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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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4th Jan 2021, 9:38 pm | #1 |
Triode
Join Date: Nov 2016
Location: Pluckley, near Ashford, Kent, UK.
Posts: 23
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Help with a transistor ID please
Good evening folks and a happy new year to you all. My husband has 2 power tab transistors, 1 red case and 1 green case- both mounted on heat sinks. The red case is an NPN 188 48929-2 7831, the green case is a PNP 188 48932-2 7904, they are in a Rock Ola jukebox on the "driver boards". Can't find any reference to the numbers anywhere. Can any one help at all with a replacement that we could use? thank you, x
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4th Jan 2021, 10:30 pm | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,798
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Re: Help with a transistor id please
THey look to be 'house numbers' literally stock numbers used by an equipment manufacturer.
7831 and 7904 are likely to be date codes Year 79 (1979) and week 04 for example. The most likely manufacturers are RCA and Motorola. A good photo might let that guess be refined a bit more. There are style details in the moulding and even the typeface that can be give aways. Failing that, given the circuit diagram, some reverse engineering can be done and suitable devices suggested. In transistor amplifiers it is unfortunately common for one failed transistor to take a number of others with it. If you try replacing one at a time, the dead ones take out the new ones and you can get locked in an infinite circle. The escape from this is to test them all and replace all faulty ones without applying power until they've all been changed. It takes a bit od self-discipline to go the long way round, but it's a lot quicker than a short-cut David
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4th Jan 2021, 10:31 pm | #3 |
Octode
Join Date: Dec 2008
Location: Wincanton, Somerset, UK.
Posts: 1,756
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Re: Help with a transistor id please
Those are Rockola part numbers so unlikely you'll find the data. They should be replaceable with any transistors in the same package. Important ratings are Vcb / Vce > 80V, Ic > 1A, and check SOE curves to ensure they are rated for audio use. e.g. BD239C/BD240C
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4th Jan 2021, 10:34 pm | #4 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,526
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Re: Help with a transistor id please
They sound rather like a complementary pair of output transistors. You could probably guess at something suitable if you have a rough idea of how much voltage/current they have to handle.
Have you got any service data? A circuit showing their application would be handy!
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5th Jan 2021, 12:32 am | #5 |
Nonode
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,152
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Re: Help with a transistor id please
Are you able to provide the Rock-Ola jukebox model number, driver board number and amplifier number?
This would help us to find a schematic and maybe a working voltage. The 'power tab transistor' may be a transistor in a TO220 package. Are you able to confirm this? |
5th Jan 2021, 1:09 am | #6 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
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Re: Help with a transistor id please
Here's the driver board I think the OP is referring to, it's the power amp transistor driver board (2 boards for stereo).
Circuit ref. Q5 and Q6 (left and right). Early boards use a TO-202 package, later ones a TO-220 package. No clue as to the specs but I'm sure a jukebox forum would be lucrative. I suspect a TIP41C/TIP42C or other audio driver pair would do plus a bias check. If the output transistors are 2N3055 and have failed, modern ones may oscillate and blow up without modification, eg base stopper.
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Kevin |
5th Jan 2021, 1:30 am | #7 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,798
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Re: Help with a transistor id please
Likely the output devices will have house numbers too, unless any have been replaced, but 2N3055 are likely to have been used however they've been marked.
David
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5th Jan 2021, 2:50 am | #8 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,324
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Re: Help with a transistor id please
From the Jukeboxaddicts forum
Rockola 474 Q5 part# 48929 Q6 part# 48932 Q7 part# 48931 Q8 part# 48931 Driver transistors TIP 41C and TIP 42C. Power transistors ECG 181. |
6th Jan 2021, 1:11 pm | #9 |
Triode
Join Date: Nov 2016
Location: Pluckley, near Ashford, Kent, UK.
Posts: 23
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Re: Help with a transistor ID please
Thank you for your help so far-am sending 2 pictures that may help in this latest challenge for you, xx
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6th Jan 2021, 2:58 pm | #10 |
Nonode
Join Date: Mar 2010
Location: Dukinfield, Cheshire, UK.
Posts: 2,033
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Re: Help with a transistor ID please
I may be well off the mark here, but those 'wire' type pins look very Motorola to me.
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Andy G1HBE. |
6th Jan 2021, 2:59 pm | #11 |
Heptode
Join Date: Jan 2004
Location: Stockport, Greater Manchester, UK.
Posts: 826
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Re: Help with a transistor ID please
In appearance, they look like GE D45H11 (green, PNP) and D44H11 (red, NPN) transistors.
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10th Jan 2021, 3:33 pm | #12 |
Octode
Join Date: May 2011
Location: Lancashire, UK.
Posts: 1,349
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Re: Help with a transistor ID please
I'm going to be boring and suggest replacing those with TIP41/2 C's and also to be aware that the bias setting may be out of range and require a tweak of the series resistor to the preset. In any case, the preset should be turned to MAX resistance initially which will give minimum bias.
Use of a DBT (bulb tester) would be advisable as well as this can save destruction should any further problems be lurking. |