I recently found a broken TI Speak 'n Spell (end of the seventies) which contains a speech synthesizer.
The broken part was easily identified as there is a small PSU-board that generates the needed -3.5V and -12V from the 6V battery or power supply, which contained a completely fried transistor. I guess a wrong polarity or higher voltage adaptor was used.
I cleaned up, checked and replaced some components, only to find out that some coil used, creates a short circuit. That coil is needed for generating the -3.5V and -12V.
Does anyone have any idea what to replace it with,or what this component is and where to find it?
See the picture, it is the component with "7 7" on it, it is round and it contains 10 pins. Here is a schematic, which is NOT the schematic of my version of the SnS and its TDK PSU, but the coils are drawn here as separate coils, which they are not. Sent mail to the guy from Furrtek, he doesn't know. The only other source (Datamath.org) doesn't know either. A schematic of my version cannot be found, and a BOM which includes some part number for that coil either. I have searched for that coil / inductor / transformer, checked for TDK, tried to find pictures through Google, but unfortunately, I have not been able to trace that crucial component
.
This PSU board is actually a weird board, as it contains some logic for Start Up and Power Down, but also 2 isolated resistors for the loudspeaker.
The broken part was easily identified as there is a small PSU-board that generates the needed -3.5V and -12V from the 6V battery or power supply, which contained a completely fried transistor. I guess a wrong polarity or higher voltage adaptor was used.
I cleaned up, checked and replaced some components, only to find out that some coil used, creates a short circuit. That coil is needed for generating the -3.5V and -12V.
Does anyone have any idea what to replace it with,or what this component is and where to find it?
See the picture, it is the component with "7 7" on it, it is round and it contains 10 pins. Here is a schematic, which is NOT the schematic of my version of the SnS and its TDK PSU, but the coils are drawn here as separate coils, which they are not. Sent mail to the guy from Furrtek, he doesn't know. The only other source (Datamath.org) doesn't know either. A schematic of my version cannot be found, and a BOM which includes some part number for that coil either. I have searched for that coil / inductor / transformer, checked for TDK, tried to find pictures through Google, but unfortunately, I have not been able to trace that crucial component
.
This PSU board is actually a weird board, as it contains some logic for Start Up and Power Down, but also 2 isolated resistors for the loudspeaker.