UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players

Notices

Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

Reply
 
Thread Tools
Old 31st Oct 2018, 12:34 am   #1
NorfolkDaveUK
Hexode
 
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 411
Default Akai GX-77 cap list

Just wondered if anyone in their archives had a capacitor list for this machine ? , I just landed and absolute mint condition one and I want to re-cap it with top quality caps before I service it and put it up for sale I paid a good amount for it but I just couldn`t believe how clean it was (see pics ) I don`t think there is going to be a massive profit in it but to be honest I bought it to make it a stunning machine more than i did to make money , its SO nice i may even find it hard to let this one go ! Believe me , the pics look great , but in the flesh , its STUNNING.
Attached Thumbnails
Click image for larger version

Name:	s-l1600 (2).jpg
Views:	57
Size:	52.3 KB
ID:	171854   Click image for larger version

Name:	s-l1600 (8).jpg
Views:	49
Size:	55.9 KB
ID:	171855   Click image for larger version

Name:	s-l1600 (10).jpg
Views:	46
Size:	56.1 KB
ID:	171856   Click image for larger version

Name:	s-l1600 (11).jpg
Views:	47
Size:	50.9 KB
ID:	171857   Click image for larger version

Name:	s-l1600.jpg
Views:	44
Size:	44.8 KB
ID:	171858  

NorfolkDaveUK is online now   Reply With Quote
Old 1st Nov 2018, 3:40 am   #2
NorfolkDaveUK
Hexode
 
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 411
Default Re: Akai GX-77 cap list

its ok i got the caps list sorted , does anyone know where i can get a set of instructions for the relay mod for these ? I`m trying to figure it out but im getting confused about it and i really cant afford to mess it up

i get that the power for the relay board goes across the motor , i get that the input voltage is -5v , but im confused as to whats connected to the NO , I get that the NC is connected to the opposite motor, but whats the NO connected too ?
NorfolkDaveUK is online now   Reply With Quote
Old 7th Nov 2018, 10:55 pm   #3
Andrew64
Tetrode
 
Andrew64's Avatar
 
Join Date: Jan 2016
Location: Ramsgate, Kent, UK.
Posts: 79
Default Re: Akai GX-77 cap list

Hi Dave,

On ebay is advertised a relay kit, follow the listing down, there is a link to the vendors site, follow this and you will find a tutorial on how to install the kit.

Just had another snout, here's the link

https://sites.google.com/a/castelose...kai-gx-77-mod/

Go to No.3 the mod kit
__________________
Andrew

Illegitimi non carborundum

Last edited by Andrew64; 7th Nov 2018 at 11:03 pm. Reason: Checking link
Andrew64 is offline   Reply With Quote
Old 7th Nov 2018, 11:01 pm   #4
NorfolkDaveUK
Hexode
 
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 411
Default Re: Akai GX-77 cap list

Thanks Andrew much appreciated , I`m going to try the official Akai fix first but , you just change a few resistors , I`ll see how that goes and if that doesnt help it along I will look in to relay mod a bit further .

thanks bud
David
NorfolkDaveUK is online now   Reply With Quote
Old 7th Nov 2018, 11:06 pm   #5
Andrew64
Tetrode
 
Andrew64's Avatar
 
Join Date: Jan 2016
Location: Ramsgate, Kent, UK.
Posts: 79
Default Re: Akai GX-77 cap list

What is the official Akai mod?

The resistor on that little motor board in my machine is not the value as given on the schematic.
__________________
Andrew

Illegitimi non carborundum
Andrew64 is offline   Reply With Quote
Old 8th Nov 2018, 1:09 am   #6
NorfolkDaveUK
Hexode
 
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 411
Default Re: Akai GX-77 cap list

I havent read the memo in too much detail as yet bud but someone sent me the official memo from Akai which was to change i think its 3 resistors and its supposed to help the issue whether it does or not I have no idea. The darn machine is stuck in transit somewhere 5 days now so I`m praying it was packaged well . Once i read the memo I`ll let you know . Does your suffer the same thing ?
NorfolkDaveUK is online now   Reply With Quote
Old 8th Nov 2018, 10:34 pm   #7
Andrew64
Tetrode
 
Andrew64's Avatar
 
Join Date: Jan 2016
Location: Ramsgate, Kent, UK.
Posts: 79
Default Re: Akai GX-77 cap list

It's not as bad as some I believe, with 7" reels it will do a whole tape but is very slow toward the end, with 5" reels it stops when it's down to about 1/3" of tape on the feeding reel. I have stripped, cleaned and relubed everything bar the reel drive motors so it's almost certainly weak motors. I've tried putting a switch in series with the resistor/diode across the supply reel motor, that helps a bit but when the reel is going slow the resistor/diode will not be applying much breaking to the reel anyway.

There is a video on utube (Akai GX77 fast spool relay mod by Nick Adams 25 minutes long roughly) about a relay mod, you get a good view of the circuit but watch very carefully when he runs the machine post mod, several times when he stopped the machine from fast winding the tape momentarily went slack and then tightened up with a jerk so more work required me thinks, maybe a lower voltage to the motor, needs investigating more, I can see tapes being damaged as it stands.

As I say I will be interested in the Akai mod and I wouldn't mind a list of the caps to change either.
__________________
Andrew

Illegitimi non carborundum

Last edited by Andrew64; 8th Nov 2018 at 10:37 pm. Reason: Clarity
Andrew64 is offline   Reply With Quote
Old 8th Nov 2018, 10:43 pm   #8
NorfolkDaveUK
Hexode
 
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 411
Default Re: Akai GX-77 cap list

The problem is , the motors aren`t made to work on the opposite direction so the non powered spool just drags , and it sounds like yours is as bad as everyone's .mine does the same thing , lubing it wont help .

The official fix is ....

Change R1 on the intermediate boards from a 100ohm 3w metal film to a 150ohm metal film ,

also

change the following on the power supply board...

R1 from 2.2k ohm to 5.6k ohm 1/4w
R2 from 1.5 ohm to 1.2 ohm 1/2w
R3 from 1.3 ohm to 1.2 ohm 1/2w

Whether that is going to make any difference at all I have no idea .

I`m not a fan of the relay mod and I`ve seen it several times . If I have to go that route I will but I will explore every other avenue first I dont think the relay mod does the tape any good really .
NorfolkDaveUK is online now   Reply With Quote
Old 9th Nov 2018, 12:55 am   #9
NorfolkDaveUK
Hexode
 
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 411
Default Re: Akai GX-77 cap list

I just got mine on the bench and opened it up and mine already has these resistors in place so it makes no odds . Mine will do a 7" to 7" but put a 7" and a 5" on and its useless . Meh , I can live with that , its just an amazing player . My advice , just love it .lol
NorfolkDaveUK is online now   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 9:11 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Copyright ©2002 - 2018, Paul Stenning.