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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Mon 27, 2020 1:32 am 
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Joined: Aug Wed 24, 2011 4:35 am
Posts: 4970
Location: Sunnyvale CA
SpaceFerret42 wrote:
This particular unit is a mix of pcb and point to point wiring but all caps in it from factory are either axial pio caps or radial ceramic disc caps with a few mica thrown in



Sounds straightforward, then. The ceramic and micas are probably fine, replace the paper/PCB caps with axial film caps, good to go.

Brett


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Mon 27, 2020 1:38 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
My thoughts exactly already got the new caps ordered.
will probably end up getting another set of matched output tubes as I always heard once a tube red plates it's shot for ever


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Fri 31, 2020 12:44 am 
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Joined: Nov Thu 07, 2019 11:11 pm
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I think replacing the caps in the audio section did the trick no more red plating and it sounds great haven't done the caps in radio section as it tunes fine but have them if they become a issue


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Fri 31, 2020 12:48 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
only remaining issue is the am tuner does not look but looking at the schematic I think it is because the 6r-e13 is burnt out correct me if I'm wrong but looks to me as it is part of the take off to the amp


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Fri 31, 2020 3:14 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
I know i should go ahead and replace the pio caps in the runer section as it is a matter of when they'll fail not if but am worried about having to realign it plus the i feel as if my soldering iron isn't regulating temp right any more as at least 3 traces where lefted from the board on the preamp pcb while replacing its caps but was able to fix by soldering leads across bad section but the tuner board is more busy and worried i might accidentally short something


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Fri 31, 2020 5:37 pm 
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Joined: Aug Wed 24, 2011 4:35 am
Posts: 4970
Location: Sunnyvale CA
SpaceFerret42 wrote:
I know i should go ahead and replace the pio caps in the runer section as it is a matter of when they'll fail not if but am worried about having to realign it plus the i feel as if my soldering iron isn't regulating temp right any more as at least 3 traces where lefted from the board on the preamp pcb while replacing its caps but was able to fix by soldering leads across bad section but the tuner board is more busy and worried i might accidentally short something



Having the traces delaminate is extremely common on circuit boards of this vintage. I have never worked on a ROTEL that old but just about all the others from this era are extremely fragile.

If you are just talking about the paper capacitors in the tuner section, the chances that they will have any significant effect on the alignment are slim. The capacitors that are involved with the RF front end alignment are typically ceramic or mica and have values in the low picofarad range. Having said that, getting tube FM tuners to work properly can be a very frustrating experience sometimes, and don't expect miracles.

Be sure to suck each terminal with a solder sucker clean, don't just heat it up and pull it out. That will minimize the chances of damaging the traces. Also, suck it clean after the part is removed, so you won't push the trace away trying to insert the new part.

If it was me, I would just go in and replace any paper caps anywhere in the unit, and see what happens. Presumably it doesn't work now, it's not likely to get any worse than dead by the attempt.

Brett


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Fri 31, 2020 5:57 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Actually right now the fm section works great its only the am that is still mia cant check the phono pre amp section until my record player is fixed waiting parts for that. Will see anout ordering a vucuum desoldering iron to help with desoldering have never been good with the heat and pulse sucker method


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Fri 31, 2020 7:04 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
In fact the fm tuner on this thing amazes me its so sensitive that its picking up stations i didn't know existed around here plus i have to turn the gain on my antenna amplifier down to avoid over driving it. Only thing odd that i have noticed is upon power up it sounds odd while warming up and occasionally i need to move the tuning knob a inch in one direction or the other to get the station locked back in sometimes i even need to turn off the afc circuit before it'll pick it back up. Dont know if this is just a common thing with tube fm turners or indication of a problem


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Jan Fri 31, 2020 10:56 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
anyone know where to get some bulb covers for the pilot lamps when naked they tend to wash out the stereo indicator lamp


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Sat 01, 2020 3:59 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
never mind found some yellow ones on amazon would have preferred teal or some blue tint but all well


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Sat 01, 2020 8:17 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
oops didn't order enough capacitors there is some hiding behind some switches


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Sat 01, 2020 11:39 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
oops didn't order enough capacitors there is some hiding behind some switches


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Tue 04, 2020 3:18 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Well finally got all the pio caps out and replaced with quality modern foil caps only 2 left to replace are behind the loudness switch and part of that circuit


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Wed 05, 2020 4:10 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Okay this is weird it has just started red plating 3 of the output tubes again not sure if some of the new caps failed or if i just have 3 tubes that was killed by the original caps


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Wed 05, 2020 11:31 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Okay its just bad tubes swapped one of red plating ones with the one not red plating and issue followed the tube


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Thu 06, 2020 12:34 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Okay found the actual problem one of the 12ax7's filaments was failing causing it to fliker bright and dim and since it was probably the one that is a cathode bypass resistor for the 6bm8's it caused all of them freak out when ever it opened for a second


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Mon 17, 2020 3:16 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Okay now I am perplexed it is acting up again with one 6bm8 red plating and 2 12ax7's not glowing right when it does this wondering if I should just replace the 6bm8's as the one that red plate will do so regardless of position or should I replace all the 12ax7's as well since 2 of their filaments in parallel are the cathode bypass resistor for the 6bm8's?


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: Feb Wed 19, 2020 3:00 am 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Okay apparently some dirty tube sockets was causing the issue here plus the 12ax7's are burning out wonder if they are being driven with too much filament voltage somehow


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 Post subject: Re: Roland/Martel (Rotel) FAX-200C
PostPosted: May Mon 11, 2020 10:15 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
Okay question is it possible that having the cord in backwards is causing one of the 6bm8 output tubes to redplate
plug cord in one way and new tubes redplate in one socket put old tube that didn't redplate back in and reverse the cord it doesn't redplate


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 Post subject: weird red plate issue
PostPosted: May Tue 12, 2020 11:11 pm 
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Joined: Nov Thu 07, 2019 11:11 pm
Posts: 95
I have noticed that if i plug the power cord one way on my rotel fax-200c one of the 6bm8 tubes red plate but if I reverse the cord it works fine.
Is this normal or can some one point me in the direction of the cause?

{Moderator note: This new topic about the issue was merged with the original thread about your Rotel receiver. Multiple threads about the same item is not allowed.}


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