I just came across a Hafler DH-220 amplifier in a box that had never been opened. Yep, it's a brand new 30 year old amp. Anyway I know the DH-220 came both either assembled in the factory or as a kit to be assembled by the user.
This amp has all the electrical components soldered to the circuit board, however, all of the input, output, transformer and power wires and connectors are in plastic bags inside the amp. The box that it came in has "assembled" printed on the outside.
Does anyone know if this is a Hafler DH-220 Kit, or is this the way Hafler shipped all their amplifiers?
Thx,
Hal
This amp has all the electrical components soldered to the circuit board, however, all of the input, output, transformer and power wires and connectors are in plastic bags inside the amp. The box that it came in has "assembled" printed on the outside.
Does anyone know if this is a Hafler DH-220 Kit, or is this the way Hafler shipped all their amplifiers?
Thx,
Hal
I just came across a Hafler DH-220 amplifier in a box that had never been opened. Yep, it's a brand new 30 year old amp. Anyway I know the DH-220 came both either assembled in the factory or as a kit to be assembled by the user.
This amp has all the electrical components soldered to the circuit board, however, all of the input, output, transformer and power wires and connectors are in plastic bags inside the amp. The box that it came in has "assembled" printed on the outside.
Does anyone know if this is a Hafler DH-220 Kit, or is this the way Hafler shipped all their amplifiers?
Thx,
Hal
Yes, this was Hafler's approach for Dynakit as well as Hafler, except for the Dyna FM-1 and FM-3 tuners.
As you know those electrolytic caps are almost certainly bad by now.
If they're carefully reformed, they may very well work out ok.
"If they're carefully reformed, they may very well work out ok. "
Doubtful.
Try it with the 10,000 at 75V (after cooking them at 85°C for one hour), but just buy new ones for all the smaller caps (they're inexpensive).
Add 22µF at 100V to the main filter caps if they go 'squeeg' when the amp turns off.
Doubtful.
Try it with the 10,000 at 75V (after cooking them at 85°C for one hour), but just buy new ones for all the smaller caps (they're inexpensive).
Add 22µF at 100V to the main filter caps if they go 'squeeg' when the amp turns off.
Last edited:
Is this worthless?
Even though I know more about electronics than the average consumer, I am not an electronic tech so I don't know how to test the electrolytic caps. ( I only know how to charge one and watch it discharge.)
Replacement caps at Mauser cost about $50 each so it seems to me that this amp at best could be sold for parts or at worse used as a boat anchor.
What is your opinion?
Even though I know more about electronics than the average consumer, I am not an electronic tech so I don't know how to test the electrolytic caps. ( I only know how to charge one and watch it discharge.)
Replacement caps at Mauser cost about $50 each so it seems to me that this amp at best could be sold for parts or at worse used as a boat anchor.
What is your opinion?
Replacement caps at Mauser cost about $50 each so it seems to me that this amp at best could be sold for parts or at worse used as a boat anchor.
Give the old ones a try by reforming. Use a power supply set at the capacitor's rated voltage,
through a power resistor of a value that limits the current to 10 mA into a short, and of enough
power to absorb that short. Be careful around the caps until they seem ok.
If it's a 75V capacitor, use a 10k, 1W resistor. Charge the cap until the current is under 1 mA
(until the voltage drop across the resistor is less than 10V). Reforming may take an hour or two.
Once they seem ok, leave them burning in for several more hours.
Last edited:
The cost of a variable power supply would be greater than the value of the amp. The caps are 10,000 uF, 75V
Is there a way to reform this cap using line voltage?
Well, that could be done with a fused diode block, but it's very dangerous without a transformer.
Can you borrow a power supply somewhere?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Solid State
- Hafler DH-220 AMP. Is it a kit?