Palomar 225 amp with a smoking resistor

[AronDouglas]

Lol. Point taken and noted. I know they aren't pills, but at this stage I would call them that because I've been into radio/scanner for all of 3 months. Its sort of a jab to the ones who know what I'm talking about and a boasting that I dont know squat yet But every day you learn something new.

I'm assuming I cant just hook my test battery strait up to these the relays (with 800 run amps), unless I want to see sparks fly. What do you guys use for power supplies? I have plenty of computer power supplies lying around, maybe I'll pull out one of those.

 

[RC286]

The battery will be fine, you may want to put a fuse on the wire your using though.
Just in case you accidentally short the leads.

A device will only draw the power it needs. The relay is 12v and so is the battery so your good to go.

I used to use the little wall transformer things for power supplies, and old computer power supplies
before I got my test equipment.

 

[AronDouglas]

Here is the data sheet for the DS2Y-S-DC12V http://www.alldatasheet.com/datasheet-pdf/pdf/82419/NAIS/DS2Y-S-DC12V.html


I Ohm tested the coil (suppose to be 720) on the relays and I got 680 and 620. I'll hook the amp back up and power test it later today.

I'm thinking about changing out both relays anyways because they are mechanical parts and I'm not 100% confident in it. Their cheap and easy to replace, so why not. And i did not get a perfect reading form the two transistors (small ones), so I'll replace those as well.

 

[AronDouglas]

Ok, hooked up power and tested the relays. The rear most relay (closest to the antennas) is the PWR Amp relay, and it always reads 12v on the solder joints you pointed out( the picture RC286 edited) and never on the other. Whether the amp switch is 'on' or 'off' and whether the high/low is 'high', 'off' or 'low', it always reads 12 volts.

The pre-amp relay is (obviously) the one behind it. It does not read any power whether 'on' or 'off'. (obviously, the radio initializes it).

 

[prcguy]

Based on the shorted reverse protection diode and possibility of other bad parts it really sounds like the power leads were hooked up backwards and it could be cheaper to get another amp at some point. I bought one similar but more elaborate on Ebay recently for $35 and it works fine so there are alternatives to spending unreasonable time and money fixing an unknown amp.
prcguy

Ok, hooked up power and tested the relays. The rear most relay (closest to the antennas) is the PWR Amp relay, and it always reads 12v on the solder joints you pointed out( the picture RC286 edited) and never on the other. Whether the amp switch is 'on' or 'off' and whether the high/low is 'high', 'off' or 'low', it always reads 12 volts.

The pre-amp relay is (obviously) the one behind it. It does not read any power whether 'on' or 'off'. (obviously, the radio initializes it).

 

[RC286]

which terminals? The ones I showed in red?
Or the two off by themselves (the coil)

 

[AronDouglas]

My friend was actually going to get a 500 watt amp, but when I told him I had this amp he opted to fix it up and use it. If this one is broke and requires more money than its worth, I wont bother with it and he'll just get a bigger amp. What I'm saying is, I dont need an amp (I dont have my CB yet). The only reason I'm putting an effort behind this one is because I got it for free.

The reverse polarity was my fault. I failed to read my own wiring diagram when putting in larger power wires. So at this point I want to see this thing fixed because there is a high chance I broke it

 

[AronDouglas]

Ok, I pulled the two RF PA transistors and the ohm test showed 665 on both. So the 'pills' are fine. I replaced the two smaller transistors today (just for giggles). I've got the two relays on order. So we'll see in a few days if all this work pays off

 

[RC286]

That's good news that the finals are in tact. They are the most expensive part in the whole amp.
Every other part can be replaced for under $20 if you know how to look for deals and/or salvage parts.

When you get the new relays installed, let us know how it goes.

Good luck

73's

 

[AronDouglas]

New relays came in today. They where made in Japan where as the old ones where made in China.....pointless information

And to no surprise, the amp still does not work. Looks like I'll be packaging it up and sending it off to be looked over...unless anyone has any better ideas.

To me, personally, it looks like a short. With 99% of the parts checking out ok, it acts like a grounding issue or something.

 

[RC286]

Last thing I can think of its to check all of the diodes to make sure they are not shorted.

All the transistors check out so my last thought is the diodes.

 

[AronDouglas]

All diodes are 'A' ok. I replaced one because I burnt it out, and I replaced another just for giggles. Other than the coils (the two with the ferret breads in them) and every resistor (i've checked about half of them already), I dont know what else to do.