ppi pc2150 distorted right channel

67elcamino · 31st March 2009, 12:35 AM

just replaced power supply fets and output transistors in a pc2150. hooked it up and left channel has full power but the right channel is week and kind of distorted sounding. what could be the problem?
thanks

1moreamp · 31st March 2009, 05:59 AM

Did you check the big resistors tied to the outputs, they like to open up.

after those I would look at the SIP driver card, among other possibilities these come to mind as most prevalent failure wise.
Look for melted or missing components on the ceramic cards...and possibly you might have to carefully reflow all the solders on the SIP card < this works very often to restore the proper operation> Careful though, it does not like solder flux and excessive heat on those SMD solder connections, you can destroy the card if you not careful

And these cards must be hand made to replace, PPI does not support these anymore, and unless you strip another amp you must build replacements ...At least that's what Perry and I do when we need these....

67elcamino · 31st March 2009, 09:40 PM

ok i will check the resistors first. if those are all ok i will look at the cards, i think the one on the right is discolored where it attaches to the main board, it is dark brown like it may have been overheated. if i do need to rebuild the board, are the parts easy to find? thanks for your help

67elcamino · 2nd April 2009, 02:49 AM

i checked the resistors and they are all ok. the small board is screwed up. the legs on the bottom were loose and not connected to it anymore and a couple surface mount transistors were also not connected.. i could not resolder anything, i cant figure out how you do it. but i did solder some jumper wires to the components and the right channel now works fine. i would like to fix it the right way could you tell me the secret on how to solder these thing back to the porcelin board? thanks

Perry Babin · 2nd April 2009, 03:10 AM

The solder pads on some of these boards are not solderable. When you apply heat (nothing else) the solder will draw up taking the pads with it. Other boards are readily solderable and have no problem with pads lifting.

Sometimes, you can scrape the mask off of the trace and make the connection with a small strand of wire.

Can you post a photo of the board?

1moreamp · 2nd April 2009, 03:36 AM

If you see brown colored surfaces where the solder needs to be, your SOL on resoldering those contacts. The surfaces are destroyed and un-solderable under any conditions I have ever seen.

Believe me I have tried in the past, and its a no go situation. Not even flux will make solder adhere to that brown surface.

If, you still have solder left at the contact site, then you must use a tad bit more heat, and some good fine electronics solder. Don't get carried away and over heat whats left as it is easy to finish off the connection this way.
The ceramic SIP card has unique thermal characteristics hence the reason I think it was used for this device. All the devices mounted on these SIP's thermal track one another and this limits DC offset issues due to temperature variations...IMO

Perry and I both build our own replacements on a as need be basis, because Directed / PPI has left all there loyal old school customers hanging on these cards.

jol50 · 3rd April 2009, 10:40 PM

I had some glue, it was in tape form. You heat it to I forget but 350F or something and it will glue metal together and when it cools I think it will not melt again. Is very thin, I think you could glue copper onto ceramic but it would be a matter of being able to physically do it. I can find a datasheet on it maybe if you think it would be of use. I can get a piece of it. May be this stuff: http://multimedia.3m.com/mws/mediawe...6EVs6E666666--

You could put it on the copper then hold it on and iron it more or less. It turns dark when cured. Just an idea. It is only 10 mills thick so it does not slop around. We would clamp it together in an oven.

67elcamino · 7th April 2009, 12:15 AM

i will post a pic of the board asap, i got the channel to work by running small jumper wires to the components. im not sure how long it will last though. thanks for all the help.

TO-3 · 28th August 2009, 01:12 AM

Quote:

Originally Posted by 1moreamp

Perry and I both build our own replacements on a as need be basis, because Directed / PPI has left all there loyal old school customers hanging on these cards.

How do you really feel? Have a beer.

DigitalJunkie · 28th August 2009, 01:23 AM

Humm,This reminds me of those ceramic terminal strips used in old Tektronix equipment - they required silver solder,regular solder would 'contaminate' the plating,and dissolve it.
Perhaps those cards are similar?

31st March 2009, 12:35 AM	#1
67elcamino diyAudio Member Join Date: Mar 2009	ppi pc2150 distorted right channel just replaced power supply fets and output transistors in a pc2150. hooked it up and left channel has full power but the right channel is week and kind of distorted sounding. what could be the problem? thanks

2nd April 2009, 03:10 AM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The solder pads on some of these boards are not solderable. When you apply heat (nothing else) the solder will draw up taking the pads with it. Other boards are readily solderable and have no problem with pads lifting. Sometimes, you can scrape the mask off of the trace and make the connection with a small strand of wire. Can you post a photo of the board? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

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31st March 2009, 05:59 AM	#2
1moreamp diyAudio Member Join Date: Dec 2005 Location: Northern California	Did you check the big resistors tied to the outputs, they like to open up. after those I would look at the SIP driver card, among other possibilities these come to mind as most prevalent failure wise. Look for melted or missing components on the ceramic cards...and possibly you might have to carefully reflow all the solders on the SIP card < this works very often to restore the proper operation> Careful though, it does not like solder flux and excessive heat on those SMD solder connections, you can destroy the card if you not careful And these cards must be hand made to replace, PPI does not support these anymore, and unless you strip another amp you must build replacements ...At least that's what Perry and I do when we need these....

31st March 2009, 09:40 PM	#3
67elcamino diyAudio Member Join Date: Mar 2009	ok i will check the resistors first. if those are all ok i will look at the cards, i think the one on the right is discolored where it attaches to the main board, it is dark brown like it may have been overheated. if i do need to rebuild the board, are the parts easy to find? thanks for your help

2nd April 2009, 02:49 AM	#4
67elcamino diyAudio Member Join Date: Mar 2009	i checked the resistors and they are all ok. the small board is screwed up. the legs on the bottom were loose and not connected to it anymore and a couple surface mount transistors were also not connected.. i could not resolder anything, i cant figure out how you do it. but i did solder some jumper wires to the components and the right channel now works fine. i would like to fix it the right way could you tell me the secret on how to solder these thing back to the porcelin board? thanks

2nd April 2009, 03:36 AM	#6
1moreamp diyAudio Member Join Date: Dec 2005 Location: Northern California	If you see brown colored surfaces where the solder needs to be, your SOL on resoldering those contacts. The surfaces are destroyed and un-solderable under any conditions I have ever seen. Believe me I have tried in the past, and its a no go situation. Not even flux will make solder adhere to that brown surface. If, you still have solder left at the contact site, then you must use a tad bit more heat, and some good fine electronics solder. Don't get carried away and over heat whats left as it is easy to finish off the connection this way. The ceramic SIP card has unique thermal characteristics hence the reason I think it was used for this device. All the devices mounted on these SIP's thermal track one another and this limits DC offset issues due to temperature variations...IMO Perry and I both build our own replacements on a as need be basis, because Directed / PPI has left all there loyal old school customers hanging on these cards.

3rd April 2009, 10:40 PM	#7
jol50 diyAudio Member Join Date: Nov 2007	I had some glue, it was in tape form. You heat it to I forget but 350F or something and it will glue metal together and when it cools I think it will not melt again. Is very thin, I think you could glue copper onto ceramic but it would be a matter of being able to physically do it. I can find a datasheet on it maybe if you think it would be of use. I can get a piece of it. May be this stuff: http://multimedia.3m.com/mws/mediawe...6EVs6E666666-- You could put it on the copper then hold it on and iron it more or less. It turns dark when cured. Just an idea. It is only 10 mills thick so it does not slop around. We would clamp it together in an oven.

7th April 2009, 12:15 AM	#8
67elcamino diyAudio Member Join Date: Mar 2009	i will post a pic of the board asap, i got the channel to work by running small jumper wires to the components. im not sure how long it will last though. thanks for all the help.

28th August 2009, 01:23 AM	#10
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	Humm,This reminds me of those ceramic terminal strips used in old Tektronix equipment - they required silver solder,regular solder would 'contaminate' the plating,and dissolve it. Perhaps those cards are similar?