AKAI M-10 Reel to Reel tape recorder - Page 1
Forum section: electronics / repair

author: abhi1981
author_rank: Regular Contributor
timestamp: July 30, 2023, 06:55:58 pm
content: Hello everyoneRecently got an Akai M-10 for around $141 (Rs. 12000) after a lot of hagglingPlay, FFWD, REW, auto reverse works, but no sound on playing a tape. Tape counter works, belt is loose. I checked the amp by aux cable through line-in, and one channel is working.VU meters are a bit sticky due to corrosion build-up. Lights are working.Opened it and there was tons of dust inside. And a lot of wax from a capacitor.Regarding the leaky cap, what should be a suitable replacement for it? These 2uf 250v caps come in lots of sizes - ceiling fans have large ones, but same one in an air conditioner indoor unit is quite small.

author: abhi1981
author_rank: Regular Contributor
timestamp: July 30, 2023, 06:56:54 pm
content: Some more pics

author: abhi1981
author_rank: Regular Contributor
timestamp: July 30, 2023, 08:35:42 pm
content: Did some googling.All the motor run capacitors have two values - one for 60Hz and the other for 50Hz. I need only 50Hz, but not sure which value.Used google to translate the Japanese text on the cap. It color dots represent the value of that terminal.

author: wasedadoc
author_rank: Super Contributor
timestamp: July 30, 2023, 09:48:25 pm
content: Quote from: abhi1981 on July 30, 2023, 08:35:42 pmShould be simple enough to trace which capacitors are brought into play by the 50/60 selector on the back.

author: coppice
author_rank: Super Contributor
timestamp: July 30, 2023, 11:26:47 pm
content: Quote from: abhi1981 on July 30, 2023, 06:55:58 pmIsn't inflation wonderful. That's more than it cost new.

author: abhi1981
author_rank: Regular Contributor
timestamp: July 31, 2023, 06:03:57 am
content: Checked the schematics, the 50Hz switch is just shorting the 1uf and 2uf pins of this cap, and the other two caps. This makes it a 3uf cap. The switch has already been factory set to 50Hz.A 3uf ceiling fan cap should work. A similar modification has been done in this video -I'll change this cap and clean the switches and then see whether there is sound.

author: abhi1981
author_rank: Regular Contributor
timestamp: August 01, 2023, 06:51:16 am
content: A 3uf ceiling fan cap worked. Also cleaned all the switches with contact cleaner.Now there is sound from tape playback, but right channel is still dead.

author: abhi1981
author_rank: Regular Contributor
timestamp: November 05, 2023, 03:57:42 pm
content: Changed all the capacitors. Lubed the motors. Fixed the VU meters. Fixed everything mechanical. Now its working perfectly mechanically, but extremely noisy during playback and recording. Lot of hissing and popping and hum at higher volume.Should I change the marked transistors on the preamp board? What should be the replacement for these?(pic shows the board with the old caps)

author: quadtech
author_rank: Regular Contributor
timestamp: November 05, 2023, 06:09:11 pm
content: https://youtu.be/QJwuqaDuuqI?si=vB9Fu04xP1KJrLmKhttps://youtu.be/0ikjHpZevQs?si=E7hev2Ak_63_NitvDid you replace the main filter capacitor. The YouTube links show a comprehensive restoration including the replacement capacitors and transistors.

author: abhi1981
author_rank: Regular Contributor
timestamp: November 05, 2023, 07:55:59 pm
content: Thanks for posting the video links. Very comprehensive.I have changed each and every electrolytic capacitor present in this machine.I have not changed the box type capacitors.

author: abhi1981
author_rank: Regular Contributor
timestamp: November 05, 2023, 08:21:13 pm
content: Just found out that those box capacitors are 0.1uf-120ohm snubbers.I'll change them with X2 ones.

author: David_AVD
author_rank: Super Contributor
timestamp: November 05, 2023, 08:39:03 pm
content: With all tape recorders that have a mechanical record switch, clean it (spray contact cleaner and exercise) as one of the first steps.Because they sit in the playback position 99.9% of the time they are often oxidised and a cause of audio issues.

author: quadtech
author_rank: Regular Contributor
timestamp: November 06, 2023, 05:28:12 am
content: Quote from: David_AVD on November 05, 2023, 08:39:03 pmTrue. and also check/clean for contact corrosion in the headphone / monitor jacks

author: abhi1981
author_rank: Regular Contributor
timestamp: November 06, 2023, 07:42:30 am
content: Quote from: David_AVD on November 05, 2023, 08:39:03 pmThanks for your suggestion. That was the first thing I did.But what I have learned from my experience is that contact cleaners do not work on hard oxidized surfaces. At the most they flush away dirt and other soft residue. Black hard carbon has to be scraped clean or by using hard chemicals - like acids.The best way to clean switches is to disassemble them and scrape the contacts clean. But sometimes it is impossible to disassemble a switch due to its design, then contact cleaner is the only option.

author: Jeff L
author_rank: Contributor
timestamp: November 29, 2023, 09:58:33 am
content: Regarding squeel on playback-- are you familiar with SSS? Certain makes of (old) tapes degrade with age and stick/release stick when going through the transport path. *Tapeheads. org* has lots of info./ lists of tapes to avoid.

author: abhi1981
author_rank: Regular Contributor
timestamp: November 29, 2023, 10:57:50 am
content: No, its not SSS. The squeal was coming from the speakers at full volume. Since then I have changed all the remaining transistors. The problem seems to have gone. Playback and recording is good. But, sometimes while recording, the left channel dies. Cleaned the record slider switches, but the problem remains.The only thing left was the AA072D ICs. Pins 7 and 8 of the left IC was kind of open (12 meg). It should measure 470 ohms. Upon desoldering, I found that it was working again. Maybe the heat of solder rejoined the connection inside. I reinstalled it and recording worked fine for sometime. But. now its back to square one. I have ordered the parts for making a replacement IC. I'll test again after installing the replacement ICs.The whole metal body of the recorder has a little bit of mains voltage on it. Not enough to give a shock, but I can definitely feel it vibrating under my finger. Is this normal or is there a leak somewhere??

author: walt_y
author_rank: Newbie
timestamp: June 26, 2025, 12:05:08 am
content: Hi there,How did you get on with this? I have an Akai-M10 and I'm in a very similar process, having issues with the preamp block. "but extremely noisy during playback and recording. Lot of hissing and popping and hum at higher volume" and left channel has recording issues.I'm about to pull out the PCB and look at replacing caps and transistors. The previous owner already replaced the AA072D ICs.Does the PCB just pull out?

author: abhi1981
author_rank: Regular Contributor
timestamp: June 26, 2025, 04:31:39 am
content: Hello walt_y,I gave up on my M10 as the rec completely stopped. Its playing fine though. It will be a future project.The pcb pulls out just like a pc card. There are screws at the sides and the grey colored connector is the slot.Before changing any caps, first clean the switches and pots, and check if the sound improves. Also check with an external amp because the inbuilt speakers are not of good quality.Also, before doing anything, photograph each and every connection because the service manual does not show any wire color coding.Please share the pics and good luck with the repair👍👍

author: abhi1981
author_rank: Regular Contributor
timestamp: June 26, 2025, 04:44:24 am
content: a very good videohttps://youtu.be/0ikjHpZevQs?si=Jpr5res5Tebn7bzR

author: abhi1981
author_rank: Regular Contributor
timestamp: June 26, 2025, 09:39:11 am
content: This is how the preamp board looks like

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: June 26, 2025, 11:05:07 pm
content: 2SC458 transistors had some batches that went noisy after time and maybe some others that might be in there.Jeff

author: walt_y
author_rank: Newbie
timestamp: June 29, 2025, 09:47:28 am
content: Thanks so much! Great tips, really appreciate it. I've been testing with line out / headphone out and line in as well trying to narrow down where the issues are. Thanks for sharing the video as well!I'll try to share some updates as I go.