Thread Rating:
  • 1 Vote(s) - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Philco TPA-1
#16

That would be just dandy.
#17

You might try injecting a low level signal from a source such as the headphone jack of a CD or MP3 player into the volume countrol - disconnect the crystal pick up of course, and start out at very low volume settings and sneak it up until you hear something. This may clear your amp and let you know if the amp is capable of passing a good signal, and tell you if the problem is in the crystal or the amp. I agree that with type of amp and all, you arent going to get much sound... also, if that is a 1956 + or - model, those electronics are pushing 60 years old, and this is likely one of the 1st transistor phonographs made, plus it is battery operated. Keep this in mind. Also, might not hurt to clean the pins/sockets where your transistors plug into, and check for any cracked solder connections.

Tim
#18

We found the capacitor you are referring about it was right near the l-5021 transistor and I put a 22mf at 160 volts cap in place of the cap which said 40-3 whatever that means 40 mf at 3 volts? and the volume was still distorted but louder and when you turn it down slightly it decreases the volume fast very distorted.
#19

This should not create distortion (if the cap is good) but if you swap the polarity it might.
Did you observe the polarity?
By decreasing the cap you did decrease the AC gain low frequencies (below maybe 200Hz).

Actually the other ream suggested something which is not a bad idea - if you do have a musical signal other than your pickup, you could try to feed it into the amp and see if it also distorts. We still do not know how good your cartridge is.
#20

We made sure polarity was right what number should I of put in there thanks
#21

Well, what you put in there should not make matters much worse. if you have a cap close to the original, put it there, make sure it is a new cap (or known good one). A bit larger won't hurt either.

47uF, 56uF, 68uF....

You don't have a scope, do you.....I mean, when we discussed it first, you did not say that your friend helps you. With him around a scope becomes useful again.

Well, how about that musical signal source? (After you put a good cap in).
#22

not sure uif klast mnessage went through I will try to put a higher mf one in there and check the it with the head phone idea. I do not have a scope and my friend helper does not know electronics that well.
#23

OK, tomorrow then I guess.
#24

We soldered a 47 uf at 100 volts but the volume lowers okay but still scratchy sounding but volume is higher. I hooked a headphone to the unit and it still sounded not clear
#25

Well, use a good source and see now if your music is OK or a sinewave tone is clear.
With no new crystal pickup this is the only way to exclude a bad one.

Otherwise we will be chasing ghosts. Granted this is a small amp and if it were in my possession it'd probably take me 1/2 hr to check everything I want in it. But then .... you do nto have the equipment, so get a source, and let us know what kind it is so we figure out where to hook it up.
#26

Well, use a good source and see now if your music is OK or a sinewave tone is clear.
With no new crystal pickup this is the only way to exclude a bad one.

Otherwise we will be chasing ghosts. Granted this is a small amp and if it were in my possession it'd probably take me 1/2 hr to check everything I want in it. But then .... you do nto have the equipment, so get a source, and let us know what kind it is so we figure out where to hook it up.

Meantime you could try to pull the output transistors one by one. First pull one, listen to the music, see if you hear typical half-wave clip sound and if the scratch is still there.
(Do all insertions-extractions with power OFF).
Then put the first transistor in, pull the second one, see if you hear exact same sound as with the other one in.

This way we will know we are not dealing with a bad transistor.
I am quite sure they are OK - "scratchy" does not describe a bad triode, but just to have a quick idea.
#27

I am not understanding when you say find a good source but I will try to pull the l-5022 transistors and see if there is a difference thank you.
#28

A music source with some low signal output. A DVD player Audio Out, for example.
#29

I pulled each output transistor and the same you can hear the rhythum of the song but not the voice clear. I hooked the line out head phone plug from my computer head phone jack to the terminals where the crystal goes and the sound through the amp of the record player is the same not clear
#30

1. When connecting headphone output, did you try to regulate the volume low?
The signal from the phonejack is much stronger and the output impedance is orders of magnitude lower.
2. when doing it did you disconnect the crystal?

Can you do this:

1. Disconnect R2 from transformer.
2. Try to inject the signal from headphone jack between the disconnected pin of the resistor and the Positive of C1.




Users browsing this thread: 10 Guest(s)
[-]
Recent Posts
Shadow Meter Bulb
Phorum members, I am trying to find the bulb # for PHILCO Shadow Meter part number 45-2180 that is from a 37-640 chassis...georgetownjohn — 06:53 PM
Philco 41-608 changer coupler
3D-printing...short of machining, of course. Or molding.morzh — 05:20 PM
Philco 41-608 changer coupler
Thanks, Morzh. That solves the issue of the rubber pieces. Now, I need to find a way to replicate the pot metal piec...alangard — 05:07 PM
12' Philco
If it is 12', either Kareem or Andre would have to jump pretty high to look at the front panel. Kareem would have an e...morzh — 01:48 PM
12' Philco
And here's a story about the tires on the truck. Same "no-stoop" guy must have installed these! Take care a...GarySP — 01:17 PM
Hickok AC51 tube tester
I think they have only shown the secondaries of the transformer. Two of them feed the rectifiers' filaments.morzh — 12:58 PM
IF can wire size and Rubber mounts?
Arran If the wire inside cans is the gauges you mentioned, the sole reason for that would be mechanical, to stiffen t...morzh — 12:56 PM
12' Philco
Rod, Yes, I know, but the Giant Philco is not around anymore either, so I go by whoever was alive fairly recently. H...morzh — 12:54 PM
Hickok AC51 tube tester
Absolutely no one is going to reverse engineer that circuit. Even the iron core is missing.RodB — 10:37 AM
IF can wire size and Rubber mounts?
Thanks to both members for your help regarding wire and tuner mtg supports. regards--Johngeorgetownjohn — 09:33 AM

[-]
Who's Online
There are currently 4809 online users. [Complete List]
» 1 Member(s) | 4808 Guest(s)
Avatar

>