Singer HE-2200 Kids Record Player
Would not want you all to get bored troubleshooting quality gear, so here is some low end for you.
I was just gifted a non functional Singer HE-2200 record player from the 60's. (Phonograph sounds too snooty for this children's player.) I had one when I was a kid.
It wasn't doing anything except producing sound akin to white noise when I got it. I was able to free up the seized motor. Jury is out on the rubber roller for the rim drive but it might be actually be okay, much to my surprise.
But no audio except the white noise. This thing has a ceramic (mono) cartridge. I have tried connecting the cartridge to a variety of mic inputs and I get nothing at all from touching the stylus. To prove the test concept I have taken a piezo crystal headphone and connected to these various amps and I get loud audio including feedback. Most recent test was going into the solar cell input of a film projector and nada. I also hooked it to a scope. So the cartridge must be bad.
But I also get nothing from taking that same crystal headphone and connecting it to the record player's amp. So apparently the amp is bad too.
There is a remote chance that someone here is familiar with these and may know the common failure point in the tiny three (germanium) transistor amp.
But barring that bit of good luck I'm hoping someone can suggest a very simple (and cheap!) amp module that I can put in. It would need to work with a ceramic cartridge. I realize I can replace the cartridge and output to external gear but I'd rather recreate the original self-contained functionality.
You can find a LM386 amplifier module at DigiKey.com, however, you still need to add an emitter-follower in front for the ceramic pickup.
|
I'm going to look in to what can be done with the amp. I misspoke above, it is actually 4 transistors: 2 2SB54 one after the other on the input end and 2 2SB56X2 paralleled driving the output transformer, one driving each end of the center-tapped transformer input winding. (I think all are Toshiba. Maybe they made the entire little amp.) I cannot even find specs on the output transistors but given the static output I'm guessing they might be okay. The preamp stage transistors are available. I may go ahead and unsolder those two and see if I can make a rudimentary determination--perhaps look for the diode effect. I will probe around to see what I can find on the resistors and unsolder for a proper test if anything is suspicious. 60 year old electrolytics should probably be replaced but we'll see. |
The 2SB54 is a PNP transistor, so you can try a MPSA942 in its place. I could not find the 2SB56X2 but I did find a datasheet for a 2SB56, which is also a PNP unit. In that case, you can use MPSA92 for all the transistors. I suggest you try that first, as it is dirt cheap to experiment with the MPS transistors. Failing that, it might be easier to just build a small audio amplifier using one or two of the devices I mentioned in my first post. I guess it depends on how close to original you want to keep it. |
Here's the latest update. I unsoldered the two 2SB54s which seem to be a first and second stage of the amp. I did a very rudimentary test: Using the diode test feature of a DMM, I detected a diode effect (infinite resistance with meter leads connected one way, low resistance the other way) between two pairings of transistor leads on one of them but on the other I only got that effect between one pair of leads. I believe that one is likely bad. I've got a couple coming from eBay. |
