Hello DIYAudio
I have inherited a rare Mitsubishi MC-8000 aka X-10 ...
this is a Vertical Linear Turntable with a builtin Amplifier/Tuner/Cassette !
Date of build is 1981
Problems with its amplifier -
Appreciate any help I can get to get this working and keep it out of the trash!
Was told it powers up ok when it was given to me -
- however on power up the Right channel is silent.
Left Channel worked sort of - Sound could be heard but then the volume decreased and static heard - this happens intermittently
and at the same time the volume decreases the units VU Meters lamps would dim.!
After dissasembly I found right channel output Fuse F821 3.15Amp Blown
The Amps IC is a Sanken Dual Channel SI-1135HD - I believe these have been used in other Amps (Rotel) Only a couple on Ebay I could find
(however are they fake?)
Thanks in advance for replies - what are peoples thoughts... how best to test/check the module? - approach to finding the exact problem given the symptoms?
If it turns out to be the Sanken SI-1135HD wonder is a comparable alternative IC Amp available ?
Suppose if not and its the Sanken then I could try and retro fit a Class D Amplifier Module...
Any thoughts on the above most appreciated
I have inherited a rare Mitsubishi MC-8000 aka X-10 ...
this is a Vertical Linear Turntable with a builtin Amplifier/Tuner/Cassette !
Date of build is 1981
Problems with its amplifier -
Appreciate any help I can get to get this working and keep it out of the trash!
Was told it powers up ok when it was given to me -
- however on power up the Right channel is silent.
Left Channel worked sort of - Sound could be heard but then the volume decreased and static heard - this happens intermittently
and at the same time the volume decreases the units VU Meters lamps would dim.!
After dissasembly I found right channel output Fuse F821 3.15Amp Blown
The Amps IC is a Sanken Dual Channel SI-1135HD - I believe these have been used in other Amps (Rotel) Only a couple on Ebay I could find
(however are they fake?)
Thanks in advance for replies - what are peoples thoughts... how best to test/check the module? - approach to finding the exact problem given the symptoms?
If it turns out to be the Sanken SI-1135HD wonder is a comparable alternative IC Amp available ?
Suppose if not and its the Sanken then I could try and retro fit a Class D Amplifier Module...
Any thoughts on the above most appreciated
Attachments
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For an Amp replacement - Im thinking about the possibility of using an AMP circuit based around an LM8886 ..what is peoples thoughts using this chip for this receiver - Is the original power OK?...Original output specs of the sanken are 35w/35w.
Tone Controls are currently wrapped around the Sanken - anybody have an idea how I could get the tone controls to work with an LM3886 Amp Circuit? - Volume and Balance are prior to the Sanken in the Signal Path so assume they can be left as is.
Thanks
Tone Controls are currently wrapped around the Sanken - anybody have an idea how I could get the tone controls to work with an LM3886 Amp Circuit? - Volume and Balance are prior to the Sanken in the Signal Path so assume they can be left as is.
Thanks
3886 not in production.
Unless this is of sentimental value, buy another.
Or build a new one with FM / USB module, and a ready chip amp kit.
Look at Lunch Money Amp and similar projects.
Looks like AC 23V for amp side...many Class D options are available.
But you will not get cassette player parts, and records are rare.
So you will use it as an amp.
Clean it up, use as a shelf queen, and obtain another amp.
Unless this is of sentimental value, buy another.
Or build a new one with FM / USB module, and a ready chip amp kit.
Look at Lunch Money Amp and similar projects.
Looks like AC 23V for amp side...many Class D options are available.
But you will not get cassette player parts, and records are rare.
So you will use it as an amp.
Clean it up, use as a shelf queen, and obtain another amp.
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Any Amp options which would not affect FM reception? - Ive read posts that Class D amps do affect Analog FM Tuners
Here I get FM module + amps starting at about 7 pounds, brand new.
The module also has SD Card, memory stick, Bluetooth, aux, AND a remote.
Digital tuning, clear sound.
The chips on those are Chinese 4440s.
20W / ch / 8R. Enough.
Lunch money.
Leave that antique alone, as you have inherited it.
The module also has SD Card, memory stick, Bluetooth, aux, AND a remote.
Digital tuning, clear sound.
The chips on those are Chinese 4440s.
20W / ch / 8R. Enough.
Lunch money.
Leave that antique alone, as you have inherited it.
So need a 25 - 50w amp/module best option - preferably something that will likely not affect FM listening...also work with Supply Voltage is +/-30VDC
I know there are so many options - if anyone has got a thought what might be best - not looking for bluetooth/Digital tuners combined amps - just a straight Amplifier.
I came across an interesting possibility - whilst searching for a replacement Sanken..
Its an LM3886 based drop in replacement! - see pic
One question I have - It says in the description
"This board is designed to be used with a split power rail to give the lowest distortion and will require a capacitor to be bypassed on the host PCB - very easy to do."
My understanding is that I already have a split rail there being +30Vdc and -30Vdc or am I misunderstood?
I know there are so many options - if anyone has got a thought what might be best - not looking for bluetooth/Digital tuners combined amps - just a straight Amplifier.
I came across an interesting possibility - whilst searching for a replacement Sanken..
Its an LM3886 based drop in replacement! - see pic
One question I have - It says in the description
"This board is designed to be used with a split power rail to give the lowest distortion and will require a capacitor to be bypassed on the host PCB - very easy to do."
My understanding is that I already have a split rail there being +30Vdc and -30Vdc or am I misunderstood?
Attachments
That is for the experts to decide, as the heat sink mounting is an issue. This is similar to the old STK modules, and in those heat sinks were the main issue. The chips have to be properly bonded to the module, in turn that has to transfer heat to the existing heat sink.
Apart from that, it is difficult now to get any Class AB chip amps which are genuine and new.
In conclusion, try and find another amp, this will take a lot of effort and expense to restore. It depends on how valuable you think it is.
Apart from that, it is difficult now to get any Class AB chip amps which are genuine and new.
In conclusion, try and find another amp, this will take a lot of effort and expense to restore. It depends on how valuable you think it is.
I believe the replacement LM3886 Chips bond direct to the heatsink - (looking at the picture) The Module also itself bonds to the heatsink.
This job is a project Im happy to play with..as I have the time these days. If nothing else I will learn a lot for the next and just maybe we get this thing working.
Saying that - it would have been a whole lot easier if a Sanken was available in spite of the cost. Im yet to see any for sale I could trust.
If I dont hear from anyone here about which module may best suit I may just purchase a couple of relatively cheap Amp modules and see how they perform.
I know the original Sanken was common in a few receivers...so perhaps something for sale will pop up which is more genuine.
In the meantime I am curious if anyone else has thoughts on this LM3886 Drop in Replacement for the Sanken...
Currently I have a 120mmx110x45mm heatsink for the Sanken on the existing Amp.
You mentioned heat - now I wonder if the existing Heatsink will be up for the job.?
and of course not sure about the split rail needing a capacitor bypassed?
This job is a project Im happy to play with..as I have the time these days. If nothing else I will learn a lot for the next and just maybe we get this thing working.
Saying that - it would have been a whole lot easier if a Sanken was available in spite of the cost. Im yet to see any for sale I could trust.
If I dont hear from anyone here about which module may best suit I may just purchase a couple of relatively cheap Amp modules and see how they perform.
I know the original Sanken was common in a few receivers...so perhaps something for sale will pop up which is more genuine.
In the meantime I am curious if anyone else has thoughts on this LM3886 Drop in Replacement for the Sanken...
Currently I have a 120mmx110x45mm heatsink for the Sanken on the existing Amp.
You mentioned heat - now I wonder if the existing Heatsink will be up for the job.?
and of course not sure about the split rail needing a capacitor bypassed?
You could end up doing a lot of damage with fake chips.
Check out Salcon in India for a sample of what is available.
The reason I keep telling you not to mess around is that I am not sure of your level of expertise in this field.
The STK modules were infamous for going bang, catching fire, blowing transformers, speakers, and circuits in the process, apparently without any cause.
They developed from those Sanken modules.
Leave well enough alone.
There will be many aged and damaged parts there, a long and tiring job.
Check out Salcon in India for a sample of what is available.
The reason I keep telling you not to mess around is that I am not sure of your level of expertise in this field.
The STK modules were infamous for going bang, catching fire, blowing transformers, speakers, and circuits in the process, apparently without any cause.
They developed from those Sanken modules.
Leave well enough alone.
There will be many aged and damaged parts there, a long and tiring job.
Thanks for the Salcon tip I will look into what they have.
Yes Fake chips - thats what Im afraid of - there are two Sankens for sale on ebay at the moment - one says its NEW the other says REFURBISHED...the refurbished chip seller has a picture of the chip covering the pins...so assume its just a pulled chip from an existing device.
Have fixed a few things in my time - I know enough to have a go - and enough to ask if not sure!
Old gear can be inherently more risky I give you that - but also can be more interesting.
This a take it slow project - no rush.
Hoping someone please has a look at that drop-in module and could comment.
Thanks
Yes Fake chips - thats what Im afraid of - there are two Sankens for sale on ebay at the moment - one says its NEW the other says REFURBISHED...the refurbished chip seller has a picture of the chip covering the pins...so assume its just a pulled chip from an existing device.
Have fixed a few things in my time - I know enough to have a go - and enough to ask if not sure!
Old gear can be inherently more risky I give you that - but also can be more interesting.
This a take it slow project - no rush.
Hoping someone please has a look at that drop-in module and could comment.
Thanks
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This thread has not generated much interest but stll maybe someone in the future might get something out of it especially in regards to working out a solution to the lack of unobtanium Sanken SI-1135/1125-HD Chips
Plan A
And with that in mind I have spoken to the BMA company wrt to the Sanken SI-1125/1135-HD 'Drop-in' Replacement (LM3886 based) Amp Module...the company checked over the circuit of the Receiver and they believe it will work ok...with only a single Gnd Reference modification - (remove cap and join/short the remaining solder pads together to achieve that.)
So that replacement module is on order...will drop it in do the gnd ref mod and see if we have a winner.
Plan B
Now I have also ordered for two reasons a NobSound Ns-20G .. this if the replacement Module does not work out! -
Why the ready built Nob Sound
I looked at a gazillion Amp modules today etc etc...but in the end the Nobsound works out of the box has a separate power supply...I've just got to feed it a signal - plan to do that by tapping signal from the existing receiver volume control - if this works ..I would retain the use of the Receiver Volume and balance control - but not the bass and treble...
Plan B+
To get Bass and Treble as well...I could look at installing a tone/preamp board module with seperated Pots feed the board from the output of the output selector switch...install the pots into the existing Tone control locations on the receiver and feed the nobsound from the new tone board ..(all receiver controls would be removed)
Comments on the plans above welcome
Will be posting the results good or bad when the Module gets installed!
Plan A
And with that in mind I have spoken to the BMA company wrt to the Sanken SI-1125/1135-HD 'Drop-in' Replacement (LM3886 based) Amp Module...the company checked over the circuit of the Receiver and they believe it will work ok...with only a single Gnd Reference modification - (remove cap and join/short the remaining solder pads together to achieve that.)
So that replacement module is on order...will drop it in do the gnd ref mod and see if we have a winner.
Plan B
Now I have also ordered for two reasons a NobSound Ns-20G .. this if the replacement Module does not work out! -
Why the ready built Nob Sound
I looked at a gazillion Amp modules today etc etc...but in the end the Nobsound works out of the box has a separate power supply...I've just got to feed it a signal - plan to do that by tapping signal from the existing receiver volume control - if this works ..I would retain the use of the Receiver Volume and balance control - but not the bass and treble...
Plan B+
To get Bass and Treble as well...I could look at installing a tone/preamp board module with seperated Pots feed the board from the output of the output selector switch...install the pots into the existing Tone control locations on the receiver and feed the nobsound from the new tone board ..(all receiver controls would be removed)
Comments on the plans above welcome
Will be posting the results good or bad when the Module gets installed!
Worth checking the speaker relay. I've just swapped out the relays on Mitsubishi M-A01 amp due to some very similar issues with channels going quiet or getting crackling.
It's a very easy thing to check, as you just need to touch the positive of the speaker wire to the input on the speaker relay (D909 in the second image you attached in the first post) and see if that gets you a clean output. If it does, you've found the source of your problem.
Not saying this is your problem, but the silvering can come off the contacts on a forty-year-old relay easily enough, and it's a simple thing to check and a cheap thing to replace.
It's a very easy thing to check, as you just need to touch the positive of the speaker wire to the input on the speaker relay (D909 in the second image you attached in the first post) and see if that gets you a clean output. If it does, you've found the source of your problem.
Not saying this is your problem, but the silvering can come off the contacts on a forty-year-old relay easily enough, and it's a simple thing to check and a cheap thing to replace.
Thankyou - that's a good idea!
Only the one channel was crackling sort of working - I noted a blown fuse on left channel - Given the age thats when I ordered the new Amp module and some replacement Caps for the Amp and PSU.
All Boards are disassembled atm - still awaiting the replacement amp module from the UK..Covid is causing havoc with deliveries as Im sure many will be aware.
Im keeping all my options open on this one - as the process will dictate what solutions will work out best.
I will keep your idea in mind and will use it - its a great idea to prove the relay is the problem or not and quickly ! Cheers
Only the one channel was crackling sort of working - I noted a blown fuse on left channel - Given the age thats when I ordered the new Amp module and some replacement Caps for the Amp and PSU.
All Boards are disassembled atm - still awaiting the replacement amp module from the UK..Covid is causing havoc with deliveries as Im sure many will be aware.
Im keeping all my options open on this one - as the process will dictate what solutions will work out best.
I will keep your idea in mind and will use it - its a great idea to prove the relay is the problem or not and quickly ! Cheers
Hi all, I stumbled across this thread with great interest. I have one of the above systems and I'd be grateful if anyone could tell me how to locate the fuses mentioned in the OP. I've gone and blown the left channel fuse (i hope) all else is good and the left was good til I thought I'd try and get away with connecting the left speaker "live" my own fault I know.
Thanks
Steve
Thanks
Steve
Problem sorted, my impatience (which led me to have this problem in the first place) had me taking the back off and located the fuse pretty quickly, sure enough it was blown. As luck would have it I had an old receiver in the garage which had a comparable fuse in it, but it all started with the schematics posted here, so thanks very much indeed for that