Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Bob F Newsgroups: sci.electronics.repair Subject: Re: Altec Lansing ATP3 Speaker system transformer failed. Date: Sun, 28 Apr 2024 20:49:16 -0700 Organization: A noiseless patient Spider Lines: 76 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Mon, 29 Apr 2024 05:49:26 +0200 (CEST) Injection-Info: dont-email.me; posting-host="e5f70956cb5fb1dc0208151c3b2a5cf3"; logging-data="1616288"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+J5L/XRKWsvY/PZ6JhJkBo" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:T2X4R7qklTLuEOHw6FpOZXXVlzo= Content-Language: en-US In-Reply-To: Bytes: 4148 On 4/28/2024 7:57 PM, Jeff Liebermann wrote: > On Sun, 28 Apr 2024 16:08:57 -0700, Bob F wrote: > >> This speaker system I used on my main computer died yesterday - no power >> at all. >> >> I traced the problem to the transformer, a 12.5V 2.5 A TP57U25F from Ten >> Pad Industrial. > > Check your typing. The company is Ten Pao. > > There is usually a part number on their transformers. Find the number > and A2061 > >> Testing the transformer coils, neither the 117V input or >> the 12.5 V secondary show conductivity - they are both open circuit. The >> fuse for the primary circuit was not blown. > > Conductivity? Plug it in and measure the AC voltage produced at the > output of the transformer. No output. Ohmmeter resistance shows infinite on primary and secondary. 2 leads on primary, 2 on secondary, going to 4 diodes on the circuit board. > >> My question here is, if both coils are open circuit, does this suggest >> that a major short on the PC board got the transformer too hot so it >> tripped temp circuit cutoffs in both coils, so it is unlikely that >> replacing or fixing the transformer will fix the speaker? Or, is this >> kind of failure common for such transformers? > > I've seen opens on commodity power transformers are when there is > mechanical or chemical damage to the wires. More common are the > thermal fuses hidden under the tape covering the transformer windings. > >> If I wanted to try a different transformer to test the board, what >> should I want the transformers open circuit voltage to read on my >> Greenlee DM-20 DVM. Should that be 12.5V? I do have a variable voltage >> variac I could use to adjust a slightly higher voltage transformer down >> to 12.5 or whatever should be needed. > > I can't answer that without knowning something about the type of power > supply. Is the bridge full wave, full wave center tapped, or > something else? Is the 12.5 V before or after the voltage regulator? > Digging with Google: 12.5 is the voltage written on the transformer. > > Looks like you're not the only one with a transformer problem in the > ATP3. At least we now have the part number, but for the 230 VAC > version: > TEN PAO Model no.:TG51219F0 > Input: AC 230V/50Hz > Output: AC 12.5V/2.5A > I can't figure out the 117VAC version part number. > > > > > > "Hacking an Altec-Lansing ATP3 Subwoofer for Stand-Alone Operation" > > This doesn't answer your question, but might be useful reading. Please > note the external on-off switch wiring. One a different model speaker > system, I had a similar "no power" failure that was caused by me > kicking the sub-woofer enclosure and eventually breaking the on-off > switch. > > >