hello TapeFreaks so... after resurrecting my purchased from new at the dawn of time in another century Im sadly confounded by the frankly abysmal MegaBass ... looking at the service dox and with the back off one cant fail but notice the flexi connector to the door mounted controls. Seems to me theres a way into this without resulting to vandalism. Have a gander at the schematics... are the front faders and switch in the audio path? Clearly a break out here into a better output solution is possible... bypass the tacky headphone ic while we’re at it... plenty of room inside for more improvements. Stop me before I commit ... any sensible suggestions gratefully accepted. thankyou for listenin..
ok... here’s more to see in no particular order... the DBB unit is in the door.. faders on the front of that... theres a flexi inter board connector cable running from inside offa the main pcb to it... which is begging to be used otherwise..
now.. Im not trying to lead anyone astray with me solderous benz .. as the sokkit is allready there, just callin to me.. and well, theres a lorra options for the brave. Are there any other Walkmans that are so open to abuse as this? Please... feel free to share. Thankyou for listenin
Alot depends on whether they rely on that DBB block for gain. If they don't you could link it out. It wouldn't surprise me if there was a cheaper model using the same main PCB but without it fitted.
interesting... well the tape head uses a similar entry . .. then to the front half of the LA4570M... then out to the DBB module... back in for dobblee and the pityful gain out in the second bit of LA4570M! one could choose a new flavour anywhere... keep the biasing half of LA.. lose the DBB.. insert a daughter board with a nicer cleaner linear head phone amp to the trs sokkit adding an extra vol pot or do the opposite...or go from head to out with a custom circuit of ones own choosing! Im trawling for schematics and ic data sheets .. even the handy ready made pcbs on the ‘bay offer a better chip set. So if anyone has opinions to share .. pray please do.. im agog! Surely someone has tore into one of these oportune machines? again thankyou for your ears
I can not understand if you want to bypass the chip because it does not work ... if you can try this way ... sorry but I use the translator and I can not understand what you would like to do
yes... this is possible. Perhaps i should be clearer. 1. Firstly .. the Walkman works. Its had a long twenty odd year rest on my shelf. I replaced the belts, cleaned the remains of the originals away completely with isopropyl alchohol. Then went all over it removing every last speck of dust. No dried grease in this model with white cogs.. Cleaned the head.. demagnetized...applied tiniest dabs of Deoxit D5 and Deoxit Fader where appropriate. All switches and faders quiet and crackle free. 2. New quality rechargeable batteries. 3. With a test tone tape I made before inside ready to play, from my oscilloscope I hooked up a set of probes to my output jack.. and a second set to the set of probes from the second input of the scope I had ready to inspect along the audio path. 4. Play back commences.. with meagabass off i can now see left and right outputs as a waveform. Showing expected slight inbalance but close enough for a portable. 5. Leaving left connected.. trace path from the head through to the final out on pin 7 of IC301 the Lm4570M. 6. Same again for Right after moving output probes to Right out.. end at pin10 of the IC301 the LM4570M. OK .. now i have an idea and can make an observation about how the circuit and the test tone interact. Well, the DBB module is not helping. It is operated by two teeny faders that traverse 10mm and colour the audio a lot. There isnt a sweet spot at all.. choice level slightly shy of half way to overloading muddy detailess noise within a mm or so.. at full on its essentially shifted the slope very unmusically and clipping on the bass and introducing what seems phase anomalies and disortion in the treble. But it does work and the LM4570 is doing a minimum of gain politely. Ok.. now i enjoy a brief period getting to know my old friend... play some tape... oh god yes! Well.. a short four hours later and .. well .. it started .. I felt let down, i want more.. So i switched to my goto and listened to a few of the tapes id just suffered in the WM-B19. Better. Tape sounded exactly as i had recorded it. At this point ... not being shy under the lid tools and probes at hand. It occured to me that the Sony is wide open to accept optional alternatives.. one doesnt have to settle for anything in there if one so desires. An early replier has suggested that perhaps other machines are as moddable.. its true! Today I saw several and have the service dox to read at my leisure. So where was i ? oh yeah.. Exactly i could jumper the W302 sokkit and no more CXA1249M... I could also fit a nice bit of real linear gain. Clearly the LM4570M is expecting a lift from the door... This is where I joined all you wonderful freakyTape people ... to share ... maybe find a hint ive never considered. There is benz in here this machine. No vandalism neccesary... conform to the Vcc thats it. My WM is a healthy girl, there is space in the trunk.. plenty of room for a daughter board. Im a engineer .. neither optimistic nor pessimistic.. its clear to me the gain is flexible in there. Why would i think anything else, ive had it since the early 90’s... it aint ganna go.. and its fixt a’ready now. Ceptin that freakyTape loving thing of knowing how great tape sounds.. So whaddya think? Capacitor value tweaks? New daughter board with a matched transister pair for each channel? a diode ring of gentle compression? Transformers Jensen Sowter and Lundahl? a blue covered page from the BBC departmental archives? There is listening to do!
so it works but you would like to edit it by putting a new audio electronics .... here are other models similar to your My cheap Sony Walkmans | Stereo2Go forums
yes... exactly Silver965. I want to exploit the circuit. Id like to add something to its glory as it passes through its twilight years. I dont want to discard it for being what it is but put some Stereo2go quality appreciation applause in there. Why? Because. im awake and i breathe and im a TAPEFREAK. ],) thanks for the links... i’ll devour them now
