Delatronics, I can’t thank you enough for sharing your wisdom on the A77!!! I’m about to undertake a full electronic and mechanical overhaul on my A77 mk4, and videos like yours are priceless...THANK YOU ;-) Please be safe, cheers!
Good Video. After many years, the glue that holds the meter arrow in the VU meter, destroys the pivot. If your good with surgery, you may be able to repair. There are some replacement VU meters that are just a tiny bit larger.
"I'm not charging too much on these units coz the pandemic has led to people not having too much money and I don't want to make the situation worse for them and people with a slightly technical bent of mind can sort this out " Wow..if we all had this outlook in life towards other people. ❤
The second switch from the left (NAB | Input | IEC) isn't just a tone control that you can set any way you like; it determines which of two standard equalization curves will be applied in playback (including monitoring off-tape while recording). Whichever one is underlined is the equalization that the machine records with; that's a function of which record amplifier card was installed in the machine during manufacture. Thus if you're setting up the machine, or playing back tapes that were made on it, this switch MUST be in the underlined position (NAB in this case; IEC on many machines sold in continental Europe). For all other tapes, the correct switch setting depends on the recorder that made the tape. --best regards
Thanks for a great video. I have a 2-track A77 and the VU meters only light during rec-mode as you say. Wish you had moved to Sweden instead of Brazil and then you could have helped me with service on the machines.
I recommend cleaning the brake spindles and replacing the brake fabric. Nagravox has a nice kit for this purpose. Adjusting the brakes is a trial-and-error process but the service manual explains this thoroughly. You will need a small spring-scale to properly adjust the brake tension. I found one a nice digital one online for less than $20 - the kind used to weigh airline carryon bags. Or one that fishermen use to weigh fish - sounds crazy but they work fine and don't cost a lot.
@@delatronics3257 Hi again could you possibly give me some advice? I have an A77 it plays fine foward rewind ect all ok the record meters show good level but when I actually record the sound is very low you can just about hear something when the volume is turned up to max I actually thought it wasnt recording just blanking out the tape until I turned it right up. Do you have any ideas what it could be? Thanks
@@ayepeemusic9543 check that the tape is even across the head, if the sound is muffled too; it's likely to be a bias problem, the bias boards should be available on eBay.
Great video ! I just got a Revox A77 and it won't play I try to remove the wood case ,removed all the screws and it's stuck I don't want to force it , theres any other way to remove it ? did you emigrated to Brasil ?
If you want a warmer classic tape sound the A77 is a great machine, but the Mk1 had better sound to me because of more transistors than ICs in the circuit. All the other marks sound similar but good, the B77 onwards look great but sound very thin and character less IMO.
Hey all, I have a problem, I want to set bias trap in rec mode and in playback mode. In rec mode I make it settings successfully the bias trap , but… in playback mode the bias trap is unable to set in the Chanel 2 with coil L801. I screwing with the screwdriver the core of coil L801 but no changing in milivolts. In Chanel 1 I make it setting successful (less then 50mv) but in Chanel 2 no modifications. I changed the repr. Ampl. Card with card in Chanel 1 thinking the coil L801 is defect but no changes ! What is the problem??
You can download a service manual for this model and fault find. You have already done what I would have suggested. Parts for these are freely available on ebay. I haven't had any Revoxes for over 2 years and I live in Brazil now, if my memory serves me correctly, there is a bias card in this unit.
Thanks for great video. Mine has CH I & II audio going into VU's ok. No audio present on just CH2 from RCA & headphone outputs. I even swapped Repro pcb's and same issue exists. Any suggestions ?
I am no longer in England and don't buy these anymore. Download a service manual for this model free online is my advice. I recall I had a problem on the meter board like this once but don't remember the component. Electrolytic capacitors would be my guess.
Hello sir.I saw your restoration..I was referring to the my revox a77/mk4 that goes below normal speed in play..it goes below normal speed but constantly.. kind of 18 instead of 19 ...what could be ?? Thank you Laurentiu....@
I can see that you have lots of experience with Revox , I need to ask you about I just bought a Revox A77 MK IV it rewinds and fast forward but when I hit playback the capstan engages but freezes nothing happen . where could be the problem ?
There are a lot of posibilities, belt, lack of lubricating, spike capacitors (Rifa). If you want to service yourself, you can get a free service manual on line.
All electrolytic capacitors have a limited life of between 2000 hrs and 80000 hrs, depending on maker; Revox used reasonable quality and no cheap Chinese rubbish. Other types of caps have very long lives (eg. Poly, paper/oil, ceramic etc) só there's no need to replace them unless you are replacing for better quality to improve sound. The Frako caps used in this machine are I believe electrolytic and do have a poor reputation; so yes, do replace these whilst the machine is open.
hi sorry to be a pain i have a acc with RS what's the make's of the caps that you recap as RS do the listing by what they are made out of not the make some are makes
I get my caps from Digikey. They work fine. I have had good results with Panasonic, Nichicon, Vishay. The A77 uses at least a dozen different sizes and capacities of capacitors. To do a full recap, you need the part lists in the Service Manual. Specifications are listed but assume all brands in the SM are now considered obsolete parts (i.e., no longer available). Use the specs to locate replacement caps. Pay attention to the farad and voltage ratings. Or to simplify, buy a recap kit from Nagravox - it has exactly what is needed, nothing more. Instructions and after-sale support is very good. I recommend an LCR meter (Amazon has them) to measure the caps. And a decent digital multimeter.
When I replaced the capacitors I used Vishay of the same rating and safely level bought from CPC or RS Components. Just don't use Chinese cheap rubbish! At the end of the day, they are only spark suppressors; the machine will still work with the parts removed...
Delatronics, I can’t thank you enough for sharing your wisdom on the A77!!! I’m about to undertake a full electronic and mechanical overhaul on my A77 mk4, and videos like yours are priceless...THANK YOU ;-) Please be safe, cheers!
Good Video. After many years, the glue that holds the meter arrow in the VU meter, destroys the pivot. If your good with surgery, you may be able to repair. There are some replacement VU meters that are just a tiny bit larger.
"I'm not charging too much on these units coz the pandemic has led to people not having too much money and I don't want to make the situation worse for them and people with a slightly technical bent of mind can sort this out " Wow..if we all had this outlook in life towards other people. ❤
Well, thank you for the info on this REVOX….May God bless you in Brazil..
Thank you Sir. I've just has TWO of the Revox model A77 come into the shop. This will save me MUCH grief. God bless ya
Thanks, God is blessing me (as always). Happy I could help.
The second switch from the left (NAB | Input | IEC) isn't just a tone control that you can set any way you like; it determines which of two standard equalization curves will be applied in playback (including monitoring off-tape while recording). Whichever one is underlined is the equalization that the machine records with; that's a function of which record amplifier card was installed in the machine during manufacture. Thus if you're setting up the machine, or playing back tapes that were made on it, this switch MUST be in the underlined position (NAB in this case; IEC on many machines sold in continental Europe). For all other tapes, the correct switch setting depends on the recorder that made the tape. --best regards
Thanks for a great video. I have a 2-track A77 and the VU meters only light during rec-mode as you say. Wish you had moved to Sweden instead of Brazil and then you could have helped me with service on the machines.
The Rifas were good, too. No one planned for them to be used for 40 to 50 years...
Hey just acquired one of these do you have a video on brake adjustments and buy the way I really enjoy your simple talk over tecno speak thank you.
I recommend cleaning the brake spindles and replacing the brake fabric. Nagravox has a nice kit for this purpose. Adjusting the brakes is a trial-and-error process but the service manual explains this thoroughly. You will need a small spring-scale to properly adjust the brake tension. I found one a nice digital one online for less than $20 - the kind used to weigh airline carryon bags. Or one that fishermen use to weigh fish - sounds crazy but they work fine and don't cost a lot.
Very valuable information thanks! Do you know anywhere that sells the VU meters in the uk I'm struggling to find one?
I live in Brazil nowadays but ebay is likely to have them, or there's a place who specialise in Revox in Australia.
@@delatronics3257 Much appreciated. Thanks mate!
@@delatronics3257 Hi again could you possibly give me some advice? I have an A77 it plays fine foward rewind ect all ok the record meters show good level but when I actually record the sound is very low you can just about hear something when the volume is turned up to max I actually thought it wasnt recording just blanking out the tape until I turned it right up. Do you have any ideas what it could be?
Thanks
@@ayepeemusic9543 check that the tape is even across the head, if the sound is muffled too; it's likely to be a bias problem, the bias boards should be available on eBay.
Great video ! I just got a Revox A77 and it won't play I try to remove the wood case ,removed all the screws and it's stuck I don't want to force it , theres any other way to remove it ? did you emigrated to Brasil ?
Yes I work and live in Brazil. Unfortunately there are not so many Reel to reel machines to service here, but I other audio related stuff.
Great I’m from São Paulo where are you staying?
@@imsaint007Meu assistência Delatronics.com ficar no Curitiba
Hello and thank you for the video, my question is can you recommend the Revox A77 mk3 or something else, best regards
If you want a warmer classic tape sound the A77 is a great machine, but the Mk1 had better sound to me because of more transistors than ICs in the circuit. All the other marks sound similar but good, the B77 onwards look great but sound very thin and character less IMO.
I did not find 20 kohm potentiometers. Maybe 22 or 25 kohm? Thank you.
@@vitezmiroslav1389 that would be OK
Bellissimo
Great video mate. Do you have to remove the power supply board to recap and also the relay board? Or can you recap while in the machine? Thanks
It's probably a good idea to remove the boards but I managed to replace the spark supressor caps on the relay board without removing it.
Hey all, I have a problem, I want to set bias trap in rec mode and in playback mode. In rec mode I make it settings successfully the bias trap , but… in playback mode the bias trap is unable to set in the Chanel 2 with coil L801. I screwing with the screwdriver the core of coil L801 but no changing in milivolts. In Chanel 1 I make it setting successful (less then 50mv) but in Chanel 2 no modifications. I changed the repr. Ampl. Card with card in Chanel 1 thinking the coil L801 is defect but no changes ! What is the problem??
You can download a service manual for this model and fault find. You have already done what I would have suggested. Parts for these are freely available on ebay. I haven't had any Revoxes for over 2 years and I live in Brazil now, if my memory serves me correctly, there is a bias card in this unit.
Thanks for great video. Mine has CH I & II audio going into VU's ok. No audio present on just CH2 from RCA & headphone outputs. I even swapped Repro pcb's and same issue exists. Any suggestions ?
I am no longer in England and don't buy these anymore. Download a service manual for this model free online is my advice. I recall I had a problem on the meter board like this once but don't remember the component. Electrolytic capacitors would be my guess.
@@delatronics3257 ok that makes alot of sense. Perhaps the signal goes from meter board to the output. Worth a check - thx mate from Canada
Hello , how do I replace that white next to the play head ? theres replacement for this bulb ?
The end of tape lamp is a common part available on eBay.
@@delatronics3257 Thanks for the info , that tape lamp controls the playing command ? , mine is not playing just rewind forward
I just ordered it coming from Germany @@delatronics3257
Hello sir.I saw your restoration..I was referring to the my revox a77/mk4 that goes below normal speed in play..it goes below normal speed but constantly.. kind of 18 instead of 19 ...what could be ?? Thank you Laurentiu....@
I can see that you have lots of experience with Revox , I need to ask you about I just bought a Revox A77 MK IV it rewinds and fast forward but when I hit playback the capstan engages but freezes nothing happen . where could be the problem ?
There are a lot of posibilities, belt, lack of lubricating, spike capacitors (Rifa). If you want to service yourself, you can get a free service manual on line.
Great tanks for the info ,the first thing that I looked was belts but I did not see any belts on mine. @@delatronics3257
Could you please recommend a list of Caps needed to restore a B77. thanks
B77 service manual has full details of caps and ratings. Easy to find on line. Too many to list here.
If it ain't broke don't fix it
What is a GOOD substitute for those failed RIFA caps? Thanks
Panasonic are good PSU caps
Vishay are the ones I used but Panasonic are good too and less expensive
would you recommend replacing the Frako caps as well? many sources I’ve read say they tend to go bad too.
All electrolytic capacitors have a limited life of between 2000 hrs and 80000 hrs, depending on maker; Revox used reasonable quality and no cheap Chinese rubbish. Other types of caps have very long lives (eg. Poly, paper/oil, ceramic etc) só there's no need to replace them unless you are replacing for better quality to improve sound. The Frako caps used in this machine are I believe electrolytic and do have a poor reputation; so yes, do replace these whilst the machine is open.
hi sorry to be a pain i have a acc with RS what's the make's of the caps that you recap as RS do the listing by what they are made out of
not the make some are makes
I get my caps from Digikey. They work fine. I have had good results with Panasonic, Nichicon, Vishay. The A77 uses at least a dozen different sizes and capacities of capacitors. To do a full recap, you need the part lists in the Service Manual. Specifications are listed but assume all brands in the SM are now considered obsolete parts (i.e., no longer available). Use the specs to locate replacement caps. Pay attention to the farad and voltage ratings. Or to simplify, buy a recap kit from Nagravox - it has exactly what is needed, nothing more. Instructions and after-sale support is very good. I recommend an LCR meter (Amazon has them) to measure the caps. And a decent digital multimeter.
When I replaced the capacitors I used Vishay of the same rating and safely level bought from CPC or RS Components. Just don't use Chinese cheap rubbish! At the end of the day, they are only spark suppressors; the machine will still work with the parts removed...
ace man i know about that place i know RS are very hast one shipping to me next day
revox a77 / mk4
Rifa RS don't stock this is the thing
Nagravox has green polyester capacitors what are excellent replacements for the RIFAs