||||
| C417 | Same as above, in the pack of 5 | - | ||||||
| C418 | Same as above, in the pack of 5 | - | ||||||
| VAT | £2.42 | |||||||
| Shipping | - | |||||||
| TOTAL | £14.51 | |||||||
Practice
Removal and clean-up of all capacitors:
Installation of the new components, plus bias readjustment:
This little amp is now singing like a champion!
Reference
For your reference, here are the owner's manual and service manual:
After sitting in the garage for nearly 10 years I tried to resurrect my old hi-fi system that includes this amp. Hadn't a clue what was happening when amp fuses blew but looking at the power caps, after reading this, all had leaked electrolyte. Got mine going again just changing the power caps, if I have problems with sound I'll also switch out the others but so far so good -such an easy job using this as reference. Thank You Nico!!
P.S. on other sites discussing repairing caps in this and similar model rotel amps I have seen notes that the cap polarity labels on the PCB and the maintenance manuals do not agree so take careful note of the polarity when you remove the old ones.
It's glue not leaky csps
Hello Nico, I hope your are well. Thank you so much for this tuto. I would like to try and do the same as you, and change at least the two secondary capacitors that do not look good. But when I look at the electronic board, i don't really know what/how to unmount to have access underneath to replace the capacitors. I wonder if you would have a piece of advice to start this adventure. Thank you, Taika (France)
Remove top cover and two screws on either side (just behind front panel. Turn over and remove three screws from front behind panel and the four heatsink screws. Turn back over and the whole front panel & PCB will slide upwards. You now have access to bottom of PCB.
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Hi
great Job
by the way C605&C606 is 10V/100uf
Gil
Excellent write up, many thanks for this as this will let me repair my own RA820BX amp.
The Nichicon 10000uF caps specified are too tall to fit in case. I used Vishay (BC) 10000uF 40v. RS ref. 1802043.
Hi, I can't see where the test points are to check bias adjustment—where do you take readings? Thanks.