Toshiba TV29C90 problem; Image fades to black...

[Smarty]

On 2/14/2014 5:23 AM, georgesantel@gmail.com wrote:

On Sunday, June 1, 1997 3:00:00 AM UTC-4, John Whitmore wrote:
I've recently acquired a Phase Linear 400. This was
an historically important audio amp, as it was the first of the
wave of high-powered amplifiers that came out of the 1970's.

This unit, though, has been through some tough times.
I've found lots of shorted and fried components, but the
main difficulty is in the output transistors.

There are four different types plugged in to the
sixteen TO-3 sockets. The outputs are four composite-Darlington
transistors, each having a single driver feeding three
paralleled output transistors. Someone in the past
replaced some of the paralleled outputs with various types.
So, I don't trust the types of transistors I see there.
Also, I don't know what the original drivers were.

Driver types: GE-37, DTS-701, RCA410
The first two are 700V, 1A; the third is 300V, 5A rated.

Output types: GE-37, PL-909
The first is clearly inappropriate in this application,
and the second is (apparently) a Fairchild special part
number for Phase Linear. I assume it's intended to be
a high current type, and possibly similar to 2N5264
(a Fairchild power transistor of the right era).

From the emitter degeneration resistance (0.22 ohms)
I suspect the output transistors should be roughly 5A rated.
Does anyone know? Should I just jam in MJ15003's?
Or maybe MJ410's (very similar to the RCA410)?

And as for the drivers; should they all be the same
type as the outputs? What were the original drivers?

Thanks for any info; this can't interest many folk,
so e-mail is preferred.

John Whitmore
whit@hipress.phys.washington.edu

If interested I have some XPL909 for sale
georgesantel@gmail.com

Service manuals for Phase Linear 400s, 700s, etc. with schematics, PCB
layouts, instructions, are available at numerous places for free. A
Google search turned this one up, among others:

http://www.vintageshifi.com/repertoire-pdf/Phase-Linear.php

 

[David Platt]

If interested I have some XPL909 for sale
georgesantel@gmail.com

Service manuals for Phase Linear 400s, 700s, etc. with schematics, PCB
layouts, instructions, are available at numerous places for free. A
Google search turned this one up, among others:

But, as the original posting and inquiry has a 1997 date on it, the
issue is probably moot (from the OP's point of view)/

 

[Jon Elson]

jurb6006@gmail.com wrote:

Dammit ! Why are people regurgitating old posts now ? This is not hte
first time this has happened. It has happened a few times lately.

Oh well, if anyone need advice on those thins I guess there it is.

It seems to be a problem with some news server that does this, then the
messages propagate to other servers which have long since forgotten
they ever had this message, so it shows as new. Yup, seen a LOT of these
relics from the VERY distant past!

Jon

 

[Leif Neland]

Fřlgende er skrevet af Jon Elson:

jurb6006@gmail.com wrote:

Dammit ! Why are people regurgitating old posts now ? This is not hte
first time this has happened. It has happened a few times lately.

Oh well, if anyone need advice on those thins I guess there it is.
It seems to be a problem with some news server that does this, then the
messages propagate to other servers which have long since forgotten
they ever had this message, so it shows as new. Yup, seen a LOT of these
relics from the VERY distant past!

These ghosts of christmas pasts almost always comes from somebody
replying to a message on google groups.

I wish Google would add a test: "You are replying to an old message. Do
you really want this?"

Leif

--
Husk křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

 

[Phil Allison]

<georgesantel@gmail.com>

If interested I have some XPL909 for sale

** They the ones with inbuilt B-E resistor or is that the XPL910 ?

A DMM will show about 68 ohms B-E with either polarity at the probes.

BTW:

Phase 400s had in *interesting* design flaw that would cause both channels
to go DC when one channel suffered an output device failure, due to using
common DC fusing for both channels. It worked like this:

1. A single output device fails short in channel A sending that output full
rail DC.

2. The same channel tries to pull the output back to zero by driving the 3
output devices on the other side hard - so one or more of them fails short
immediately due to SOA being grossly exceeded.

3. Channel A's output stage is now shorted rail to rail.

3. One of the two DC rail fuses instantly opens removing the short on the
PSU.

4. Both channels now have their DC supplies connected to a single rail of
either + or - 85V.

5. One of the "flyback" diodes wired from DC rail to speaker output become
forward biased in channel B.

6. The speakers connected to both channels now start smoking .....

FYI:

One can normally remove either DC rail fuse on a PL400 with no ill effect.

The PL700 has 4 DC rail fuses, which eliminates the problem.

Many stereo power amps have NO rail fuses, which also eliminates the
problem by forcing the AC supply fuse to blow.


..... Phil

 

The B-E resistor really makes no difference since the amp has a 10 ohm across it anyway.

Yes, I am not really happy with the fusing arraingement in these, they should be separate for each channel. I can't seem to find 8 amp fuses easily, right now mine has 5s. It works you just can't crank it up too much. I'll p[robably put 19s in it eventualy. It would probably not be a good idea to eliminate them though because in the case of a short the thing can put out significant current. Hell, you can probably get over 10 out of it under normal conditions, 85 volts... and it WILL run into 4 ohms.

One little thing I was thinking of doing is to build a little protection circuit for such amps. At these power levels a I could use the NC contacts of a relay, use a couple resistors and a cap to filter out DC and rectify it to operate the relay and possibly save the woofers. If not at least prevent a fire.

A guy contaced me about a GAS, so for the hell of it I looked up the Ampzilla. It also has no relay, but it does at least have speaker fuses. I bet those things smoke pretty good because they have the outputs in series rather than parallel. I think the power out is close, and the Ampzilla uses only four outputs instead of six but is cooled by forced air.

Anyway, the diodes and the fuse situation is why I told the guy to take the outputs out to test.

 

>"** It does if you mix up devices. "

Not much. In each bank you got the bases all connnected directly together and the emitters are only separated by 0.33 resistors. However you are right that it will matter because if you tray to push these things and the current isn't shared it will fry fast and the outputs will probably read zero all the way arond.

>"** The relay contacts will arc and burn soon as they open under a DC fault. "

Well now I got a solution to that believe it or not and I am surprised that noone does it. (or maybe they do)


take a nice 47 uF or so bipolar cap across the contacts. Period. think aabout it no before to go saying anything.

First of all the cap is not in the circuit during normal operation. The relay only kicks "out" by the application of high DC, which of course WOULD produce an arc due to the inductance, but a capacitor will take care of that. We are not concerned with AC here, just DC blowing your fucking $3,000 Tannoy. Plus when amps put out full DC, they are not puttin gout any AC except for maybe some power supply ripple.

You know, that was a damn goo danswer about why they put those magnets around the speaker realys in amps that make the Ampzilla look like Kermit the frog, but my question is why didn't they just put a fucking capacitor across the terminals ?

You tell me. I am not being sarcastic. I can't tnink of a single reason why they couldn't just put a 10/300 bipolar across there and be done with it anstead of fucking with magnets. that solution probably cost directly in manhours to implement, a cap could simply be on the board.

What's more, from a fidelity standpoint, if the realy had any inductance the cap would improve its performance there. Maybe even better the slew rate.

I wonder why these highly paid enjunears cunt figger dat out.

I see no downside to the caps. they are probably even cheaper than magnets. they are certainly cheaper to install.

 

[Phil Allison]

<jurb6006@gmail.com>

>"** It does if you mix up devices. "

Not much. In each bank you got the bases all connnected directly together
and the emitters are only separated by 0.33 resistors.

** If you have 3 of one kind on one side, then 10 ohms drops to 7 and the
pre bias is skewed.

"** The relay contacts will arc and burn soon as they open under a DC
fault. "

Well now I got a solution to that believe it or not and I am surprised that
noone does it. (or maybe they do)
take a nice 47 uF or so bipolar cap across the contacts. Period. think
aabout it no before to go saying anything.

** Far cheaper to use a triac, DC crowbar to protect speakers.

OR a changeover relay wired to open the output link PLUS short the speakers
to ground under DC fault conditions.

Must have installed 50 of those in PL400s and PL700s years ago.



.... Phil

 

[Phil Allison]

<jurb6006@gmail.com>

The B-E resistor really makes no difference since the amp has a 10 ohm
across it anyway.

** It does if you mix up devices.


One little thing I was thinking of doing is to build a little protection
circuit for such amps. At these power levels a I could use the NC contacts
of a relay, use a couple resistors and a cap to filter out DC and rectify it
to operate the relay and possibly save the woofers.

** The relay contacts will arc and burn soon as they open under a DC fault.





..... Phil

 

[Mick Nowell]

Vinyl seems to emit a gas which will react with and destroy many
substances. A good example is those vinyl book covers which have
turned the outside of many a book into eternal sticky mush.

It's not a gas, it's the plasticizer that keeps the vinyl flexible. I had the
same trouble with textbooks that had a kind "plastic-coated-board" covers. And
I've seen the plasticizer in patch cords attack plastic surfaces.

I am no aware of any plasticizer in the rubbery contacts of remote controls.

I've taken apart the keypad for my Ford. There is a silicone goo in it, which
I assume is there to prevent rust or corrosion.

Similar problem with paint on guitars. Stands containing certain foam
protection or vinyl hooks don't do well with enamel necks.

 

you're stereo probably has a small pece off metal inside on the bord try to tip it upside down and tap on it to see if you here any thing lose if not then you receiver board may be defective but this is only because I've owed alot if them I'm in need of the front price mine simply burnt out

 

On Wednesday, February 19, 2014 4:54:05 AM UTC-5, blhbr...@gmail.com wrote:
> you're stereo probably has a small pece off metal inside on the bord try to tip it upside down and tap on it to see if you here any thing lose if not then you receiver board may be defective but this is only because I've owed alot if them I'm in need of the front price mine simply burnt out

Did you happen to notice the DATE ? This thread is FOURTEEN YEARS OLD !


Would YOU wait 14 years to get a junkass Sony reciever fixed ?

BTW, where is Jerry ? In fact where are all the people who usaed to post here ?

 

Actually I used to get here from AOL. Right now I am using google. Sucks, but it works. Anyway, since I know how google sucks, err works, what I don't understand is how he is getting so far back.

Google presents the threads newest first, 30 at a time. To get 14 years back, this guy must have sat there all day scrolling down until it says "Loading more topics" about 100 times.

 

[Michael Black]

On Wed, 19 Feb 2014, jurb6006@gmail.com wrote:

On Wednesday, February 19, 2014 4:54:05 AM UTC-5, blhbr...@gmail.com wrote:
you're stereo probably has a small pece off metal inside on the bord
try to tip it upside down and tap on it to see if you here any thing
lose if not then you receiver board may be defective but this is only
because I've owed alot if them I'm in need of the front price mine
simply burnt out

Did you happen to notice the DATE ? This thread is FOURTEEN YEARS OLD !

The guy didn't even quote what he was replying to, and didn't even format
things properly, so it looked like a first post in a thread rather than a
reply to one. Look inside, and it barely was readable.

Would YOU wait 14 years to get a junkass Sony reciever fixed ?

But he didnt' really reply to be helfpul, he replied because he's looking
for a junker. I doubt he realized the message was old, but I suspect
wishful thinking is why he replied, hoping to get that front panel he
needs (or I think that's what he's asking).

It boggles my mind that people think there's value in replying to old
messages, when they aren't even in the right place. If they want
something, there are venues for buying and selling, and which see more
traffic than we get here. There's that new thing, ebay, that seems to
be getting a lot of attention, and is more likely to produce the needed
scrap unit (or just the front panel) than posting here.

BTW, where is Jerry ? In fact where are all the people who usaed to post
here ?

Some just changed their lives I think. Later this year it's 20 years
since I first saw this newsgroup, and the only other one in the hierarcy
was sci.electronics. Some of the regulars disappeared long enough ago that
I just assume their lives changed and they had less time for the
newsgroup. I've always assumed Sam, who was so big here at one
point, had less time to spend here. People who disappeared later, it
might be that they were lured by other forums.

Michael

 

[Allodoxaphobia]

On Wed, 19 Feb 2014 08:12:21 -0800 (PST), jurb6006@gmail.com wrote:

On Wednesday, February 19, 2014 4:54:05 AM UTC-5, blhbr...@gmail.com wrote:
you're stereo probably has a small pece off metal inside on the bord try to tip it upside down and tap on it to see if you here any thing lose if not then you receiver board may be defective but this is only because I've owed alot if them I'm in need of the front price mine simply burnt out

Did you happen to notice the DATE ? This thread is FOURTEEN YEARS OLD !

heh.. The OP was just another Google Grooper:

Message-ID: <c8eec3dc-b626-4b16-90a9-5efb7a0f0fae@googlegroups.com>

... with to-be-expected grammar and spelling issuse.

 

[Michael Black]

On Wed, 19 Feb 2014, jurb6006@gmail.com wrote:

Actually I used to get here from AOL. Right now I am using google.
Sucks, but it works. Anyway, since I know how google sucks, err works,
what I don't understand is how he is getting so far back.

Google presents the threads newest first, 30 at a time. To get 14 years
back, this guy must have sat there all day scrolling down until it says
"Loading more topics" about 100 times.

The search engine may work sometimes still.

IN this case, he was looking for a front panel, so he likely did a search,
and then didnt' pay attention to the date (though why he didn't try email
is a wonder, except google garbles so much that I suspect the email
address isn't readily available).

But I just saw one in another newsgroup to a post a four years old, and
it's some "useful help" to the original poster. I can't figure out how
someone comes upon that, and then has something of value to add. I can
see someone looking for a solution and then asking further in an old
thread (not that I think it's a valid way to do things), but to add a
suggestion for help?

Some of those, the problem has long been solved, since the software has
changed. Then it gets silly as someone else replies to the original post
now that it's been bumped up at google, and tells the original poster "get
newer software" as if in 1994 there was newer software.

Or, the late repliers never bother to read the whole thread, so they never
see that ample suggestions were given way back then to possible solutions.

Michael

 

[Leif Neland]

Den 19-02-2014, skrev Michael Black:

But I just saw one in another newsgroup to a post a four years old, and it's
some "useful help" to the original poster. I can't figure out how someone
comes upon that, and then has something of value to add. I can see someone
looking for a solution and then asking further in an old thread (not that I
think it's a valid way to do things), but to add a suggestion for help?

I've done that sometimes.

I was looking for an answer, but only found unanswered questions.

Then I found the answer off-line, or by myself, and went back and added
my answer, so somebody else could use it.

And I felt good afterwards

But I wish google would ask "Are you really sure you want to answer
such an old message?"

I've also asked about how to repair my garden scredder (sp?), and two
years later I got a call if I still got it, because he needed it for
spare parts. I did have it, and got some money for it.

Leif

--
Husk křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

 

[Kaz Kylheku]

On 2014-02-19, jurb6006@gmail.com <jurb6006@gmail.com> wrote:
> Did you happen to notice the DATE ? This thread is FOURTEEN YEARS OLD !

That person will never read your reply, because he's likely landed on that
thread out of a keyword search in Google, and has no idea how to find it
again once he closes that browser window.

And, remember, this is someone who thinks that "you're" is a possessive
pronoun.

 

Know what though ?

Fourteen years ago this place was a gas. It had very competent techs and we had real life experience.

Case in point, I posted about this Pioneer RPTV shutting down. I got a reply in a few hours, "R131" or something like that, which was the problem. A 130K going open in the shutdown circuit. that one response saved me hours of time, because someone had done it before. This is good, I thought.

I was on here before then actually. Of ocurse this was my thing, my jovb as well as soe entertainment, whatever. I was very interestd in my profession at the time because I was aking goo d money at it. I helped people here and people helped me.

but things got fucked up over the years like anything else. for one, AOL dropped newsgroups. then late it dropped the hosting whereI could have webpages. At that point I dropped them and I could not find a free wat to get here at gunpoint.

Whatever, I have gained from SER and I hope I have contribbuted equally. In service I know I did.

That's what it('s) (was) al about.

Damn, did I punctuate that right. DOH - correctly. Right is over there >

 

[Liam O'Connor]

On Fri, 28 Feb 2014 23:34:48 -0500, nospam wrote:

how many of those could you reliably establish a connection and then do
something with it?

merely showing up in a list doesn't mean much if it's not usable.

This is a good and valid point.

I had also spoken (complained) to two people about this,
one of whom is actually my ISP, who said that he gets
frustrated when a customer can't connect to his wall and
ceiling mounted access points that he installs in the larger houses.

I trust his experienced judgement when he said he called them
iCrap. It was also his view that the iPad/iPhone equipment had
lousy radios (he called them "radios").

However, it would be nice to find a study that shows what
the true decibels of gain are for the iPad radio/antenna
combination, transmit power, and receive sensitivity.

Does Apple publish those numbers?