Toshiba TV29C90 problem; Image fades to black...

[Sofie]

Patch:
Of course you are absolutely correct in your response to Arnold stewart
....... a "regular" diode won't "clamp" if the voltage exceeds design
spec..... then damage to capacitor and the down stream circuitry could
result. If everything is functioning properly, the zener diode is not
active in the circuitry and in fact will not affect performance one way or
the other.......
.....but just as soon as there is a power supply failure that causes excess
voltage, the Zener will clamp, protect the down stream circuitry, and
probably blow a primary or secondary power supply fuse... or fusible
resistor.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



"Patch" <bob_acord@hotmail.com> wrote in message
newsoUYa.276872$o86.194579@news1.central.cox.net...

"Arnold stewart" <arnold.stewart@sympatico.ca> wrote in message
news:hSTYa.5143$ox5.492766@news20.bellglobal.com...
Last week I posted a message asking the value of a zener diode (D866ZD)
connected across a 22mfd 25V cap (C866) in a Toshiba TAC9008 TV power
supply. I didn't get the answer on this NG but got it on another (based
in Montral) This zener was connected between pin 4 (at 0V) and pin 6
(-6V) of a regulator. The value of the zener was 30V. Can anybody tell
me why put a 30V zener across a 25V cap? Seems to me that I could just
as well just put in a regular diode. Earlier models of Toshiba didn't
have this diode at all.

Probably to keep the voltage level from exceeding 30 V.

 

[Imran]

Mark,

Thanks for your response.

I have couple of more questions for you.

If one were to try to repair this problem and assuming that the
failure is in the DSP, how much would it typically cost to do the
repair.

Does the repair involve replacing the DSP board? Is it like just a
single board that is removed and replaced or does it involve replacing
number of other components.

Is it something one can do if one has a basic skills in soldering? Are
there any manuals with instructions with what to do (like which
IC/capacitor to resolder/replace)?


I really appreciate your taking the time to answer my questions.

Regards,
Imran

"Mark D. Zacharias" <mzacharias@nospam.earthlink.net> wrote in message news:<NGsVa.123943$Io.10592724@newsread2.prod.itd.earthlink.net>...

Hello,

I'm not actually an expert on the RT-2280, but I am an authorized RCA
servicer, and I hear stuff and have seen posts on this model before.There
was one servicer who was able to troubleshoot a bad feedthrough connection,
which I would usually be too lazy to bother with.
I would say that the numerous feedthrough connections on the DSP board are
the likely cause of many DSP failures - the physical quality of these boards
doesn't seem too good. Of course the general soldering of the board and it's
connectors should be checked, and one could try resoldering any large IC's -
those surface-mounts sometimes need resoldering.

Mark Z.


"Imran" <aimran50@yahoo.com> wrote in message
news:f7edd128.0307281548.11e69578@posting.google.com...
Mark,

I have been having exactly the same problem. The sound works fine when
I turn off the DSP.
I read you response on two posts and gather that you may have some
expertise on this.
Would you care to share how you came to this conclusion and if you
know of any specific work arounds?

Thanks,
Imran.


"Mark D. Zacharias" <mzacharias@nospam.earthlink.net> wrote in message
news:<2n5Na.24314$C83.2280450@newsread1.prod.itd.earthlink.net>...
Lots of DSP board failures on these. Good luck with that.

Mark Z.


"Sean Piper" <inskipp@shaw.ca> wrote in message
news:BB29CA22.4F0B%inskipp@shaw.ca...
I have a one-year old RCA RT2280 surround system. Yesterday all of a
sudden
it stopped producing sound. I checked all the obvious problems like
mute,
cables, speaker connections and so forth but was unable to get it
working.
I
made sure the input and output settings were correct and they are. If
anyone
has any ideas about this problem please email kingsnoofer@msn.com. I
would
really appreciate any help you can off as I cannot afford to take it
in
and
will only do so if absolutely necessary.

Sean

 

[David]

In most areas of the US $600 for a proper and complete capacitor rebuild on
that set is not out of line if it was an in home repair.

Typically $300 to $400 if he can take the set into the servicer for a
complete check and repair. I usually find between 30 and 100 bad capacitors
in Mitz sets from that vintage. Most are borderline but would fail within
another year or two.


David

george stringe <annsmg@attbi.com> wrote in message
news:6d1b1dc7.0308080419.13020912@posting.google.com...

Thanks Dave, my inquiry was because the set belongs to a relative and
is actually 1500 miles away. I have never worked on this particular
model and am completely unfamiliar with it. He was quoted $600 to
replace the power supply so you info helps in that it appears
component repairable rather than box replacement.
thanks again.
george

"David" <dkuhajda@locl.net.spam> wrote in message
news:<3f335b2d@news.greennet.net>...
Troubleshoot and repair to the component level.
It is a pretty straightforward simple design to fix.

Given the vintage of the Mitz set, you will/should ESR check every
critical
electrolytic capacitor in the set and replace all the weak/bad ones, as
well
as a full visual and heat test.

David

george stringe <annsmg@attbi.com> wrote in message
news:6d1b1dc7.0308071744.27b0818f@posting.google.com...
Looking for source for power supply for mitsubishi CS40805

many thanks

 

[Jason D.]

On Fri, 8 Aug 2003 14:53:07 -0700, "Sofie" <sofie@olypen.com> wrote:

Vince:
Other than expensive flybacks, you should check the B+ regulation circuitry
to verify that it is indeed regulating at the correct voltages. Also, with
a variac on the AC line, vary the line voltage +/- 10 volts or so to see if
the B+ holds steady.
Check all the pcb solder connections around and near the high heat producing
components such as power resistors, diodes, semiconductors, ICs mounted on
heatsinks, and the flyback xfmr.
I would also ESR check all the electrolytics in the PS and in the Flyback
area and flyback derived B+ circuits..... no ESR meter?.... then the only
alternative is the more time consuming task of substitution and replacing
electrolytics.
--

In this Daewoo, good news for you, problem isn't flyback, I know this
well CN-200a and 200i, fixed so many of those chassis...Replace three
100uf 35V caps. Two near vertical IC heatsink, one in middle of PSU
between rows of ceramic axial resistors.

There two more which is really responsible for shutting down after 1/2
hour or killing the HOT is two 1uF 160V caps in H. driver circuit.
Replace both with 1uF 160V or 200V. All caps preferably 105C
temperature rating.
Fly on daewoo wasn't the problem actually. The heat building in there
is excessive because chassis is tiny, crammed so tight that hot
components are cooking these caps to death and browning the PCB.

Zenith, you might have a bad tube overheating that STR-53041. Check
the two small capacitors in that hot side of switching power supply
first.

Get ESR meter if you're repairing for a living.

Cheers,

Wizard

 

[Mark D. Zacharias]

I'll have to research the board cost at work. Availability of these boards
is usually limited.

I don't think any soldering is required, but I could be wrong - it's been a
while since I've seen the inside of one of these.

Mark Z.


"Imran" <aimran50@yahoo.com> wrote in message
news:f7edd128.0308081501.35b87322@posting.google.com...

Mark,

Thanks for your response.

I have couple of more questions for you.

If one were to try to repair this problem and assuming that the
failure is in the DSP, how much would it typically cost to do the
repair.

Does the repair involve replacing the DSP board? Is it like just a
single board that is removed and replaced or does it involve replacing
number of other components.

Is it something one can do if one has a basic skills in soldering? Are
there any manuals with instructions with what to do (like which
IC/capacitor to resolder/replace)?


I really appreciate your taking the time to answer my questions.

Regards,
Imran

"Mark D. Zacharias" <mzacharias@nospam.earthlink.net> wrote in message
news:<NGsVa.123943$Io.10592724@newsread2.prod.itd.earthlink.net>...
Hello,

I'm not actually an expert on the RT-2280, but I am an authorized RCA
servicer, and I hear stuff and have seen posts on this model
before.There
was one servicer who was able to troubleshoot a bad feedthrough
connection,
which I would usually be too lazy to bother with.
I would say that the numerous feedthrough connections on the DSP board
are
the likely cause of many DSP failures - the physical quality of these
boards
doesn't seem too good. Of course the general soldering of the board and
it's
connectors should be checked, and one could try resoldering any large
IC's -
those surface-mounts sometimes need resoldering.

Mark Z.


"Imran" <aimran50@yahoo.com> wrote in message
news:f7edd128.0307281548.11e69578@posting.google.com...
Mark,

I have been having exactly the same problem. The sound works fine when
I turn off the DSP.
I read you response on two posts and gather that you may have some
expertise on this.
Would you care to share how you came to this conclusion and if you
know of any specific work arounds?

Thanks,
Imran.


"Mark D. Zacharias" <mzacharias@nospam.earthlink.net> wrote in message
news:<2n5Na.24314$C83.2280450@newsread1.prod.itd.earthlink.net>...
Lots of DSP board failures on these. Good luck with that.

Mark Z.


"Sean Piper" <inskipp@shaw.ca> wrote in message
news:BB29CA22.4F0B%inskipp@shaw.ca...
I have a one-year old RCA RT2280 surround system. Yesterday all of
a
sudden
it stopped producing sound. I checked all the obvious problems
like
mute,
cables, speaker connections and so forth but was unable to get it
working.
I
made sure the input and output settings were correct and they are.
If
anyone
has any ideas about this problem please email kingsnoofer@msn.com.
I
would
really appreciate any help you can off as I cannot afford to take
it
in
and
will only do so if absolutely necessary.

Sean

 

{Old message posted 2002-09-13 in comp.dcom.telecom}

Hi all,

Writing in as a last resort to find out how I can fix this phone. It's
a Panasonic Cordless Speakerphone with both a base and handset dialing
keypad. Has been working great until yesterday, when the handset fell
and hit hard on the ground. When I press the 'TALK' button on the
handset, all the LEDs on the phone light up as if it's working, I can
even dial a number on the handset and turn on the speakerphone and
it'll be working fine -- all the features on the handset works
absolutely ok except the sound from the earpiece. There is NO dialtone
on the earpiece. The mouthpiece works great too -- I put the handset
on intercom, and you can hear anything you say over the mouthpiece
over the base speaker.

I opened the handset unit, and there are absolutely no broken parts,
the LEDs light up fine, even the handset on-screen display works
great, you can program and all -- just as if nothing happened, but
there wouldn't be 'any' noise from the earpiece unit.

Seems unfair to junk this phone just because the earpiece speaker part
isn't working -- and every last programmable options, dialing, etc
works fine, plus cost about a couple of hundred bucks.

Any suggestions will be most helpful,

Thanks in advance,


Nataraj Dasgupta.
--------------------------------------------------------------------------------------------

I know this response is a little late, but maybe it can help someone
else searching for answers, like I was.

I had the same thing happen to my cordless Panasonic phone. kx-tc1450
The speaker in this phone has wires in it smaller than the size of a
human hair. A shock to the handset breaks the wire(s) inside the
sealed speaker.

If you have basic soldering skills, you can order a new speaker and
solder it in. I orderd mine from http://www.partsolver.com/ $8.27
usd.

Dwight.

 

[techforce]

Well Well well. Good Ol NTE Xref Says: NTE2061

Still Will entertain anything if anyone has something.



"techforce" <techforce@!~NOSPAM!~.juno.com> wrote in message
news:__ZYa.11486$jg.3669277@news1.news.adelphia.net...

Trying to find one of these, New Preferred , but will entertain as Used
too.
I think this was made by National Semiconductor circa 1983. Hitachi
Carried
it under their Part No. 5359181 , but I fear it is obsolete although it
shows as Active.

 

[Mark D. Zacharias]

Probably a cracked circuit board or broken solder connection(s).

Mark Z.


<sponger9@comcastONOSPAM.net> wrote in message
news:mqj8jvco58onmh2dn71qj1d6sonb71m08g@4ax.com...

{Old message posted 2002-09-13 in comp.dcom.telecom}

Hi all,

Writing in as a last resort to find out how I can fix this phone. It's
a Panasonic Cordless Speakerphone with both a base and handset dialing
keypad. Has been working great until yesterday, when the handset fell
and hit hard on the ground. When I press the 'TALK' button on the
handset, all the LEDs on the phone light up as if it's working, I can
even dial a number on the handset and turn on the speakerphone and
it'll be working fine -- all the features on the handset works
absolutely ok except the sound from the earpiece. There is NO dialtone
on the earpiece. The mouthpiece works great too -- I put the handset
on intercom, and you can hear anything you say over the mouthpiece
over the base speaker.

I opened the handset unit, and there are absolutely no broken parts,
the LEDs light up fine, even the handset on-screen display works
great, you can program and all -- just as if nothing happened, but
there wouldn't be 'any' noise from the earpiece unit.

Seems unfair to junk this phone just because the earpiece speaker part
isn't working -- and every last programmable options, dialing, etc
works fine, plus cost about a couple of hundred bucks.

Any suggestions will be most helpful,

Thanks in advance,


Nataraj Dasgupta.
--------------------------------------------------------------------------
------------------

I know this response is a little late, but maybe it can help someone
else searching for answers, like I was.

I had the same thing happen to my cordless Panasonic phone. kx-tc1450
The speaker in this phone has wires in it smaller than the size of a
human hair. A shock to the handset breaks the wire(s) inside the
sealed speaker.

If you have basic soldering skills, you can order a new speaker and
solder it in. I orderd mine from http://www.partsolver.com/ $8.27
usd.

Dwight.

 

[Danny]

Possible parts to check/replace:
Daewoo
Open C401 in horiz driver ckt. 1ufd/160V
Q402 D1880,Q804 C2500, Q805 E13009-2, 5A FUSE
If you have repeated failure of H.O.T. Add a 33 ohm 1/4 watt resistor
across the Base and emitter of H.O.T.

 

[Jason D.]

On 9 Aug 2003 09:48:28 -0700, danny@dselectronics.com (Danny) wrote:

Possible parts to check/replace:
Daewoo
Open C401 in horiz driver ckt. 1ufd/160V
Q402 D1880,Q804 C2500, Q805 E13009-2, 5A FUSE
If you have repeated failure of H.O.T. Add a 33 ohm 1/4 watt resistor
across the Base and emitter of H.O.T.

Actually there is another cap in horizontal circuit same specs, 1uf
160V. Change both, also few other caps sitting in hot spots like I
listed in other post. Every one I checked, they were bad, ESR is too
high or totally open.

Cheers,

Wizard

 

[ddr]

I have two MO 100 that use the 6550 tubes. One is partially modified, with
LCR cap and needs to be completed, the other is completely stock.

The amps need the ez 81 but have Chinese and American 6550 tubes.

Any one want the pair?

I would like to sell them but do not know where or how.

the stock one is untouched, the other has some ceramic sockets and needs the
bias circuit completed.

thanks

Loren


"opcom" <nounwantedmail_eccm@swbell.net> wrote in message
news:3F35D193.489FACA8@swbell.net...

My Bogen MO-200 came with no tubes. (basically eight 8417's, driving two
parallel connected transformers for 200W)

8417 are expensive. I modified the bias supply for 50V, and put an
adjustment for each tube, and stuck 6550's in it. 6CA7's also work fine. I

split the amp into two 100W channels and put 6GH8's in the driver sockets,
with mods.

Mine does have a 1.0uF/100V plastic cap from filament to ground. too new
to be original. Never thought about it.

Patrick

"George R. Gonzalez" wrote:

Sometimes you wonder how some products ever made it out of the design
lab.

Sometimes there's so much wrong, you wonder if the item is a joke.

Someday I may relate the story of the no-name amplifier, but today's
story
is from a quite respected company, Bogen.

I aquired this Bogen PA amplifier, 50 watts out allegedly, pair of
8417's
for output.

Nicely built, heavy-duty transformers.

No works, so I put it on the bench.

I look it over.

The bad news:
Output tubes have white getters, don't hold vacuum anymore.

The only visible good news: the pilot light is okay.

I don't have any 8417's, so I go to the computer to look them up. The
number doesnt sound familiar.

I look up the tube specs, and whoo-boy, they have a heck of a
transconductance, 23,000 micromhos!

I do a Google search, and find several references like "these tubes
sometimes run away".
Hmmm..... let's be careful...

I go to order some new ones, and no matter where I look, they're
pricey--
$50-80 each.
I finally find some on eBay for a somewhat reasonable price.

Meanwhile I look over the amp for obvious things wrong.

The cathode current balancing pot doesnt want to turn! It's not rusty,
what's going on?
I open up the pot and see something unusual-- it's a wire-wound 30-ohm
pot
with a the wire wound around a gray plastic form. The form is badly
MELTED
and DEFORMED. How the ^#!$%!^? Let's see, 30 ohms, maybe takes 5 to 10
watts to melt it this badly, that's----- 400 to 800 milliamps!! No
wonder
the tubes gave up. I replace the pot.

The tubes aparently ran away to a very high current level. I check the
bias
circuit, looking for a bad voltage regulator, or a bad bias adjust pot.

No problems there.... there is no bias regulator OR bias adjust pot.
Just
your basic capacitor stealing a bit of the high-voltage AC and
rectifying
it, then dropping it down with some fixed resistors.

Hmmm, a pair of the most sensitive tubes ever made, and the
designers
don't make the bias adjustable! It's set by a couple of resistors, at
about -15 volts. Luckily, this is just about right according to the
cathode
current I measure.

But if the line voltage goes low, so will the bias, and it doesnt take
much of a drop to make these tubes conduct like crazy.... I make a
mental
note to add a Zener, or more appropriate for the era, a neon bulb, to
regulate the voltage. And oh yes, I make a mental note to sell any
Bogen
stock I have.

A week later the tubes arrive, I plug them in, put a 8 ohm resistor and
scope on the output, sine wave in. Time for FUN!

I turn up the line voltage slowly--- cathode currents are low and
stable,
whew. Everything looks good. I turn up the sine wave, and at about 20 w
atts
out, the amp starts some ragged oscillating in the MHz on the sine-wave
peaks. In about 5 seconds the tubes start running away! Good thing the
Big
Red Switch is nearby.

I look at the circuit to see what may have gone wrong with the
oscillation-snubbing components. We'll there's nothing wrong with them,
because they don't exist. There's NO snubbing resistors, not on grids,
screens, cathode, or plates. No rolloff capacitors on the plates
either.
These are some of the highest gm tubes ever made, and apparently Bogen
made
NO ATTEMPT to tame the tubes!!

Argghh... I have no idea what the optimum value for grid-snubbers is
for
this tube, so I wire in a ballpark value, 2.2K. The combination "red
red
red" is a bit garish, but what the heck, we're somewhat peeved and
desperate.

With the grid resistors in place there's no more trace of MHz
oscillation at
20 watts. But when I crank it up to near-clipping, the fuzzies reappear
and
the tubes run away again. This time I'm soo befuddled I don't hit the
switch until the cathode current has passed 500 milliamps! Well, at
least
we know these pricey tubes have plenty of cathode emission, or at least
had
it.

I think ahead about protecting these tubes in case they ever run away in
the
future when I'm not watching. The line fuse isnt going to do it, as it
hasnt in the past. I ponder the desecrating effect of drilling two 1/2
inch
holes to mount a pair of cathode fuse holders. Hmmm, better do it,
originality be danged..

There's no easy way to add screen-snubbers without drilling holes and
mounting terminal strips, so I look to taming the plates. I add a
roughly
in the ballpark plate-to-plate taming capacitor, 1100pf. Well actually,
two
2200 pf 1KV capacitors in series. There's lots of voltage up there.

Now there's no oscillation on the peaks, and the tubes don't start any
spiralling current death marches. But there's something else- the
leading
edge of the sine-wave has a big scallop cut out of it. How can this be?

A lot of probing around with scope probes and capacitors reveals nothing
interesting. This is the worst of times, when everything looks okay
except
the output, and nothing you try seems to help.

For lack of anything better to try, I decide to measure the heater
voltage.. I know, I know, the 6.3 volts on the heaters can't be far
off,
and even if it was it wouldnt scallop the sine wave this way, but let's
waste 15 seconds anyway. I should use the voltmeter to measure the
heater
voltage, but I change my mind and use the scope. You see the new test
leads
on the meter have really hard to squeeze alligator clips, while the Tek
scope probe is much easier to use. Plus I can use the mental practice
of
trying to divide the p-p voltage by 3 in my head. So due to pure
lazyness,
I use the wrong tool for the job. And due to this mistake, all the
answers
pop out at me!

The scope reveals that the heater voltage has a non-negligible amount of
signal on it! I'm really puzzled now, wondering how 500mv of signal
gets
into the heater lines, wondering how the designers never noticed this,
wondering why I'm getting steamed at the shortcomings of a 45 yr old
design.

I decide to attack the symptom and put a .22uf capacitor from heater to
ground. The signal disappears from the heater voltage, and the output
sine
wave now looks perfect! Apparently there was feedback from the output
tubes to the preamp tube, back thru the heater wires!

What the bellepety-bleep! What the friggity-frig! How did this ever
get
past the designers? I solder in a 0.47 uf capacitor into the heater
circuit. Lots of playing around with various frequencies and levels of
sine
waves, and I *think* the amplifier is finally stabilized.

( I should try it with some square waves too now that I think of it, but
the
square wave generator is out in the garage, which is at about 98
degrees,
90% humidity right now).

So that's it so far. Had to get this off my chest. How could the
designers
have come out with such a shaky design? I put a nice sedate load on
it,
and it ran away every time!
An expensive-looking amplifier, with many critical components apparently
never designed into it.

Any ideas out there how this could have ever worked right?

Regards,

George

 

[max]

I have the same problem with Mitsubishi TV CS-35707 and I checked with
oscilloscope that blue doesn't come up to CRT board with enough voltage
output.I tried to find out by tracers where blue coming out but I didn't.Lot
of mass in Mitsubishi TVs,so I will order repair manual from Mitsubishi and
when I'll get schematic I'm easy find out the problem and later tell you
what I got.
"Scott Evil" <faster@go.com> wrote in message
news:37522992.0308091501.5bdaa5cd@posting.google.com...

I have lost the blue on my Mitsubishi VS-5017S. I can tell not only
from the green hue on the set while watching TV, but there is no blue
crosshair under the setup. My local repair shop doesn't want to touch
it-- has anyone had any experience with the problem? I'm in Ottawa,
Canada and I would hate to have to throw the TV out, but I NEED BLUE!

 

[Tim Williams]

"opcom" <nounwantedmail_eccm@swbell.net> wrote in message
news:3F35D193.489FACA8@swbell.net...

... and put 6GH8's in the driver sockets, with mods.

Ack, GH8.. half of mine are all crackley or don't work at all.. :^)

Tim, listening to Frankenhouse with a 6U8

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

 

[Lionel]

On Fri, 08 Aug 2003 03:40:03 GMT, in <3F331BF9.225C@psu.edu>, Andy Cuffe
<baltimora@psu.edu> said:

It's a long shot, but I've seen a couple of sonys with a bad cap in the
CRT heater supply. Make sure you have 6.3 v on the heater.

Okay, that's worth a try. I checked most of the rails, but didn't think
to look at the heater supply.

If the CRT
is weak, you might be able to try boosting it a little by using the old
few turns of wire around the flyback core trick. I've never tried to do
this with a monitor though, so I'm not sure if it would work.

I don't think I've quite brave enough to try that with a 21" monitor!

Most
monitors get the heater supply from the power supply instead of the
flyback. I don't see why it wouldn't work. If there are any resistors
in series with the heater supply, you could try bypassing them with wire
before doing anything else.

I'll have a look at the schematic.

Thanks for the ideas, much appreciated.

 

[Sidney]

About 70% or so of all Zenith tv's and Citizen tv's made by Zenith
since around 1992 till now have defective picture tubes that cause
either a defective green gun giving you bright green screen or a G1
short causing the power supply to become defective:

http://www.iwaynet.net/~nesda/Zen90.html

either way 70% of them or so have a defective crt and many are only a
couple of years old,I tell the customer that an average tv should last
over 12 years and I give my customers Zenith's phone number and I tell
them to complain to them:

LG ELectronics
Alabama,USA
Ph:1-800-243-0000

I have had at least 100 customers call Zenith and complain about those
garbage crt's.

 

[Mark D. Zacharias]

DSP board: part number 255876

Dealer cost 58.00
List price 84.50


Mark Z.



"Imran" <aimran50@yahoo.com> wrote in message
news:f7edd128.0308081501.35b87322@posting.google.com...

Mark,

Thanks for your response.

I have couple of more questions for you.

If one were to try to repair this problem and assuming that the
failure is in the DSP, how much would it typically cost to do the
repair.

Does the repair involve replacing the DSP board? Is it like just a
single board that is removed and replaced or does it involve replacing
number of other components.

Is it something one can do if one has a basic skills in soldering? Are
there any manuals with instructions with what to do (like which
IC/capacitor to resolder/replace)?


I really appreciate your taking the time to answer my questions.

Regards,
Imran

"Mark D. Zacharias" <mzacharias@nospam.earthlink.net> wrote in message
news:<NGsVa.123943$Io.10592724@newsread2.prod.itd.earthlink.net>...
Hello,

I'm not actually an expert on the RT-2280, but I am an authorized RCA
servicer, and I hear stuff and have seen posts on this model
before.There
was one servicer who was able to troubleshoot a bad feedthrough
connection,
which I would usually be too lazy to bother with.
I would say that the numerous feedthrough connections on the DSP board
are
the likely cause of many DSP failures - the physical quality of these
boards
doesn't seem too good. Of course the general soldering of the board and
it's
connectors should be checked, and one could try resoldering any large
IC's -
those surface-mounts sometimes need resoldering.

Mark Z.


"Imran" <aimran50@yahoo.com> wrote in message
news:f7edd128.0307281548.11e69578@posting.google.com...
Mark,

I have been having exactly the same problem. The sound works fine when
I turn off the DSP.
I read you response on two posts and gather that you may have some
expertise on this.
Would you care to share how you came to this conclusion and if you
know of any specific work arounds?

Thanks,
Imran.


"Mark D. Zacharias" <mzacharias@nospam.earthlink.net> wrote in message
news:<2n5Na.24314$C83.2280450@newsread1.prod.itd.earthlink.net>...
Lots of DSP board failures on these. Good luck with that.

Mark Z.


"Sean Piper" <inskipp@shaw.ca> wrote in message
news:BB29CA22.4F0B%inskipp@shaw.ca...
I have a one-year old RCA RT2280 surround system. Yesterday all of
a
sudden
it stopped producing sound. I checked all the obvious problems
like
mute,
cables, speaker connections and so forth but was unable to get it
working.
I
made sure the input and output settings were correct and they are.
If
anyone
has any ideas about this problem please email kingsnoofer@msn.com.
I
would
really appreciate any help you can off as I cannot afford to take
it
in
and
will only do so if absolutely necessary.

Sean

 

[George R. Gonzalez]

"opcom" <nounwantedmail_eccm@swbell.net> wrote in message
news:3F35D193.489FACA8@swbell.net...

My Bogen MO-200 came with no tubes. (basically eight 8417's, driving two
parallel connected transformers for 200W)

8417 are expensive. I modified the bias supply for 50V, and put an
adjustment for each tube, and stuck 6550's in it. 6CA7's also work fine. I

split the amp into two 100W channels and put 6GH8's in the driver sockets,
with mods.

Mine does have a 1.0uF/100V plastic cap from filament to ground. too new
to be original. Never thought about it.

Aha! Finally, some corroberation and vindication for my
amplifier-desecration.

Some late-breaking info, I just know you were all waiting breathlessly for
this-- The two power-supply filter
capacitors turned out to be a bit down in capacity, about 30% down. I
suspect this contributed to the
problems. Still, it's a pretty marginal design that depends on capacitors
at exactly 100% strength.
And they were tiny to begin with-- two 40uf's in series! Plenty of room for
bigger ones, but noooo,
Bogen saved every penny they could. Maybe they were burdened with the cost
of the rather large output
trannies and had to pinch pennies in other places? Just a random surmise.


Regards,

George

 

[N. Thornton]

I aquired this Bogen PA amplifier, 50 watts out allegedly, pair of 8417's
for output.

Nicely built, heavy-duty transformers.

Hi. If this thing is using 600v HT to put 50w out, your transformer
ratio is going to be miles out for any more common type of tube. As is
the HT of course. I would not be surprised if it made a mess and/or
shat itself if you put different tubes in and rebiased.

But I'm not familiar with any of those US tube numbers, and havent
actually tried it, so who knows.


Regards, NT

 

[Sidney]

That is the official phone number for Zenith (1-800-243-0000),it used
to be for Canada as well but now Canada's # is 1-888-542-2623,it is
accessible in Cape Breton where you are at,and of course in Dartmouth
where I am at.

 

[Mark D. Zacharias]

Had one the other day where the reel-clutch assembly needed disassembly,
cleaning and re-lubing. The thing kind of explodes when you remove the
retainer. Good luck.

Mark Z.


"Van Gardner" <vangard@worldnet.att.net> wrote in message
news:84e8709e.0308100927.37ba3e99@posting.google.com...

I have a JVC VCR Model HR-DX40U that will play or record a tape but
when the tape is unloaded the tape is not pulled back into the
cassette before it closes the door and backs out of the VCR. The tape
is still behind some of the guide post and cannot be removed without
further damage. I have to remove the top cover to lift the tape clear
of the post before the cassett can be removed out the front and the
cassett door has already folded the tape on both sides.

Anyone seen this problem before? Any ideas would be appreciated.

Van Gardner