Reel to Reel restoration - help needed

[ITChristian]

Hello!
I have a Jupiter 203 Reel to Reel Stereo, bought by my grandfather as new. I want to get it working like a new.

It was working almost very well, but it had some problems like a channel being quieter, not being able to record, slow forwarding, but after all a very nice and clear sound.

Note: All my tests were made using the integrated speakers / integrated amp + external speakers / external amp.

At first, I though it should be repaired by an electronicist (as I'm not one) so I found one but after his intervention it sounds worse. Really. He replaced the electrolyte capacitors, the head with a new, the belts...

I started to search for another electronicist, found one, but surprise... Even if he said it is now like a factory one, it is in the worst version ever. The sound is really unclear, with no treble, nor bass (even if only started in amp mode it sounds bad, unclear). It is also recording very but very bad, and it is really quiet. From time to time a vu-meter rises to the highest level and a loud "brr" sound appears. This electronicist also replaced the electrolyte capacitors, the belts, a vu-meter, again.

If you go to my profile you'll see that I am motivated to learn electronics. So I started with an online course (electronicstheory.com) which I just finished. I know I have much more to learn but it is a start point for me. Also I have started watching multiple videos on how to repair a reel to reel.

What I did:
- I tried to set the universal amplifier's variable resistors to default values on the electronic diagram. After that I was surprised to see that it plays no more quieter, and has a nornal volume.
- The sound was still unclear, but it started to sound well in amp mode, so I concluded this is now related to the head.
- I started to align the head by using a good music tape, then a "test tape" recorded by me on another good reel to reel playee, and I did the final calibration using a stroboscope. It really sounds fine now.

However, I still have following problems:
- recording is bad (one channel is quieter on recording, another channel is unclear
- one channel starts to play a "brrrrr" sound randomly so I have to set the volume to 0, then rise it slowly (I switched the universal amplifier modules and the problem moved to the other channel, so the universal amplifier produces this problem)

Can anyone tell me please what to try next? What could be generating the "brrrrr" sound and what should I do?

Also, I have attached the schematic (the plate on the top-left corner is the universal amplifier). Can anoyne explain me what is the use of the variable resistors which I spotted in the picture and how should I set them?

Thank you very much for helping me!



High quality schematics: https://ibb.co/SvngdWf

 

[daybreak2350]

First , I believe what you call "electronicist" I would term "technician".
I cannot speak to your technical issues but unfortunately it sounds like your technicians were not totally competent. Ideally you want someone who specializes in reel-to-reel decks and can trace a signal through the unit to troubleshoot and fix the record and play problems you're having.
How to find a specialist? Search the web (Google, YouTube, etc.) starting with Jupiter 203 Reel to Reel and drill down to what's out there regarding fixes and common problems; also search reel to reel repair services, find experienced tape deck specialist with solid reputation/feedback.

 

[ITChristian]

Thank you for your reply!

Electronicist = One who works with electronics. I though this is the proper term. Sorry, English isn't my primary language.
Unfortunately, both said they are specialists and also had good reviews... That's why I started to learn.

 

[daybreak2350]

Thank you for your reply!

Electronicist = One who works with electronics. I though this is the proper term. Sorry, English isn't my primary language.
Unfortunately, both said they are specialists and also had good reviews... That's why I started to learn.

Yes, I suspected English is a second language ;>)
**A quick search on YouTube shows several Jupiter 203 videos, also search repair. I suggest you disassemble and work on components systematically; not sure about your 203 but separate boards for different functions (like amps, preamps) are easier to access and work on. Study up on everything you can find on the web about the Jupiter 203, particularly troubleshooting and repair sources. After hours and hours of hands-on experience with your tape deck, learning how to replace old/failed components, repair electronics, and adjust mechanical linkages etc., then you will be the expert. Presumably you have a work space, the necessary test gear and tools, and can solder.
**I admire your spirit and wanting to learn how to restore your unit properly, to factory new operating condition, and I'm sure you'll get there with knowledgeable approach and good hands-on technical skills.
Let us know how it turns out!

 

[BrassTeacher]

If the tape deck still has its original electrolytic capacitors, they are probably due for replacement. Many humming sounds in old equipment are due to dried-out power supply filter caps.

Another thing to check - Have the tape heads been de-magnetized? Over time, playing tapes adds magnetism to the heads, which can cause an unclear sound. Using a de-magnetizing tool to reverse this can often clean the sound up significantly if the tape heads have built up strong magnetism.

 

[Richard P]

If the tape deck still has its original electrolytic capacitors, they are probably due for replacement. Many humming sounds in old equipment are due to dried-out power supply filter caps.

Another thing to check - Have the tape heads been de-magnetized? Over time, playing tapes adds magnetism to the heads, which can cause an unclear sound. Using a de-magnetizing tool to reverse this can often clean the sound up significantly if the tape heads have built up strong magnetism.

OP stated "He replaced the electrolyte capacitors, the head with a new, the belts..."

 

[gadget73]

Sounds like the head wasn't set up correctly when it was replaced. If this is a typical 3 head R2R setup, the general alignment process is to set the play head using a calibration tape for proper azimuth, then you put it in record mode and adjust the record head so the output in monitor mode is correct. basically you align the record head to the already-set play head.

There is also usually a bias current adjustment for record. The service manual should have this process in greater detail, but it all starts with an accurate alignment tape.

 

[ITChristian]

Thank you for your reply! This is an universal head (for both, playing and recording). I am pretty sure the head is properly aligned at this moment, but the recording is still bad (one channel quieter, and the other a bit distorted). I am searching for a service manual to be able to understand the schematics.

 

[Richard P]

I found a copy of the SM HERE. It's in DJVU format, but you can go to convertio.co and convert it to a PDF. I tried attaching it here but it's too large

I sent a pdf copy to be uploaded into the AK database but that will take a while . . . I'll upload it to HiFiEngine.com as well.

 

[gadget73]

probably bias adjustments not correct. Thats somewhat dependant on the specific head. With no or low bias the recording can be distorted or muffled.

 

[dr*audio]

I can tell you how to fix the "brrr" sound. Buy some Deoxit D5. Locate the record / play switch, which will be actuated by the record button. Inject some D5 into any opening in the switch and work the record button 30 times. Should fix that problem. If you can't get Deoxit in your area, you can try another brand of contact cleaner but it probably won't work because nothing else will remove oxidation from the contacts.