Відео

@@brucegreenberg1855 thank you

Loudspeakers were fine on that. Problem was the head preamplifier and the power amplifier.

Thank you, the android app I'm using (possibly exists also for ios) is "spectroid". Get it free from Play Store.

Ευχαριστώ, θυμάμαι βέβαια, καλή χρονιά !!

why ?? :) For having naked hands near the blade I guess... I survived finally 😊😊. Luckily I warned viewers on 4:36 so I am not gonna be sued 😏

@@mariosvalavanides6547 hi, send an email to dchatz@gmail.com with your info

@@dubdoodle7191 I know your solution I thought of it just in case but luckily the original worked

It's stupid that this sensing material just becomes brittle and falls apart. It's a dead end. Luckily gluing back some pieces partly restores it. The motor will not run completely smooth but on high speed it is not noticeable. I also had loose belt but I opened new holes for screws of the motor pulling it a bit to the left to tighten the belt a bit and that worked.

@@rottenrobbie66 generally so much heat should not happen. I cannot imagine where your heat comes from though. If it was a motor there would be some noise. You should open the machine, play it and trace exactly where the heat comes from

@ I took the cover off and did as you advised. It is coming from the motor. So I looked at the roller just past the capstan motor and noticed it was locked up and not spinning . After removing the screw I noticed that there are no spacer washers installed on this roller. So when the screw is tightened the roller locks up and won’t spin. This could be a possible cause of motor overheating from too much driving force on motor? What hardware should be installed on this roller to allow it to spin properly ?

@@rottenrobbie66 this roller should from factory not spin. Many replace it with bearing but factory installed there is no moving part

@@rottenrobbie66 which motor are you talking about? Capstan or reel?

@@dchatz ok isee now. so maybe i should look into brake system creating drag on motor . or maybe voltage supply issues?

Revox A77 is for me the king of servicing ability (plenty of space, discrete electronic parts found everywhere, removable cards, lots of info online etc). The motor of this here is a bit struggle to take out and put back.

@@dchatz So true !

You should say exactly where for me to understand. Guessing that you mean R121, R122, R123 on the "Tape Drive Control" (where the RIFA caps originally are), it would work but the spark suppression of the relays would be less efficient leading to more wear of the relay contacts. 4.7 is very common value at zero price available at every store. If you really only have 10ohms and you cannot get 4.7 at your area you may put 2X10ohms parallel to get 5ohms. You will loose some of the additional fuse purpose of the resistors but since you replace the RIFAs with new and reliable X2 rating capacitors I guess that will not harm.

@@dchatz to mean R121, R122, R123. One was burnt. I will buy the 4.7 though. Thank you very much for your help.

@@vitezmiroslav1389 it was burnt because a rifa was shorted obviously. Change the rifas even if they work. Otherwise you play it risky

@@dchatz ok. Thank you

@@dchatz 4.7 ohm, 2w or 1w? Thank you.

@@marconistars7384 there is always a better (but more expensive) way to do things. It depends on anyone's needs.

I didn't notice but anyway this is not part of the video goals. I have sold the unit now but certainly I noticed and placed a belt sometime. For sure I gave it with a working counter.

No, to take out the old ones, I heated the old solder and side by side I pulled out the old capacitor. Then I put the new ones again by heating up each side and pushing the cap in. I remember that they easily went in. I admit that opening the hole by sucking the old solder with a solder pump would be better practice as these pads tend to lift up and get damaged. I remember on another machine I had to add lines with wires because of pads that were lifted and cut away. I admit I'm not always doing stuff professionally.

I don't really remember what I did. Considering that readily available values today are 1000, 1500, 2200 I would say 1500 looks more suitable than 2200. I tried to see on the video what I fitted there but I did not find a frame where it's shown, maybe I missed it. Mine works as it is, so if you saw a 2200 that means it works like that. But if you now go for a recapping I would say, go for a 1500, if you have psychological urge to be exact, add a 100 in parallel to get exactly the 1600 as on the manual. Next time I open my Revox I will remember to check what value I fitted there because I don't remember at all. It's possible that if I fitted a 2200, I will replace it with a 1500, it sounds more suitable for sure. AAAAAHHHHHH now I remember, this is the mk4, I bought that with boards already recapped. I did not mess with the boards. Maybe the previous owner put 2200 and I didn't notice, I didn't even care at all to look the cap values. So you might be correct and spotted something I didn't spot. So as I said, mine works but 1500 is more suitable, 1500+100 is someone needs to be exact.

@@dchatzsorry I forgot to add the time stamp. I saw it at 16:13 . In any case thanks for your suggestion. I cannot find new 1600uF axial capacitors anywhere so I’ll look into your suggested cap values.

@@Dthebeatsmith oh yes, you are right, I never noticed and this is not done by me. So, simple answer, choose 1500 (which is available at local stores here) and if you worry too much add a 100 in parallel (I don't think it's necessary).

All the parts are in the video from 3:21 until 5:15. I also have a link to "mega" cloud with pics and the arduino sketch. To do this you need soldering skills, basic electronics knowledge, arduino knowledge, 3d printing capability and hand small constructions ability. You may send me a gmail if you need more info.

@@dchatz ok wo finde ich ihre Gmail ?

@@TheNannen501 dchatz@gmail.com

There is a small screw on the side of it. I am not exactly sure but I think it's an small allen screw. You will have to unscrew it.

@@dchatz Mulțumesc !

generally yes PB yes but will not record correctly. You will have to change the oscillator board (but there are rumors it is not absolutely necessary). After the change you will have to recalibrate the machine. Check here (it's for B77 but it's the same situation) www.tapeheads.net/threads/revox-b77-2-track-to-4-track-conversion-question.49613/

i don't think I am capable of getting into so detailed stuff. Look for a technician in your area. These machines cannot be fixed with videocalls.

@@MrBolopanos μετά την εγγραφή ο θόρυβος παραμένει και στην αναπαραγωγή; Γράφεται και στην ταινία ο θόρυβος;

@@dchatz έτσι φαίνεται. Βέβαια δεν υπάρχει δεύτερο μηχάνημα να παίξω άλλου την ταινία. Το ακόμα πιο περίεργο πως όταν κάνω μόνιτορινγκ την εγγραφή μου δεν μπορώ να ακούσω τον θόρυβο πάρα μόνο στην κανονική αναπαραγωγή.

@@MrBolopanos αν και θόρυβος τύπου ποπ δε ξέρω τι είναι θα έκανα μια αλλαγή πυκνωτές σε όλες τις καρτες

@@dchatz έχουν αλλαχθεί σχεδόν όλοι. Σκεφτόμουν μήπως έχεις το χρόνο και το κουράγιο να έβλεπες ο ίδιος εγώ έχω παραδώσει τα όπλα 😁

@@MrBolopanos δυστυχώς δεν είμαι τεχνικός και δεν αναλαμβάνω μηχανήματα άλλων γιατί πάντα υπάρχει ο κίνδυνος να κάνω κάνα χοντρό λάθος και μετά να μη βρίσκω λύση. Να βοηθήσω όσο γίνεται με όσα ξέρω ναι αλλά να αναλάβω μηχάνημα δε το κανω. Είμαι καθαρά χομπίστας και φτιάχνω/διαλύω δικά μου μηχανήματα.

If the problem is the switch then you have a problem on both FF and REW. If you have a problem only on REW your problem can be the rubber roller. Clean the switch anyway. I remember that this switch could be opened just by popping the upper cover with a screwdriver but not sure.Before doing anything check first the voltage on the motor. On normal playback it should be about 42V and on fast FF or REW it should rise to 48V (AC, not DC). If not then the switch is the problem. As I said I don't remember if I opened it. If it cannot be opened easily apply contact cleaner on any gap you can find that reaches inside and press it multiple times to act. Also check if it is indeed engaged by the metal plate when you select FF or REW. Good luck.

@@dchatz Thanks for a quick answer! No problems with fast forward, only rewind. I think it could be the rubber roller, when I test it works with no tape on the machine. When I put on a tape it does not work. Testing without tape and put a finger on the top of the tape wheel it stops working, ande the rubber roller slips. So it either the rubber roller or the "tape plate" that is warn out on the underside . It looks like a furniture cup at the underside of "tape plate" . Any ideas how to find a rubber roller or any ideas to fix?

@@DonaldThun rubber rollers cannot be found at reasonable prices. You can only grind the surface a bit with an electric screwdriver and a sandpaper. Check my video about SONY TC-200. Otherwise look for "www.terrysrubberrollers.com/" but I don't think you will agree with the price.

@@vitezmiroslav1389 I don't know. Sorry

@@dopo8333 if a head is not open circuit (not burned/blasted) then there is no reason it would not produce signal.

@@dchatz I have exactly what you have here: the same model, working mechanically, but no sound output. I'll start checking from source to output, like you did. I hoped there is a method of checking the heads themselves (it seems you say you checked them in some way).

@@dopo8333 First check the PB head if it has some resistance (which is good) or is open circuit (which is bad, BOGEN heads are notorious for getting open circuit). If it is NOT open circuit then check the head preamp output. Either by oscilloscope or by hooking it to an amplifier. When I say that the head is giving signal I think I meant it is showing resistance (to eliminate the factor that the head is blown). If you get no output from the head preamp I guess replacing all it's capacitors will fix this. Just to be sure check also the cable from the head to the head preamp to see if you have continuity and check to see if the resistance of the head is present by checking it where the cable from the head enters the head preamp. Wish you luck. Also there may be a short circuit after the output of the head preamp so disconnect also the output cable from it to check if there is output. Wish you luck.

this is the power of technology of today, knowledge sharing etc. I also grew up in the "books and friends" era but the youtube era is a revolution.

@@dchatz I agree with you. For the capstan shaft you had to do a delicate job. I remember that I simply ordered the high speed capstan back then. Of course all the frequency related components of the amplifiers had to be changed too.

@@wolfgangbachschwelloe1wbs905 nowadays original high speed capstan shaft is rare and expensive. Normal speed capstan shaft must be converted manually but you have to compromise for the accuracy. Very little but audible w/f must be accepted. Since I am an amateur it is perfectly acceptable for me.

Done that 40y ago to an old Grundig Tk27

I don't understand, what is "seapino", "threture", "earth display"

I am located in Athens - Greece. If you can bring it to me somehow I'd be happy to give some advise. But, I'm not a professional and I don't repair stuff for money. I don't take responsibility to repair other peoples machines. I'm open for any friendly advise you need. Just for what you mention as problem I can only understand that your machine requires a professional technician for check-repair-calibration.

@@dchatz can u send your whattsapp

@@vitezmiroslav1389 i dont remember but please download the 2 attachments. All values should be there. Otherwise the service manual also has all the values

@@vitezmiroslav1389 the new speed control board has a 10kohm pot

@@dchatz thank you

@@vitezmiroslav1389 sure. I also did that. 25 kohm pots cannot be found now

@@dchatz How many volts does it have to be? Does it adjust with it? Thank you.

@@vitezmiroslav1389 yes. And it must give 21v. Adjust it to about 21.4

@@dchatz Thank you very much.

@@vitezmiroslav1389 beware. I see that mine is 2.2 and NOT 22kohm

@@jurischott3189 i wish i could give a simple answer. On this machine i did not mess with the amplifiers. I would check if signal goes to the rec preamplifier. There should be a relay to arm the recording mechanism also on the relay board, i would find it looking at the service manual and see if it arms.

@@tommy33355 aliexpress

@@dchatz Hi, can you tell us the part names, i'm on alibaba now

@@blacknile1499 i have a series of videos with instructions how to build an oled vu meter with arduino. Please go and chech it to find all details.

@@blacknile1499 i also checked the video again and i see that i have shown all the parts one by one

@@vitezmiroslav1389 i am not at my computer for some days and i really dont remember. Did you check the service manual? All should be there.

@@vitezmiroslav1389 i think the one is 500 ohms and NOT kohms. But please look at the service manual.

@@radiotipo.studio thank you. Glad to help

@@vitezmiroslav1389 22k is totally fine

@@dchatz Thank you

@@dchatz Which is better, 2 or 4 track? Thanks

@@vitezmiroslav1389 4 track is more mainstream, 2 track is more headroom and zero crosstalk. 4 track is half the tape length. So you decide according to your expectations. If you want to record own music 2 track. If you want to listen to music and record existing material to listen to, 4 track.

@@BigTrouble324 thank you, will look at it but i think the problem can also be tapepath that has lost its straightness. Years ago that machine dropped on the floor 😞

@@dchatz Okay, that might have caused some damage. If one of the tape guides are bent or something like that, it can be a problem.

Well, sorry, mine did not have such a problem and I did not bother looking how to do this.