Hello everyone. I just bought a PG zx475ti and only half of it works!
The front channels work great in stereo and bridged, but the rear
channels are having 'issues'. When connected to a four ohm sub in
stereo, each channel has low output and is very distorted or staticy.
When bridged there is no sound, but I can hear static when I touch the
speaker wires to the terminals. Also the red LED (Seems like several
along the board) are lit up even without the speakers connected. Is this
something that is repairable, and is it worth repairing considering I
paid $150 for it? If so, should I send it to PG, or can a local
electronic repair shop fix the problem. Any help/advice is appreciated.
Thanks.

Cameron,

Do a google newsgroup (rec.car.audio) search for ampdoc. Usually in his
posts he has his email/telephone number to contact him. He has provided me
with some useful information in the past. I had a PG ZX450(similar design
to yours) that quit one day and it ended up being the output transistors
(actually only one) on one channel had gone south. Others have sent their
amps to him and have had great success.

FWIW: PG wanted $130 flat charge to look at mine, I fixed it for less than
$20. I'm not diss'n PG, I think they are a respectable company and I love
their stuff.

You'll have to weigh whether shelling out to PG is worth it, or have an
independant work on it.

Ivan


"Cameron" wrote in message
...
Hello everyone. I just bought a PG zx475ti and only half of it works!
The front channels work great in stereo and bridged, but the rear
channels are having 'issues'. When connected to a four ohm sub in
stereo, each channel has low output and is very distorted or staticy.
When bridged there is no sound, but I can hear static when I touch the
speaker wires to the terminals. Also the red LED (Seems like several
along the board) are lit up even without the speakers connected. Is this
something that is repairable, and is it worth repairing considering I
paid $150 for it? If so, should I send it to PG, or can a local
electronic repair shop fix the problem. Any help/advice is appreciated.
Thanks.


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Thanks Ivan. I appreciate your input. I'll try and look ampdoc


Ivan Lopez wrote:
Cameron,

Do a google newsgroup (rec.car.audio) search for ampdoc. Usually in his
posts he has his email/telephone number to contact him. He has provided me
with some useful information in the past. I had a PG ZX450(similar design
to yours) that quit one day and it ended up being the output transistors
(actually only one) on one channel had gone south. Others have sent their
amps to him and have had great success.

FWIW: PG wanted $130 flat charge to look at mine, I fixed it for less than
$20. I'm not diss'n PG, I think they are a respectable company and I love
their stuff.

You'll have to weigh whether shelling out to PG is worth it, or have an
independant work on it.

Ivan

Check the grounds at the RCA jacks. Also take a ohmmeter and check the
finals to see if any are shorted. If you don't find any problem there then
start tracing the audio through the amp with an oscilloscope. If you don't
have proper test equipment then send it to a local shop or you can send it
to us, our checkout/estimate fee is $15.00 which does apply to the repair.

--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"Cameron" wrote in message
...
Hello everyone. I just bought a PG zx475ti and only half of it works!
The front channels work great in stereo and bridged, but the rear
channels are having 'issues'. When connected to a four ohm sub in
stereo, each channel has low output and is very distorted or staticy.
When bridged there is no sound, but I can hear static when I touch the
speaker wires to the terminals. Also the red LED (Seems like several
along the board) are lit up even without the speakers connected. Is this
something that is repairable, and is it worth repairing considering I
paid $150 for it? If so, should I send it to PG, or can a local
electronic repair shop fix the problem. Any help/advice is appreciated.
Thanks.

Okay, so the grounds on the four RCA jacks are good. And I assume that
if any of the finals (Transistors??) are shorted, then I won't get a
reading. On this amp, there are 8 of the large Toshiba Transistors
covered by the heat sinks and fan, then a series of ten smaller
traansistors, and then another eight transistors (I assume they are
complimentary as well because of the diferrent markings) and then there
are 8 LED's. Six of these LED's light up when the amp is powered on.
The amp doesn't go into protection mode except briefly when the amp
powers up (Part of the soft turn on?) Like I said before, the front two
channels work great, and the rear channels kind of work... the left and
right channels put out a very distorted and noticably quieter signal,
and bridged, there's really no sound at all. Am I going in the wrong
direction checking the transistors, because it seems like the other
posts (Like Ivan Lopez' Phoenix Gold) stopped working completely, Ie: No
sound output, and going into protection mode. Is it possible for a
couple of the transistors (the big Toshibas) to go bad and have the amp
operate like mine is? I really appreciate you input, thanks.

BTW, how do you determine what the transistors are? The large Toshibas
don't start out with 2sa/2sc, just a logo and C5200-0
Check the grounds at the RCA jacks. Also take a ohmmeter and check the
finals to see if any are shorted. If you don't find any problem there then
start tracing the audio through the amp with an oscilloscope. If you don't
have proper test equipment then send it to a local shop or you can send it
to us, our checkout/estimate fee is $15.00 which does apply to the repair.

Is one side of the bank of Toshiba transistors, labeled with the C5200-0 and
the other side possibly A1943?
If so it looks like Toshiba may have just dropped the '2S' from the numbers.
When I was looking for transistors to fix my amp the 2SC5200's and 2SA1943's
were newer suitable replacements for the 2SA1302's and 2SC3281's I had in
mine (230V vs. 200V and some other parameters were slightly different).

If this is the case, which I find interesting if it is, I wonder what other
items were changed slightly in the design of the ZX450 to the ZX475ti?

"Cameron" wrote in message
...
Okay, so the grounds on the four RCA jacks are good. And I assume that
if any of the finals (Transistors??) are shorted, then I won't get a
reading. On this amp, there are 8 of the large Toshiba Transistors
covered by the heat sinks and fan, then a series of ten smaller
traansistors, and then another eight transistors (I assume they are
complimentary as well because of the diferrent markings) and then there
are 8 LED's. Six of these LED's light up when the amp is powered on.
The amp doesn't go into protection mode except briefly when the amp
powers up (Part of the soft turn on?) Like I said before, the front two
channels work great, and the rear channels kind of work... the left and
right channels put out a very distorted and noticably quieter signal,
and bridged, there's really no sound at all. Am I going in the wrong
direction checking the transistors, because it seems like the other
posts (Like Ivan Lopez' Phoenix Gold) stopped working completely, Ie: No
sound output, and going into protection mode. Is it possible for a
couple of the transistors (the big Toshibas) to go bad and have the amp
operate like mine is? I really appreciate you input, thanks.

BTW, how do you determine what the transistors are? The large Toshibas
don't start out with 2sa/2sc, just a logo and C5200-0
Check the grounds at the RCA jacks. Also take a ohmmeter and check the
finals to see if any are shorted. If you don't find any problem there then
start tracing the audio through the amp with an oscilloscope. If you don't
have proper test equipment then send it to a local shop or you can send it
to us, our checkout/estimate fee is $15.00 which does apply to the repair.



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.593 / Virus Database: 376 - Release Date: 2/20/2004

Does your zx450 have the red LED's along the board? If so, do they all
light up?
I'll let you know about the other set of transistors tomorrow. How much
did you pay for your transistors by the way? The ONLY shop in town told
me $15 for each one. A bit high compared to every online store. They
also told me $45 to bench test my amp to find out what's wrong with it.
I want to try and fix it myself, as I got in big trouble for buying it
in the first place especially since the thing is half broken.


Ivan Lopez wrote:
Is one side of the bank of Toshiba transistors, labeled with the C5200-0 and
the other side possibly A1943?
If so it looks like Toshiba may have just dropped the '2S' from the numbers.
When I was looking for transistors to fix my amp the 2SC5200's and 2SA1943's
were newer suitable replacements for the 2SA1302's and 2SC3281's I had in
mine (230V vs. 200V and some other parameters were slightly different).

If this is the case, which I find interesting if it is, I wonder what other
items were changed slightly in the design of the ZX450 to the ZX475ti?

Sometimes when the finals fail the amp will still operate, some failure
modes do not cause overcurrent or DC protect to activate. If you have a
meter with Diode check function, your transistors should read like an open
circuit when reverse biased, and from 0.350 to 0.700v when forward biased.
For a Datasheet on your 2SC5200 transistors here's a link:

http://www.semicon.toshiba.co.jp/ope...&extension=PDF

Japanese transistors always begin with 2S, so the manufacturers leave that
off the package, it's just assumed to be there, as in a B926 is a 2SB926 and
so-on. American transistors usually have the entire part number on them. As
in TIP36C.

This amp is a class AB Bipolar push-pull design, meaning that with the C5200
you will have a A1943 which is the complimentary output. 2SA and 2SB are PNP
devices, 2SC and 2SD are NPN.

It is possible for the transistors to fail and not shut down the amp but it
is unlikely. As you do not have an open ground then I'd find the op-amp your
signal first goes to after the RCA jacks and see if it's output is normal
with an oscilloscope. An open resistor can also cause the symptom you have,
but as it affects both channels, then it is more than likely a component
which carries either signal or power for only the rear channels. Does this
amp have a common power supply for all four channels, or does it have two
separate supplies, one for front & the other for rear? if so, one of the
power supplies may be bad.

--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311

"Cameron" wrote in message
...
Okay, so the grounds on the four RCA jacks are good. And I assume that
if any of the finals (Transistors??) are shorted, then I won't get a
reading. On this amp, there are 8 of the large Toshiba Transistors
covered by the heat sinks and fan, then a series of ten smaller
traansistors, and then another eight transistors (I assume they are
complimentary as well because of the diferrent markings) and then there
are 8 LED's. Six of these LED's light up when the amp is powered on.
The amp doesn't go into protection mode except briefly when the amp
powers up (Part of the soft turn on?) Like I said before, the front two
channels work great, and the rear channels kind of work... the left and
right channels put out a very distorted and noticably quieter signal,
and bridged, there's really no sound at all. Am I going in the wrong
direction checking the transistors, because it seems like the other
posts (Like Ivan Lopez' Phoenix Gold) stopped working completely, Ie: No
sound output, and going into protection mode. Is it possible for a
couple of the transistors (the big Toshibas) to go bad and have the amp
operate like mine is? I really appreciate you input, thanks.

BTW, how do you determine what the transistors are? The large Toshibas
don't start out with 2sa/2sc, just a logo and C5200-0
Check the grounds at the RCA jacks. Also take a ohmmeter and check the
finals to see if any are shorted. If you don't find any problem there
then
start tracing the audio through the amp with an oscilloscope. If you
don't
have proper test equipment then send it to a local shop or you can send
it
to us, our checkout/estimate fee is $15.00 which does apply to the
repair.

That must be a newer feature of the ZX475ti for diagnostic purposes. I only
have 3 LED's along the top of my amp, there are none inside the amp.
My transistors were $6.94 for one and $7.07 for the other. How they arrived
at these prices I don't know. Mine were replacement part number transistors
for the Toshiba originals. They were NTE parts. So far they've been
working out fine. I wanted to get Toshiba parts but my local place didn't
have them so I just decided on the NTE's only 'cause they were so
inexpensive, figuring if they crap out I wouldn't be out a fortune.

Anyway, did the transistors test bad? One of mine read differently than all
the others when it was in circuit and then I just unsoldered that one and
tested it out of circuit to be double sure it was bad.

Ampdoc is definitely the person to ask though.

PG also has a forum section on their website. Occasionally some of their
repair techs will answer questions, but they wont give out any schematics
though (I tried already).


"cjaldrich at comcast.net" "cjaldrich at comcast.net" wrote in message
...
Does your zx450 have the red LED's along the board? If so, do they all
light up?
I'll let you know about the other set of transistors tomorrow. How much
did you pay for your transistors by the way? The ONLY shop in town told
me $15 for each one. A bit high compared to every online store. They
also told me $45 to bench test my amp to find out what's wrong with it.
I want to try and fix it myself, as I got in big trouble for buying it
in the first place especially since the thing is half broken.


Ivan Lopez wrote:
Is one side of the bank of Toshiba transistors, labeled with the C5200-0
and
the other side possibly A1943?
If so it looks like Toshiba may have just dropped the '2S' from the
numbers.
When I was looking for transistors to fix my amp the 2SC5200's and
2SA1943's
were newer suitable replacements for the 2SA1302's and 2SC3281's I had in
mine (230V vs. 200V and some other parameters were slightly different).

If this is the case, which I find interesting if it is, I wonder what
other
items were changed slightly in the design of the ZX450 to the ZX475ti?


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.593 / Virus Database: 376 - Release Date: 2/20/2004

Okay, so I tested the Finals, and on the BC test Everything was okay,
but on the BE test FOrward was something like .57 and reverse was .65
+/- on the 2SC5200's except on the third one over from the right. That
one was okay forward but had no reading or was open on the reverse BE
test. The A1943's were okay except for either the second or fourth
(forgive me for not paying too much attention, but it's getting late and
my daughter started howling) had similar results as the third C5200,
but I think it wasn't the same setup (Forward/reverse). Would that
indicate a problem with those two transistors?

You also were wondering about the power supply, and whether it had one
or two. I took some crappy photos (with my phone) to show you the power
supply, and maybe you could tell me.


http://home.comcast.net/~cjaldrich/PSupply1.jpg

http://home.comcast.net/~cjaldrich/F...Resistors1.jpg

http://home.comcast.net/~cjaldrich/PSupply2.jpg


Sorry about all of these questions, I am obviously a newbie to testing
and diagnosing problems. I don't have an oscilliscope, so anything
beyond what I can do with my meter is going to have to be done by you.
If you think it's something that will need to be further evaluated with
the oscilliscope, could you please give me shipping and payment
instructions? If you read my other post, my local shop wants $40 just to
look at it, and I think you said $15. Big diferrence! Thanks a lot.

BTW, I had the RCA ground problem on a RF Punch 200a, and you know that
the RCA inputs/outputs are all together on that amp, right? Well this
one Also has two sets of inputs and one set of outputs, but the front
and rear inputs are seperate, about two inches apart on the board, so I
don't think that's the problem because I have tried both sets of inputs
with the same results. The distortion is also far worse on my PG than
the RF was before I re-soldered the grounds back to the board.

CHeck out my other post to ampdoc. I linked a few pictures, so you can
see the inside of my amp and the LED's, and yes I actually had 2 of the
transformers test diferrent that the others, which I guess might explain
why 2 of the 8 LED's don't light up. As far as the three LED's on top,
Mine don't work. I guess that was the least of my troubles . Anyway, I
suppose I could have gone back to the pawn shop and tried to exchange
it, but they don't have anything even close to this amp, and especially
not for $150. I had the front channels bridged to one of my 12's and I
couldn't believe it. I guess that's why I'm so interested in getting the
whole thing to work right. Maybe the reason that they told me $15 each
is because they're actual Toshibas. I guess I should have asked before
telling her I could get BOTH for less than that.



Ivan Lopez wrote:
That must be a newer feature of the ZX475ti for diagnostic purposes. I only
have 3 LED's along the top of my amp, there are none inside the amp.
My transistors were $6.94 for one and $7.07 for the other. How they arrived
at these prices I don't know. Mine were replacement part number transistors
for the Toshiba originals. They were NTE parts. So far they've been
working out fine. I wanted to get Toshiba parts but my local place didn't
have them so I just decided on the NTE's only 'cause they were so
inexpensive, figuring if they crap out I wouldn't be out a fortune.

Anyway, did the transistors test bad? One of mine read differently than all
the others when it was in circuit and then I just unsoldered that one and
tested it out of circuit to be double sure it was bad.

Ampdoc is definitely the person to ask though.

PG also has a forum section on their website. Occasionally some of their
repair techs will answer questions, but they wont give out any schematics
though (I tried already).

CHeck out my other post to ampdoc. I linked a few pictures, so you can
see the inside of my amp and the LED's, and yes I actually had 2 of the
transformers test diferrent that the others, which I guess might explain
why 2 of the 8 LED's don't light up. As far as the three LED's on top,
Mine don't work. I guess that was the least of my troubles . Anyway, I
suppose I could have gone back to the pawn shop and tried to exchange
it, but they don't have anything even close to this amp, and especially
not for $150. I had the front channels bridged to one of my 12's and I
couldn't believe it. I guess that's why I'm so interested in getting the
whole thing to work right. Maybe the reason that they told me $15 each
is because they're actual Toshibas. I guess I should have asked before
telling her I could get BOTH for less than that.

All the LED's on the board should be lit. It seems you may have a problem
with the predrivers and finals in those rear channels. Unit has a single
power supply as far as I can tell from the pictures, so we can rule that
out. You could take some measurements to compare the working channel(s) to
the non-working ones, the circuit should be the same for all four channels.
If you want to send it in just ship it to the address in my .sig and enclose
contact/shipping information, we do a large volume of ship-in work (warranty
for Pioneer, Sony, and JVC). We will call with an estimate before repair,
and you can pay by check, MO, credit card. Our bench fee is $15.00, (+
return shipping, actual UPS, it's whatever they charge) and does apply to
the repair cost. You do not have to pre-pay the $15.00, you just pay that if
you refuse the estimate and want the unit shipped back.

--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"cjaldrich at comcast.net" "cjaldrich at comcast.net" wrote in message
...
Okay, so I tested the Finals, and on the BC test Everything was okay,
but on the BE test FOrward was something like .57 and reverse was .65
+/- on the 2SC5200's except on the third one over from the right. That
one was okay forward but had no reading or was open on the reverse BE
test. The A1943's were okay except for either the second or fourth
(forgive me for not paying too much attention, but it's getting late and
my daughter started howling) had similar results as the third C5200,
but I think it wasn't the same setup (Forward/reverse). Would that
indicate a problem with those two transistors?

You also were wondering about the power supply, and whether it had one
or two. I took some crappy photos (with my phone) to show you the power
supply, and maybe you could tell me.


http://home.comcast.net/~cjaldrich/PSupply1.jpg

http://home.comcast.net/~cjaldrich/F...Resistors1.jpg

http://home.comcast.net/~cjaldrich/PSupply2.jpg


Sorry about all of these questions, I am obviously a newbie to testing
and diagnosing problems. I don't have an oscilliscope, so anything
beyond what I can do with my meter is going to have to be done by you.
If you think it's something that will need to be further evaluated with
the oscilliscope, could you please give me shipping and payment
instructions? If you read my other post, my local shop wants $40 just to
look at it, and I think you said $15. Big diferrence! Thanks a lot.

BTW, I had the RCA ground problem on a RF Punch 200a, and you know that
the RCA inputs/outputs are all together on that amp, right? Well this
one Also has two sets of inputs and one set of outputs, but the front
and rear inputs are seperate, about two inches apart on the board, so I
don't think that's the problem because I have tried both sets of inputs
with the same results. The distortion is also far worse on my PG than
the RF was before I re-soldered the grounds back to the board.

Just for future reference. MCM Electronics is an excellent place to buy
Japanese transistors. They still over charge but not nearly as much as you
mentioned.


--
Ge0
*******************************************
TeamAMP #4 - tech whiz type of guy
*******************************************
Low cost car stereo equipment repair/ modification
Contact me for advice or a quote.
Always interested in buying dead equipment too.
********************************************
Looking for answers on car stereo topics?
www.mobileaudio.com
www.teamrocs.com
http://go.to/bcae/
*******************************************
Geo uses:
Main Stage = a/d/s/ 336is.2
Rear fill = a/d/s/ 335is.2
Subs = Audiomobile Mass 2012 S24
Head unit = Alpine DVA-7996
Processor = Alpine PXA-H700
Sub Amp = a/d/s/ P4100.2
Main & rear fill amp = a/d/s/ P840.2
********************************************
www.microheat.com
********************************************
"cjaldrich at comcast.net" "cjaldrich at comcast.net" wrote in message
...
Does your zx450 have the red LED's along the board? If so, do they all
light up?
I'll let you know about the other set of transistors tomorrow. How much
did you pay for your transistors by the way? The ONLY shop in town told
me $15 for each one. A bit high compared to every online store. They
also told me $45 to bench test my amp to find out what's wrong with it.
I want to try and fix it myself, as I got in big trouble for buying it
in the first place especially since the thing is half broken.


Ivan Lopez wrote:
Is one side of the bank of Toshiba transistors, labeled with the C5200-0
and
the other side possibly A1943?
If so it looks like Toshiba may have just dropped the '2S' from the
numbers.
When I was looking for transistors to fix my amp the 2SC5200's and
2SA1943's
were newer suitable replacements for the 2SA1302's and 2SC3281's I had
in
mine (230V vs. 200V and some other parameters were slightly different).

If this is the case, which I find interesting if it is, I wonder what
other
items were changed slightly in the design of the ZX450 to the ZX475ti?

Do you have a DC Multimeter? If so, measure the DC voltage between speaker
+ and - for all 4 channels. What do you see? You should see zero, or
close to it.

If you don't have a multimeter then go to radio shack and spend the $10 to
get a cheap one. What do you see?


--
Ge0
*******************************************
TeamAMP #4 - tech whiz type of guy
*******************************************
Low cost car stereo equipment repair/ modification
Contact me for advice or a quote.
Always interested in buying dead equipment too.
********************************************
Looking for answers on car stereo topics?
www.mobileaudio.com
www.teamrocs.com
http://go.to/bcae/
*******************************************
Geo uses:
Main Stage = a/d/s/ 336is.2
Rear fill = a/d/s/ 335is.2
Subs = Audiomobile Mass 2012 S24
Head unit = Alpine DVA-7996
Processor = Alpine PXA-H700
Sub Amp = a/d/s/ P4100.2
Main & rear fill amp = a/d/s/ P840.2
********************************************
www.microheat.com
********************************************
"Cameron" wrote in message
...
Hello everyone. I just bought a PG zx475ti and only half of it works!
The front channels work great in stereo and bridged, but the rear
channels are having 'issues'. When connected to a four ohm sub in
stereo, each channel has low output and is very distorted or staticy.
When bridged there is no sound, but I can hear static when I touch the
speaker wires to the terminals. Also the red LED (Seems like several
along the board) are lit up even without the speakers connected. Is this
something that is repairable, and is it worth repairing considering I
paid $150 for it? If so, should I send it to PG, or can a local
electronic repair shop fix the problem. Any help/advice is appreciated.
Thanks.

It is a common (not to say it happens alot) problem with the ti amps it
usualy is caused by the amp not having enough ventilation and the heat
getting to high.
Call a local dealer and find out what it costs to get it fixed


--
Gmac
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