Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Issue with rebuilt 38-690 audio transformer
#14

Read my post above.

Start your check with pulling the rectifier and checking the AC outs.
Power down.
Then measure the load across the rectifier output, check if short is present.
If not, put rectifier in, put the loads (speakers) in, power up, briefly see if the DC develops and where it goes, once reached about 500V it should go down a bit and stabilize. Watch for smoke.
Power down AND watch the DC going down. If very slow, you have no load. If fast (second or few) - OK.

Once this is OK, start measuring voltages.
Check the transformers' continuities, check speakers.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.


Messages In This Thread
RE: Issue with rebuilt 38-690 audio transformer - by morzh - 06-30-2015, 04:28 PM



Users browsing this thread: 2 Guest(s)
[-]
Recent Posts
Philco 60 Squealing
I seem to remember eliminating a squeal by changing the IF frequency by a few KHz. Not that you should put too much tru...fenbach — 08:48 PM
Philco 42-390, code 121 speaker
These speakers pop up on eBay regularly, even if at bloated prices. Honestly, have not seen many parts on swapmeets.morzh — 08:38 PM
Philco 38-7 Speaker
The put-put is not like the speaker problem.morzh — 08:29 PM
Mission Bell Model 19A Car Radio
Hello everyone,  As mentioned in my last post I was going to see if the vibrator / rectifier section could be persuaded...Antipodal — 08:21 PM
Philco 60 Squealing
Wondering if I did it backwards. If a coil was wound backwards, the oscillator would not work at all. Old school...Chas — 07:23 PM
Philco 38-7 Speaker
4-ohm speaker. Black, Green leads.tludka — 07:00 PM
Philco 42-390, code 121 speaker
#87 on the schematic.  This radio had a 8" Zenith  speaker attached to it when I got it. I do don't know the hist...Stevelog — 06:39 PM
Philco 60 Squealing
I'm pretty sure I now have the litz wire soldered. This did not make any difference. Back in April I rewound the seconda...dconant — 06:25 PM
Philco 38-7 Speaker
Just to make sure, you chose either 4 ohm into 5K or into 10K? (blk-org or blk-grn)morzh — 06:23 PM
Philco 38-7 Speaker
I have let this one sit because of other duties. Now I am back, and I have a couple of questions. I hooked up a Hammond ...tludka — 05:34 PM

[-]
Who's Online
There are currently no members online.

>