After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
As always, many thanks.
:
:After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
:
:Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
:
:As always, many thanks.
:
I'm not familiar with the term 'target transistor'. You may have a bad drive transistor, or a shorted zener diode. Most of those power supplies didn't have a lot of parts.
Johnnysan-
'Target transistor' is a term of my own coining (for lack of the correct naming). I believe the large transistor embedded in the heat sink is the regulating transistor. It's not a 2N3055 (the case is corroded, and lettering is now gone). I'm looking for a best guess as to which transistor model it might be; the old transistor looks exactly like a 3055 (as far as the casing is concerned) but it obviously isn't.
If anyone can direct me to a NUMARK CB-170A power supply parts list or schematic that would allow me to identify the transistor I need.
Thanks for your help.
::I bought a Numark CV-170A power supply (120VAC to 12VDC), which was defective. The set ran steady as a rock and cool, but at an output of 22VDC :o(
::
::After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
::
::Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
::
::As always, many thanks.
::
:
:
:I'm not familiar with the term 'target transistor'. You may have a bad drive transistor, or a shorted zener diode. Most of those power supplies didn't have a lot of parts.
:Johnnysan-
:
:
:
A 2N3055 is a silicon NPN, and if it's the TO3 pkg (diamond shape), there are dozens of "look alikes", so part number is the deciding factor. Depending on its age, it may have been a germanium transistor, and as such, probably a PNP. There were very few, if any NPN germanium transistors made, and not aware of any available for GP use or distribution. The case of this device (NPN/PNP)is typically the collector. In a typical low end power supply/converter, if the 12V output is taken from the collector (case) it's a PNP. If the 12V is taken from the emitter, its NPN. In both cases there should be an insulator between the case and heatsink. Hope this helps
marv
:Hello,
:
:'Target transistor' is a term of my own coining (for lack of the correct naming). I believe the large transistor embedded in the heat sink is the regulating transistor. It's not a 2N3055 (the case is corroded, and lettering is now gone). I'm looking for a best guess as to which transistor model it might be; the old transistor looks exactly like a 3055 (as far as the casing is concerned) but it obviously isn't.
:
:If anyone can direct me to a NUMARK CB-170A power supply parts list or schematic that would allow me to identify the transistor I need.
:
:Thanks for your help.
:
:::I bought a Numark CV-170A power supply (120VAC to 12VDC), which was defective. The set ran steady as a rock and cool, but at an output of 22VDC :o(
:::
:::After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
:::
:::Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
:::
:::As always, many thanks.
:::
::
::
::I'm not familiar with the term 'target transistor'. You may have a bad drive transistor, or a shorted zener diode. Most of those power supplies didn't have a lot of parts.
::Johnnysan-
::
::
::
:
:
:marv
At this point, it would be risky to guess which rail the "transistor" is regulating. It could be from the negative or the positive rail, although regulating from the positive rail is more common.
Also, it may well NOT be a transistor but a power regulator such as an LM317K.
A little studying of the circuit will tell. If you find a zener diode and a few other transistors, then it probably is a power transistor. A little more studying will tell which type, PNP or NPN is needed. Assuming it is not a MOSFet (rare cases).
Now, if the only part found in the circuit is that "transitor", excluding of course the usual cap and diodes, or bridge, then my guess would lean toward a power regulator.
Well, that might certainly be a solution, though the aggravating tech aspects of fixing the NUMARK had their own appeal.
What would the UPS shipping be to Tampa FL33604. I guess I can remit the sum via paypal (my email is skyiner@storm.ca)?
In return, I'd be pleased to let you have my two brand new 2N23055 transistors, if that was helpful.
Cheers,
Leslie
How about you just get rid of that Numark. I have a Samlex RPS1207 It's a regulated DC power supply 13.8 VDC at 7-10 AMP. It's as new. You can have it FREE. Just pay for the UPS shipping. It kind of heavy though, about a good 10 LBS.
:
Again, thanks for your help. Just contact me directly by email.
Cheers.
:How about you just get rid of that Numark. I have a Samlex RPS1207 It's a regulated DC power supply 13.8 VDC at 7-10 AMP. It's as new. You can have it FREE. Just pay for the UPS shipping. It kind of heavy though, about a good 10 LBS.
:
Whoever is footing the bill for the shipping of that unit, absolutely do not overlook the USPS one price shipping in their 3 sizes of boxes or envelope, (The latter I never use.)
Pricing at either :$4.95 for the smaller box or $10.35 for the larger box .
Now, that's 70 lbs of weight to any Conus adress if it fits in that box. Leslie, could probably still talk you thru the repair of that original unit, if you want to proceed.
 |
:
:After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
:
:Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
:
:As always, many thanks.
:
::
::After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
::
::Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
::
::As always, many thanks.
::
:
:::
:::After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
:::
:::Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
:::
:::As always, many thanks.
:::
::
:
::::
::::After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
::::
::::Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
::::
::::As always, many thanks.
::::
:::
::
:
on Ebay. My email: bobbyv2@comcast.net
Thanks
::::
::::After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
::::
::::Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
::::
::::As always, many thanks.
::::
:::
::
:
I am getting 10.9 volts from mine. When I replaced the LED with a brighter one the voltage dropped to 4.9V I also replaced the Pot. which is a 200 ohm. as mine was broken. When I ran it with the pot out of the circuit the output voltage went to 18.8V.
:::::I bought a Numark CV-170A power supply (120VAC to 12VDC), which was defective. The set ran steady as a rock and cool, but at an output of 22VDC :o(
:::::
:::::After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
:::::
:::::Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
:::::
:::::As always, many thanks.
:::::
::::
:::
::
:
:Are you in need of a good power supply too ? I still have five Samlex RPS1207 13.8 VDC at 7-10 Amps. These are all as new. If you want one FREE, just pay for shipping.
:
T.
:
:After some discussion here, it was thought that the regulating transistor (a large, 'hat' shaped part attached to a finned heat sink at the back of the unit) was the likely culprit. Unfortunately, the original transistor was so corroded that I could not discern any part numbers. A guesstimate was that it was likely a 2N3055; I bought two NOS units and they do not work either (even though they looked identical to the old transistor). In fact, when the new 2N3055 replaced the old, corroded transistor the power on LED did not illuminate. It did when I put the old transistor back.
:
:Any suggestions as to another possible transistor replacement? Does anyone have a source for a NEWMARK CB-170A; if I can get a parts list I could perhaps find out what model the target transistor is.
:
:As always, many thanks.
:
Leslie, I have a newmark CB170A the address to sent to is Numark Electronics 503 raritan center Edison NJ 08817
My power suppy puts out according to my meter 12.68 volts. I bought it used but it looks like new. The box is not in the greatest shape and some papers are with it but no parts list. It sold for $24.95 at coast to coast. I am going to list a Johnson Messenger 250 on eBay probably in the next couple days and I was thinking about adding this power supply to it as the radio only works on 12 volts if you want to email me
s t o n e y m e l o d y @ h o t m a i l . c o m