[tim1]

I am working on a philco TPA-1 record player and here is the schematic for atachments.

[morzh]

And?

I mean, what is the question(s)?

Meantime, there isn't much to it, so if you have distortion (BTW what kind distortion?) - start with C1 electrolytic cap. May need to go. Unlike in tubes' schematics, it does not present any danger but might become leaky over time.
Check your batteries and your batter holders.
And check your speaker.

And if all checks out, your crystal pickup might be...worn out. Those used to cost pennies and sold separately. They (at least those I knew) were simply taken out by pulling them by the handle rotating it 90 degrees first and then the new one would go in in the reverse order. Took 30 seconds.

And, don't expect whole lot of quality sound out of this one. Asymmetric CLASS B output.....one is a follower, another is a Common Emitter......

BTW I believe they made a mistake in description saying all three transistors are "common emitter" - the lower L5022 is the emitter follower (common collector).


PS> BTW they have the troubleshooting right there in the manual. You need a scope for that but simply pulling and replacing transistors if you suspect them is easy.
I do not think you will have trouble with transformers - they are not subjected to any particular stress.

[tim1]

someone asked me to send the schematic and they asked what I was working on.

[morzh]

I asked you. But the structure of this site is such that this is the specific chapter where you discuss electronics fixing.

So if you list it, you probably do it for a reason and have questions.

[tim1]

The speaker and batteries are good I get low volume and the record sounds fuzzy out of the speaker. The cartridge comes out by removing 2 screws but the crystal ones are hard to get now a days.

[morzh]

1. Is the record good?
2. Does the volume regulator regulate volume?
Is the potentiometer in good condition? Of course the transformer is supposed to make the transistor's input look like a large impedance, but.....
3. What happens when the regulator at maximum?
4. Can you simply short the wiper of the regulator and its top pin (the one going to the crystal)? And then how does it play?

[morzh]

Have you checked that capacitor I asked about?

[tim1]

A friend checked the volume control and he said it was fine and it does lower and raise slightly. I have a in circuit capacitor checker and I can have some read it. where about is the c1 cap located thanks.

[morzh]

You cannot check the cap in-circuit, you have to take it out.
Or unsolder 1 pin (any pin) of R5 and then you can check the cap in-circuit.
It is C1 and is the only one electrolytic cap in the whole board it seems like.
measure the capacitance and if possible the leakage.
If you have any new cap of comparable (does not have to be exactly 40uF - could be 30, could be 100) and the voltage rating can be as low as 10V, so it is a cheap junk cap - simply replace it and see if it helps.

Watch the polarity. It will not blow up but the reverse polarity may lead to distortion.

[Ron Ramirez]

I moved the OP's post (first post in this thread) from an unrelated thread into this one, since it involved the repair of a Philco.

[TV MAN]

Here is a question I havent heard asked yet - what batteries does this use? What kind of batteries are you using? Akaline - OR some kind of rechargable?? I didnt see anything in the description about this using AA, C, D or just what kind. Might mention that at least the AA Ni-cad rechargables are 1.2V each instead of 1.5V like a non rechargable. Could be as simple as low voltage...

Tim

[morzh]

Well sch says +- 3V so we probably should be using 6 batteries. I suspect AA won't last long, at the size of it they probably could've used at least C size or maybe even D (Soviet portable radios often used D).

I hope Tim checked the batteries, otherwise it is a wild goose chase.

[tim1]

The TPA-1 takes 4 d batteries and I put 4 new ones in it.

[morzh]

OK, so they count on 1.5V under load from each battery.
This is probably why they also preferred Ge transistors, for the low power Vcc.

Anyways, have you check that cap?

When you exhaust all we outlined for tests before, might need to check the transistors. Just in case. They rarely go bad especially with this kind of power voltage, but who knows. Plus as Brenda told me today, some American Ge transistors are prone to the Tin Whisker plague (something I never encountered before) - could go bad for that reason, if not for the others.
Doubt it but the chance is non-zero.

[tim1]

a friend is coming over to show me which cap and I am going to put a new one in what about 30 mf at 10 volts?