In this video, I document the troubleshooting and repair of a Rotel RB 1080 stereo power amplifier. It takes several attempts but eventually I'm able to repair this unit.
Excellent. I worked with great bench techs while in broadcasting.... your troubleshooting is spot on. I appreciate how you isolated the problem and eliminated parts of the circuit. Thank you.
After I saw an episode on your RU-vid channel I had to subscribe. Articulating your processes in such detail from beginning to end teaches the viewer far more than most other channels that try to do the same! Great work!
That's one great power amplifier. I think Rotel is generally quite an overlooked brand, but this is a true classic imho. I borrowed one from a friend for a couple of years back around the millennium, and it was a sweet sounding and very powerful piece of kit.
Really enjoyed this. Nice clear photography that showed the problem areas (man, I hate that glue!), good detective work and excellent demo of the thermally mis-matched transistors.
Great job in this repair! I just want to bring up one point. All that circuit glue that turns black must be removed from all your repairs. When it turns black it is not only corrosive but it is also known to be conductive.. This can change the specs of the circuit.
@@dualityrepair4770 Subscribed from Australia. These were powerful but ran very hot. This was rectified in 2010 with the RB 1582 and further refined with the RB 1582 MkII. I bought the latter in 2017 and it's absolutely fantastic for the money. Unlike many people I take very good care of my life, wife and everything else in between. Cheers and stay safe mate.
Wow, dude, you are awesome! I have the same amp which has developed slight background noise when on idle, in right channel. I am literally glued to the screen watching your video, this has already given me some clues what to check and inspect. Could you please give me some pointers what should I check in order to find what might be causing this background noise? Any clues would be appreciated.
I was a little surprised you never mentioned checking the bias at that Vbe multiplier in the middle of the circuit. -- or if you did, I missed it! Pretty important stuff!
Did you match the replacement differential pair transistors for beta values. Always be wary of the noise figure for the transistors if using a substitute.
I also noticed this, it is the reason why the damping factor is so high. Good for low frequency distortion to have no degeneration but linearity will be compromised.
Hi . I have an issue with RB991. One of resistors caught in flame. Need replacement parts . 2SA1016 x 3 - matched pair and a single plus just to be safe 2SC2362 x 3 , also would be good to have on hand just in case 2SC2682 and 2SA1142. Do you happen to have and willing to sell these ? Or perhaps can help with substitute model numbers . Would appreciate help ob that one since they are obsolete . Great video . Regards
Nice explanation. The osciloscope is such a wonderful asset. Can you get a "music" with a pure sine wave via input rca's or do you have to use a the proper signal generator?
Sergio, RU-vid offers many videos with sine waves of various frequencies that can be used for this purpose. This is what I used before I bought my signal generator.
Hello I have a RB 1090 and. RMB 1095. Also a RMB 985 MKii. My 985 has some blown transistors. That I am going to replace much like this repair. My question is these are older units pushing 20+ years old. Is it worth while to recap all of these. From my reading electrolytic capacitors are only good for 10 years but many last upwards of 20. My equipment is getting that old. Is this something I should be looking at doing.
Nice work. I have that same model amp. It was notorious for blowing fuses on the left channel. I read about slow blow ceramic looking fuses, fixed the problem, I’m hoping it’s not a symptom of other issues in that left side. Any thoughts ?
Using the slow blow fuses allows you to use the amp, but they’re also failing to protect the left channel from the current spikes that are likely present. These spikes can shorten the life of any component in the circuit. It’s very difficult to suggest a component or area of a circuit to look into from such a limited problem statement. I’d be happy to work with you in more detail if you’d like to email me.
Same model, left channel fuses blown apparently for trying out 12V trigger from preamp. Came up with this great video because of that. Luckily my problem was much simpler. Otherwise great amp! I have had it for 20+ years now!
I Purchased one of these a few years ago and loved the app. However I always had a problem with the left channel the slightest little ding would pop the left channel I was constantly replacing the 250 V 8 amp fuse And then one day I was playing it on Axiom M 100 speakers which are a 4ohm speaker which Rotel said that would not be a problem as it could drive a 4ohm Load And then it went out. I took it to the repair shop when they stated the motherboard was not good and there was none to replace it. So here I have a beautiful amp that longer works And cannot be fixed that leading up being trash which I think was uncalled for as it should’ve been a motherboard available so very disappointed in Rotel Of coarse that did not stop me from buying another Rotel amp which I love and no problems
First of all, none of those Rotel power amps have any "motherboards". The second , even if any of the PCBs (Printed Circut Board) inside is cracked or broken it always could be fixed with a glue and a few jumper wires. And third, any defective parts on those boards should be available and could be easily replaced. Also any "cold solder" joints with loose connection could be easily resoldered. In other words, you would need to find a good electronics technician.
That glue melting is very disturbing. Glad I decided to pass on Rotel. I have Adcom and Acurus power amplifiers and they have been working fine for around 25 years.
At 16:31, please clarify: You state that "they were not connected in any way." Do I understand correctly that the 2 transistors were heat shrunk together but no thermal compound was used? Or that they were initially installed separately with no shrink or compound?
Hi , I have EV CPS2 power amplifier . I’m facing power supply continuously short circuiting . I check the power supply module PCB , in that all components are working I.e relay, NTC. I desoldered rectifier GBPC-P 3504 and check , no shortage in rectifier side. Can you please give any insights/ suggestions to me how to repair this problem. This short circuit observed when I’m doing idle current adjustment and I check replace few transistors which got short circuit but still I’m seeing power supply short circuit
I have a RMB1075, it is frying any speaker that connects to the right surround, it made the speaker smoke and there was a screaming sound. My question is for someone who cannot work on this themselves, is it worth taking this to a shop to get it repaired or would the cost be too high for an amp from 2001? I have been only utilizing 3 channels lately, but took it out of rotation because it seems like a ticking time bomb to me.
That depends on several factors. 1: Is there anyone local to you who can fix this? 2: what would it cost? 3: how much are you willing to spend? People send me their amps all the time and spend twice it’s value in shipping alone because they’re committed to their older gear. Understandably, not everyone feels that way though.
@@dualityrepair4770 Where are you located? I have no reliable place, the one in Nashville consistently took a Technics SA TX50 I had, 3 times they said it was fixed and it still had the dreaded overload error each time after 6 mos.... I would not trust them. I have 5 vintage receivers, Sansui G9000 etc, so I do like vintage gear. I know this weighs almost 50lbs...
I got same amp, left channel gets really hot after 20min "No input and Speaker connected" Do you think it might be the same transistor. Amp works fine when cold. When hot, left ch start crackling and distorted and eventually lose audio.
If I were to choose between a new Rotel RB1552 mkII or a used rb 1080 for driving my dynavoice define 8 front speakers (23 - 32.000 Hz (- 3 dB) RMS 200W, max 280 Watt 94 dB dual 8" woofers and 6,5 mids) via my 5.1 receiver preouts, which one would suit me better? I guess the 1080 could be pretty old, is there any downsides to that? If i bought a new 1552 as mentioned I would get warranty and a new unit for the same price as a used 1080.
k domster, I never charge a service fee, so just shipping & parts. Depending on what needs to be done (simple repair vs. full rebuild), the parts cost would vary between $10 to $80.
@@dualityrepair4770 In Australia it's pretty much across the board fee wise? Initial inspection fee: $110. This is the cost of diagnosing the fault and calculating the cost of repair. Each job is individually assessed and quoted. If the repair costs are unacceptable the $110 is non refundable. Ongoing Hourly charge - $110 (parts additional). All service repairs carry a full 3 month warranty on work completed.
Where are you located? I have few amazing dbx 120xds, 3bxds, 10/20eq, Rotel rc1080, rb1080. I'd like to keep them for ever. And want to recap them if needed. I'm in Chicago. But would travel anywhere in usa to get best service. Pls share ur business details. Thanks
I’m sure there are several places that can repair it, but I’m not aware of any. I’ll fix it for free (minus parts and shipping). Email me if you’re interested. nick@duality-er.com
I am located in Minnesota. If you happen to be in the twin cities you could stop by. Otherwise, if you have something you’d like me to look at, you can email me at nick@duality-er.com with the details.
I certainly don’t pretend to be a chemist, but due to it’s chemical makeup (whatever that is), the glue, having been exposed to heat over many years, can harden and become conductive. When I say conductive, I don’t mean short circuit conductive. Even in the KOhm range, glue can cause issues in certain circuits.
@@dualityrepair4770 Next time you might just measure a resistance of a piece of some old glue. I doubt that it would be less than a few MegaOhms. It's true that a glue sometimes causes problems on PCBs with SMT components. But in the most cases it's not a glue itself but rather some flux residue deposits on a glue surface.
Wow very interesting video...you are the master and very professional engineer 👏 😊I have question please on my VINTAGE SHARP VZ 3510 VERTICAL LINEAR TRACKING RECORD PLAYER when I plug in the power and switch on and select radio or cassette player and there is no sound coming out from the speakers only loud humming / buzzing sound? But if I plug my headphones in the stereo I can hear sound on the headphones radio and cassette player as I was looking at the power supply and found the Bridge rectifier getting hot?and I have cleaned all the switches and pots with contact cleaner Hosa Caig Deoxit Contact Cleaner and still the same problem humming noise coming from speakers? This is the link for the service manual download elektrotanya.com/sharp_vz-3500h_vz3500hb_vz3500e_sm.pdf/download.html Please can please kindly help me on this issue 🙏 🙂 waiting for your kind reply Thankyou 🙏
If I were to choose between a new Rotel RB1552 mkII or a used rb 1080 for driving my dynavoice define 8 front speakers (23 - 32.000 Hz (- 3 dB) RMS 200W, max 280 Watt 94 dB dual 8" woofers and 6,5 mids) via my 5.1 receiver preouts, which one would suit me better? I guess the 1080 could be pretty old, is there any downsides to that? If i bought a new 1552 as mentioned I would get warranty and a new unit for the same price as a used 1080.
The downside is the lower output capability of the 1552 compared to the 1080 (130W vs. 200W). So, if you know you’ll be driving your speakers anywhere near that limit, I’d suggest buying a refurbished 1080. If you know you will not be going near that limit, the 1552 is a fine option.
@@dualityrepair4770 okay thanks. Well I live in an apartment and cant really blast that high of music. But I though there was some gain in bass controll or cone controll even if you dont use 200w per say. Also the used1080 would be the same price as a new 1552. Maybe eaven cheaper.
