Hi i bought a Sharp gf-9191 and i can not get the right channel to work in stereo its there but very weak, i have cleaned it inside out all the switches and sliders any one eles had this problem and solved it? Aparantly it is a common problem but not any forums on it. The right channel works in stereo wide and mono, i have also reflowed the amp board, any help would be appreciated thanks

Have you thought about recapping the amplifier board, that is replacing all of the capacitors in that area as maybe the electrolytic canister caps may have dried out and no longer function with the correct ability to hold a high enough electricity charge for the circuit that they are in?   Anything with caps in them especially the 'wet' type they do dry out over time and lose their ability to work correctly but simply replacing them sounds like about the only thing you have not tried yet?

Hi james thanks for the reply i think i will give it a try and see how it goes do you think it could be the amplifier chip? got everything eles working the tape deck ive worked on a few gf-9090 and gf-555 but not come accross this problem i think it could be a problem on the 2 bords on each side of the tape deck i have reflowed all the solder joints on there aswell hopefully it could be the capacitors on the amp board will give it a try over the weekend would maplins be the best place to buy them? Its a early gf-9191 with alnico magnets. I have cleaned all the potentiometers sliders with servisol and blown them out with a air compressor there all working fine.

I haven't been to the UK since 1974

http://www.maplin.co.uk/  

Caps are cheap to buy, tedious to put in with the correct polarity, and most of the time give the best rewards.

Amp chip would be on my list too, but it would be the last thing I would try since I have just about rebuilt the main board by now. and if that don't fix it - then get another one and start over  

Hi rsm148 - let us know how you get on with the recap - if it works then I would be interested to know what caps you bought and where from in UK ... as I have a an issue with popping on one channel of one of my 9191 boxes and I think this needs a recap too ... it is just that I haven't yet had any time to investigate what caps I need and where I can get them from in order to replace them in the 9191 amp board

Hi yes i will update this once i get around to doing it in a few days hopefully it works! I'll let you know what caps i use, going to recap the amp board and the board on each side above the tape deck with the controlls on.

Pictures would be nice to view too

Yep i will defo add some pictures aswell thanks for your help so far. Heres a pic of the 9191 was in some ones wardrobe for 15 years the guy had it from new.

Would be ashame to have to break it apart.

It was in a state when i got it full of dust and dirt but turned out nice once finished i gave the speakers a light paint with acrylic titanium white paint one speaker had some stains on look excellent now.

I would try other things 1st.....iv not heard of caps or chips going bad in these...

Have you tried the record bar...and does the speaker have the same resistance as the working one....

Try these 1st  ....there a lot easier to check than desoldering components....just a thought

Hi davebush yea i have a feeling the amp chip and caps would be ok, i have cleaned the record bar alot with contact cleaner and then air compressor i think it is working ok as it records fine the speakers are working fine aswell both work in mono stereo right channel is very weak and in stereo wide its also not got as much power as the left speaker ive had a look at the amp chips they are Hitachi TBA810SH 7W amplifier x 2 i had a look on ebay and i have just bought 2 as they are very cheap £3 all in 4 2 chips

Here is the link if any one eles is after them -

http://www.ebay.co.uk/sch/i.ht...stText=&_sacat=0

It seems to be like its not getting a strong output to the right channel amplifier the switch is working solder joints are fine record bar is fine see what happens in a few days when the chips arrive. Also the VU meters are working in all sound modes.

I'll give these a try first and update this forum and let you lot know if its fixed it or not in a few days.

Quick update i should have the IC amplifiers tomorow but i have found 1 dead transistor (A495Y NTE Equvilent NTE159 PNP audio amplifier transistor) that might make sence as to why 1 channel is dead and they only do these in america so will have to order this in might be able to borrow one from my 9090 box and see what happens aslong as its the same!

Myself being an ignoramus on testing circuit boards etc. ... how did you know the transistor was dead - can you tell by just looking at it or what test did you carry out to find this out?

I know capacitors sometimes bulge when they are on their way out but what about transistors?

Hi JT Techno finally getting there heres a video from youtube and the guy will tell you how to check transistors very eaasy with a simple multimeter

https://www.youtube.com/watch?v=_3G8t-cV1d8

transistors all look as they should you have to check the terminals if that video dont work just type checking transistor on youtube.

Thanks rsm - I'll take a look a bit later when I get some time 

Quick update i have ordered the transistor a similar one to the one thats been taken out hopefully it should do the job will be here in a few days heres the link of ebay

http://www.ebay.co.uk/itm/5x-B...;hash=item35d1352a36

i will update this and let you know if it is the fix im pretty sure it will be the new ic amplifiers will arrive tomorrow

Got the new IC amplifiers today made no diffrence swaped transisor around made no diffrence so ended up puting a wire from the yellow post to the blue and white post and stereo works as it should stereo wide works but there is slightly more bass on left speaker guno use it as it is now n come back to it later on must be a something wrong with that board heres some pics

The gf-9191 has really good bass and sound to it for its size its loud and clear shame it aint 100%

rsm148  I need a tech like you to come over the pond fix all mine

haha yea would be nice to get away fault finding electrics aint easy i do it as a hobby, thought it was the transistor but it aint in mono mode works 100% in stereo mode works 100% but in stereo wide just a bit more bass on the left speaker but atleast theres left and right channel now lol will find out what the problem is the amp aint getting the right channel signal being shorted or weak somewhere need to find out what it is a capacitor diode need some one who can read a schematic and tell me where the start and end is and what components are along the way

Its a fault on the volume board or the stereo wide board so its a case of replacing all the bits and bobs n see what happens but it aint easy getting all the parts the green capacitors

Got a Hitachi  3D80 coming tomorrow see what its like had one in the family when i was 3 picked one up working for £50 posted and won a hitachi TRK-7800E for 99p! fully working of ebay

will take it apart and give it a deep clean should be nice once done

I can do all - the problem is - my hands shake for the really fine detail - I cant solder a; ic  - bigger stuff no problem, but tiny things - nope.

Yea need a steady hand make sure not to short any thing best thing with soldering is using flux makes life so easy and solder goes where you want it to.

Hi JT yea there is something wrong with the tone control board capacitor or a brake then it leads to the amplifier there is a post with a yellow wire that leads to the right channel amplifier and a post with a white and blue wire that has the right channel signal i coneccted these 2 up and it seems to work but there is slightly less bass but there is indepented left and right stereo some where on the board is a fault not found it yet have a look at the pic. There could be a faulty capacitor on the board but my local maplins store is moving so not much stock will have to wait untill saterday to get the components on the board.

Hello, very useful information about this old beauties. Glad to find they are still loved by the people. Just got an GF-9090 by myself and I have exactly the same problems, the rubber for play and the Rh ch issue. Both channels working in Mono, almost nothing on Stereo and only a wide simulation in Wide mode

Tried to figure what exactly you have strapped with that wire, but my board is different. You said that you you've put together the right signal with the right ch amp?, can't figure where is this on mine, or not working. By touching the pin with the hand, you can hear the Lh and Rh channel, but can't make it work.

Your advise/help will be much appreciated, as I saw you already have a GF-9090.

Thanks,

Sergiu.

Hi I've fixed the deck on my GF9191 (belts/wheel/rubber sleeve/oil) and also the fault with the stereo. Worked fine on mono, on stereo left channel fine but right channel hardly any volume at all and on stereo wide both channels worked but right channel sounded weaker. I replaced the small top board with the switches on and now it works fine. It wasn't the selector switch and I suspect the fault was with one of the capacitors that surround it on the board.   

I've owned 5 of these boxes, and they all had problems with the stereo & stereo wide switch.  Sometimes contact cleaner is enough to fix it, but sometimes not.  Oh and the tuner glass is soft and low-quality, so it gets easily scratched and cloudy.  These boxes were designed in the late 70's before Sharp started to get serious about build quality.  Shame, because they're some of the best looking boxes.

Congrats on the fix! 

I've got two of these and have serviced two more and always felt they were good quality myself. All of them had the gooey tire issue and usual scratchy controls but all of them serviced well and were A1 once done. One of my favourites  

Thanks yes I have two as well. One is truly mint like new and the other is the one I worked on and gets used. I also had to fix the power on/off switch which wasn't latching down and did it without having to remove it or the board from the case.